Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

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hans
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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#31 Post by hans » Fri Jul 31, 2020 11:31 pm

This should be a direct link to download the Nikon NEF files, four total including the glass cylinder comparison photos I posted in Brian's thread:
couple.zip


MichaelG.
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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#33 Post by MichaelG. » Mon Aug 03, 2020 6:07 am

A nice clear illustration of the word ‘expedient’

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#34 Post by apochronaut » Mon Aug 03, 2020 12:14 pm

Why not just use a 145 eyepiece placed at the correct reference length?

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#35 Post by hans » Mon Aug 03, 2020 3:40 pm

apochronaut wrote:
Mon Aug 03, 2020 12:14 pm
Why not just use a 145 eyepiece placed at the correct reference length?
Referring to this thread or the one with the rock-hammered glass cylinder? Personally, the 181 with corrective element is what I already have, since I ended up with more heads than I need. The other thread, unfortunately gives no further details on what "impact to the image" led them to remove the glass cylinder. I wonder if that choice of phrasing was a coincidence...

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#36 Post by Zuul » Mon Aug 03, 2020 3:51 pm

The meathod of removal also greatly hindered the chance of determining whether that cylinder is/was actually a doublet.

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#37 Post by apochronaut » Mon Aug 03, 2020 5:16 pm

I was referring to the optical engineer from photo..... I would be interested in the photo results.

No, Hans is correct. I took the dovetail off of two of them and the one that I had previously viewed has a seam like line right around the cylinder. It is probably where the bottom line of the cement ring that holds the column is . It is quite regular and does look like an optical cement line. The other one however only has a portion of that, so it does look like a glass rod of unvarying n.

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#38 Post by Zuul » Mon Aug 03, 2020 10:07 pm

I was able to get the CA-correcting optic into the path between my trinocular port and the camera for some quick testing. This was done direct to a full frame sensor in order to capture the entire width of the projected image. No optical components were in the light path other than the corrective optic. I used the Reichert Austria 25x and 40x PlanAchro. Each image is a composite of 2 captures; one with, and one without, correction. I am hosting them on my Google drive so that interested parties can download full resolution copies. I will leave them up for at least a week, but they won't be there indefinitely.

I'm not ready to start sacrificing parts to the DIY gods. (No components were harmed in the making of this film ... and there in no film. :D ) Because of this, some (not insignificant) concessions were allowed to simplify the set-up. The first is that the location of the correcting optic was in no way optimized, or even selected with purpose. It is were it is because that's where it would fit without altering any parts. It happens to be roughly 50mm from the sensor if you're keeping score at home. The second concession is that the optic is being used "backwards". The side that would face the eyepiece as assembled into the binocular is facing away from the sensor. Obviously this is not the way I would have preferred, but that's how it worked out.

https://drive.google.com/file/d/1MOMIsX ... sp=sharing

https://drive.google.com/file/d/1a4VIpP ... sp=sharing

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#39 Post by MichaelG. » Mon Aug 03, 2020 10:19 pm

Zuul wrote:
Mon Aug 03, 2020 10:07 pm
Each image is a composite of 2 captures; one with, and one without, correction.
Those look pretty convincing !

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#40 Post by hans » Mon Aug 03, 2020 11:39 pm

Zuul, thanks for posting, I was curious about this configuration and your results look promising. To make sure I understand the setup before commenting further:
Zuul wrote:
Mon Aug 03, 2020 10:07 pm
No optical components were in the light path other than the corrective optic.
Does this mean telan --> corrector --> sensor? Were any of the flat glass elements (prism, splitter, or cylinder) involved?
Zuul wrote:
Mon Aug 03, 2020 10:07 pm
I used the Reichert Austria 25x...
Was this objective designed for use on the 410? I ask because I think the uncorrected transverse CA looks worse than I am used to seeing on the standard 4/10/40/100 plan acho objectives, which is alI I have.
Zuul wrote:
Mon Aug 03, 2020 10:07 pm
...direct to a full frame sensor in order to capture the entire width of the projected image.
So the minor divisions on the micrometer are 10 um, and these are showing the entire image circle coming out of the optics, well beyond where it would normally be cropped at 20 mm diameter in the intermediate image plane by the field stop in the eyepiece?

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#41 Post by Zuul » Tue Aug 04, 2020 1:09 am

hans wrote:
Mon Aug 03, 2020 11:39 pm
Zuul, thanks for posting, I was curious about this configuration and your results look promising. To make sure I understand the setup before commenting further:
Zuul wrote:
Mon Aug 03, 2020 10:07 pm
No optical components were in the light path other than the corrective optic.
Does this mean telan --> corrector --> sensor? Were any of the flat glass elements (prism, splitter, or cylinder) involved?
I did not alter the trinocular head in any way. The elements that Reichert put in there are still in there. There was no eyepiece, no camera lens, no relay lens, no teleconverter, etc.

hans wrote:
Mon Aug 03, 2020 11:39 pm
Zuul wrote:
Mon Aug 03, 2020 10:07 pm
I used the Reichert Austria 25x...
Was this objective designed for use on the 410? I ask because I think the uncorrected transverse CA looks worse than I am used to seeing on the standard 4/10/40/100 plan acho objectives, which is alI I have.
I believe that all DIN 45mm parfocal Reichert objectives are compatible. Apochronaut can tell you more. That said, I was surprised to see so much less CA on the uncorrected 40x. Other test shots were more in line with the 25x to my eye. Regardless, these are unedited other than color temperature and exposure normalization.

hans wrote:
Mon Aug 03, 2020 11:39 pm
Zuul wrote:
Mon Aug 03, 2020 10:07 pm
...direct to a full frame sensor in order to capture the entire width of the projected image.
So the minor divisions on the micrometer are 10 um, and these are showing the entire image circle coming out of the optics, well beyond where it would normally be cropped at 20 mm diameter in the intermediate image plane by the field stop in the eyepiece?
Yes, those are 10 um divisions, and yes, this goes well beyond the 20mm allowed to pass the field stop.

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#42 Post by apochronaut » Tue Aug 04, 2020 1:13 am

Finally! it has been clarified. Like ghee.

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#43 Post by Zuul » Tue Aug 04, 2020 1:22 am

apochronaut wrote:
Tue Aug 04, 2020 1:13 am
Finally! it has been clarified. Like ghee.
I’ll never understand clarified butter. The milk solids (and salt!) are the good part!

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#44 Post by apochronaut » Tue Aug 04, 2020 1:30 am

The solids burn at a low temp. Nothing wrong with backwards. that is more consistent with what I see using the optics at the correct reference length. I don't mean the correct projection length, which doesn't matter, except for the sensor size.

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#45 Post by hans » Tue Aug 04, 2020 2:51 am

apochronaut wrote:
Tue Aug 04, 2020 1:30 am
...using the optics at the correct reference length. I don't mean the correct projection length, which doesn't matter, except for the sensor size.
What is reference length, and how do you set it independently from projection length, for a given sensor size?

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#46 Post by apochronaut » Tue Aug 04, 2020 3:06 am

Reference length is roughly the distance from the telan lens to the intermediate image. It usually is measured surface to surface of the lenses and structures involved in the system but it actually is meaured from the back focal plane of the telan lens system to the upper edge of the optical tube. This is the convergent section of the optical system in an infinity corrected system.

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#47 Post by hans » Tue Aug 04, 2020 4:05 am

apochronaut wrote:
Tue Aug 04, 2020 3:06 am
Reference length is roughly the distance from the telan lens to the intermediate image.
I think I understand... the reference length is considered correct as long as the objective is kept at the intended working distance from the specimen. And in your experience, modifying the distance between the eyepiece and intermediate image, as is necessary to project a real image sized appropriately for something like APS-C, generally doesn't degrade image quality?

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#48 Post by MichaelG. » Tue Aug 04, 2020 5:39 am

hans wrote:
Tue Aug 04, 2020 4:05 am
apochronaut wrote:
Tue Aug 04, 2020 3:06 am
Reference length is roughly the distance from the telan lens to the intermediate image.
I think I understand... the reference length is considered correct as long as the objective is kept at the intended working distance from the specimen. […]
Here is Nikon‘s description, with helpful illustations:
https://www.microscopyu.com/microscopy- ... al-systems

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#49 Post by hans » Tue Aug 04, 2020 6:03 am

So in practice "using the optics at the correct reference length" is equivalent to "using the optics with the objective at the intended working distance from the specimen"?

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#50 Post by MichaelG. » Tue Aug 04, 2020 6:52 am

hans wrote:
Tue Aug 04, 2020 6:03 am
So in practice "using the optics at the correct reference length" is equivalent to "using the optics with the objective at the intended working distance from the specimen"?
Yes, I agree

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#51 Post by apochronaut » Tue Aug 04, 2020 1:35 pm

hans wrote:
Tue Aug 04, 2020 4:05 am
apochronaut wrote:
Tue Aug 04, 2020 3:06 am
Reference length is roughly the distance from the telan lens to the intermediate image.
I think I understand... the reference length is considered correct as long as the objective is kept at the intended working distance from the specimen. And in your experience, modifying the distance between the eyepiece and intermediate image, as is necessary to project a real image sized appropriately for something like APS-C, generally doesn't degrade image quality?
It does. You will get ca for one thing. In my set up the reference length isn't exact because I have a physical component that provides a nice location for an axially aligned photo optic. 181 doesn't work so well there, so I found a better solution.

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#52 Post by hans » Tue Aug 04, 2020 7:38 pm

Thanks, if you don't mind a bit more questioning:

From Brian's thread it sounds like you have a complete Photostar system but aren't using the relay optic, was it just not a good magnification for APS-C? Is it possible the glass window in the top of the shutter assembly is actually this same corrective element that is at the base of the binocular eye tube? (It looks like that would be about the right location if the Photostar stuff was closely following the design of the binocular path.)

The corrective effect you are getting from the 145 eyepiece (intended for 570 StereoStar?) is presumably some combination of CA due to modifying the distance to the intermediate image with intentional design difference between the 181 and 145. Do you have any sense of the relative importance, for example from trying a 145 in a 410 or a 181 in a 570 for normal viewing?

Regarding correct reference length, in your setup I understand you put the 145 where is because of the convenient, existing mounting location, but why not make the reference length exact by moving the camera/sensor a bit?

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#53 Post by apochronaut » Wed Aug 05, 2020 2:16 am

The photostar lens had a slight imperfection, plus it does not capture the entire 20mm field .
I don't view the optical window in either the visual eyepiece tubes or the photostar as corrective optics at this point. I need to see that the optical window is in fact a sandwich .

I never tried a set of 181 eyepieces in a Stereostar but I will. I do know that the 145 eyepieces work very well in a series 4, as good as the catalogued 146 eyepieces.

Moving the camera/sensor won't change the reference length but moving the eyepiece will. I have checked into that some and plan to adjust the eyepiece location some in future. I will probably delete the shutter box from the system and install a helicoid in order to fine tune the eyepiece location.

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#54 Post by hans » Wed Aug 05, 2020 6:12 am

apochronaut wrote:
Wed Aug 05, 2020 2:16 am
I need to see that the optical window is in fact a sandwich .
This is the one I mentioned earlier with some spottiness in the AR coating. It actually came out more easily than I was expecting without major physical damage. I used a propane torch on the eye tube (heating the aluminum only) until there was a slight pinging/popping noise I guessed was the adhesive giving up as the tube expanded, then it pushed out easily. No idea how hot things got except that the aluminum was well above 100 deg C. At temperature the adhesive became sticky then while still warm the residue cleaned off the edge of the element easily with 99.9% IPA. I didn't try any solvents on the adhesive before heating but would have been surprised if IPA worked since I have cleaned a bunch of the assemblies with the same stuff and never noticed any effect. Maybe some permanent degradation during heating made it susceptible?

There is a slight brownish tint to the cement in the element, not sure if was like that before or was caused by the heating.

Pretty sure the orientation shown in the photo is correct but I forgot to keep careful track after taking it out:
reichert-410-corrector-removed.jpg
reichert-410-corrector-removed.jpg (152.18 KiB) Viewed 117 times

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#55 Post by MichaelG. » Wed Aug 05, 2020 6:20 am

Well done, Hans !!

Now you have extracted it, could you please refine the estimated dimensions for me

Thanks
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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#56 Post by apochronaut » Wed Aug 05, 2020 11:02 am

Very good. Wonder what glass formulas they used?

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#57 Post by hans » Wed Aug 05, 2020 3:43 pm

apochronaut wrote:
Wed Aug 05, 2020 11:02 am
Wonder what glass formulas they used?
I wonder too, in particular: Is it designed like a typical achromatic doublet, with optical power equal at two wavelengths, and the chromatic difference of magnification is a typical side effect? Or is the choice of index and dispersion characteristics fundamentally different, optimizing for large chromatic difference of magnification with no attempt to make it achromatic in terms of optical power? Or are there not enough degrees of freedom in designing something like this for that to even be a useful distinction?

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#58 Post by hans » Wed Aug 05, 2020 3:54 pm

MichaelG. wrote:
Wed Aug 05, 2020 6:20 am
Now you have extracted it, could you please refine the estimated dimensions for me
Thickness is 6.8 mm, joint is 1.6 mm from the face. I don't really get any better sense of internal curvature now than what I estimated earlier with the violet laser.

Since I decided not to experiment with configurations without eyepieces I have no specific use in mind for the removed corrector other than reverse engineering. If anyone wants to suggest ways to separate the doublet I would be happy to try.

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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#59 Post by MichaelG. » Wed Aug 05, 2020 3:58 pm

hans wrote:
Wed Aug 05, 2020 3:43 pm
... and the chromatic difference of magnification is a typical side effect?
as per my ‘guesses’ on page_1

Happy rework this if you can give me better numbers.

MichaelG.

.
Edit: Just seen that you have posted them already !!
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Re: Reichert 410 "Microstar IV" head -- corrective element present in binocular path but not trinocular camera port

#60 Post by Zuul » Wed Aug 05, 2020 4:14 pm

hans wrote:
Wed Aug 05, 2020 3:54 pm
Since I decided not to experiment with configurations without eyepieces I have no specific use in mind for the removed corrector other than reverse engineering. If anyone wants to suggest ways to separate the doublet I would be happy to try.
Soak in Xylene or Acetone? I'd use a diamond saw if I had access. :lol:

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