A question about 16mm camera mechanics

[Sam Risley]

Hi everyone. I had a query about image quality produced by different cameras when shooting 16mm. I was wondering whether if one had two 16mm cameras, for example a Bolex on the one hand and an eclair ACL or Aaton on the other, both with the exact same lens, shooting on the same film at the same frame rate, and assuming both viewfinders are as clear etc, so that the only thing different was the mechanics of the camera itself would the image quality be very different? Would you actually get a very similar result, or are there other things to consider about the mechanics of certain cameras that would affect image quality? 

[Simon Wyss]

A principal difference comes with the various shutter opening angles. The wider it is the longer each frame gets exposed giving smoother movements. Short exposure times produce sharper pictures or with less motion blur. That can be useful, puzzling as it is, when shooting at higher frame rates.

Technical differences have to do with the lateral guidance of the film, with the positioning distance (perforation holes counted from the optical axis), and how well stocks are held flat at the aperture.

Edited June 11, 2023 by Simon Wyss

[David Mullen ASC]

Steadiness will affect sharpness. The other issue is that if the viewfinder is very poor, then there is a greater chance of missing the focus.

[Dom Jaeger]

I think probably one of the main differences comes from how well the viewfinder system allows the operator to accurately focus, which is a combination of magnification, clarity and accuracy in the ground glass setting. Then in terms of using lens marks to focus, you have things like accuracy of the flange depth setting, accuracy of the lens back focus and quality of the lens - including mechanical consistency as well as focus throw and accuracy of the marks. In those terms, professional cameras like an Arriflex or Aaton with a mirrror shutter and high end optical finders using professional lens mounts like PL will be superior to a Bolex with a C mount, or even something in between like an Eclair.

Then you have the mechanical aspects of the film transport which determine image quality - things like steadiness, scratches or light leaks, flatness in the gate, etc. These settings might be stable or they might be more susceptible to wear or physical knocks. An Arriflex will usually be more durable than an Aaton or an Eclair, a Bolex will usually be more durable than a Beaulieu, etc.  It can of course come down to how well a kit is maintained and serviced. 

As Simon mentioned, different shutter angles can subtly change the quality of motion capture too.

Certain cameras can have common issues that can sometimes cause image quality to suffer - using a reflex Bolex without RX lenses, Scoopics creating pulsing exposures, butterfly shutter CP16s causing smeared highlights, cameras that need exactly the right size loop or they cause problems etc. 

But in general, a camera is only the box holding the film, the stock and the lenses and the cinematographer are what really make the image. A high quality camera just tends to allow those factors to reach their full potential.

[Sam Risley]

This is all super interesting. Thank you all so much for sharing your knowledge! 

But yes it seems obvious to me too that it is what is in front of the lens and who is behind the camera that makes the greatest difference.