This is a very nice review of old vs new. This type of review is rare, b/c reviews are often driven by sales and no on is selling old stuff. Thank you for the perspective.
thank god , someone that actualy showed how it works, no you are scientific , very much scientific you tested it , other guys didnt , you are the winner , so much im writing this on 2 year old video
Many thanks for this review. I found one of the old C90's on Ebay and wanted to know how well these old scopes work. Now I know what to expect from the old C90 when I get it. You review was apples to apples!
Good video! I have a "real old" orange-tube model from 1983. I recently star-tested it and was pleased with the collimation. I have been thinking about how I could attach a helical focuser on the back, for visual and photographic use. It did not come with a dew shield, but I am impressed with the contrast gain you demonstrated. I'll look into that! Another discovery I made was that I was using the Celestron Barlow lens I bought back then in entirely the wrong manner. It is designed to fit into the telescope BEFORE the star diagonal! And if you remove the eyepiece tube from the Barlow, you can still fit the T adapter on the 'scope. The focus is even trickier with the Barlow, but I'm not giving up!
That is interesting; I would never have thought about attaching the barlow first! I can see that an alternative focuser could be a good plan if you can find a way of connecting one. Let me know how you get on.
Picked up a vintage c90 orange tube. Impressed with the optical quality- collimating is right on. Tough build and perfect grab and go scope. Got mine at a flea market, with the added benefit of re-cycling Dollars in the local economy.
+Steve George Thanks Steve, I hope you have some fun with your scope. I had mine dismantled on the kitchen table the other day just to have a poke around, and it struck me that there was no way I would normally strip down another scope like that unless I absolutely had to. But for the price I paid, why not? The collimation is my next job...!
Nice video. My opinion of the original was that it needed to be shorter and faster, Celestron decided to go longer and slower. They do make a F6.3 reducer, for the 4"SCT and larger.
Yes, tricky one. They made it closer to a traditional Mak focal ratio rather than going towards a rich field scope. Personally I like the new model. To me the old one has nice styling but the focusing arrangement needed to change! Clear skies to you. Graham
Celestron did make an f5.6/500mm version of the C90. It was physically a bit shorter, had a bigger secondary, was not meant for visual use. I got one about ten years for a 500mm camera lens. Way too much CA. I can’t recommend it. Maybe I got a bad one. The 500mm f8 Zuiko I already had is far better. By the way, I got an orange tube C90 in 1980 or ‘81 from University Optics. Up to about 100x it’s pretty good, but my C80 fluorite refractor is better (up to and a bit over 200x). But the C90 travels easier.
Hi Jenham, I'd like to ask you for your opinion regarding spotting scopes for 300 and 600 meter range use. I currently use a Celestron 52252 100mm Ultima Spotting Scope and I'm just able to see 20 caliber holes on my targets at 300 meters. How would the C90 compare to the 100mm Ultima?
Hi Wade, that would be an interesting back to back test. I haven't used an Ultima scope as my interest is astro, but talking generally i can see that the field of view of the Ultima varies from 1.8 to 1.0 degrees, whereas the C90 with a 26mm EP would give 1.1 degrees, and a 10mm EP 0.45 degrees. So you could achieve a higher power with the C90, with a correspondingly smaller field of view. For resolution of holes, a 100mm scope with no central obstruction should resolve smaller details than a C90. That's just theory though. I like the C90's quality vs price and you will have a better feel as to the quality of the Ultima's optics. So it isn't that clear to me that the C90 would be superior to your scope. Let me know if you get to try one out. Graham
I remember drooling over Questar 3.5 ads in the astronomy mags in the 80s, I knew I'd never get one so this was my desired instrument. I've now got a skymax 102 mak which does me fine. I still want to get the celestron C90 though, and the Questar
what a weird way to focus I never seen that before. I think what surprised me the most was the difference in contrast the dew shield made. I just replaced my celestron 8 dew shield with one that has flocking after I had to purchase a off brand one for my 4se and i liked that it had flocking so much. great review!
A very good explanation of old vs. new scopes. When I contacted Celestron to get some info on the old and what they would recommend to go to the next scope, they were totally unhelpful. I kept getting transferred around with no real resolution to any of my questions. This is not the way to promote their product. The old C-90 is really not a bad scope if you use it properly. Scopes should be user friendly and that was the main question I wanted to ask, a better scope than what I have and simple to use. Thanks Jenham
Celestron is not the same company these days. One was based in California; the current is Taiwanese. It'd be great if the old company passed on their documents, but sadly brand names and trademarks are often the only things transferred in such situations.
Something the old scope has going for it: compactness. If you're packing a backpack or carry-on suitcase and are looking to maximize space, the old scope beats out the new one.
Hi Graham, I've a C90 which I use with a Williams bino viewer and the supplied 1.5x Barlow for moon viewing. For a decent closer view would a quality 3x Barlow work with the this set up or am I barking up the wrong tree? Should I be looking at a larger scope such as a C5 for use with the 3x Barlow and the Williams? Cheers Martin
Hi Martin, I think the 3x will be pushing it with the C90 unless the seeing is very steady. Focusing may be tricky. A 2x would be worth a try. Failing that you need more light grasp, such as from the C5, or maybe a SW 127. Cheers, Graham
Hi Graham, Thanks very much for your advice and I understand that more light grasp particularly when using a binoviewer is a big bonus. From what I've read the SW127 seems to be OTA of choice compared with the C5 and quite a bit less expensive too. How would you value the two? Is the C5 worth the extra? Cheers Martin from soggy south Wales
Martin Higgins Hi Martin, I think the 127 is better value than the C5 especially if you are keen on lunar and planetary. The two are quite different beasts ie Mak vs SCT, f12 vs f10, and the C5 might be considered more versatile overall. Still I think it costs too much! The new 127 plus Az GTI mount costs less than a C5!
Thanks Graham, I have a mount and I'll just be viewing the moon from a loft and wide south facing skylight so the 127 OTA at about £250 seems a good deal. Many thanks for your advice. I think next week promises some decent viewing! Cheers Martin
I'm not sure about the bushnell, and the reviews i have seen are quite old and a bit mixed. The C90 is optically the same as an Orion Apex 90mm or a Skymax 90 though, as these brands are all owned by Synta.
Hi, Many thanks for this concise review. I'm looking for a compact scope to compliment my current 16x80 bino to look at the moon and also star clusters and fuzzy objects. I was considering the Celestron 100 Trailmaster but I'm tending towards the C90. As I'll be viewing through fairly modest magnification on a photo tripod I'd appreciate your opinion on which will give the better view? Cheers Martin
Hello Martin, thanks for the positive feedback. I haven't used a Trailmaster but having googled it I think it's a birding-type scope like the Ultima series? If so it may be a close contest if you don't want to use higher powers (which would favour the C90). I can only say that the C90 is great for the moon, brighter planets and also for compact star clusters such as globulars. The C90 isn't well suited to dim fuzzy objects. You can fit a moon filter to any standard astro eyepiece which can be useful for a bright moon, whereas I'm not sure if you can do this with the trailmaster. The other factor may be false colour, which is not an issue for the C90. I'm not sure if the Trailmaster is an ED model or not; this may affect the amount of colour fringing (CA) you notice. I hope this is of some help. Cheers, Graham
Hi Graham and thanks for your reply which has helped me to make up my mind: the C90. Picking up on your references to discussions on various forums and also your own use of the C90 it seems there's a great number of happy users, supporters and tinkerers - even before I've bought the thing I'm being informed about flocking the primary baffle! I'm in Cardiff across the water so I hope you had last night, Tuesday, the exceptional viewing we had. Cheers Martin
Hi Martin, I hope you like the C90. I was trying out digiscoping with mine this afternoon and was happy with the results (if not the wildlife, which had gone on strike!) It is cold and clear over rural Somerset right now, hopefully for you as well.
Nice comparison, Jenham. I’ve owned an orange tube C90 since the mid 1980s, optically a real leap from the white tube Tasco I started with, though the experience of using a flimsy photo tripod convinced me of the value of a good Astro mount. I’m in the process of rehabbing my old C90 and am searching every corner of the net for the disassembly and focusing mechanism lubrication instructions everyone tells me is easy to find! Would you happen to know where I might find said instructions, or, even better, are you planning on shooting a video n this subject?
Thanks, yes my Tasco type early experience was not good! I haven’t seen any instructions in the form of a manual, I only recall comments on the forums about use of certain grease. I’m sure you’ve already seen these.
Yes, I had. No worries, I disassembled the C90 last night, cleaned and regreased the threads last night using a white lithium grease (don’t use too much!) and reassembled the scope after using a bit of compressed air to blow off a couple stray dust strands off the mirrors. Very easy and the focusing is so smooth now. Of course, I learned something when I initially used too much grease, causing it to come out the ends like toothpaste. But it was no problem to take it apart again and clean out the excess!
A highly unscientific (read "possibly inaccurate due to handheld ruler") suggests the old one is 30mm across vs 27mm for the newer model. These are the diameters of the silver spots measured looking at the corrector plate, so the actual secondary could be slightly smaller when the baffle is factored in.
Intersting thanks, so would you make that a clear aperture area of about 82mm equivalent to a 3" and a bit refractor? I suppose it will also depend on the hole in the primary
Graham, Can you explain what kind of mounting plate/adaptor you have attached to your new C90? I'm considering purchasing one and using it with a gimbal mount for long-range photography aboard a cruise ship balcony. I'm looking into suggestions for gimbals & tripods, as well as the kinds of mounting plates that you would use with a C90?
Dave Doe Hi, the plate you can see is actually for a Telrad finder rather than to mount the scope itself. For the scope I use the supplied dovetail bar as it fits most astro mounts. There is a camera tripod thread under the bar to allow easy attachment to photo tripods, so you should find things straightforward. I don’t have a sophisticated photo tripod only a cheap/light one which suits a camera, but I would say to make sure whatever you buy matches the weight/bulk of the C90, as a flimsy tripod could topple. Sorry not to be more help, Graham
Thank you for your help. Is the dovetail plate mechanically compatible with the "Acra-Swiss" system shown here: photographylife.com/arca-swiss-quick-release-system i.e. is the dovetail plate 35 mm across?
Hi Dave, I think i have that type of ballhead and plate on my iOptron Skytracker. The width of the dovetail is 42mm, so the C90 dovetail would not slide into the clamp without further adaptation. The plate i use on the iOptron has a standard camera bolt, to screw into the DSLR base, and the C90 dovetail does have a thread to receive such a bolt. I have just tried this. So you could probably attach it, but it relies on the single bolt.
Thank you for your detailed response! I did some more research, it sounds like Celestron use the "vixen" style dovetail, shown here: www.astro-physics.com/products/accessories/mounting_plates/DvsVBars.pdf Seems like the video, photography, and astro markets are in disarray, with a variety of competing dovetail plate standards. That's unfortunate.
My old C90 is the astro model and is a superb scope. The new C90 is good for what it is: cheap & readily available. The intra & extra focal blur circles show differential abberation in your two scopes.
I am always on the lookout for one of the old astro model Celestrons but they are rarely seen for sale in the UK. As a package they just "look right"! Yes there is some aberration but i agree that the new model is worth its price tag. Clear skies to you.
@@JenhamsAstro I’ve seen a half dozen Astro models on eBay in recent years. The asking price varies from about $250 to over $500 (too much). There’s a problem putting the fork mount on a wedge - won’t fit larger (C5 & up) wedges. C90 wedges are nearly extinct. You can use a Majestic geared large format head. Any of them should work well. Don’t pay more than $100 dollars for a Majestic head - I have bought two for $50-$75 ea. I also made an adapter plate to put the C90 Astro fork mount on a C8 wedge, but the Majestic head is easier to use.
Hello Joseph, if you mean the brighter radial line I'm not sure what is causing it. Maybe the star's rays, being off axis, are diffracting around the baffle tube. Or perhaps it's an artefact of a surface in the DSLR. I'm guessing really. Do you have any theories? Graham
No theories myself, and the reason I ask is because my new C90 has the exact same thing! lol I have not seen anything like that in any of my other 8 scopes, or in any diffraction images in books or articles, etc. Thought about asking Celestron themselves but hard to say if I would get a reply. The diffraction pattern looks great otherwise, and I'm pretty have with the little scope. Just really curious what that could be.
Maybe worth a mail to Celestron but in my experience you might not get a reply. If i manage to figure it out I'll make a video of it as it seems likely that all the new C90s will exhibit this "feature"!
Thanks. I am in the UK so am not familiar with the retailers nearer you. I suggest looking an the Celestron (or Skywatcher) websites and looking for the distributor in Brazil. Some retailers in the UK will ship internationally - my "local" shop First Light Optics is one example. But of course you need to take care of shipping costs and taxes to see if the approach makes sense for you vs finding a closer supplier.
Thank you for this video. It's very useful. I'm thinking about to get either a spotting scope or this Celestron C90 for a easy grab and go / holiday setup. My experience is, that it's best to take sth with which is really compact.
One question, my first intention to buy this Celestron is for spotting scope at the shooting range ,with no more of 150 yards distance and also to watch the full moon ,let me know if this is the right one for me ,thanks
Hi, the current model of C90 will work for both of those uses. It will focus on an object as close as a few metres away. With the supplied eyepiece the moon will comfortably fit into the field, and then of course you can get extra power from other eyepieces or barlows if you want it. The website astronomy.tools/calculators/field_of_view/ allows you to see the FOV, for a given astro object. You can enter the C90's focal length (1250mm), aperture (90mm) and eyepiece (32mm).
Ramón Chavez Yes a Maksutov like a C90 is a good choice for planetary photography, used with a webcam or other astro camera. The new model is much better than the old one! Clear skies.
@@JenhamsAstro thanks! i have this option c90 and this Tasco Newtonian articulo.mercadolibre.com.mx/MLM-687887038-telescopio-reflecto-tasco-luminova-900-x-45-profesional-_JM?quantity=1&variation=38435604255 402mm x 60mm Wich one you pick?
on my ne C90 a 1.25" barrel eyepiece is sloppy in the back end of the C90 -- this is nuts! Tightening the two thumbscrews means that the eyepiece is off-center.
@@JenhamsAstro Thank you, Graham for your reply. I will get a GSO 6 inch classical Cassegrain rather than a C90 because the latter will be far superior in resolution and sharpness than the C90.
You failed to mention the disgustingly horrible mirror shift of the new Chinese C90 scope compared to a properly greased original Celestron C90, which will have essentially none. Yep, I'm late to the party but the internet is forever.
Any advice on greasing an old model? Seems like something like Plastilube, like they use in microscopes, might be a good choice for warmer conditions. Not sure what would be a good choice for winter observing.
If I was to replace my 114 reflector (it has a built in barlow) for something smaller and more portable, would a mak 90 give clearer, sharper views of the moon? Allowing for some basic photography.I realise DSO is out the question. Was thinking of a virtuoso 90 with the tracking or this. Very nice channel by the way.
Hi, thanks for the positive feedback. I haven't used that particular scope & mount, but I understand it is very portable. I would say the mak will be better than your reflector for the moon and planets. Collimation is not an issue with maks unless you drop them (!) and they naturally have long focal lengths and hence give high power view for bright objects. I won't judge your 114 but some scopes of that size are not the best quality. As often a package like this will have its weaker points and maybe the 10mm eyepiece isn't the best, but you may already have some alternatives from your current setup. Lunar imaging should definitely be worthwhile. Reading the reviews some say the C90's contrast is slightly better than the SW, but it isn't going to be a big issue and you are looking for a package which the SW provides. Both of these maks would beat the 114. Sorry for the long ramble but I think you will like a mak. They are small and tough!
Hello, you can only buy the old model via auctions, and the price varies between versions (the astro being the most expensive). Looking on ebay today I can see a few in the US between $100 and $200. I got mine in the UK for about £100, as i recall. So it's not much cheaper than the new model!
Will AstroMaster Telescope Accessory Kit ( which accept 1.25" eyepieces and filters ) fit with Celestron C90 Mak Spotting Scope ? Because they are telling about " AstroMaster " series...But this series is " C90 Maksutov-Cassegrain Optical Design "
if you want one of these do yourself a favor and look for it on ebay under spotting scopes and you can get one with the 45 deg and a eyepiece and a spotting tripod for just under 150 bucks. if you get the c90 telescope it will run you 200 to 250 dollars, and you wont get the 45 or the eyepiece or tripod for that amount. if you look at the specs they are the same, except one is gold and the other is black!. and it does come with a vixen style of dove tail
Good review! One thing I noticed is that the coatings on your older one are either very thin or nonexistent. I have one similar to yours but I think it is older. I don't believe the dew shield was offered at the time. It's coatings look very similar to your newer one. The rubber focusing ring on mine is much wider, about an inch and a half, and thinner, with a very grippy surface. It is quite easy to use. Yours looks like that focusing ring alone might be part of the focusing problem. Thanks!
Thanks for the info, I think Celestron tweaked a few parts of the design during the production run, as I've also seen a few pics of other scopes with slight differences. The dew shield is helpful though, and it looks good too!
Hi Jenham! By 'new' C90 you refer to model "52268". How about the slightly older model 52265? There's an ongoing discussion about that here: www.astronomyforum.net/catadioptric-telescope-forum/256947-c90-old-vs-new.html#post1058692430 Are you aware by any chance if the current C90 1250mm is Synta made? Thank you in advance
Hello Jason, I haven't got any experience of the 52265; it looks quite a different beast. As far as i know Synta make the 52268 yes. For me the quality is very good.
Hello from Chicago .Thank you my C-90 sits 29 years I need to get it but need T adopter for Nikon 3300 camera ,I just got adopter for canon slr film .Pleas if you know proper ring adopter let mi know .i will love to use again as I did long ago. Thank you on your ifo vidio it is awesome great work. Celestron need to send you a bonus
Thanks for the great feedback! If I google your camera model I think a standard Nikon t-ring will fit the camera body. You could then use a 1.25" prime focus adapter screwed into the t-ring, and then a 0.965 to 1.25" adaptor to connect to the old C90. It is not ideal but it works and the parts are cheap.
Hello again, I put a picture of the adaptor setup I use on my website: jenhams.co.uk/astrophotography/planetary-imaging/ There may be a better way! I hope this helps. Graham
Hi, yes i think the old C90's collimation is not that good, based on the diffraction rings not being fully concentric. I am not an expert on these patterns but it doesn't look as clean as the new C90's pattern.
+MD. Fardin Islam Niloy The magnification is calculated by dividing the focal length of the telescope by the focal length of the eyepiece which you chose. So for the new C90, with a focal length of 1250mm, if you use a low power eyepiece with a focal length of 25mm then you will have a magnification of 1250/25 = 50x, whereas if you used a higher power eyepiece of focal length 10mm then you would have a magnification of 1250/10 = 125x. The old C90 has a shorter focal length (1000mm) and hence lower magnification for a given eyepiece. In general a good rule is not to use more than about 50x for each inch of mirror/lens diameter. So with a 90mm scope like the C90 that gives a usable maximum power of about 175x. If you try to use more power than this the image will be too dim. I hope this helps.
+MD. Fardin Islam Niloy Hi, if you buy a new C90 it is supplied with a 32mm "Plossl"-type eyepiece, which will give a magnification of 1250/32 = 39x. This is a good low-power eyepiece to start with.
Could barley make it paste 4 min. I have the volume cranked and unless I put headphones on I can't hear you. Not doing it because when an ad starts it will blow my eardrums
@@JenhamsAstro audacity 1.2.6 is the definitive free audio editing software. If you whisper, make sure you Mike yourself up. People will shy away if you ever shout at them. Anything conversation below 30% , should be considered marginal.
Didn't search yet,.. with filters, ., can this work with our closest star. The Sun? Really started watching the sky let's sat I wuz,, a bit 4~5 year young child.. then saw Orion, M-42, ten M-1..the. Crab in Taurus. . JUST SO AMAZING. Really let's us realize,. we are so proud, Smart and din not a Very smart after all 😢
The old one seem to have very good optics, but need some collimation. The new one seem to suffer a little on the star test. See figure 3 and 4. www.astrosurf.com/altaz/startest_e.htm
Hello, yes I agree that the new scope's patterns look like the spherical aberration in your link. In practise the new C90 gives very pleasing and sharp views so the effect is not noticeable in normal use. I found another link which seems to explain this observation. www.telescope-optics.net/Mak_spherical.htm. The "Star Test" paragraphs suggests that different orders of aberration cancel eachother out. I don't profess to understand the explanation though, maybe you will! Graham
Hello from New Orleans! I own an old orange-tube C90 and the new one, and find your observations spot on. . I keep my orange tube model with a solar filter attached, and prefer the new C90 for digiscoping. GREAT video; thank you for sharing it with us! James
This is a very nice review of old vs new. This type of review is rare, b/c reviews are often driven by sales and no on is selling old stuff. Thank you for the perspective.
thank god , someone that actualy showed how it works, no you are scientific , very much scientific you tested it , other guys didnt , you are the winner , so much im writing this on 2 year old video
Many thanks for this review. I found one of the old C90's on Ebay and wanted to know how well these old scopes work. Now I know what to expect from the old C90 when I get it. You review was apples to apples!
Good video! I have a "real old" orange-tube model from 1983. I recently star-tested it and was pleased with the collimation. I have been thinking about how I could attach a helical focuser on the back, for visual and photographic use. It did not come with a dew shield, but I am impressed with the contrast gain you demonstrated. I'll look into that! Another discovery I made was that I was using the Celestron Barlow lens I bought back then in entirely the wrong manner. It is designed to fit into the telescope BEFORE the star diagonal! And if you remove the eyepiece tube from the Barlow, you can still fit the T adapter on the 'scope. The focus is even trickier with the Barlow, but I'm not giving up!
That is interesting; I would never have thought about attaching the barlow first! I can see that an alternative focuser could be a good plan if you can find a way of connecting one. Let me know how you get on.
Fantastic video. It's shocking you only have 25 subscribers, your content is outstanding.
I have the old version and it's little brother the 500mm. I just got the new C90 and as old as this video is, it's a big help!
I hope you like the C90. I think it’s a great little scope. It might not look as smart as the old one but it works a lot better. Clear skies.
Just watched your excellent videos on vintage telescopes last week. Subscribed today😃
Picked up a vintage c90 orange tube. Impressed with the optical quality- collimating is right on. Tough build and perfect grab and go scope. Got mine at a flea market, with the added benefit of re-cycling Dollars in the local economy.
Excellent, a great little scope.
I just bought an orange tube C90 with a heavy Slick tripod and 5 eyepieces for $100 CDN. Impressed with how sharp it is. Need a dew shield now.
good vid, just bought an old c90 from Ebay, and found your vid, i learned a lot thank you!!
clear skies!
+Steve George Thanks Steve, I hope you have some fun with your scope. I had mine dismantled on the kitchen table the other day just to have a poke around, and it struck me that there was no way I would normally strip down another scope like that unless I absolutely had to. But for the price I paid, why not? The collimation is my next job...!
Nice video. My opinion of the original was that it needed to be shorter and faster, Celestron decided to go longer and slower. They do make a F6.3 reducer, for the 4"SCT and larger.
Yes, tricky one. They made it closer to a traditional Mak focal ratio rather than going towards a rich field scope. Personally I like the new model. To me the old one has nice styling but the focusing arrangement needed to change! Clear skies to you. Graham
Celestron did make an f5.6/500mm version of the C90. It was physically a bit shorter, had a bigger secondary, was not meant for visual use. I got one about ten years for a 500mm camera lens. Way too much CA. I can’t recommend it. Maybe I got a bad one. The 500mm f8 Zuiko I already had is far better. By the way, I got an orange tube C90 in 1980 or ‘81 from University Optics. Up to about 100x it’s pretty good, but my C80 fluorite refractor is better (up to and a bit over 200x). But the C90 travels easier.
Hi Jenham, I'd like to ask you for your opinion regarding spotting scopes for 300 and 600 meter range use. I currently use a Celestron 52252 100mm Ultima Spotting Scope and I'm just able to see 20 caliber holes on my targets at 300 meters. How would the C90 compare to the 100mm Ultima?
Hi Wade, that would be an interesting back to back test. I haven't used an Ultima scope as my interest is astro, but talking generally i can see that the field of view of the Ultima varies from 1.8 to 1.0 degrees, whereas the C90 with a 26mm EP would give 1.1 degrees, and a 10mm EP 0.45 degrees. So you could achieve a higher power with the C90, with a correspondingly smaller field of view. For resolution of holes, a 100mm scope with no central obstruction should resolve smaller details than a C90. That's just theory though. I like the C90's quality vs price and you will have a better feel as to the quality of the Ultima's optics. So it isn't that clear to me that the C90 would be superior to your scope. Let me know if you get to try one out. Graham
I have the original one with the orange color and a newer one with the black rubber tube.
Nicely done ! Very through and excellent points. Thank you.
I remember drooling over Questar 3.5 ads in the astronomy mags in the 80s, I knew I'd never get one so this was my desired instrument. I've now got a skymax 102 mak which does me fine. I still want to get the celestron C90 though, and the Questar
The Questar is also on my "list", but i think i'd be afraid to use it if i actually owned one! I would just look at it, and then take the C90 outside.
Arthur C Clarke had one, but only after his first royalty cheque for 2001, I agree, too expensive to use, unless you had 2?
When I saw a video of Phillips Exeter Academy's row of 10 Questars, I thought: that's the entire science budget for about 50 public high schools.
what a weird way to focus I never seen that before. I think what surprised me the most was the difference in contrast the dew shield made. I just replaced my celestron 8 dew shield with one that has flocking after I had to purchase a off brand one for my 4se and i liked that it had flocking so much. great review!
Thanks Eric
A very good explanation of old vs. new scopes. When I contacted Celestron to get some info on the old and what they would recommend to go to the next scope, they were totally unhelpful. I kept getting transferred around with no real resolution to any of my questions. This is not the way to promote their product. The old C-90 is really not a bad scope if you use it properly. Scopes should be user friendly and that was the main question I wanted to ask, a better scope than what I have and simple to use. Thanks Jenham
Celestron is not the same company these days. One was based in California; the current is Taiwanese. It'd be great if the old company passed on their documents, but sadly brand names and trademarks are often the only things transferred in such situations.
Great review Jenham. Do you know how much does the old C90 weights?
Something the old scope has going for it: compactness. If you're packing a backpack or carry-on suitcase and are looking to maximize space, the old scope beats out the new one.
outstanding......THANKS for doing this!
Thanks mr Jehnham, very complete coparison; I just decide got my own new C90; thanks for your usefull information.
I didn't realise that Celestron made the C90 step through, I thought that was Honda! 😮🤣
😂
Hi Graham,
I've a C90 which I use with a Williams bino viewer and the supplied 1.5x Barlow for moon viewing. For a decent closer view would a quality 3x Barlow work with the this set up or am I barking up the wrong tree? Should I be looking at a larger scope such as a C5 for use with the 3x Barlow and the Williams?
Cheers
Martin
Hi Martin, I think the 3x will be pushing it with the C90 unless the seeing is very steady. Focusing may be tricky. A 2x would be worth a try. Failing that you need more light grasp, such as from the C5, or maybe a SW 127. Cheers, Graham
Hi Graham,
Thanks very much for your advice and I understand that more light grasp particularly when using a binoviewer is a big bonus. From what I've read the SW127 seems to be OTA of choice compared with the C5 and quite a bit less expensive too. How would you value the two? Is the C5 worth the extra?
Cheers
Martin from soggy south Wales
Martin Higgins Hi Martin, I think the 127 is better value than the C5 especially if you are keen on lunar and planetary. The two are quite different beasts ie Mak vs SCT, f12 vs f10, and the C5 might be considered more versatile overall. Still I think it costs too much! The new 127 plus Az GTI mount costs less than a C5!
Thanks Graham,
I have a mount and I'll just be viewing the moon from a loft and wide south facing skylight so the 127 OTA at about £250 seems a good deal.
Many thanks for your advice. I think next week promises some decent viewing!
Cheers
Martin
Do you think the Bushnell 90mm is the same of the C90?
I'm not sure about the bushnell, and the reviews i have seen are quite old and a bit mixed. The C90 is optically the same as an Orion Apex 90mm or a Skymax 90 though, as these brands are all owned by Synta.
Can you tell me if a Celestron NexImage 10MP Solar System Imager - 93708, will fit on the old style C-90? Thanks for your help!
Hi Scott, if your old C90 is still setup for 0.965” diameter eyepieces then no, but you can get an adapter to allow the 1.25” camera to fit.
Thanks for the website ,really cool !!
Hi,
Many thanks for this concise review. I'm looking for a compact scope to compliment my current 16x80 bino to look at the moon and also star clusters and fuzzy objects. I was considering the Celestron 100 Trailmaster but I'm tending towards the C90. As I'll be viewing through fairly modest magnification on a photo tripod I'd appreciate your opinion on which will give the better view?
Cheers
Martin
Hello Martin, thanks for the positive feedback. I haven't used a Trailmaster but having googled it I think it's a birding-type scope like the Ultima series? If so it may be a close contest if you don't want to use higher powers (which would favour the C90). I can only say that the C90 is great for the moon, brighter planets and also for compact star clusters such as globulars. The C90 isn't well suited to dim fuzzy objects. You can fit a moon filter to any standard astro eyepiece which can be useful for a bright moon, whereas I'm not sure if you can do this with the trailmaster. The other factor may be false colour, which is not an issue for the C90. I'm not sure if the Trailmaster is an ED model or not; this may affect the amount of colour fringing (CA) you notice. I hope this is of some help. Cheers, Graham
Hi Graham and thanks for your reply which has helped me to make up my mind: the C90. Picking up on your references to discussions on various forums and also your own use of the C90 it seems there's a great number of happy users, supporters and tinkerers - even before I've bought the thing I'm being informed about flocking the primary baffle! I'm in Cardiff across the water so I hope you had last night, Tuesday, the exceptional viewing we had.
Cheers
Martin
Hi Martin, I hope you like the C90. I was trying out digiscoping with mine this afternoon and was happy with the results (if not the wildlife, which had gone on strike!) It is cold and clear over rural Somerset right now, hopefully for you as well.
Nice comparison, Jenham. I’ve owned an orange tube C90 since the mid 1980s, optically a real leap from the white tube Tasco I started with, though the experience of using a flimsy photo tripod convinced me of the value of a good Astro mount. I’m in the process of rehabbing my old C90 and am searching every corner of the net for the disassembly and focusing mechanism lubrication instructions everyone tells me is easy to find! Would you happen to know where I might find said instructions, or, even better, are you planning on shooting a video n this subject?
Thanks, yes my Tasco type early experience was not good! I haven’t seen any instructions in the form of a manual, I only recall comments on the forums about use of certain grease. I’m sure you’ve already seen these.
Yes, I had. No worries, I disassembled the C90 last night, cleaned and regreased the threads last night using a white lithium grease (don’t use too much!) and reassembled the scope after using a bit of compressed air to blow off a couple stray dust strands off the mirrors. Very easy and the focusing is so smooth now. Of course, I learned something when I initially used too much grease, causing it to come out the ends like toothpaste. But it was no problem to take it apart again and clean out the excess!
2Uiator Excellent, my preferred error was to smear a bit on the mirror! Clear skies with your refurbished scope. Graham
I'm wondering, what's the size of the secondary on these 2? How does it affect the clear aperture?
A highly unscientific (read "possibly inaccurate due to handheld ruler") suggests the old one is 30mm across vs 27mm for the newer model. These are the diameters of the silver spots measured looking at the corrector plate, so the actual secondary could be slightly smaller when the baffle is factored in.
Intersting thanks, so would you make that a clear aperture area of about 82mm equivalent to a 3" and a bit refractor? I suppose it will also depend on the hole in the primary
Graham,
Can you explain what kind of mounting plate/adaptor you have attached to your new C90? I'm considering purchasing one and using it with a gimbal mount for long-range photography aboard a cruise ship balcony. I'm looking into suggestions for gimbals & tripods, as well as the kinds of mounting plates that you would use with a C90?
Dave Doe Hi, the plate you can see is actually for a Telrad finder rather than to mount the scope itself. For the scope I use the supplied dovetail bar as it fits most astro mounts. There is a camera tripod thread under the bar to allow easy attachment to photo tripods, so you should find things straightforward. I don’t have a sophisticated photo tripod only a cheap/light one which suits a camera, but I would say to make sure whatever you buy matches the weight/bulk of the C90, as a flimsy tripod could topple. Sorry not to be more help, Graham
Thank you for your help. Is the dovetail plate mechanically compatible with the "Acra-Swiss" system shown here: photographylife.com/arca-swiss-quick-release-system
i.e. is the dovetail plate 35 mm across?
Hi Dave, I think i have that type of ballhead and plate on my iOptron Skytracker. The width of the dovetail is 42mm, so the C90 dovetail would not slide into the clamp without further adaptation. The plate i use on the iOptron has a standard camera bolt, to screw into the DSLR base, and the C90 dovetail does have a thread to receive such a bolt. I have just tried this. So you could probably attach it, but it relies on the single bolt.
Thank you for your detailed response! I did some more research, it sounds like Celestron use the "vixen" style dovetail, shown here: www.astro-physics.com/products/accessories/mounting_plates/DvsVBars.pdf
Seems like the video, photography, and astro markets are in disarray, with a variety of competing dovetail plate standards. That's unfortunate.
Apparently there's adapter plates like shown here: www.cloudynights.com/topic/361995-vixen-dovetail-to-arca-swiss-plate/
My old C90 is the astro model and is a superb scope. The new C90 is good for what it is: cheap & readily available. The intra & extra focal blur circles show differential abberation in your two scopes.
I am always on the lookout for one of the old astro model Celestrons but they are rarely seen for sale in the UK. As a package they just "look right"! Yes there is some aberration but i agree that the new model is worth its price tag. Clear skies to you.
@@JenhamsAstro I’ve seen a half dozen Astro models on eBay in recent years. The asking price varies from about $250 to over $500 (too much).
There’s a problem putting the fork mount on a wedge - won’t fit larger (C5 & up) wedges. C90 wedges are nearly extinct. You can use a Majestic geared large format head. Any of them should work well. Don’t pay more than $100 dollars for a Majestic head - I have bought two for $50-$75 ea.
I also made an adapter plate to put the C90 Astro fork mount on a C8 wedge, but the Majestic head is easier to use.
Can you tell me what that line is in diffraction rings at 14:30? My C90 has identical pattern, same line.
Hello Joseph, if you mean the brighter radial line I'm not sure what is causing it. Maybe the star's rays, being off axis, are diffracting around the baffle tube. Or perhaps it's an artefact of a surface in the DSLR. I'm guessing really. Do you have any theories? Graham
No theories myself, and the reason I ask is because my new C90 has the exact same thing! lol
I have not seen anything like that in any of my other 8 scopes, or in any diffraction images in books or articles, etc. Thought about asking Celestron themselves but hard to say if I would get a reply.
The diffraction pattern looks great otherwise, and I'm pretty have with the little scope. Just really curious what that could be.
Maybe worth a mail to Celestron but in my experience you might not get a reply. If i manage to figure it out I'll make a video of it as it seems likely that all the new C90s will exhibit this "feature"!
Veri good...Thinking of buying one which is the best place to buy. ?? I live in Brazil
Thanks. I am in the UK so am not familiar with the retailers nearer you. I suggest looking an the Celestron (or Skywatcher) websites and looking for the distributor in Brazil. Some retailers in the UK will ship internationally - my "local" shop First Light Optics is one example. But of course you need to take care of shipping costs and taxes to see if the approach makes sense for you vs finding a closer supplier.
Thank you for this video. It's very useful. I'm thinking about to get either a spotting scope or this Celestron C90 for a easy grab and go / holiday setup. My experience is, that it's best to take sth with which is really compact.
One question, my first intention to buy this Celestron is for spotting scope at the shooting range ,with no more of 150 yards distance and also to watch the full moon ,let me know if this is the right one for me ,thanks
Hi, the current model of C90 will work for both of those uses. It will focus on an object as close as a few metres away. With the supplied eyepiece the moon will comfortably fit into the field, and then of course you can get extra power from other eyepieces or barlows if you want it.
The website astronomy.tools/calculators/field_of_view/ allows you to see the FOV, for a given astro object. You can enter the C90's focal length (1250mm), aperture (90mm) and eyepiece (32mm).
Would this be a good option to photography planets? i love saturn , want to do pics a lot, i cant make a choice for telescope.
Ramón Chavez Yes a Maksutov like a C90 is a good choice for planetary photography, used with a webcam or other astro camera. The new model is much better than the old one! Clear skies.
@@JenhamsAstro thanks! i have this option c90 and this Tasco Newtonian articulo.mercadolibre.com.mx/MLM-687887038-telescopio-reflecto-tasco-luminova-900-x-45-profesional-_JM?quantity=1&variation=38435604255 402mm x 60mm Wich one you pick?
on my ne C90 a 1.25" barrel eyepiece is sloppy in the back end of the C90 -- this is nuts! Tightening the two thumbscrews means that the eyepiece is off-center.
I wonder how will the new C90 compare with the Meade ETX90. Which would give sharper views?
Unfortunately I haven’t got an ETX to try it - it would be almost a direct comparison. The new C90 is a nice scope though.
@@JenhamsAstro Thank you, Graham for your reply. I will get a GSO 6 inch classical Cassegrain rather than a C90 because the latter will be far superior in resolution and sharpness than the C90.
You failed to mention the disgustingly horrible mirror shift of the new Chinese C90 scope compared to a properly greased original Celestron C90, which will have essentially none. Yep, I'm late to the party but the internet is forever.
Any advice on greasing an old model? Seems like something like Plastilube, like they use in microscopes, might be a good choice for warmer conditions. Not sure what would be a good choice for winter observing.
Thanks a lot Jenham !!
If I was to replace my 114 reflector (it has a built in barlow) for something smaller and more portable, would a mak 90 give clearer, sharper views of the moon? Allowing for some basic photography.I realise DSO is out the question. Was thinking of a virtuoso 90 with the tracking or this. Very nice channel by the way.
Hi, thanks for the positive feedback. I haven't used that particular scope & mount, but I understand it is very portable. I would say the mak will be better than your reflector for the moon and planets. Collimation is not an issue with maks unless you drop them (!) and they naturally have long focal lengths and hence give high power view for bright objects. I won't judge your 114 but some scopes of that size are not the best quality. As often a package like this will have its weaker points and maybe the 10mm eyepiece isn't the best, but you may already have some alternatives from your current setup. Lunar imaging should definitely be worthwhile. Reading the reviews some say the C90's contrast is slightly better than the SW, but it isn't going to be a big issue and you are looking for a package which the SW provides. Both of these maks would beat the 114. Sorry for the long ramble but I think you will like a mak. They are small and tough!
Thanks for the reply, think I will try it out and anything that takes up less space and portable with easy set up is a bonus!
Thank you.
Great break down.
What is the price of the old model?
Hello, you can only buy the old model via auctions, and the price varies between versions (the astro being the most expensive). Looking on ebay today I can see a few in the US between $100 and $200. I got mine in the UK for about £100, as i recall. So it's not much cheaper than the new model!
Where can i buy this in the UK?
Try Rother Valley Optics or Harrison Telescopes.
@@JenhamsAstro Thanks Jenham :)
Very interesting
Will AstroMaster Telescope Accessory Kit ( which accept 1.25" eyepieces and filters ) fit with Celestron C90 Mak Spotting Scope ? Because they are telling about " AstroMaster " series...But this series is " C90 Maksutov-Cassegrain Optical Design "
Yes the accessories should fit.
17:23 The new C90 has a little of residual spherical aberration
Yes you are right, but it doesn't seem to degrade the image noticeably.
if you want one of these do yourself a favor and look for it on ebay under spotting scopes and you can get one with the 45 deg and a eyepiece and a spotting tripod for just under 150 bucks. if you get the c90 telescope it will run you 200 to 250 dollars, and you wont get the 45 or the eyepiece or tripod for that amount. if you look at the specs they are the same, except one is gold and the other is black!. and it does come with a vixen style of dove tail
Thanks a lot !!!!
very hard to hear you clearly due to echo
Sorry, I hope the sound is better on more recent videos.
Good review! One thing I noticed is that the coatings on your older one are either very thin or nonexistent. I have one similar to yours but I think it is older. I don't believe the dew shield was offered at the time. It's coatings look very similar to your newer one. The rubber focusing ring on mine is much wider, about an inch and a half, and thinner, with a very grippy surface. It is quite easy to use. Yours looks like that focusing ring alone might be part of the focusing problem. Thanks!
Thanks for the info, I think Celestron tweaked a few parts of the design during the production run, as I've also seen a few pics of other scopes with slight differences. The dew shield is helpful though, and it looks good too!
Hi Jenham! By 'new' C90 you refer to model "52268". How about the slightly older model 52265? There's an ongoing discussion about that here: www.astronomyforum.net/catadioptric-telescope-forum/256947-c90-old-vs-new.html#post1058692430 Are you aware by any chance if the current C90 1250mm is Synta made? Thank you in advance
Hello Jason, I haven't got any experience of the 52265; it looks quite a different beast. As far as i know Synta make the 52268 yes. For me the quality is very good.
52268 is on it's way to me, my first scope. Can't wait! Thank you Jenham
Hello from Chicago .Thank you my C-90 sits 29 years I need to get it but need T adopter for Nikon 3300 camera ,I just got adopter for canon slr film .Pleas if you know proper ring adopter let mi know .i will love to use again as I did long ago. Thank you on your ifo vidio it is awesome great work. Celestron need to send you a bonus
Thanks for the great feedback! If I google your camera model I think a standard Nikon t-ring will fit the camera body. You could then use a 1.25" prime focus adapter screwed into the t-ring, and then a 0.965 to 1.25" adaptor to connect to the old C90. It is not ideal but it works and the parts are cheap.
Hello again, I put a picture of the adaptor setup I use on my website:
jenhams.co.uk/astrophotography/planetary-imaging/
There may be a better way!
I hope this helps. Graham
14:55 - the best
The c90 old is descolimated no?
Hi, yes i think the old C90's collimation is not that good, based on the diffraction rings not being fully concentric. I am not an expert on these patterns but it doesn't look as clean as the new C90's pattern.
what's the magnification of this telescope ?
+MD. Fardin Islam Niloy The magnification is calculated by dividing the focal length of the telescope by the focal length of the eyepiece which you chose. So for the new C90, with a focal length of 1250mm, if you use a low power eyepiece with a focal length of 25mm then you will have a magnification of 1250/25 = 50x, whereas if you used a higher power eyepiece of focal length 10mm then you would have a magnification of 1250/10 = 125x. The old C90 has a shorter focal length (1000mm) and hence lower magnification for a given eyepiece. In general a good rule is not to use more than about 50x for each inch of mirror/lens diameter. So with a 90mm scope like the C90 that gives a usable maximum power of about 175x. If you try to use more power than this the image will be too dim. I hope this helps.
+Jenham's Astro Don't they give me the 10mm eyepiece ? what kind of eyepiece they will give me ?
+MD. Fardin Islam Niloy Hi, if you buy a new C90 it is supplied with a 32mm "Plossl"-type eyepiece, which will give a magnification of 1250/32 = 39x. This is a good low-power eyepiece to start with.
Could barley make it paste 4 min. I have the volume cranked and unless I put headphones on I can't hear you. Not doing it because when an ad starts it will blow my eardrums
Sorry, the audio quality gets better on later videos.
Your audio level went from low to impossible when you explained intimate details. Collapse. I could only make out some words.
Sorry Stanley. On more recent videos I have improved the sound quality but I accept it was lacking early on.
@@JenhamsAstro audacity 1.2.6 is the definitive free audio editing software. If you whisper, make sure you Mike yourself up. People will shy away if you ever shout at them. Anything conversation below 30% , should be considered marginal.
Didn't search yet,.. with filters, ., can this work with our closest star. The Sun?
Really started watching the sky let's sat I wuz,, a bit 4~5 year young child.. then saw Orion, M-42, ten M-1..the. Crab in Taurus. .
JUST SO AMAZING.
Really let's us realize,. we are so proud, Smart and din not a Very smart after all 😢
The coatings are night and day
Very true.
that flower never really got sharp
The old one seem to have very good optics, but need some collimation.
The new one seem to suffer a little on the star test. See figure 3 and 4.
www.astrosurf.com/altaz/startest_e.htm
Hello, yes I agree that the new scope's patterns look like the spherical aberration in your link. In practise the new C90 gives very pleasing and sharp views so the effect is not noticeable in normal use. I found another link which seems to explain this observation. www.telescope-optics.net/Mak_spherical.htm. The "Star Test" paragraphs suggests that different orders of aberration cancel eachother out. I don't profess to understand the explanation though, maybe you will! Graham
@@JenhamsAstro This is so useful, thank you! I have a brand new 127 skymax and C90 in my hands and I am comparing such things!
Hello from New Orleans! I own an old orange-tube C90 and the new one, and find your observations spot on. . I keep my orange tube model with a solar filter attached, and prefer the new C90 for digiscoping. GREAT video; thank you for sharing it with us! James
James Prine Thanks James
Please get a lapel mike; you are TOO far from the built in mike on the camera and it makes your audio just lousy.
Bill A. Fair comment. I hope the audio on the more recent videos has improved.
Oops wrong person lol