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Assuming you are keeping the exposure the same, doubling the exposure time would require that you reduce the ISO (or aperture) by one stop, yes.

Always appreciated, no matter how long after I make a video. Clear skies!

Great to hear that…thank you David!!

Thanks for your comments Martin. Do feel free to consult me when you get stuck. Clear skies.

Thank you!!

Thank you so much for your kind words.

It works out where to point on its own…just choose a target and let it do its thing!

@@martinsastrophotography Thanks so much

Sorry, but I don’t agree. I put Polaris in the centre of the crosshairs then use altitude bolt to move it up to the outer rings. I then rotate the RA to put 12 o’clock on Polaris, which ensures that 12 o’clock is exactly “up”. If you just place Polaris at the position shown on the app, you do not have 12 o’clock up so it won’t be accurate.

​​@@martinsastrophotography If you place Polaris at the correct position and rotate the RA then only the numbers rotate. Polaris will remain there regardless of the position of the RA axis. The only benefit of putting the 12 on top is to guess the position more accurately on the ring. Last night I had my elevation spot on and the azimuth was 6 seconds out. I always do the Synscan polar alignment routine after manually aligning to check my accuracy. No RA rotation necessary. The RA rotation was for before there was apps showing the position of Polaris and you had to calculate it by rotating the RA axis to the correct hour.

@@Astronurd There is no need to be rude. We are having a discussion. Please remain calm and respectful. I believe you do not understand my explanation, which means I have not explained it effectively enough. I can try to explain my approach more clearly if you wish, but only if we can have a constructive discussion.

​@@martinsastrophotographyI didn't mean to sound offensive or rude and if I came across that way I sincerely apologise. I will edit the comment. I am eager to hear your explanation regarding this. .

@@Astronurd Thank you. Ok, let me try to explain better… The PS Align Pro app shows a picture of the polar scope graticule with 12 o’clock at the top. It then shows where Polaris needs to be on this graticule based on your location and the current date and time. To position Polaris in this position it is helpful to first orientate your polar scope graticule so that 12 o’clock is at the top. Then you can simply put Polaris in the position displayed on the app and you are done. Now to get the polar scope graticule orientated with 12 o’clock up, a simple technique is to use the Az/alt bolts to put Polaris at the centre of the graticule and then use altitude bolt only to move it up from there to the graticule rings. This is simply an accurate way to find where “up” actually is. Then you just rotate in RA to turn the graticule so that 12 o’clock is where you put Polaris. I think it’s a neat technique and I used it successfully for years before I switched to a Polemaster to save my bad back, and later to three point polar alignment in NINA. I hope this is clearer.

Thank you. I use the Sky-Watcher EQ8-R Pro mount which I am very happy with. I have not encountered Backfocus trouble with the EdgeHD 11 and Hyperstar….I turn the focus knob fully anti-clockwise until I reach the end stop, and then turn it clockwise 27.5 turns. This achieves focus with the Hyperstar v4 (with ZWO filter drawer option)

Thank you. I have a ZWO AM3 mount. When you get to the point where you get remote control working, you can fit a PoleMaster or use the three point polar alignment plugin in NINA, which I highly recommend you use for remote control of your sessions. I have my PC in the dining room and so I stay nice and warm!!

Thank you George. I am currently working on that. Please be patient…I hope to release a video about this within a few months.

Thank you so much Martin. I will keep an eye.

I’m glad you asked, and in my opinion there is no such thing as a stupid question, since you are seeking to learn something. You cannot polar align a tripod, since it does not have a Right Ascension axis for tracking. It is a tracking mount that you typically polar align, and this mount is often fixed on the top of a tripod. Now, think about what polar alignment is…it is the process of aligning the Right Ascension axis of the mount such that it is parallel with the Earth’s rotational axis. Assume you have just done that… now you move the tripod… you just ruined your polar alignment! So, even if you just knock the tripod with a foot, let alone pick it up and move it, you would need to check or re-do your polar alignment. I hope this helps your understanding.

Thanks for gracefully clarifying that. So Im Guessing to track the milky way you need to face the camera towards the Milky Way once polar aligned while being careful not to bump the tracker out of alignment. I’ve had a ioptron skyguider pro for a few years now but never actually put it to use. Your video and knowledge is going to help me with my first attempt so thank you very much

@@D-GAF For very wide angle photos, for example of the Milky Way, you can get away without tracking at all but you still need a tripod. Divide 200 by your focal length to get the maximum number of seconds of exposure time you can use without getting visible star trails. Set aperture wide open (lowest f/ number), set ISO very high, frame scene, drop ISO to about 1600, take your shot. Can repeat and get multiple shots for stacking later. Note that if you are using a polar aligned tracker the sky will look fixed from shot to shot and the ground will move from shot to shot, and you can use much longer exposure times. With no tracker the ground will stay fixed and the sky will move from shot to shot. It’s a good idea to use a remote control to avoid causing camera shake when you take the shots.

Thank Tony. I’m sure there are many variations out there. Interesting what you say about Hyperstar setup collimation. I have never had an issue with that. I guess I got lucky! Clear skies.

Hi Tim. First, thanks for your kind words about my video. Much appreciated. Ok…on to your questions. First, the mount is the Sky-Watcher EQ8-R Pro. It’s one of a few hefty mounts up to the task of carrying this scope with all the other accessories I use. Ok…so you are a photographer…well we have that in common, at least I was an amateur photographer for about 40 years before I ever tried Astrophotography. I have a similar set of lenses to you, covering a wide range of focal lengths, and as you rightly say the range of target sizes in Astrophotography is simply huge…from the whole sky Milky Way to the tiniest planet many millions of light years from Earth. You say that “it doesn’t seem that the majority of Astrophotography enthusiasts keeps a slew of different focal length telescopes”. Well I think this could be an incorrect perception. I, for example, have the EdgeHD 11 giving me 540mm, 1960mm and 2800mm, then I have an 8” Newtonian at 800mm, and a Redcat 51 at 250mm. I have accumulated these over 8 years, and spent a crazy amount of money on them and everything that goes with them. I think many if not all experienced astrophotographers will have multiple telescopes.. but perhaps they are a bit reluctant to blatantly reveal this as they don’t want to be seen to be bragging about all the kit they have. But I am quite certain that there are a lot of angry partners and spouses out there who resent the house full of Astro gear and the amount of money that has been spent on it!!! During spring (Galaxy season) I use the long focal lengths to photograph galaxies, and during autumn and winter I generally use the Hyperstar on the EdgeHD 11 for nebula work. In the summer I take a break while I wait for proper darkness to return at my 51° latitude. So..on to your question about compromise with the Hyperstar. Well, yes in principle adding more glass to the imaging train degrades the quality, but two other factors make it the right choice I believe. 1. A wider field of view means the atmospheric distortion is smaller compared with your field of view, so the details of a nebula are plenty good enough with the Hyperstar setup at 540mm. 2. With so few clear nights per year I need to make the very best of every clear night, and the photon gobbling f/1.8 setup of the EdgeHD 11 with Hyperstar is perfect for doing that. Finally, if it’s any measure at all…I have only had one award for an Astrophotography photo, and it was taken on the EdgeHD 11 with Hyperstar. I hope I have addressed all your excellent questions.

@@martinsastrophotography Hi Martin. Thanks so much for your prompt reply. All those answers help with regard to my own plans. I'm 65, living in the USA, and am about to retire back to my Australian homeland, specifically an area of rural Australia where the Bortle conditions are near perfect. It seems as good a time as any to finally indulge a long held interest in astronomy and astrophotography. I've read all the excellent reasons for starting small and building up with experience, but at my age I don't have that luxury and have decided to jump in at the deepest of deep ends. Initially I was going to purchase an Edge 9.25 coupled to an EQ6-R Pro, but decided I might as well leap right in and get the Edge 14" with a suitable mount, and toss in a Redcat 51 or 71 to compliment it. It's going to be a huge and hair-pulling learning curve, but as time isn't on my side I figured it was worth it, plus I'm very adept with software, have built a number of PCs and am reasonably comfortable with electronics, and am obsessive enough with details to pick things up fairly quickly. Toss in my years of experience with photography, and I think I'll get there, accepting the fact that there'll be a degree of frustration along the way. Channels such as yours certainly help!

Thank you!! Enjoy.

I get asked this question A LOT!!! It really is not an issue AT ALL. If you really want to rotate it you can but you risk breaking it as it can fall out very easily, and unless you do it perfectly you will still need to rotate in RA to get 12 o'clock at the 'up' position. Think of it this way...how will you know where 'up' is when you try to rotate the graticule??? When I polar align, I put Polaris on the centre crosshair first, then use the altitude bolt to move Polaris up to the top of the rings. Then I rotate in RA until 12 o'clock and Polaris are in the same place...that way I make sure Polaris is really at 12 o'clock. Check out my Polar Alignment video to see me doing this. Clear skies!!

@@martinsastrophotography Thanks 🤗 very helpful

I don’t use ASIAIR... I use NINA. If the curve is too shallow I increase the step size used. Perhaps you can do the same on ASIAIR?

Sky-Watcher Telescope Tube Rings for 200mm Newtonian from First Light Optics.

Thank you Barry. Go for it!!!

I think you meant the Greenwich Meridian, which is 0 degrees longitude. Everyone is “bang on the Meridian”. The Meridian is the (circular) line from North Pole to South Pole via your location so it goes directly overhead you wherever you are.

It’s best to choose somewhere about 30 degrees above the horizon to the east or west (choose same side of Meridian as your intended target) to do the calibration of PHD2. Then slew to your target, frame it and start guiding.

How exciting!! Glad it was helpful for you. Enjoy your new purchase…and if it’s cloudy I will know whose fault it is!!!! ;-)

When you say “shows” what do you mean? Paperwork, online manual, measured from an image?

@@martinsastrophotography it was plate solved

@martinsastrophotography sorry when i plate slove it shows 1980mm i m jusy trying to asertain if i should be reducing or adding spacers? Also Martin, i am guessing you are using auto focus on the essatto when deep sky imaging. Does the draw tube need to be kept mid way in the back focus measurement? All all the way in?

@hakankaya-gj1su PHD2 will display values based on your inputs. The EdgeHD 11 native focal length is 2800mm and with a 0.7x reducer fitted this becomes 2800x0.7=1960mm. I use ASTAP for plate solving from NINA and have never had an issue provided I have the focal length set to 1960mm and the camera pixel size correct (which it picks up automatically when I connect my camera). Whether or not your Backfocus distance is correct can be determined by checking you have nice round stars across the whole image when focusing is complete. Yes, I use autofocus with whatever focuser I am using, including the ESATTO. I put the ESATTO at the mid way position then get rough focus using the manual focus knob. Then I lock the mirror and run autofocus.

@martinsastrophotography sorry do you mean mid way position or 0 all way in

Thanks Jon. Yes, autoguiding is still necessary unless you are using a short focal length and/or short exposure times. Every mount is different so I can’t give you precise values for when you need to autoguide to improve results. You just have to try it and see. These days I never image without autoguiding.

Hi Roy. Some confusion is apparent in your question. You tell me the guide scope focal length is 206mm, but then at the end you ask me if it is 126mm. The important thing to check is that the image scale of your guidescope/guide camera setup is suitable for guiding your main scope/camera. With 336mm imaging focal length and 206mm guidescope focal length, and the same size pixels on both cameras, you have a very suitable setup. If you go into my website www.martinsastrophotography.com you will find a tool that enables you to calculate the minimum required guidescope focal length for your setup. Here’s a link to the calculator: martinsastrophotography.com/calculator-tools/

@@martinsastrophotography I was simply using the formula in your presentation. can I can email your with our converstation going forward? I have issues with my guiding.

never mind, I went to your website for the calculator - good stuff!

@@roymixon Glad it helped. You could guide a significantly longer focal length imaging scope with that guider setup, because the guiding can detect a fraction of a pixel movement of a guide star on the guide camera image.

Consider the other one, which is cheaper. Smartphone Telescope Adaptor - APEXEL ruclips.net/video/pwWc1QDZamE/видео.html

Thank you for your kind words, and for subscribing! I really appreciate it when someone takes the trouble to give feedback.

Glad to hear that! Thank you for taking the time to comment. Clear skies to you too!

Are you aware that the light does not work unless the unit is switched on?

Thank you!

Yes, it’s a clever concept, and a nice piece of kit to use. I had to send it back after the review but I miss it now!

Thank you. Very sensible questions there! My video addresses the best ISO/gain for Astrophotography specifically. If doing daytime photography the “optimum” ISO would depend on how much available light there is in the scene and what shutter speed and aperture are desired. This would then automatically answer your second question. For dedicated Astrophotography cameras a gain of 100 is usually best, except where the target is very bright and you need to maximise dynamic range to enable longer (and hence fewer) exposures, in which case a gain of zero might be best. Most Astrophotography cameras use sensors that were designed for DSLR cameras, and so they have a gain control facility inherent to the sensor. This facility is therefore passed on to the user as part of the product. I hope this helps.

@@martinsastrophotography thank you very much for your thoughtful and thorough reply . I love your channel - keep up the good work. Regards , Rob

Thank you! What is your approximate location? I can then check for you re Pleaides.

@@martinsastrophotography hi there, Bury, North Manchester UK

@@craynerd Thank you. From your location the Pleiades are 18 degrees up in the WNW at 9:30pm and then fall towards the horizon setting in the NW at 11:43pm. That is based on today’s date. I wonder if you have your location properly set in Stellarium?

@@martinsastrophotography I just wanted firstly to say thanks again. Amazing video and I don’t know why this hasn’t got more views. I wish I’d have seen it months ago. Yes, fair enough. I’ve just checked again and perhaps because it’s so late in the month but Astro twilight is just short of 10pm and it’s only 18 deg like you said so far too low for me to shoot and even then it’s dropping lower and below the horizon after only an hour. I guess in theory it is available, just not practically for me. I stand corrected and it is theoretically available. I’ll have to look for a new target for tonight if the weather does hold! Chris

@@craynerd Thanks for that. I am disappointed it hasn’t got more views…the 12 videos took a long time to make! It’s Galaxy season now so tricky if you have a short focal length. If you tell me what telescope and camera you are using I can try to suggest something for you.

Thank you!!!

Sorry if you wanted to see that, but my camera settings combined with your display screen characteristics and settings would have made any representation of the light levels very misleading. It was a dark clear night in my Bortle 5 back garden, if that helps at all.

@@martinsastrophotography lol. I guess it will have to do. Im awaiting the arrival of mine and im hoping for some great horizon captures of the sun rising over the sea where i live. Great equinox moons rise over a local castle a few times a year. And campervan journeys are going to be more fun now 😁

I agree! We are always learning. Thank you for pointing that out.

Thank you!!