Lomo Foton-A Follow Focus?

David Hessel · August 20, 2018

I have one of these and due to the nature of its design, the separate anamorphic front being held down by rails ends up making the lens more resistant to focus, I can never seem to get everything perfectly aligned so there is zero binding. It is not bad at all but I have found that follow focus units wear down quickly and build up backlash rather quickly during prolonged use with this lens. Some of this is due the lower level of follow focus's I have used so far but I am looking for suggestions on a solid metal robust follow focus I might be able use with this lens that will stand the test of time.

Thanks in advance.

Adam Froehlich · August 30, 2018

Here's some of my limited experience with the Foton-A:

I just ACed a feature where we did 10 days with a Lomo 37-140mm and the Foton-A front. During prep, we tried to go wireless with a Cinegears system, but obviously the motor wasn't strong enough, so we ended up using an older Arri FF-2, a solid metal beast. 8 Days in and the Foton had stripped several of the teeth from the drive belt that connected the gear to the main body of the follow focus. I pulled focus from the barrel for the rest of the day, and just kept doing that for the next 2 days because it ended up being way easier. So bottom line, even a tank of a follow focus will have some trouble.

We ended up ditching the lens once we moved from principle to greenscreen/vfx, it just caused too much trouble. Through trial and error we found that you can adjust the drag of the focus by adjusting the tension on the 4 indicated small screws along the A portion of the lens in this picture. Be EXTREMELY CAREFUL, however. Too much tension, and the focus is basically locked in place, too little, and the parts labelled A & B will start to drift, and elements will become misaligned to produce a very soft image (this was one of the main reasons for switching to different lenses.) Each screw also seems to dictate the drag on different sections of rotation, making it harder to set it consistently across the entire rotation. Setting a common mark between A & B before doing anything may be a good idea, should they become misaligned.

I would be interested to hear from someone with more technical knowledge of the Foton-A. All of my information has come from trial and error, and in the end, we still had to accept defeat, so take my advice with a grain of salt.

David Hessel · August 30, 2018

Thank you for the response, I am seeing the same thing. Basically there is no follow focus out there that can hold up to consistent use with this particular lens. In my particular instance there is play in the rig like a little rotation in the bridge plate when attaching it where I might not have the rods perfectly perpendicular to the sensor plane. That along with the lens support have some wiggle room makes it easy for some binding to develop if everything is not perfectly aligned.

Mine was just serviced and both elements individually are not stiff at all, but together on the rig there is much more resistence. So that is going to be my next move is to try and dial in everything perfectly, one of the problems with using cheaper rigging gear I suppose.

Lastly, I am not completely sure but I believe those 4 screws are there to hold outer shell with the distance markings in place, probably the reason it went soft when you moved it was it altered the synchronization of the front with the taking lens. So if the taking lens in on infinity, the anamorphic front is not. It is how you fine tune the synch to get the best image.

Thanks again for all the advice and I will post any solution I come up with, for now I have reverted to using the focus rods instead.

Edited August 30, 2018 by David Hessel

Adam Froehlich · August 30, 2018

Lastly, I am not completely sure but I believe those 4 screws are there to hold outer shell with the distance markings in place, probably the reason it went soft when you moved it was it altered the synchronization of the front with the taking lens. So if the taking lens in on infinity, the anamorphic front is not. It is how you fine tune the synch to get the best image.

You're likely correct. Luckily, we were moving on at the point it became a problem. Thanks for the advice, I'll be sure to re-calibrate the one we used with that in mind soon.

David Hessel · September 9, 2018

So I think I found a solution. First, when attaching the lens to the camera you want to attach just the spherical part first then adjust and attach the anamorphic front by adjusting its position until it slides easily down on the spherical section. This significantly reduced binding and the lens is much easier to focus. It is still stiff compared to most lenses but improved. Second, I purchase a Cinevate Durus follow focus. This is a very strong follow focus with no plastic in the gears other than the last focus gear which is rather thick. I have been using this combo for nearly a week now and no built up in backlash or any signs of wear happening anywhere.

Edited September 9, 2018 by David Hessel

Kyryll Sobolev · September 28, 2018

i just received a foton 37-140 (without the anamorphic attachment), and it is also exceptionally difficult to move the focus ring.

i had a suspicion that because of its age and lack of maintenance the grease inside has dried up. so i talked to oleks, and that is exactly the problem. grease in that lens over long periods of time becomes more like glue.

so it is likely your lenses have not been serviced in a long time.

and to properly re-grease this lens is quite a process.

here is a photo oleks showed me of this lens taken apart.

the brass ring is the threaded focus block - which you can take out from the front of the lens, and grease the threads.

in this particular photo the threads are actually filed down (i don't know why).

but then you have to disassemble from the back of the lens to access the focus ring, and grease its threads.

anyway... periodic maintenance is what your lenses need

Edited September 28, 2018 by Kyryll Sobolev