Switar non reflex lens on C mount camera

[Patrick Cooper]

Just a very simple query. I'm assuming that I could mount a non reflex Switar lens on any 16mm camera with a C mount and not suffer any optical aberrations or other issues? I'm under the assumption that a Bolex C mount is just the same as any other C mount. Correct me if I'm wrong. It's just that I never hear about people using Switar lenses on any other 16mm cameras other than a Bolex H16. And yes, I would only use such a lens with regular 16mm and not super 16. 

[Simon Wyss]

Kern-Paillard lenses for Paillard-Bolex H Reflex cameras are marked RX, the early ones DV for direct vision. All others are interchangeable freely. AR, by the way, stands for anti-reflex coating, nothing more. Switar was the expensive line, then you have the simpler Pizar designs, and the economic Yvar collection, mainly triplets. The telephoto macro Yvar are four glass.

 

[Patrick Cooper]

Simon, thank you for your reply. So to clarify, if I come across some Switar lenses that are not designated RX or DV, they should be fine for use with other 16mm cameras that have a C mount like for example a Beaulieu R16 or Bell & Howell 70DR? 

[Simon Wyss]

Not only Switar, there are also RX Pizar, but else you grasped it.

[Dom Jaeger]

6 hours ago, Patrick Cooper said:

So to clarify, if I come across some Switar lenses that are not designated RX or DV, they should be fine for use with other 16mm cameras that have a C mount like for example a Beaulieu R16 or Bell & Howell 70DR? 

Optically, yes they will be fine.

Be careful however of older 25mm AR Switars that have a very deep C mount thread protrusion. I’m not sure exactly, but I think it tends to be serial numbers under about 250000. Both the f1.4 and f/1.5 versions. They look like this:

If you screw one of these with enough force into a Beaulieu R16 or 4008 or an Eclair ACL or a reflex Bolex, you risk damaging the camera, in some cases catastrophically. Always check that the C mount protrusion of any lens used with these cameras is no more than about 4mm past the flange.

You can actually use RX lenses on C mount cameras that are not reflex Bolexes. You will simply get more aberrations than usual at wide open apertures. Some will be worse than others, but generally closed down a few stops or more they should be ok. At f/5.6 or 8 I doubt you’d see any difference at all.

[Patrick Cooper]

Dom, thanks for the warning about some of the old 25mm AR Switars. So I guess that protruding section should be no more than 4mm from the screw thread? I assume the bottom of the screw thread would be the 'flange.'

Yes Ive read a bit about the possible use of RX lenses on cameras that are not reflex Bolexes. And that stopping down the aperture improves the results. I am considering buying a high speed camera with C mount lenses some time in the future. Hence why I was making this query. And when running this camera at 1000fps, I guess I would probably be at a fairly large aperture - even with lots of light and fast film. So yea if I was going shopping for a Switar lens, I wouldn't have much choice but to get a non RX version.

Another alternative is using my Canon FD prime lenses (designed for 35mm SLRs) with a C mount adapter. Ive seen some samples on youtube of still camera lenses being used on 16mm and the results look very promising. 

 

 

[Simon Wyss]

The protrusion from the lens back face, thread inclusive

[Patrick Cooper]

Ah so the thread is included in the measurement (no more than 4mm.) With no prism in the earlier Bolex cameras, I guess it didn't really matter how far the lens extended into the body.

I guess I had better check C mount adapters too to make sure the thread on those doesn't extend past 4mm. 

 

Edited January 18 by Patrick Cooper

[Dom Jaeger]

The flange is the flat ring where the lens seats on to the camera, at the base of the C mount thread. There is a mating flange on the camera, hence the terms flange depth or focal flange distance to describe the distance from this point to the film plane.

If you have Vernier calipers you can check yourself how much depth you have on any particular C mount camera from the flange to the protective baffle or first internal surface inside. On some cameras you don’t have much room before you hit a reflex mirror or prism. 4mm is a safe protrusion depth, sometimes you can have more. Non-reflex cameras tend to have more room. 

[Patrick Cooper]

Dom, thanks for the explanation. I can see that great care would be needed when inspecting lenses and adapters for use on a reflex camera body.

With a high speed camera filming at 1000fps outdoors on a bright, sunny day with a reflector and 500T film stock and compensating for an 85 filter and also overexposing by about half a stop, I guess I would be shooting at around f2.8. It would be nice if I could stop down the aperture a bit for more depth of field. The only way I could think of doing this would be to push the film by about a stop but of course that would introduce more grain. I guess I could check out some samples of 500T pushed and see how grainy it gets. 

 

[Dom Jaeger]

You want to shoot 1000 fps on 16mm?

I hope you have a stack of film.. you’ll go through a 400 ft roll in 1.6 seconds! You really need to time the shot perfectly.

One of the first things to go digital was high speed cinematography, for good reason I think. But don’t let me put you off if that’s what you want to do.

[Simon Wyss]

In fact it takes a little longer, all masses need to be accelerated up, so only about the last quarter of a load will be exposed at the desired speed. If you assume 150 feet at full speed, you have 6,000 frames, six seconds.

[Patrick Cooper]

Dom, valid points. Yes, I would need to get my timing pretty spot on when shooting high speed 16mm footage.

Though you do realise how insanely expensive digital high speed cameras are. I simply can't afford one. And yea 16mm film is pricey as well. Though this wouldn't be something that I would run all the time. Just something I would like to do once in a while when I have some spare cash. Shooting stuff like milk pouring onto cereal, dropping fruit into a tank of water etc. Perhaps I could make a compromise and film at 500fps instead!

Simon, I had a feeling that might be the case - that it might take a little time for things to get up to speed. Though the last quarter of a load being exposed correctly doesn't sound very economical. I didn't think it would be that bad.

In this youtube video, a 100ft daylight load is used in a high speed camera. And at 1000fps, they get at least 18 seconds of usable footage. 

 

 

 

 

[Mark Dunn]

2 hours ago, Patrick Cooper said:

.

In this youtube video, a 100ft daylight load is used in a high speed camera. And at 1000fps, they get at least 18 seconds of usable footage. 

 

 

 

 

Yes, they do, because they're projecting at 25fps.

But there are 40 frames of 16mm.film to the foot, so the camera is running for a bit over 4 seconds.

I've checked the ramp up for the 500pps Locam and it's about one second. If you're to assume that your Hycam takes 2 seconds to get to 1000pps, this will use about 50' of your 400'. The camera will then run on for about 30sec. It's one roll per shot, you won't get down from 1000pps with the film intact. The Locam will stop and start- we never tried it above 200 but the manual says it's fine.

Above 500pps we triggered both camera and event with a sequence timer, with few exceptions.

Edited January 19 by Mark Dunn

[Mark Dunn]

Sorry- runtime for 400' @1000pps is about 15sec, not 30.

[Patrick Cooper]

That's close to my intended projection frame rate - 24fps.

15 seconds for 400 feet of film still sounds a little generous. Of course I wouldn't be running the camera anywhere near that length of time for a single shot. If two seconds is needed to get the camera up to speed, I'd probably run it for an additional two or three seconds for most quick movements. 

 

[Mark Dunn]

On 1/19/2024 at 5:41 PM, Patrick Cooper said:

15 seconds for 400 feet of film still sounds a little generous.

I am assuming your example was scanned at 25.

24fps is, or was, the frame rate for cinema presentation, 25 for 50Hz PAL TV transmission (that's broadly UK and Australasia and whichever countries the UK supplied with equipment). Americans, and they countries they supplied, still shot at 24 for TV as it suited NTSC at 60Hz.

It's a simple calculation, at 40 frames/foot there are 16000 frames on a 400' roll. So 16 seconds maximum at 1000pps.

Edited January 22 by Mark Dunn

[Patrick Cooper]

8 hours ago, Mark Dunn said:

24fps is, or was, the frame rate for cinema presentation, 25 for 50Hz PAL TV transmission (that's broadly UK and Australasia and whichever countries the UK supplied with equipment). Americans, and they countries they supplied, still shot at 24 for TV as it suited NTSC at 60Hz.

 

Yes true - 24fps for cinema projection and 25fps for Australia, Europe, Hong Kong and some South American countries for local TV. And 29.97fps for the US and Japan TV.

The last time I had movie film transferred - super 8 - was at 24fps. This is what I prefer as apparently, it's easier to convert to 25fps or 29.97fps. 

 

 

 

[Dennis Couzin]

48 years ago there was much confusion concerning the intercompatibility of standard C mount lenses on Bolex reflex cameras quite asside from the obvious probem of some lenses smashing into the prims.  Kern, Angenieux, Schneider and others made special RX-mount lenses for those cameras for an optical reason.  Imaging through a 9.5 mm thick glass prism can introduce profound aberration.  Their special RX lenses were made with compensatory aberration.  I wrote about this in 1976, 1978, and finally in 1987.  I see that  https://cinetinker.blogspot.com/2014/12/rx-vs-non-rx-lenses.html discussed my articles, but it links to my Google site "cinetechinfo" which has since vanished.  Here's a new link to the 1987 article: https://mediafire.com/file/6rh6f6tth12l625 . 

In a nutshell: A C-mount lens works weil on a RX camera or a RX-mount lens works weil on a C camera, if and only if: (1) the lens is slower than about f/2 or f/2.8, or stopped down this far;
AND (2) the lens has a deep set exit pupil, about l½ inches or farther into its screw mount.

 

[Jon O'Brien]

Wow, thanks so much Dennis for contributing to our knowledge of RX lenses! This is very helpful knowledge.

Edited February 11 by Jon O'Brien