3D-Printed 3D Pancake Lenses?

Here's a bit of a teaser for some projects I'm messing with: stereo lenses! A certain bokeh-exploring stereogram master here in the Adapted Lens Talk forum has inspired me, and I figured it would be fun to try it out with some Surplus Shed optics and some 3D-prints! I'll definitely still try out the sequential photos technique as well, but this thread is for the potentially ill-conceived projects. The amount of 3D-depth these can produce is a bit surprising given the relatively small distance between their "eyes," even if it's still a bit like looking at a diorama!

[ATTACH alt="Robo-Bonobo (left - with 37mm f/2.67-ish lenses - why does he have a face? Don't ask me) and in the center mounted to the S5 is a dual 25mm f/2.67-ish pancake lens. These are sitting on my 3D-printer, a Bambu Lab A1 Mini (love it by the way, it's been in "it just works" mode for a couple months straight out of the box). Both binocular optics have a rear baffle to mostly keep their sensor halves separate. Both adaptations have the same small "inter-pupillary distance". Both are wall-eyed. Fun fact: this photo was taken by a third 37mm lens adapted to M42."]3392215[/ATTACH]
Robo-Bonobo (left - with 37mm f/2.67-ish lenses - why does he have a face? Don't ask me) and in the center mounted to the S5 is a dual 25mm f/2.67-ish pancake lens. These are sitting on my 3D-printer, a Bambu Lab A1 Mini (love it by the way, it's been in "it just works" mode for a couple months straight out of the box). Both binocular optics have a rear baffle to mostly keep their sensor halves separate. Both adaptations have the same small "inter-pupillary distance". Both are wall-eyed. Fun fact: this photo was taken by a third 37mm lens adapted to M42.

The Optics

Surplus Shed has a couple of mounted lens assemblies that looked interesting to me. They go on sale every once in a while.

• The estimated-to-be 37mm f/2.67-ish lens is sold by Surplus Shed as a 40mm lens assembly . It comes with its own focus helical that is easily mounted and it was likely destined to be in a film-era AF or MF point-and-shoot (I cannot yet identify which one) with a max aperture of f/2.8 positioned directly behind the lens. Depending on the marketing department's mood it was probably shipped as a 35mm, 38mm, or 40mm optic, but never as what it really is hehe. The optics employ a Tessar-type design; 4 elements in 3 groups with a doublet in the rear.
  • Having bought a total of five of them, sample variation is pretty low(!), build quality is high (nice coatings, good edge-blackening), and image quality is very nice, but three out of the five unfortunately have noticeable strands of fungus internally - one eye in my 37mm doodad has some - like father like son.
  • The build and image quality is reminiscent of the lens from a Pentax PC35AF, which I adapted in the past, but these are not the same.
  • On their own these have 4mm of safe focusing extension for a theoretical MFD of 0.42 meters give or take.

• The 25mm f/2.67-ish lens is sold as being a 22mm triplet magnifier with an aperture close to f/2! Unfortunately that is not quite the case, but it's not all bad news. The true focal length is closer to 25mm or 1-inch, and the aperture is closer to f/2.8, but it is also an admirably performing Tessar-type with decent coatings. It performs well in the MFT image circle, while definitely not (understandably) covering FF. I have to wonder what their intended/original use case was as it does seem to be corrected for photography.
  • These are built nicely enough but the lens housings are of the sealed metal variety so they can't be easily improved upon (ZERO edge-blackening, it's a snowy mess in there that flares hard) or adjusted (one of two "eyes" is differently coated and is also mildly defective [stressed/crooked elements]).
  • The retaining hardware is very shiny which may account for some additional flaring and off-axis wonkiness.
  • These were threaded into a 3D-print to have about 3mm of safe focusing extension for a theoretical MFD of about 0.27 meters give or take.

Some Image Samples

Below are some sample images taken by the doodads in their current form. Instead of having each lens image on exactly half of the sensor, the left and right lenses are pushed towards the outer edge of the sensor by about 2mm apiece. This was due to the size of the 37mm lenses, but the blessing in disguise here is that the IPD is increased, which hopefully helps with any 3D depth captured. I decided to put the 25mm lenses at the same position in case the possibility of slapping some prisms and/or mirrors in front of these becomes more than a possibility.


An uncropped shot of what it's like to shoot with the dual 37mm

In this uncropped shot there are a couple of things I'd like to point out - as much as a third of the sensor is wasted mainly in the center where the images bleed together a little, and because the lenses are wall-eyed (what I mean by that is that they can't gimbal to a central subject like our eyes), the useful field of view narrows further starting from the edges of the sensor. I believe this gets worse as you focus closer. One other thing to notice is that both of these lenses can be a bit bubbly in terms of bokeh - this could prove to be very fun when singly adapted for some macros/close-ups!

The rest of the samples will be cut up a bit, and you're expected to use the cross-eyed viewing method, which can be straining. I am not able to do the parallel eyes method, try as I might. It may help to put blinders on some glasses to force your left eye to look right, and your right eye to look left. Hands work just as well. While there is no way to view these zoomed in and still in stereo, I've left them at full size in case someone has an 8K monitor/TV or in case anyone wants to peep some fine details, of which there are plenty if you care to find them.


37mm now cropped. All the images from now on will take this format. You may notice that your eyes are pretty good at cropping away portions of the image that don't quite work, making for an even-thinner-than-expected sliver of an image in the final view.


37mm.


37mm.


37mm


A stereo crop from the image above.


25mm.


25mm.


25mm.


A stereo crop of the image above centered on my intended focus point. There's definitely some depth here.


25mm


stooomed in once more


25mm

And lastly here's a couple from a single 25mm:







Some sample footage...

Well, I don't have any to share yet. But it's totally doable and not too hard to look at! Both Robo-Bonobo and the dual 25mm pancake have 62mm filter threads that I'll need to employ for the footage hehe.

Some thoughts...

• This has been all sorts of things - fun, challenging, silly, etc.
• I'm currently using a rear baffle/divider that can only get so close to the sensor - if you have any tips as to how to improve it, or if you have thoughts about a front-mounted solution, please chime in!
• I will likely eventually rig up some prisms / mirrors 1) to overcome the wall-eye and 2) to increase the IPD, especially if salvage from defective binoculars and dead SLRs (both of which I have a few) have enough coverage.
  • I will probably also pick up a viewer and one of the David White Stereo Realist bricks to view/shoot some film 3D photos with it eventually.
  • I will probably NOT get any of Leica's stereo lens sets hehe.
• Being wall-eyed doesn't matter a whole lot at infinity, but the imagery is especially paper cut-out diorama-like there.
• The image processing and viewing pipeline is a bit of a clustertruck right now.
• Composing shots is not easy, and I'm learning to work around the wall-eye limitation.
  • My S5's nifty custom overlay feature is a little helpful for this.
  • It seems especially important to keep the camera parallel with the hor[eyes]on.
• You can compose images on the back LCD while cross-eyed - if your subjects can't help but laugh at you, maybe one could get some great stereo portraits!