Camera Adjustment necessary when switching from 35mm Color to BW?

Alexander Boyd · January 22, 2023

I‘m wondering if any camera/movement adjustments are required when switching from 35mm Color Film to BW film due to the BW film being thinner (correct me if I‘m wrong)?

So if mag A would be loaded with 35mm color film and mag B with BW film, would I need to change anything in order to switch?

Thanks!

Edited January 22, 2023 by Alexander Boyd

Simon Wyss · January 23, 2023

No adjustment necessary.

Dan Finlayson · January 23, 2023

8 hours ago, Alexander Boyd said:

So if mag A would be loaded with 35mm color film and mag B with BW film, would I need to change anything in order to switch?

I was told some years ago by the head tech at Arri CSC (when it was called that) that on occasion you do need to tune the pressure plate adjustment for double-x. More-so if you were doing something weird like running tri-x through the camera. But what they advised is to only bother adjusting if you started finding extra hairs or buildup on the guides below the gate. They suggested that in most cases this wouldn't be necessary.

Tyler Purcell · January 23, 2023

I believe the older Arri A/B/C cameras had a slightly different pressure plate adjustment for running B&W, but none of the modern cameras have anything like it. B&W film can run louder on some cameras, but there are no adjustments "required" what so ever.

Edited January 23, 2023 by Tyler Purcell

Dom Jaeger · January 23, 2023

How much thinner is B&W movie film, anyone know?

The specs for stills Tri-X give a thickness of 127 microns, while colour neg tends to be around 140 microns, so there’s not much difference there. I’ve personally never heard of adjusting the pressure plate tension or channel spacing for B&W.

The only thing B&W film usually requires is a blackened pressure plate due to the lack of rem-jet.

Frank Wylie · January 23, 2023

Not in 35mm; in 16mm, yes.

I shot on an Aaton LTR that had to have the gate spacing retuned by Able Cine when you switched between B&W negative and Color Reversal.

The camera had just been serviced by Able Cine and we were going to shoot some camera tests on cheaper reversal, but the camera would jam constantly.

We called Able Cine and they told us the camera would have to be adjusted to run the extra thickness.

We just shot negative camera tests instead; much cheaper than 2 more service visits.

That was in the early 1990's...

Simon Wyss · January 23, 2023

It’s Abel Cine, isn’t it?

The difference between jams and none may be that negative stocks are perforated short pitch and reversal films full pitch. An LTR claw pushes onto the hole edge at a very narrow angle. With long or full pitch stock you would have to adjust the claw stroke length which is not possible.

Frank Wylie · January 24, 2023

Simon,

Yes; Abel is correct. I am getting lazy in my proofing and auto correct has done me no favors in that regard over the decades...

You are probably correct, but the explanation given to me (decades ago) was thickness.

Marcin Mikolajczyk · July 10, 2023

Hi I've found this and I'm curious - I've run a test with BW stock and lab has sent me footage jittering. I wonder if this is the problem of the lab or the camera using BW stock? Camera is in 3 perf and works good with color.

Tyler Purcell · July 12, 2023

On 7/10/2023 at 1:42 PM, Marcin Mikolajczyk said:

Hi I've found this and I'm curious - I've run a test with BW stock and lab has sent me footage jittering. I wonder if this is the problem of the lab or the camera using BW stock? Camera is in 3 perf and works good with color.

Usually this is the camera. Lab really can't do anything to do this unless it's a scanner issue.