I’ve been experimenting with a telecentric lens rig. My rig is cloned from a similar one created by Rik Littlefield, using gear I already own.
I’m guessing you’re thinking “What is a telecentric lens?” The honest answer is “I don’t know.” I’m not sure I’ll ever understand what telecentric lenses are and how they work. I’m hoping practical experience will result in better understanding of the theoretical.
So why have I written a blog post about a topic I don’t really understand? Good question! The simple answer is because I have learned enough, mostly from Rik Littlefield, to know there are practical advantages to using a telecentric lens for macro photography.
The best advantage of a truly telecentric lens is there should be little or no “focus breathing” as the camera moves closer to/farther from the subject. Essentially that means the apparent size of the subject should remain the same. That should enable better focus stacking because the outline of the subject is constant.
My Rube Goldberg telecentric lens rig
Rik Littlefield’s telecentric lens rig features the same gear as mine (described in the next paragraph) minus the Canon-to-Fujifilm lens adapter because he uses a Canon EOS Rebel T1i DSLR camera body with his rig.
My Rube Goldberg telecentric lens rig is cobbled together using a Raynox DCR-250 close-up filter attached to my Canon EF 100mm macro lens using the plastic clip-on adapter supplied by Raynox. The lens assembly is mounted on my Fujifilm X-T3 APS-C digital camera using a Fringer EF-FX Pro II adapter.
Rik developed another telecentric lens rig that results in lower magnification (0.8x versus 1.69x) but better image quality. I need to order some inexpensive parts before I can build and test that rig.
Testing 1, 2, 3.
The following closely-cropped composite image shows the result of my first test of the telecentric lens rig.
I shot 57 images of a toy plastic lizard using my NiSi NM-200 manual focus rail. I used an aperture of f/8 and a step-size of 100 microns, as recommended by Rik Littlefield.
Helcion Focus Method B was used to focus stack the “as is” JPGs from my camera. The resulting TIF file was cropped using Apple “Preview” — that’s about as quick and dirty as cropping gets!
Post Update
The first time I heard about telecentric lenses is when Allan Walls teased the topic during one of his YouTube live-streams. During a subsequent live-stream, Allan demonstrated how to make a lens telecentric using a rig similar to one that Rik Littlefield created.
Telecentric Lenses – Macro Talk Too – from Allan Walls Photography, June 29, 2023 (1:12:10)
Allan’s YouTube live-streams are one hour in duration, but there’s usually a lot of chit-chat during a typical live-stream that might not interest readers of my blog.
In this case, I recommend that you watch the segment from 11:22 to 30:21. A lot of what I have learned about telecentric lenses from Rik Littlefield and Allan Walls is covered during that part of the video. (If you continue watching the video beyond the 30:21 mark, then you will hear my name mentioned twice.)
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