Question on an SL2 dimension

[rubidium]

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Does anyone happen know the distance between the sensor plane and the bayonet flange on the SL2? I am trying to put together a macro setup using a bellows and a low-power objective from a Leitz Orthoplan microscope. The objective optics is intended for a so-called "tube length" of 160 mm, which is the distance from the objective's exit pupil to the desired image plane for optimal sharpness across the field.

Thanks,

Jim

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[jaapv]

20.00 mm

https://en.m.wikipedia.org/wiki/Flange_focal_distance

[rubidium]

Wow. I never would have thought of searching for the term "flange focal distance", but there it is! Perfect! Thanks.

Jim

[graeme_clarke]

I created a similar set up with an M bellows and adapters to fit onto an SL601. (M- L mount adapter for the body, M42- RMS for the lens onto an extension tube and bellows).

The first attempt was with a 4X objective marked 160/0.17 which was the size of the objective I used in microscopy when I taught biology.  The working distance was tiny - only a few mm.  Research on Google informed me I needed a 4X objective set for infinity.   Obtained cheaply from China the one I have is marked 8/- and does give a little more working distance.

It has a fixed aperture which the camera tells me is f19. Focusing ensured by using the magnification facility on the screen and a rack and pinion device between tripod head and camera to move the whole assembly.

What I found frustrating was the  difficulty with making manual focus adjustments for focus stacking because of the extremely narrow DoF.  All this was inspired by Levon Biss's images of insects made by moving his camera and lens with a stepper motor turning a micrometer screw feed.  I believe Novoflex now produces a device that does all this electrically but I've no access to this kind of kit.

Images I've seen made using this equipment can be stunning!  Google Robert Thompson for his reviews.

I've gone back to using a 100mm macro R 2.8 and 1:1 adapter with a solid tripod, then cropping in on the image.

Good luck in your quest...

Graeme

[rubidium]

I'm just experimenting at this point. I have had the superb Leica 100/2.8 Apo-Macro-R (and the 1:1 Elpro made for it) for some years. Arguably it's my most cherished lens and I'm pleased to have it getting a new life with the SL2 and R-to-L adapter.

I have also had a Leitz Orthoplan for about 10 years, refurbishing it as a hobby project, but with on-and-off motivation to set it up for any serious photography. But recently, I've gotten inspired (again) and finally got around to integrating the SL2 to it and doing some focus stacking. Since the microscope is presently configured for transmitted light, I've only been exploring specimens suitable for that, like diatoms. Focus on the Orthoplan can be adjusted in 1 micron increments (perhaps a bit less with care), so focus stacking works nicely with these specimens at high levels of magnification. But, now I am developing an interest in insects and the transmitted light setup isn't useful there.

So recently I acquired a second-hand Novoflex bellows (not the super expensive one with the stepper motor that you mentioned) along with a focusing stage - the smallest increments of which being 10 microns (perhaps I can do half that with care.) So that limits me to the magnification level of about 5:1 or less to successfully do focus stacking. Coincidentally I have a 4x NA=0.20 APO microscope objectives that I would like to try with this setup. In principle, it should have a 14.8 mm working distance at 160 mm exit pupil - to - camera sensor plane distance for which it was designed. That working distance is borne out on the Orthoplan, which has that 160 mm "tube length", so I should be able to achieve the same with the bellows. Of course setting up the right lighting will be the next challenge.

 

Cheers,

Jim

[graeme_clarke]

Hi Jim,

Interesting - your descriptions look like we've both followed similar paths. Let us know how you get on please...

Best wishes,

Graeme