Main Body 6.1.1 too short with optics_picamera_2_rms_infinity objective


Tooday I was hopping doing some nices pics with an objective Olympus planN 4x infinity so I print the optics_picamera_2_rms_infinity_f50d13

When I mount this optics the main body isn’t tall enought and must be rise to use this optic even if we rise the sample.

If we rise the sample for 2-3cm so the illumination dovetail became too short too…

Have you any tips or stl for that use ?

Best regards

hmm - that’s odd, I must admit I’m not sure if I’ve ever used the infinity corrected version in anger, it was added in response to some people who requested it. I designed it for the same parfocal distance as the regular objectives (45mm from shoulder to sample if you use the 10mm riser). Is the problem that your objective is taller than that?

It’s easy enough to render a taller illumination dovetail, though it’s not in the standard automatic build. Do you know the parfocal distance of your objective?

45.06 mm Parfocal Length indeed.

After some test the sample rise need to be 20mm if you fix the optic on the max upper side of Z, and by the way, the key passthought for the optic screw is to low and not that helpfull in this position…

The problem is I need to fix the optic as high as possible because if not the bottom of the 3d printed obtic is touching the Pi.

What happen if we put an infinity objective on an none one ?

If you have an infinity corrected lens and use with a finite back focal distance the working distance to the sample will increase (if you think of it as a simple lens). The image quality will also degrade, probably much more than you might think.

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Just thinking a little more. The parfocal length is 45mm: when you construct the microscope with the parts you have, what is the distance from the objective mount to the sample stage? If it is less than 45mm, that may be why you need the sample higher. If it is 45mm, the problem is in the optical part: the focal length of the tube lens and distance from tube lens to camera. Have you checked the tube lens is f=50mm? The simplest way is to focus the image of a window or lamp on the other side of the room onto a piece of paper and measure the distance from lens to paper. It will be slightly more an 50mm for a f=50mm lens, and does not need to be very precise: you are only checking that it is not f=25 or 40 or 70 by mistake (a mistake I often make)

Ah I see - probably the best solution is to make a taller version of the microscope stand. If you are able to clone the repository and build the STL yourself from the OpenSCAD file (either using the build script or just the OpenSCAD program), then it should be fairly easy to make a taller version of the base (I think the height is set at 30mm by default, so you can just dial up the extra height you need).

I check and I find 45 mm indeed

Here a pic of the mounting optic and final result

I need to learn OpenScad first, I just follow basic training and really I dont want to mess it up, but can give a try.

Thanks for your support

That is a really nice image @Gris74 . The 45mm is measured with the metal and blue risers in place and you cannot move the lens down because of the pi base below? Modifying the parameter in OpenSCAD as @r.w.bowman suggests would give you the neat microscope, but OpenSCAD needs a little learning. Could you instead put the metal stand-offs between the microscope and the base to give you the extra room? Or house the pi beside the microscope instead so that the lens can go down into the pi base?

Yes the 45mm was mesure this way.

Not in this configuration with my metalic rise, but from the official release 6.0.0 the infinity corrected lens is pushing the Raspberry cam connector.

Thanks for your tips about moving my metalic rise between microscope and the base, i will give a try.
Anyway I need to do some mesurement for the exact rise value for this infinity corrected lens and will share here, and I will go for some hours of OpenScad learning I dont see other alternative.

Really appraciate your help

Gris74, on such a simple model (slide_riser_LS10.stl) you can increase the size along the Z axis in the slicer.

That’s a good shout - the sample riser ought to work just fine if you double its height, though you’ll need some longer M3 screws.

I’ve made you a taller version of the stand, as it wasn’t a big change (it’s always easier to tweak things when you know where to look already :wink: If you’re curious, the tweak to the code is here:

Here’s the STL:
microscope_stand_45.stl (831.0 KB)

As I don’t have an infinity corrected microscope to test it with, I would be grateful if you could confirm this works. If it does, I’ll get it included in the standard build and instructions. In case it saves you a print, I’ve made it 15mm taller. If that sounds like too much or not enough, just shout and I can easily tweak that. Looking at your photo, I suspect I’d have gotten away with 10mm, but the extra 5mm won’t take long to print, and improves your chances of getting it to work first time!


Thanks, printing on his way !

I will give you my feed back ASAP

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So the last body you send me feet as a charm !.. perfect for any distance with 10mm rise sample holder.

Can you do a BS version of this body as I can test it with infinity lens with BS

I Didnt test this option, the body one was better to my point of view.

microscope_stand_45-BS.stl (849.4 KB)

Hopefully that does the trick :slight_smile:

This is now in the auto-build script, so will be in the next release.