Any AC can comment on focusing with photography lenses?

V

Victor Nhat Nguyen

Well-known member
So I have never use a follow focus system and it sounds interesting for when I do complex moves with focus shift. However all my lenses are vintage photography lens. I wonder if any actual AC can comment on the pros and cons of using photography lenses for cinema.
 
not sure what youre looking for. aside from possible vignetting, lens "breathing" is about the only thing id consider a categorical "con" of older still glass
as an inexperienced user of a follow focus, id suggest you pay as much attention to the specific follow focus unit as the lens type. nothing wrecks a focus change like a cheapo or poorly set up follow focus
 
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The big problem I have with photography lenses is the impossibly short focus throw. 0 to infinity is a 30 degree turn of the ring. A real cinema lens would be a full turn for the same rack.

The good thing about older lenses is that they don't have electronic focus, so the rings have hard stops. I really really hate the rings taht don't have hard stops, because then my focus marks get all out of whack if I go too far.
 
edinc90 said:
The big problem I have with photography lenses is the impossibly short focus throw. 0 to infinity is a 30 degree turn of the ring. A real cinema lens would be a full turn for the same rack.

The good thing about older lenses is that they don't have electronic focus, so the rings have hard stops. I really really hate the rings taht don't have hard stops, because then my focus marks get all out of whack if I go too far.
Click to expand...

All my lenses are vintage so it's manual. All my lenses turns at least 180 degree and some do over 360 degree, so that's not a problem for me.
 
I'm not an AC but I pull my own focus. I use a ton of vintage lenses for all the reasons you talked about here. They have a longer focus throw. But challenge however if you switch from say old M42 glass to Nikkor glass. Nikon things its a good idea to have their focus lens pull the wrong direction.

I got a cheapo follow focus at first ( like this one but i paid around $150 a 18 months ago) It works ok but the focus pull has play in it so sometimes the begining of the pull is shackey. The other problem is that i always use a grip on my camera and this follow focus lacks any vertical adjustment so i had to modify my rail system to get the lens closer to the gears or use those really large gears like these

I also ended up with an iDC friction based follow focus that obviously doesn't have that play in it and is a lot better with most lenses that aren't a super heavy lens pull. Old Nikkor glass pulls just fine with it but old Leica glass, Old M42 glass, too heavy and the friction wheel occasionally slips. I added a few of those yellow rubber bracelets to the lenses (those live strong bracelets sure are cheep these days) and that helped a bit.

I am currently looking at buying the $50 Follow Focus ( here ) since its a nice middle ground between the geared follow focus' and the friction ones.
 
Pro's and Con's JUST related to focus mechanism and pulling focus:

Photography lenses (especially autofocus lenses) typically have very short focus throws, as mentioned, sometimes around 45* or so. 180* is good for a photo lens but not for a cinema lens, which often aims for 280-300* if not more.

Accurate focus marks are a big deal too. Most professional AC's use good old marks and distance estimates to pull, while having a monitor to simply check focus, not to rely on it.

Modern cinema lenses have focus scales (accurate and well spaced/marked) on both sides so the focus puller can change to accommodate camera position if necessary.

Many modern cinema lenses have cam focus not threaded focus, so the focus scales can be better mapped on the rotation. (Cooke and Leica for example, it's how Leica has every Summilux C have the same scale placement over 5' on every lens.)

Photography lenses don't typically have gears to easily mesh with professional tools such as a hard Follow focus gear or a wireless FF motor gear.


Many other reasons not listed to why cinema lenses for cinema.
 
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Another issue with photography lenses is they often don't track well, & the image can shift during a pull. This is especially problematic with 3D, but can also be in 2D.
 
Bern has a good point, while tracking is definitely undesirable, it's subtle when compared to another issue I'll throw on the pile: severe lens backlash. The mechanics can be sloppy or become sloppy much faster on photography lenses due to heavy use or inconsistent QC in photography lens production. Backlash is when you change direction pulling focus and all of the internals 'jump' from the change. The image literally jumps as well, and it looks like a very quick and decisive 'hit' happens to the camera. I just did a commercial job where production could not afford Cine-primes and we used the very nice photography Nikon ZF's, however they were a couple years old and had horrible backlash when I was pulling. Despite all the other hardships listed above, the backlash almost made any focus pull with a direction change impossible, at least unusable in the edit. If I were racking focus, I'd have to set my focus for the first object going in the direction of the pull as to not change directions. On a reset I'd have to pull back past my first mark, so I could change direction to set to one. Forget any pull where I pull away, and then close, or vice versa!

I was the focus puller on RedUser.net's SALT 3 test, the highspeed one. We tested Leica Summilux C's, Master Primes, Super Speeds, CP.2 SuperSpeeds, Canon C-NEs, K35's, Illumina's, Optica Elite's, and we also tested Canon L series. Although some of the very old lenses, such as K35's had a little backlash, almost all of the PL cine lenses (old or new) had none. The Canon-L series, which were just a couple years old, at most, had consistent image jump/shift, presumably worse from use.

I'm not exactly sure where this slop occurs and why (besides use), but I think it's much-to-do with the mount. I know the issues cleans up when using the extra rotating lock on the Red Canon mount. However, we were using that on the commercial, so I must say, the extra lock doesn't fix the problem if it's bad enough.


I'm not here to trash photography lenses. They are very good lenses for a very different use than cinema. I typically use photography lenses on my documentary work for how small, light and fast they are in comparison to cine. They are simply made for a different application. Photographers don't care about slop, tracking, consistency in physical size, front size and ring placement, consistent set color matching, focus marks, focus throw, etc. They don't .
 
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