commanderspike
Carbonite Member
This may be a daft question but I don't know much about C Mount lenses. Are all C Mount lenses designed for 16mm cameras or are there any lenses which would work with the GH1's sensor size without vignetting?
c-mount lenses
- Thread starter Barry_Green
- Start date
I recently spent 8 hours with my second best friend google to get to know more about them. There are also c-mount tv lenses and cctv lenses, used for security cameras and are designed for different formats (from 1/3" to 1" I think) and apparently resolutions as well. I found a manual 8-48mm 1.0 Pentax cctv lens that made me curious for this c-mount thing, but Barry already pointed out the vignette issue for shorter lenses. Too bad, so many nice, fast, cheap lenses out there 
commanderspike
Carbonite Member
I think it's less of an engineering challenge to design a fast C Mount lens as the same amount of light can be channelled into a smaller area, resulting in a automatically brighter picture (think ant under magnifying glass).
That's why my original question still stands... are any of these bargain lenses available in formats larger than 16mm?
The GH1's sensor size seems tailor made for these smaller-than-35mm format lenses.
That's why my original question still stands... are any of these bargain lenses available in formats larger than 16mm?
The GH1's sensor size seems tailor made for these smaller-than-35mm format lenses.
Ah ok, now I get your point.
I only know Schneider Kreuznach having larger c-mount lenses, Xenoplan (with a circle diameter of 22mm), but they are made for 3d measurement and traffic engineering
If there are any interesting c-mount lenses that fully cover GH1 sensor they're probably no bargains, but I doubt it anyway
I only know Schneider Kreuznach having larger c-mount lenses, Xenoplan (with a circle diameter of 22mm), but they are made for 3d measurement and traffic engineering
If there are any interesting c-mount lenses that fully cover GH1 sensor they're probably no bargains, but I doubt it anyway
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Horncastle
Well-known member
C Mount lenses have been designed and made for the following:
1. The original use - 16mm film cameras. They were also made for 8 mm film cameras though these obviously usually project a smaller image circle. Many 8 mm lenses though have the smaller D mount.
2. Early video/TV cameras (up until about the mid 80's I believe). These were prior to CCD sensor days and used a Vidicon tube. The typical Vidicon was 1" so the lenses in theory had to give pretty good coverage (By the way, unless I'm mistaken, these were the tube diameters that gave rise to the modern sensor measurements where 2/3, 4/3rds etc has no physical relationship to the sensor size). After the mid 80's the camera manufacturers started using smaller CCD sensors and more sophisticated mounts like B4.
3. CCTV and industrial cameras up to the present day. There is no rule of thumb as to what sensor sizes these were designed for: the common sizes are 1/3 and 2/3" sensors but they can also be 1/2", 1" or (rarely) 22mm.
As Barry says above, most lenses will start to vignette on the GH1 below about 25 to 35mm (most 25mm lenses already seem to give a little vignetting, although plenty of G1 owners are using them). The 16mm lenses designed for the 16mm Bolex Reflex cameras are also probably best avoided since these were designed to project light through the Bolex prism. Lack of this prism in the G1 might give chromatic aberrations such as colour fringing unless used stopped down. The Bolex Reflex lenses are usually marked "RX" (or in the case of the Angenieux zooms are followed by the suffix "C" - as in "10 x 12C").
Early Vidicon TV camera lenses - these were typically zooms. Ranges were commonly in the 12.5 - 75mm, 16-100mm sort of area. They are usually pretty bright: f1.8, 2.0, 2.2 etc. It remains to be seen what sort of coverage (especially at the wide end) and quality these lenses will give. The cameras they were originally used on did not require high resolution and probably gave precedence to low light capability. However, the only example I have seen used on a G1 - a Canon 2/17-102mm - looked surprisingly good (http://forum.getdpi.com/forum/showthread.php?t=7676).
Some of the Industrial/CCTV prime lenses seem astoundingly good. Second hand prices for both these and the 16mm c mount lenses are also soaring due to the new demand. The Xenoplans mentioned above are for two different sensor sizes: the 8mm and 17mm ones are designed to cover 2/3", the 25mm one is for 1". Schneider also has Xenons, Cinegons (wide angle) and Tele-Xenars in its 1" industrial lineup. I believe the 25mm Xenons will cover the G1 sensor as will the 25mm Carl Zeiss Jena Tevidons (price going bonkers) and possibly the 25mm Cosmicars and others.
Cross check anything I say if you're thinking of buying because I'm in the middle of a learning curve and may get things wrong. There's quite a lot of info on the web at this point from people using C mount lenses on the G1.
Hope this helps a little
Jason
Very nice Horncastle. I second going over to the g1 forums because they have been using cine c-mount lenses for some time with great results, at least with still pics.
I think with these 4/3 and m4/3 cameras coming out it'll be only a few more months before these c-mounts get up there in price. I can't even afford kern switars anymore. I should have purchased those lenses just two months ago.
Just do your do diligence and ask lots of questions from the sellers especially on ebay. I got a number of lenses where they claimed there was no haze or fungus and sure enough there it was. I would also find a good local guy who knows lenses to take a look at your lenses once you get them just to make sure in case you need to return them. I'd never pick up any lenses with out at least some kind of return policy. Also, make sure you look at the pics and check out the mount. Don't pick up D-mounts the smaller mount to the c-mount. Those lenses will not work. I guess you can get them to work but you'll have a very small image circle. Happy hunting and good luck. I already amassed several c-mounts so once the GH1 gets into my hands (please soon!) I'll be posting comparisons and results and I look forward to seeing some interesting c-mount footy from you guys too!
I think with these 4/3 and m4/3 cameras coming out it'll be only a few more months before these c-mounts get up there in price. I can't even afford kern switars anymore. I should have purchased those lenses just two months ago.
Just do your do diligence and ask lots of questions from the sellers especially on ebay. I got a number of lenses where they claimed there was no haze or fungus and sure enough there it was. I would also find a good local guy who knows lenses to take a look at your lenses once you get them just to make sure in case you need to return them. I'd never pick up any lenses with out at least some kind of return policy. Also, make sure you look at the pics and check out the mount. Don't pick up D-mounts the smaller mount to the c-mount. Those lenses will not work. I guess you can get them to work but you'll have a very small image circle. Happy hunting and good luck. I already amassed several c-mounts so once the GH1 gets into my hands (please soon!) I'll be posting comparisons and results and I look forward to seeing some interesting c-mount footy from you guys too!
zcream
Well-known member
Are you sure Vidicon was 1-inch and not 2/3-inch. I though that it was closer to 0.5" diagonal and they changed the diagonal naming convention to make it sound larger than it was. Hence the 2/3" tube.
If its 1" then the vidicon lenses will fit on 16:9 crop on the GH1.
If its 1" then the vidicon lenses will fit on 16:9 crop on the GH1.