LensRentals Celebrates Independence Day with Some Gratuitous Lens Mutilation


A couple of weeks ago I got an email asking if we would be willing to take some lenses, remove the electronics, fix the aperture wide-open, and permanently lock them at infinity focus. It seems the person who needed this done was having trouble finding a legitimate repair shop or service center that was willing to do it.

Well, illegitimate is our specialty, so I started negotiations about just how exorbitant a fee we would charge for this work. We quickly arrived at a fair price (no money, but we get to take pictures) and yesterday received brand new copies of the Canon 100mm f/2 and Sigma 35mm f/1.4 Art to work on. If you’re the kind of person who slows down to view car wrecks or spent $200 on fireworks for the 4th of July holiday, you might like this.

(For those of you who aren’t American, the 4th of July is when we celebrate our Independence by getting sunburned, making burnt offerings of animal parts in our backyards, and then eating said offerings. During the entire day, we drink massive quantities of American beer and once it gets dark we shoot off massive quantities of Chinese fireworks. All too often, the results of mixing alcohol and explosives prove that Darwin was correct — but hey, that’s what celebrating is all about, right?)

If torn apart camera lenses make you squeamish, then you won’t like this, and I suggest you not read further. You won’t miss learning anything; it’s just for fun. As best I can determine, this post has absolutely no practical use whatsoever. It’s just something to amuse and entertain those of you who are amused and entertained by such things.

Canon 100mm f/2.0

Being an older lens, we assumed this one would be simple to do. The plan was to remove the aperture assembly and electronics, then solder the focusing key at infinity. You know how plans go, though, so that isn’t exactly how it happened.

We started with removing the bayonet mount and rear barrel.


Then disconnected the flexes and removed the circuit board.


The mount removes as a single subassembly along with the rear focusing group. The focusing collar (red arrow pointing to it) sits in a fork connected to the focusing ring. Turning the ring moves the focusing element up and down in its helicoid. We had planned on soldering the fork in place, but with the lens disassembled, we couldn’t accurately check the infinity focus position so we had to go with our fallback plan.


Examining the front half showed the aperture assembly was going to be a problem to remove. One lens element is within the assembly, and it also has two light baffles that were important.


So instead of taking it out, we just put a drop of solder on the mechanics of the aperture ring, locking it in place wide open.


When we reassembled the front and rear halves we noted a lot of openings in the lens mount plate. Since this lens has something of a reputation for getting internal dust, Aaron decided to seal the openings up with double sided tape. Mostly, Aaron likes opportunities to fall back on his Fine Art degree. He spent 30 minutes carefully cutting out tape shapes.


For the same dust control reasons, we replaced the electrical connectors. They no longer connect to anything, but do plug up what would otherwise be a large hole at the rear mount.


We decided to set infinity focus using the MTF bench. Since the bench delivers collimated light (appearing to come from infinity) we just manually focused the lens until we had maximum MTF and minimum astigmatism. (As expected, this was not quite at the infinity mark on the distance scale.)


Once we had infinity focus locked on, we glued the focusing barrel to the rear lens barrel.


And, for good measure, glued it to the front barrel, too.


It’s not as slick and elegant as we would have liked, but it sure works.

Sigma 35mm f/1.4 Art

We thought the Sigma, with its more modern and modular construction, would be simpler to do and it was. As usual, we removed the bayonet to expose the PCB.


Then removed the PCB, exposing the aperture motor and controls.


The rear barrel then comes off by removing a few side screws.


Soldering the aperture lever worked well on the other lens, so we repeated it here.


After which we remounted the bayonet, but left the rear barrel off.


That let us mount it to the MTF bench with part of the focusing mechanism still exposed.


Once we had infinity focus locked on, we filled the focusing stays with Loctite silicone.


Once it dried, the focusing mechanism wouldn’t move with a pry bar.


We put the barrel back on before sending it to its new owner, of course.

About the author: Roger Cicala is the founder of LensRentals. This article was originally published here.

  • Frogonastring

    I may be being completely ignorant here, but what purpose would you have for locking it at infinity focus with a wide open aperture? What’s the end task for these two?!

    (Great pictures – and thanks for sharing such an oddball process!)

  • Matthew Dillon

    Very cool, I have a couple lenses I’d like to have modified in this way! I shoot a lot of landscapes in full moonlight, and that requires just this… wide open and infinity focus… and most lenses these days don’t have focus marks, and are often inaccurate when they do.

  • OtterMatt

    I was seriously just about to ask the exact same thing. I assume some sort of landscape work, maybe low-light?

  • Zos Xavius

    Video maybe? Its the best I can come up with.

  • Kristian H. Nielsen

    My best guess is that there is guy out there, who don’t have trust in the electronics. Maybe it’s that important to him that his lense focus at infinity that he doesn’t trust the electronics to do the job accurately.

  • Jason Wright

    I would guess some kind of Astro Photography?
    Having the focus fixed so you don’t knock it is a GREAT help in the pitch black of night, focusing on stars is a pain.
    You also pretty much just want wide open to get the most light in.

  • Roger Cicala

    Actually, it was for a laboratory. I don’t know exactly what they plan to do with them, but I imagine it’s got something to do with lasers.

  • Mike

    They sure are producing really weird pornography at that lab. I’d pay to watch.

  • Theo Lubbe

    “most lenses these days don’t have focus marks” I don’t know about MILC lenses, but the majority of (D)SLR lenses actually have focus scales on them as far as I’m aware. I’ve only ever seen budget lenses not have focus scales/windows.

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  • Marcus Manchester

    You were right, that was painful to see! But the internals of lenses always fascinate me, and it would be interesting to see why they needed this done!

  • Zos Xavius

    Those scales are rarely all that accurate. Notice how the one lens the tore apart had an inaccurate scale.

  • Zos Xavius

    Frikkin lasers!

  • Lukas Prochazka

    on every lens I’ve shot stars, stars on infinity are blured out and you have to bring focus little bit back…

  • Theo Lubbe

    I’ve not personally had much of a problem with the scales on the lenses I’ve used. At most I’ve had my EF-S 17-85mm have to focus past infinity when it got fairly hot while shooting outdoors, and I’ve seen my uncle’s EF 70-200mm f/2.8 L non-IS do the same once in a while.

    Manually focusing using the distance scales or setting the lens to precisely infinity, though – never had a problem.

    This being said, the faster the lens, the narrower the DoF, the less forgiving it is of not being calibrated properly, and calibration to my knowledge will influence the correlation between where one is focusing and where the lens’ focus scale will line up as well – so that may well be what lens calibration is for in the first place. To calibrate it.

  • Zos Xavius

    Most of my MF lenses (especially the older ones) all have good scales that have good infinity stops. The lenses I see the most with slightly off scales are the newer AF lenses. Probably because it doesn’t matter as much anymore to be honest. Some zooms tend to focus shift a bit too.

  • Jason Wright

    Depends if you are going by the “infinity” marking, the end of the focus range or “actual” infinity. They mention in the article they did a correct calibrated focus to infinity ignoring the markings/end stop.
    You are right that you have to bring focus back a little bit but as far as I was aware that was to bring it back into “real” infinity focus to which these lenses were fixed.
    I am far from a professional at this though so somebody with more knowledge may call BS on this…

  • Lukas Prochazka

    oh I dont know it might be the case, I just said it from my experience…but it makes much sense if that’s the case