Objective Corrections - Differences between Achromatic, Plan, and Apochromatic Lenses
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- Опубликовано: 28 ноя 2021
- Hey folks! If you've dipped a toe into upgrading your microscope, you might have come across terms like "plan" and "apochromatic." And you've probably wondered - "is this something I really need?" Well in this video, we'll show off the same scene with some different lenses so you can get an idea of what to expect!
I'm comparing the Journey to the Microcosmos 10x objective with Olympus DPlan and SPlanApo objectives of the same magnification. You'll definitely be able to see the differences!
Finally someone who explains optics simple and efficient.
Yes! Finally! A microscope channel like I've always wanted!! You present in a perfect manner.
Welcome! Let me know if you have any specific video requests! I have a ton of ideas rattling around in the ol’ noodle but there’s always room for more.
Amazing video and details. Best one on youtube for this!
Nice video. I have a acromatic microscope and it´s very hard to film protists with focus, especially when they don´t stop moving. Now I know that worth make a upgrade.
Dude, you have done what a week of google research couldn't do, thanks
This is the best demonstration of these corrections I have ever seen. I need to bookmark this video so I can share it with folks who ask about this. One question: what's the deal with the reduced apparent contrast in your apo objective? Am I right in thinking that's because it is letting in more light due to the higher numerical aperture?
Greetings, and welcome! Yes you have a good eye! Apochromatic lenses, especially older ones, tend to exhibit less native contrast due to having more optical elements. My understanding is that this is somewhat mitigated today by improved coating designs in modern objectives. That said, there are certainly folks who prefer fluor objectives for their better contrast - it’s something I intend to look into in the future.
I will provide an excerpt from legendary microscopist Shinya Inoué’s excellent book “Video Microscopy”: “ever since I have come to use video routinely on our polarizing microscope, my choice of objectives has dramatically shifted from the highest extinction achromats to the higher NA plan apochromatic objective lenses…” The invention of electronic sensors and media was a major boon to microscopy. No longer did you have to settle with what the film captured - an experienced microscopist could pull more detail out of an image or video with nonlinear video response curves and so the lower contrast became less of an issue. For me, the lower contrast is an easy trade to make for more detail, especially since it’s a couple adjustments away in Davinci or GIMP from being just as contrasty with more detail and more accurate colors.
Finally, the explantion I was searching for!
Excellent explanation
Great video, I am able to understand the difference between the different types of lenses so much better thank you
Thank you, very informative! I really enjoy your style.
Great demonstration and presentation!!!!
Very informative!
So informative and well done. Thank you.
Thank you so much !
hell yes, very useful, didnt know where to even start looking for objectives, gona buy some cheap plan lens now :33333
now that is amazing
🔥
Very meaningful video.
Which video camera did you use to capture these? Looks great
Hi great channel. I am into amateur microphotography (beginner), just ordered a ‘scope with 4 plan pbjectives 4,10,40 and 100x.
I am trying to figure out whether or not to swap out my plan achromatic objectives for semi plan EP45 achromatic lenses. There does not seam to be any info on the latter and was hoping you, or your subscribers may be of help.
KEEP UP THE GREAR WORK. Love your presentation.
Sandy from NZ.
Not sure what the EP designation means but “plan” should be superior to “semi plan” for the most part. You would probably want to upgrade to plan apochromats if anything. Thanks for the kind words!
@@diettoms yes my thoughts too. Thankyou.
It's strange, when talking about achromatic camera lenses, the nomenclature goes simple lens -> achromat -> apochromat -> superachromat, with each representing the degrees of "correction," increasing the number of times the spectral curve crosses the line of perfect focus - once for an uncorrected lens, twice for a one-degree-of-correction flint-crown achromatic doublet, three times in an apo lens, and four times in a superachromat. The terminology isn't rigorous, and confuses people as "apo" is used to market lenses as having no chromatic aberration, which they still always will, and the amount of which will still vary from one lens formula to another. There aren't many lenses with "superachromat" labelling, and reading about it you are usually told fluorite glass is necessary to achieve the required three degrees of correction. This makes me suspect that all the expensive Canon "L" lenses which use a fluorite element are actually superachromats, just not labelled as such, and I also suspect that camera lenses using two formulations of low-dispersion glass are achieving superachromatic correction without fluorite (Sigma have a page describing their "exclusive low-dispersion glass" which mentions both two LD glass formulations AND fluorite, and suggests they build some lenses with all three, which I guess could result in a "superapochromat").
Anyway, the bit that confused me was "semiapochromat," because I don't know how you could have one-and-a-half degrees of correction. Maybe the third crossing of the zero-error line is outside the visible spectrum, or the second correction brings the curve back towards the line, but never actually crosses it..?
Other questions: how do immersion lenses fit into all of this? Is there as much marketing wank in microscope objectives as there is in camera lenses? Are manufacturers allowed to use lead glass for their lenses? They aren't for cameras! 😅
I wish I had an answer for why they're super-A- and not super-Apo-. Unfortunately, the paper related to the invention of super-achromats is locked behind a paywall. You'd think, after 60 years, research papers ought to be in the public domain, but capitalism is king, I guess.
I found a couple of interesting things you might want to read:
Defining apochromatism: www.csun.edu/~rprovin/tmb/definition.html
Semi-apo and apo lens design: www.telescope-optics.net/semiapo_and_apo_examples.htm
I'm not an expert at interpreting optical performance plots, but if you look at the semi-apos in figure 149, they have distinctly different behavior than for apos - especially for short wavelengths.
Immersion lenses simply allow you to get better numerical aperture than is possible with an air gap because high angle rays that would normally undergo TIR (or at least refract severely) at the coverslip-air interface are able to propagate to the lens. These high angle rays sharpen up the interference pattern at the focal plane, which leads to shaper images.
I'm not super connected to the current microscope industry - the lenses I buy are going on 40 years old. That said, you may find it illuminating to view the marketing materials for Nikon's CF lenses: krebsmicro.com/Nikon_CF.pdf versus Olympus' LB series: www.alanwood.net/downloads/olympus-lb-objectives.pdf These days, transmitted light microscopy is somewhat commodified - it's things like fluorescence or super-resolution microscopy that are being marketed as the state-of-the-art. Aside from simple epi-fluorescence with a mercury lamp and filters, there's not much modern microscopy that's hobbyist-accessible. And, since many advanced techniques are based on stochastic approaches, there's not much interesting there for someone who's focused primarily on 60fps video.
Don't know specifically about leaded glass, but RoHS has been a factor at every job I've worked so I would guess microscope objectives are no exception.
Fantastic videos ! I wonder... I remember some image/video editing apps, and also video player apps have these digital geometry filters... Would it be possible to bend light at the corners, coming from the corners throug the apo objective back into focus using such filters?
No is the simple answer.
Hi, can you please recommend a good microscope with good optics along with a good USB camera, mainly for videomicroscopy?
I don't have a massive budget but was thinking to do a step up from my beginner's microscope
Did you get a microscope yet? I recently got my first microscope and could give you some good pointers.
@@intensecutn i have a decent microscope but wasted to uodgrade to something decent without going bankrupt and also I need a decent eyepiece camera. I bought one but was really awful.
This is a brilliant video thank you for the time taken to make this from achromatic plan to plan Fluor will it give better image quality in bright field.
Hi federico - yes plan fluor objectives will generally exhibit significantly less color fringing and usually have a slightly higher numerical aperture. They are also often UV fluorescence compatible however this can make them overly expensive if you don’t need that.
@@diettoms thanks for the reply... Guess I'm gonna have to convince my wife I need them😁
Haha, best of luck! What scope do you have?
@@diettoms it's a customised built omax with kholer illustrations din standard and eBay plan lenses
@@fred9za Oh wild! You should share images or a video of it! I'm assuming you've seen my "upgrading your scope" vid too but if not check that out!
Hello .. I have the Motic BA210 LED .. What about updating to Plan Fluor?
Welcome! Can you explain your question a little more? The Motic is a Chinese infinity-corrected scope so it needs infinity corrected objectives. I believe their objectives have a focal length of 180mm. If you purchase non-Motic objectives, those with a 180mm focus (aimed to match current Olympus standard) will give you the best results.
I have an Omax, can i get Olympus SPlanApo for it? Appreciate your help
See my vid about upgrading amateur microscopes - there’s a PDF as well that is useful linked in the description
Good video. What's up with the prices though? Everything seems to be way more expensive. Achromatic lenses are costing me up to 100 euros, plan achromats several hundreds and apochronats several thousands. Did you get them secondhand or am I looking for premium brands only?
If you’re looking at infinity corrected lenses, that sounds about right. The finite lenses I use are considerably cheaper since they are also older and technically outdated (but are still excellent for hobbyist microscopy).
@@diettoms Thanks, finite apochromats are cheaper indeed. Are you aware of finite microscopes with köhler illumination? The field diaphragm improves contrast by cutting off any light outside the field of view, which scatters around in the tube with normal illumination. It seems like a very good thing to have.
Yes, Koehler illumination has been around for a long time. Most clinical grade microscopes from before the infinity optics era will have Koehler. The Olympus BH2 (which I’m using in the video) is a Koehler scope and one that I highly recommend.
Maybe slightly off-topic.. but what is the blobby worm on 0:12 of the intro? I found several of them in some muddy ditch water but cannot identify them.
They're a group of worms known as catenulida!
Hey on my lenses it says "E A (insert number here)" what does the E A stand for?
Hi Jacob, what brand scope and/or objectives are they? On Olympus, the designation E A10, for instance, was for an "Education-grade Achromat 10x". I believe these were usually sold with the CH/CH2 microscopes which were the lower end model as compared to the clinical-grade BH2. But many manufacturers have similar sounding nomenclatures that don't always mean the same thing.
@@diettoms it is a Fischer science education microscope. So the education achromat explanation makes sense. Thanks!
Okay yeah I agree! Honestly I have no idea what separates an "education grade" achromat from a regular achromat. It may well be that they are optically identical and just have different levels of build/material quality!
Even the paramecium are staying close to listen to what you have to say.
Like well behave dogs!