3D-printed RMS adapter for Sony, Canon, Pentax, Nikon cameras for 4x macro

[thenickdude]

Hey all,

I had been shooting in the 1x-3x realm using mostly 50mm lenses on extension tubes, but I had been getting tired of the large-diameter of the front of the lens and the tube itself, which pushed leaves out the way, blocked the light, and generally disturbed my subjects. So I designed and 3D-printed a slimline RMS adapter for Canon EF/EF-S, Sony E/FE, Nikon F and Pentax M42 cameras:

At the tip this narrows to be basically just the diameter of the objective itself, which makes it considerably smaller than typical flat or even conical adapter setups.

I've been using it with the Amscope Plan 4x objective, and even without considering the cheap price of this objective ($20) the performance has been remarkable, with absolutely minimal vignetting or chromatic aberration, good resolution and contrast across the frame, and I've seen no problems with flare. Going forward I think I'll be using this objective rather than lenses on extension tubes!

I have a small gallery of photos I've taken using this here:

https://imgur.com/a/2rUz2U8

You download the files to 3D-print your own copy of the extension tube here:

https://www.thingiverse.com/thing:5130912

[ray_parkhurst]

Nice pics. Looks like either the shape of the extension or the "ribbed" internals are doing a good job of minimizing reflections. Or did you also add some flocking, or paint the inside, or ? The cone-shaped adapters generally need these treatments. Yours is more like a long RMS extension tube so maybe that is better for reflections. In any case, the pics have good contrast and no hotspot so "good job".

[Scarodactyl]

Very slick! Though it does add some cost, it might make sense to have threaded ends to allow an m42 helicoid to be added to the stack, though I don't know how much this particular objective tolerates different extensions.

[thenickdude]

This one is only ribbed, no flocking. Painting would be a good idea on the PETG version I printed because it's pretty shiny (performance already seems fine with the ribs though). The ABS one I printed is matte enough that it probably outperforms paint already.

The internal cavity is round at the objective end, and this smoothly expands over the length of the tube to a rounded rectangle shape to match the sensor at the camera end. The goal was to eliminate any sharp profile transitions and to hug the light cone to maximise the scattering applied to off-axis light.

An M42 mount at the camera end could be interesting for slipping in other adapters. EDIT: I've now added an M42 version

[thenickdude]

Here's a comparison of the surface finish of the PETG and ABS versions:

And here's a cutaway showing the smooth transitional shape of the internal cavity and the ribbing:

[rjlittlefield]

Note also the discussion at https://www.dpreview.com/news/653806495 ... newsletter .

Same material, different audience.

--Rik

[MarkSturtevant]

This is excellent, and offers a way to try this sort of lens at minimal cost. In fact, since my oldest son is a 3-D printing guru, the adapters would be pretty much free! Thank you for doing this!
The ribbed internals suggest to me that flocking would not hold on very well. But that does not seem necessary anyway.
A threaded M42 insert might offer a way to do focus stacking by minute turns.

[physicsmajor]

Would you consider making a Nikon F mount variant?

[thenickdude]

There's one designed by Kajashey here:

https://www.thingiverse.com/thing:5155122

I'm not sure what the internal reflection performance is like, but I suspect it'll need flocking added to perform well.

I think I could design one too. Do you have a crop sensor or full frame?

[thenickdude]

I've now added versions for full-frame and crop Nikon F mount cameras. However these need more testing on modern Nikon cameras (I only tested it on the Nikon F (1959) which probably misses mount features found in newer cameras). Be sure to check the printed mount doesn't jam against newly-invented mount structures.

https://www.thingiverse.com/thing:5130912