Arri S rotating turret and focus.

LangISback · August 25, 2004

I just bought an Arri S and I am really eager to go out and shoot a short film I planned. I have read somewhere that the problem with this cameras was that they just can't stay focused when in very critical depth of field situation. This, because when they designed the camera, back in the 20s or 30's, I don't know, lenses where not so fast, so the turret didn't need to be so steady since such critical focus situations never came. The shots I am planning, do have lots of focus changes with super blurry background. Any experience with this problem out there, or how to solve it? is it more of an urban myth?.

As extra info in case it helps: The camera comes with a set of three Schneider prime lenses (16mm, 35mm and 50mm).

Thanks a lot for your help!

Mitch Gross · August 25, 2004

That's a myth. An Arri-S that is in decent shape and has not been abused or worn down in its decades of service (these are not new cameras) should hold it's flange focal depth just fine. If you have problems then the camera is in need of an overhaul. The Arri-S actually uses a clamping rear pressure plate which keeps the film very flat to the gate, so that plus a turret that isn't banged all to hell gives the camera excellent rear depth consistency.

Nathan Milford · August 27, 2004

I absolutly love my Arri 16S. I have never had a problem with it!

The camera came to market in 1952 and wasn't huge in the US initially.

You're refering to the point written somewehre (can't remember where but I've read it too) about the flange focal distance not being that reliable due to the rotating turret. It shouldn't be that much of a concern.

You throw a Tobin motor on it, rent some decent lenses (hopefully you have an SB) and you have a very usable camera for most concievable MOS situations (I actually really dig my old Cookes, but that's another thread). It's been perfect for my needs: music videos, product shots and nature work.

I've been told it has better registration than the SR, but I'm sure that is very debatable.

Either way's it's still a very sexy camera in my opinion.

September 4, 2004

The Standard Mount (non Bayo) mounts do indeed have problems holding critical back focus. The Standard Arri mount is soft aluminum and gets sloppy very quickly in every axis. I could not get the same resolution with the sames lens in a side by side comparison with my SR.

One solution is to find a used Bayo turrent and replace the standard mount turrent. I have an Arri-S which I use as a MOS/Technical camera. Jorge@cinematechnic in Miami found an SB turrent used and "Spiked" it on my camera as a hard front adjusting the backfocus with shims. I got very improved results which matched my SR.

Another solution for a Standard turrent is to set up three lenses with shims adjust the back focus and avoid changing lenses which can be clumsy-but cost effective.

The difference between really "crisp" results and blurry poorly resolved images, especially with anything wider then 16mm is holding backfocus.

LangISback · September 17, 2004

My camera is a normal "S" not a S/B (it is much cheaper though!). I'd make some tests and check how the backfocus is. I'd like to ask you also if this issue would get more of a problem if I use a heavier lens, like a zoom lens.

Thanks very much for your replies! :)

Sam Wells · September 17, 2004

I have a standard (non B) 16S and use and often use Angenieux 9.5-57HEC with it, this is a lightweight zoom. It works, but...

Anything heavier is getting risky at the wide end (I've seen a 12-120 on an autocollimator, tap the end w/ a pencil zoomed to 12mm, it's an earthquake :o )

-Sam (giving new meaning to 'Richter Scale')

LangISback · September 21, 2004

Hey!, thanks again for your replies!.. I want to ask you what zoom lens would you consider the best in the $1000 range. I know they are only old lenses but I'd really like to buy a zoom for my camera. Or maybe you consider it is a waste of money to spend?.

Regards!,

:)