Nikon gene sequencer objectives
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Re: Nikon gene sequencer objectives
Hmmmmm. Never thought about that since PSFs are obtained for each channel, shift and rotation corrected in software. That applies even for the best objectives. Would be more than nice to have one "perfect lens" though:-)
But I would guess, yes. If the objective were perfect, and the imaging train is perfect also, I would agree with your criteria. I just don't have the background to give confirmation.
But I would guess, yes. If the objective were perfect, and the imaging train is perfect also, I would agree with your criteria. I just don't have the background to give confirmation.
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Re: Nikon gene sequencer objectives
The point spread function of the tube lens is just a part of the point spread function of the entire optical system. The ideal would be that required by the requirements of the objective. Tube lenses can be neutral, correcting or compensating depending on where the engineers have decided to load the system.
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Re: Nikon gene sequencer objectives
The earliest Nikon tube lens I know of (in the head of an infinity Optiphot) can easily cover ultra widefield eyepieces or aps-c given the right objective. Nikon's ITL200 also covers full frame with a Mitutoyo m plan apo fairly well. I don't think the tube lens is a limiting factor. Some modern Nikon objectives can cover more than a 25mm image circle, some less.
Unfortunately I don't think I'll be able to do more tests of my own any time soon, but if I get the chance I'll do some more.
Practically speaking, Nikon objectives work well enough without specific compensating optics to meet the standards of very picky photomacro/micrographers, which probably qualifies the CF claim as at least 'close enough.' Why eyepieces would be a limiting factor is a bit headache-inducing, especially with cheap modern ones doing better (to the camera and the eye). I can only say that's what my own limited testing seemed to indicate.
Unfortunately I don't think I'll be able to do more tests of my own any time soon, but if I get the chance I'll do some more.
Practically speaking, Nikon objectives work well enough without specific compensating optics to meet the standards of very picky photomacro/micrographers, which probably qualifies the CF claim as at least 'close enough.' Why eyepieces would be a limiting factor is a bit headache-inducing, especially with cheap modern ones doing better (to the camera and the eye). I can only say that's what my own limited testing seemed to indicate.
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Re: Nikon gene sequencer objectives
Yeah, I’ve seen your comparisons on the Nikon Users Group on fb. Those oculars are impressive considering their price.
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Re: Nikon gene sequencer objectives
How can you have a chromatic aberration free achromat?
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Re: Nikon gene sequencer objectives
Why is it calleda Gene Sequencer objective?
Re: Nikon gene sequencer objectives
As I understand it, TIRF microscopes (a type of high resolution fluorescence microscope) are used to figure out things like gene cut and splice points. And the 20x Nikon Plan Apo objective was once incorporated in one of these TIRF microscopes - bought in large numbers to facilitate gene sequencing - but replaced by somethng better:
https://blogs.swarthmore.edu/Illumina+G ... own/?cat=4
End result, a whole bunch of $3000 objectives suddenly became available. An enterprising Ebayer or two picked them up. And the market ended up deciding they were worth $100-250. Had they not been Nikon's somewhat unusual 25mm thread and even more unusual 60mm parfocal spec, they might now cost more like $500? Just buying a high quality Nikon scope to host this objective is more than most hobbyists can afford - and researchers who wanted both a Nikon infinity scope and a 20x objective probably got it when they spent tens of thousands for a new Nikon infinity setup.
Re: Nikon gene sequencer objectives
I always assumed "chrome-free" referred specifically to lateral CA, since as far as I understand axial correction has always been handled primarily in the objective?
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Re: Nikon gene sequencer objectives
Axial must be the axis, where there is no ca. Where is lateral? Is it 10 degrees off axis, 20 degrees? It is actually, zero plus any degrees. The wider the field the more extreme it is. Lens systems have varying degrees of controlling off axis ca. One is to use low dispersion glass, another is to use various critically chosen glass types to cancel or re-converge dispersion. Another is to use larger lenses. It is all complicated by the fact that the effort to control lateral ca can create spherical aberration and not necessarily do anything about astigmatism. This has created some really complicated lens formulas and resulted in an increasing expansion of lens dimensions. By the 1980's, everyone was expanding their barrel diameters and lengths in order to fit wider and more lenses into them so the could control ca over a wider field and as well keep the other aberrations and distortions within bounds. So everybodies achromats got better but they were still achromats. Why call them achromats if they are better colour corrected than achromats. Is it so they could still sell apochromats?
In an infinity system the tube lens is actually the back lens of the objective. All of the objectives are corrected to utilize , or rather corrected as much as possible to utilize the tube lens as their final convergent lens. I say " as much as possible" because with many systems one or more objectives are idealized , whereas others are imperfect . Sometimes different eyepieces will resolve those imperfections. Depending on the design objectives, the tube lens in any given system will be made to certain requirements that the objectives require to make them as perfect as possible. There is no reason why a final lateral ca correction cannot be a part of the tube lens' equations. The ultimate result out of the eyepiece can be the same.
The B & L system has always intrigued me because they split the objectives, lengthening them considerably and widened them considerably when compared to their 160mm stuff. The actual objective body appears to be responsible for the field flattening aspect of the design and the negative common back lens of the entire system completes the corrections, while also modifying the focal point. The interspace between them is convergent. From that common fairly complicated lens system downstream, the system must have a high degree of corrections because most of the work has been done by the time the image gets to the tube lens. The tube lens itself buried in the head, is quite simple, a doublet that primarily appears to be a convergent focusing lens. It may be slightly compensating, since it would itself create some lateral ca and the objective system might be slightly overcorrected. One of the hallmarks of the system is the diameters. The tube lens is quite wide. It seems they utilized diameter as a simple but useful tool to limit dispersion.
If the Nikon objectives do provide ca free performance or in the case of the achromats...almost : how does the system compensate for the ca created in the tube lens? Presumably, that is the job of the eyepieces?
In an infinity system the tube lens is actually the back lens of the objective. All of the objectives are corrected to utilize , or rather corrected as much as possible to utilize the tube lens as their final convergent lens. I say " as much as possible" because with many systems one or more objectives are idealized , whereas others are imperfect . Sometimes different eyepieces will resolve those imperfections. Depending on the design objectives, the tube lens in any given system will be made to certain requirements that the objectives require to make them as perfect as possible. There is no reason why a final lateral ca correction cannot be a part of the tube lens' equations. The ultimate result out of the eyepiece can be the same.
The B & L system has always intrigued me because they split the objectives, lengthening them considerably and widened them considerably when compared to their 160mm stuff. The actual objective body appears to be responsible for the field flattening aspect of the design and the negative common back lens of the entire system completes the corrections, while also modifying the focal point. The interspace between them is convergent. From that common fairly complicated lens system downstream, the system must have a high degree of corrections because most of the work has been done by the time the image gets to the tube lens. The tube lens itself buried in the head, is quite simple, a doublet that primarily appears to be a convergent focusing lens. It may be slightly compensating, since it would itself create some lateral ca and the objective system might be slightly overcorrected. One of the hallmarks of the system is the diameters. The tube lens is quite wide. It seems they utilized diameter as a simple but useful tool to limit dispersion.
If the Nikon objectives do provide ca free performance or in the case of the achromats...almost : how does the system compensate for the ca created in the tube lens? Presumably, that is the job of the eyepieces?
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Re: Nikon gene sequencer objectives
In the higher end Nikon heads the tube lens is not really a single lens. It's hard to get direct data but they sell an industrial standalone through Thorlabs (the itl200) which is described as apochromatic in its specs and looks very similar to what I've seen in their higher end heads.apochronaut wrote: ↑Wed Jan 13, 2021 1:33 pmIf the Nikon objectives do provide ca free performance or in the case of the achromats...almost : how does the system compensate for the ca created in the tube lens? Presumably, that is the job of the eyepieces?
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Re: Nikon gene sequencer objectives
I understand that Nikon has some pretty good optical solutions and sells a lot of pretty high end and expensive systems but whatever refined convoluted optics are applied there, don't really relate to the tube lens of an Eclipse 100.
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Re: Nikon gene sequencer objectives
Sure, the eclipse 100 is made in China and uses a simplified tube lens as well as lower FoV eyepieces, and it's also equipped with lower end objectives with smaller image circles. It has lower end optics made to lower overall standards, which is kind of the point. I'm not sure what relevance that has to the system as a whole, since the answer to 'how do we deal with inherent aberrations in a cheap system meant for students' is pretty much always just 'we don't.'
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Re: Nikon gene sequencer objectives
Yes but Nikon says they are CFI., just like the rest of their scopes. Are they or are they not? What then about the Eclipse 200 or 400. Are they more chroma free than chroma free? I'm not drinking the kool aid.Scarodactyl wrote: ↑Wed Jan 13, 2021 7:50 pmSure, the eclipse 100 is made in China and uses a simplified tube lens as well as lower FoV eyepieces, and it's also equipped with lower end objectives with smaller image circles. It has lower end optics made to lower overall standards, which is kind of the point. I'm not sure what relevance that has to the system as a whole, since the answer to 'how do we deal with inherent aberrations in a cheap system meant for students' is pretty much always just 'we don't.'
Re: Nikon gene sequencer objectives
I think we are talking about different things. As far as I know normal use of those terms is describing the direction the focal point is shifted in relative to ideal, not where in the field the aberration is present:apochronaut wrote: ↑Wed Jan 13, 2021 1:33 pmAxial must be the axis, where there is no ca. Where is lateral? Is it 10 degrees off axis, 20 degrees? It is actually, zero plus any degrees.
- Lateral/transverse: perpendicular to the optical axis, chromatic difference of magnification, for example.
- Longitudinal/axial: parallel to the optical axis, can be present on axis in the center of the image, what achromatic, apochromatic, etc. refer to.
Re: Nikon gene sequencer objectives
If you interpret CFI as meaning "objectives are not designed to have some standardized, non-zero chromatic difference of magnification" then I would say yes, nothing wrong with calling the cheaper less-corrected objectives CFI. Maybe makes more sense to think of CFI as a common specification objectives are designed to for interchangeability rather than a grand claim that CFI objectives have no chromatic aberration of any kind. Has Nikon ever claimed that?apochronaut wrote: ↑Wed Jan 13, 2021 10:32 pmYes but Nikon says they are CFI., just like the rest of their scopes. Are they or are they not?
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Re: Nikon gene sequencer objectives
Of course Nikon's lens designers never meant that all their CF and CFI series objectives were completely free of chromatic aberrations. Why would there be achromats in their lineup in that case? What it means, and I think you know this, is that the design principle was to let all the intended corrections take place in the objective, and let the eyepieces act as neutral relayers of the intermediate image. But an achromat will still have been designed to produce an intermediate image that is corrected at the level of an achromat.apochronaut wrote: ↑Wed Jan 13, 2021 10:32 pmYes but Nikon says they are CFI., just like the rest of their scopes. Are they or are they not? What then about the Eclipse 200 or 400. Are they more chroma free than chroma free? I'm not drinking the kool aid.Scarodactyl wrote: ↑Wed Jan 13, 2021 7:50 pmSure, the eclipse 100 is made in China and uses a simplified tube lens as well as lower FoV eyepieces, and it's also equipped with lower end objectives with smaller image circles. It has lower end optics made to lower overall standards, which is kind of the point. I'm not sure what relevance that has to the system as a whole, since the answer to 'how do we deal with inherent aberrations in a cheap system meant for students' is pretty much always just 'we don't.'
I think what you are trying to say is that the Nikon CF (chromatic aberration free) name is misleading. I can agree with that. But that's marketing, not optical design.
I don't think anyone is drinking any Kool-Aid here. It's just pretty neat to have apochromatic objectives that perform like apochromatic objectives even when used with direct projection. The final image isn't better than any other top brand from the same era, it just allows using the objectives in some ways that simply isn't possible with other brands.
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Re: Nikon gene sequencer objectives
Ooooooook then. I thought we were discussing the corrective/noncorrective nature of nikon eyepieces and tube lenses, but I guess I misread the thread. This feels weirdly personal so I'm out.apochronaut wrote: ↑Wed Jan 13, 2021 10:32 pmYes but Nikon says they are CFI., just like the rest of their scopes. Are they or are they not? What then about the Eclipse 200 or 400. Are they more chroma free than chroma free? I'm not drinking the kool aid.
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Re: Nikon gene sequencer objectives
Incorrect. I'm just saying I'm not buying what Nikon is advertising that's all.
Re: Nikon gene sequencer objectives
-Side info-
About those objective, I've found this nice blog with a few posts disassembling/hacking the sequencer they came from (Illumina GAII); it is a nice custom made microscope.
They were working with two lasers fluorescence and TIRF! Only the objective (and maybe the tube) is Nikon; rest wwew assembled parts. He say costed like 350-500 K$ new.
https://blogs.swarthmore.edu/Illumina+ ... n/?p=27
About those objective, I've found this nice blog with a few posts disassembling/hacking the sequencer they came from (Illumina GAII); it is a nice custom made microscope.
They were working with two lasers fluorescence and TIRF! Only the objective (and maybe the tube) is Nikon; rest wwew assembled parts. He say costed like 350-500 K$ new.
https://blogs.swarthmore.edu/Illumina+ ... n/?p=27
Re: Nikon gene sequencer objectives
Hello lads,
Regarding these Nikon OEM/sequencer objectives, should I buy one for my Motic B1 scope?
If yes which one 0500-0087 or 1501-9398 ?
Thank you!
Regarding these Nikon OEM/sequencer objectives, should I buy one for my Motic B1 scope?
If yes which one 0500-0087 or 1501-9398 ?
Thank you!
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Re: Nikon gene sequencer objectives
Maybe. You might be able to get the stage low enough to focus it, though there's a good chance it won't. The image is superb if you can get the right cover glass thickness.
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Re: Nikon gene sequencer objectives
Those are big objectives . With the necessary 25mm to R.M.S. adapter ( 25.00) needed to mount it, you will need at least another 20mm focus travel in order to use it. That just solves the problem of focussing the Nikon objective. You then have to struggle with such a hugely disproportionate difference in parfocality between it and your existing objectives. Add in 4 15mm adapter collars to the cost ( maybe about 40.00) and now you are over 200.00. Now you have a Nikon 200mm f.l. objective on an Olympus formatted stand. The corrections are not equivalent between the two and usually need some tweaking at the eyepiece.
I would be looking at an Olympus formatted planfluor. Won't be that much more.
I would be looking at an Olympus formatted planfluor. Won't be that much more.
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Re: Nikon gene sequencer objectives
I've tested the normal Nikon 20x planapo on a BX40. There really weren't any noticeable correction mismatches--the Nikon had very slightly more CA than an Olympus superapo (but that was hints when pixel peeping corners that were outside the nominal 25mm coverage) and no issues with planarity. The BX40 stand could just barely fit the objective but it would be guaranteed to crash if you mixed it with 45mm objectives withiut spacers and left no room for even slightly thicker subjects. Parcentricity was also bad with a lower-cost Chinese 25mm to rms adapter. More practical to wait for a deal on an olympus 20x fluor or apo which do sometimes appear.
Re: Nikon gene sequencer objectives
You are right, that objective is huge... Definitely not going to fit. Do you know if this objective(Nikon Plan Fluor 20x/0.50 DIC M WD2.1 Green stripe) will fit the Olympus IMT-2 ?Scarodactyl wrote: ↑Mon Aug 08, 2022 1:38 amMaybe. You might be able to get the stage low enough to focus it, though there's a good chance it won't. The image is superb if you can get the right cover glass thickness.
Re: Nikon gene sequencer objectives
The IMT-2 uses finite objectives. The one you've identified as a Nikon 20x "M" DIC is likely infinite - 60mm parfocal just like the gene sequencer 20x plan apo -- and meant for a more recent version Nikon Eclipse scope.
Seems that just a bit ago you were looking for a 20x compatible with a 45mm parfocal Motic "infinite" optics scope? If so, Olympus UIS objectives would, as noted earlier, be a good option.
Different story if you want a 20x for an Olympus IMT-2.
Seems that just a bit ago you were looking for a 20x compatible with a 45mm parfocal Motic "infinite" optics scope? If so, Olympus UIS objectives would, as noted earlier, be a good option.
Different story if you want a 20x for an Olympus IMT-2.
Re: Nikon gene sequencer objectives
Will that objective fit a Nikon E400 then?
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Re: Nikon gene sequencer objectives
The indicated 20x plan fluor is a cfi60 objective (the 'M' indicates it uses the M DIC prism in the condenser). It will fit an e400, same as the gene sequencer objectives. The normal 20x plan apo is still depressed in price and is oftenavailable for similar prices to the plan fluor.