FM Lens Hack for Anamorphic Single Focus

September 23, 2016

It’s time to take things to another level on these tutorials. I asked Cosimo Murgolo to detail his steps on making this FM Lens Hack, the FM2 (Focus Module MODULE) Lens. The post below is derived from his explanation. I have not done the mod myself. I’ll part with the FM when I finish all the reviews. If I were to keep it, I would surely chop it. Cosimo’s main motivation with the mod was actually to fit his baby scopes inside and take them anywhere.

FM Lens Hack

Who is Cosimo Murgolo.

Cosimo is a big enthusiast and fond of good stuff like anamorphic. He’s trying to learn the most he can while journeying the long road to be a real cinematographer. His words, not mine! Oh, and as you might notice below, he likes to smash lenses. Cosimo was one of the pioneers with the FM Lens. He was constantly feeding the conversation about it with new information and his experiences. He is a great enthusiast of doing things yourself and he’s not afraid of the risks. Below is some of his work. All the images are so moody! It feels like jumping into a time machine due to their vintage feel.

girl with candles
vintage girl picture
flowers in the foreground, girl running in the background
kids playing by the water
girl playing by the water
boy playing by the water
girl with yellow lens flare


DISCLAIMER! WE ARE NOT RESPONSIBLE FOR ANY BROKEN OR DAMAGED LENSES. DO THE PROCEDURE AT YOUR OWN RISK! Now that we’re past the warnings, Cosimo did it successfully, and so did Jesse Heidenfeld, following the same instructions. So, if you’re using the right tools and working with care, you should succeed.

I want to open with a quote of his experience doing the mod. You know, for inspiration:

“This can be easily done with a lathe, the cut will be very tiring to do with the hacksaw. It was fucking exhausting, but desperation brings you anywhere” – Cosimo Murgolo, 2016.


The first step is to disassemble both positive and negative glass out of the lens body. Do this by removing the retaining ring on the front of the lens. Store them away in a safe location. There’s no need to risk their integrity hacking and sawing with them attached.

FM Lens front view
FM Lens glass elements

Now go on and take apart the body in two main pieces, the INNER and the OUTER tubes. The screws that hold them together are by the focus scale on the OUTER tube. There are a few more inside. Nothing tricky or new. Document your process, take photos and notes so you can put it back together

FM lens inside tube

Cutting and Drilling

More of a reminder than an actual step. Make sure you have clean cuts and holes. The threads should align even after being drilled through and cut short.

cutting and drilling marks

Looking at the INNER tube, cut it close to the end of the threads. Cosimo really stresses out you should play safe here. Save yourself another 10mm past the end of the threads. This is where you are going to be making holes for clamping the tube to your anamorphic. Cosimo’s recommendation is to use 5mm nylon screws. After you drill their threaded holes you can shave any excess at the end of the INNER tube.

Cosimo chose not to leave any room at all for compactness’ sake and drilled right onto the end of the threads. One big advantage of cutting a little further from the end of the threads is you can always shave off that extra space afterwards if you want to. You’re unable to extend what’s already been cut, though. So if you’re not 100% confident on your machining skills, or how the process is going, play safe. Don’t risk the entire lens on drilling the perfect holes.

FM lens hack: chopped up parts

Size and compromise

The mod’s goal is to make the FM shorter. It’s up to you to decide how much shorter you want it to be. The more of the OUTER tube you keep, the shorter is your minimum focus going to be. In Cosimo’s mod he knew what he wanted and 1m was enough for close focus, so he chopped off most of the OUTER tube. He cut at the end of the tapering from the wider front. You can keep a little more of the OUTER for the ability of going closer with focus.

Going back to the INNER tube, there are a few more things to consider. The most important ones are the small brass stops which calibrate minimum focus and infinity positions. For the mod’s sake, you are going to take these away. You will not be able to control where the OUTER tube stops unscrewing. As you don’t want your modded FM to unscrew right off the threads at minimum focus, we have to fix this issue.

Prevent it from falling off

Side note: My Iscorama pre 36 came with the close focus mod. That worked by removing a stopper inside the lens. It was neat, the problem was exactly the same: the front element would fall off the lens if rotated too much. You don’t want to have that happening to you on set. Or anywhere, for that matter.

Time to fix the unscrewing issue. On the unthreaded part at the front of the inner tube, just past the positive diopter, make two 3mm threaded holes on opposite sides. You are going to put little 3mm nylon screws in those. DO NOT SCREW THEM ALL THE WAY THROUGH THE TUBE as, if the screws go on the inside of the tube, they will be in the way of any scope you pair with the FM. The goal for these screws is to act as stoppers, preventing that the OUTER tube falls off the threads.

add holes for stoppers

Once the minimum focus screws have been put in, it’s time to create new infinity stoppers. Same thing, drill small threaded 3mm holes at the end of the threads to act as infinity stoppers. If you skip this step, every time you focus to infinity the positive and negative glasses will kiss (touch), and that’s no good over time.

Regrease and reassemble

Since the two pieces (INNER and OUTER tubes) now have a lot less contact area, the outer tube can become wobbly. Use a thick grease to fix this problem and reassemble the FM2. On a side note, Cosimo recommends you keep the rest of the body, as you can easily make clamps and things like that by drilling new holes on it! Here’s a comparison between a DIY clamp made with the leftovers of the mod and the FM Collar 24.

Now you are ready to take on the world with your old (but new) FM2 single focus setup. This mod allows you to fit way more scopes in the FM as well as solves the problem posed in the assembly video, with the Kowa B&H. The problem is the Kowa B&H stays either too far from the focusing diopter or too far from the taking lens when fit inside the FM Lens.

FM lens hack with a scope behind it
FM lens hack on Canon 5D3

I’m trying to expand the written posts with other collaborators, besides the videos themselves. If you have something that you think it’s a great idea and you want to share it with the community, don’t be shy and reach out, send me a message, leave a comment!

– all photos by Cosimo Murgolo and used with his authorization