Call for C-mount lens info

[John Wyatt]

C-mount lenses are coming back into fashion for people using scientific/industrial box cameras for creative video production. It can, however, be a problem to know what to buy and what to avoid. Buying new needs care: most of the inexpensive C-mount lenses are not high definition and only intended for CCTV security cameras. I've found it difficult though tracking down information on the older lenses originally used for 16mm cine cameras.

The C-mount screw thread can come in different diameters: 1", 2/3", 1/2". The accepted standard is the 1" format. Also be aware there is CS-mount; this uses the same thread as C-mount, but has a different flange distance (the lens shoulder to sensor/film plane distance): C-mount = 17.526mm; CS-mount = 12.526mm. You can easily get a CS-to-C mount adapter. Watch out for C-mount lenses (eg. Switar lenses) made for 16mm Bolex reflex cine cameras (such as the RX5). These lenses are marked "RX" and have a non-standard flange-to-film distance to accomodate the reflex prism in these cameras.

There are some great C-mount lenses out there to buy second hand: Zeiss, Cooke, Kinoptik, Schneider, Angenieux, Bausch and Lomb, etc. I include below (in separate posts so it'll be clearer to read) information that I have so far, which isn't that much! To avoid repition, assume all lenses are 1" C-mount format unless otherwise indicated. I'm hoping contributors will join in with more information, plug the gaps, make corrections, give personal recomendations, suggest places to buy (I suppose we already use ebay as a catalogue!), provide useful links, etc. It might build into a useful resource; the cameras are nothing without good lenses...

Regards,
John.

[John Wyatt]

Schneider lenses
These are professional quality lenses. I received a helpful email reply from them which provided most of the info below.

www.schneideroptics.com

1" C-mount primes
10mm Cinegon, f1.8, filter thread = 55mm.
16mm Cinegon, f1.4, filter thread = 35.5mm.
25mm Xenon, f0.95, filter thread = 39mm.
25mm Xenoplan, f1.9, filter thread = 30.5mm.
50mm Xenon, f1.2, filter thread = ?
50mm Cinegon, f?, filter thread = ?
360mm Alpha Tele-Xenon, f4.5, filter thread = ?

2/3" C-mount primes
17mm Xenon, f0.95, filter thread = 35.5mm.
17mm Xenon, f1.7, filter thread = 30.5mm.

2/3" C-mount zooms
12.5-75mm Variogon, f1.8, filter thread = 52mm.
10-100mm Variogon, f1.8, filter thread = 77mm.

[John Wyatt]

Angenieux
This manufacturer has a good reputation for lenses suitable for professional use. I couldn't find any mention of the older lenses on their website, and currently no reply to my email request for information.

www.angenieux.com

Primes
5.9mm, f1.8, filter thread = ?
10mm, f1.8, filter thread = ?
15mm, f1.3, filter thread = ?
15mm, f1.8, filter thread = ?
25mm, f0.95, filter thread = ?
25mm, f1.4, filter thread = ?
50mm, f2.0, filter thread = ?
75mm, f2.5, filter thread = ?

Zooms
9.5-95mm, f2.2, filter thread = ?
12-50mm, f2.5, filter thread = ?
12-120mm, f2.2, filter thread = ?
12-240mm, f4.8, filter thread = ?
17-68mm, f2.2, filter thread = ?
17.5-70mm, f2.2, filter thread = ?
20-80mm, f2.5, filter thread = ?

[John Wyatt]

Bausch and Lomb
Sharp lenses but for some reason underrated and therefore quite cheap. Not much info to list here at the moment!

Primes
1-inch Animar, f2.7, filter thread = ?
26mm Animar, f1.9, filter thread = ?

[John Wyatt]

You can easily get C-mount adapters to use manual 35mm SLR lenses; most brands are accomodated -- Olympus, Canon, Nikon, Pentax (M42 screw and K bayonet), Minolta, etc. However, the narrower field of view (using only the middle portion of the still camera lens) means you can expect up to a 6x increase in effective focal length compared to the original 35mm values. If you like shooting with long lenses this will be an advantage; if you need wide angle shots you'll be disapointed. You can get adapters from:

www.srbfilm.co.uk
www.edmundoptics.com

[Bob Hart]

"""""""""""The C-mount screw thread can come in different diameters: 1", 2/3", 1/2". The accepted standard is the 1" format."""""""""""""



There probably needs to be clarified, that the common C-Mount is the 1" (25mm??) as I understand it. C-Mount lenses listed at Fujinon for the different applications including some newer sharper lenses are described in charts being 1/3", 1/2", 2/3", 1". This refers to the area of image thrown by the lens at the film plane.

""""""""""""Also be aware there is CS-mount; this uses the same thread as C-mount, but has a different flange distance (the lens shoulder to sensor/film plane distance): C-mount = 17.526mm; CS-mount = 12.526mm. You can easily get a CS-to-C mount adapter. """"""""""""""

As I understand things, you can use a C-Mount lens on a CS mount camera by adding a spacer which is about 5mm thick. You cannot succesfully fit a CS mount lens on a C-Mount camera unless you want to use it in a permanent close-up (macro) application such as a home-made video assist.

"""""""""""""""""""""There are some great C-mount lenses out there to buy second hand: Zeiss, Cooke, Kinoptik, Schneider, Angenieux, Bausch and Lomb, etc. """""""""""""""""""""""

Some of the older Schneider-Kreuznach lenses for non-reflex Bolex will work on small-chip 1/3" or smaller cameras but for 1/2" or 2/3" such as JVC KY-F50 and KY-F32, the image area is sometimes a bit tight and there can be a vignette in the corners. I would not be inclined to separate these from any vintage camera they might be installed to as added usage will subject them to risk of damage or loss.

On ebay, two older C-mount lenses for older tube video cameras turn up from time-to-time. These are from the old Sony cams, the Tamron 12.5mm - 75mm zoom lens, aperure f1.8. - closed. I used this lens for stringer news work on a non-reflex Bolex and later, RX5 Bolex. There is a Canon 17mm - 85mm?? lens which was fitted to the first generation of Panasonic colour VHS portapack style systems. These were consumer grade lenses.

There is a scarcer lens which turns up from time-to-time, a Fujinon 16mm to 160mm f1.8 lens. "TV-Z". It is larger and heavy but is a good light collector. It is a bit heavy as a C-Mount lens, possibly damaging to a small security or scientific cameras. As there is no tripod support built into this lens, one has to be innovated around an adequate shoulder in the lens body. The C-Mount on my specimen of this lens appears to be an adaptor option, retained by a threaded ring.

The lubricants are likely to have dried off and the lens movements baulky and stiff ion these lenses.

[Bill Porter]

Avast ye

On a DIY camera them be fine... but fer those of ye thinkin of using C-mount lenses on a shallow-DOF-adapter, wit ye're C-mount lenses ye got a much smaller image circle, ay

This be meanin ye'll have much bigger grain from ye're GG

Arr matey

[Oscar Spierenburg]

I'm discussing the same thing with someone who uses the Elphel (1/2 inch) CMOS camera. He's not really happy with his computar C-mount lens (is that a TV lens?) So he ordered a SLR-canon to c-mount adapter.
What lens do you guys (and Bill) think he should try out to get a decent field of view? Say you have an 28mm lens, would it be somewhere near 50mm or 55mm or a lot bigger?

[Bob Hart]

Ay be tinkin moast thu ludd's mart bi contemplartin offrin' oop thu see-mount lins tuh thu vuddio carmara uz uh riillay lins. Uz uh varliid commintarry yuh be arferrin compadre.

Arz loong arz we be piratin oon thuh har sees an noort the viddeo undustry we be sairff. -- mebbye. Narr beck to grarndin, un cuuttin, un glooin, un mairkin gard fillums.

[Bill Porter]

Originally Posted by Oscar Spier

What lens do you guys (and Bill) think he should try out to get a decent field of view? Say you have an 28mm lens, would it be somewhere near 50mm or 55mm or a lot bigger?

Oscar, are you asking whether a 28mm SLR lens on a 1/2" chip camera, compares to a 50mm or 55mm SLR lens on a film camera, in terms of field of view?

If so, I don't know, as I'm not that well-informed on the cropping factor of a 1/2" chip camera, but I do know that it still will have plenty (of cropping factor).

This is a great link on the subject of actual chip sizes (it ain't 1/2"!) and of field of view:

http://www.navitar.com/zoom/cctv_op_char.htm

As is this:

http://www.dpreview.com/news/0210/02...ensorsizes.asp

[Oscar Spierenburg]

Thanks Bill, that's what I meant. Those links are very helpful indeed.

[Bill Porter]

No problem. As payment you may paint a picture of a Heinkel Kabine for me. You have my address.

[Oscar Spierenburg]

You have to give me a lot more good answers to make me paint that little...

[Bill Porter]

If it's such a little painting I don't see the problem...

[Jason Varner]

The short flange depth of c-mount lenses makes them poorly suited for relay lenses. The distance from the ccd to the IR filter in a Canon is about 30mm.