c mount lenses?

NewYorkLion · Feb 24, 2011

Hey all,

So, I've been seeing a lot of used fast zoom 16mm c mount lenses on the market. How do these work on the af100? Has anyone been using them?

Would love some advice.

Thanks!
Colin

David G. Smith · Feb 24, 2011

A lens designed for 16mm film will NOT cover the full sensor on the Af-100.

Alpern · Feb 24, 2011

most prime c-mount lenses 25mm and longer will cover. I have several.

dvbrother · Feb 24, 2011

Alpern said:
most prime c-mount lenses 25mm and longer will cover. I have several.

You have a 25mm c-mount that covers the sensor? None that I have used will do that without a lot of vignetting. I have to go up to a 50mm before a c-mount lens covers the sensor without vignetting. Which 25mm c-mount do you use?

nyvz · Feb 24, 2011

I ve found that none of my c-mount lenses will even mount properly on the af100 due to the protective glass in the mount

mixedclimber · Feb 27, 2011

Does anyone know where I can purchase a m4/3 to c mount adaptor?

Ryan Patrick O'Hara · Feb 27, 2011

Have you done optical tests? Most of the time, having the lens projection circle cover an area the lens wasn't designed to cover can have some optical issues in that outside area.

Be sure to check... of course, some people might not have high standards or a keen eye when it comes to image quality as others. To some, if it fits, it fits. Others might venture further to see unfavorable CA, exposure and or sharpness vignetting, and etc.

Some lenses can pull it off, some can't. Be sure to check carefully.

Apefos Adapter · Apr 22, 2011

Oliver Rush · Apr 22, 2011

I have a 35mm f1.7 c-mount that covers m4/3... The problem is that you are using parts of the image circle that were not designed for the image, so you are not getting the image quality that the lens was designed for out of the lens. They can be fun to play around with or to give a shot a unique look, but I would not consider including any of them in my everyday lens kit.

Razz16mm · Apr 22, 2011

Apefos Adapter said:
These are links to C-MOUNT 1/2 and 2/3 fast wide angle lenses that probably would fit GH2 and would fill the ETC 2.6x sensor area (some lenses needs modification in body or rear barrel):

the rule to find the 35mm equivalent focal lenght is:
C-Mount focal lenght / 8.3 x 43,2 = full frame 35mm equivalent

If you are talking standard 2/3" HD video, the frame width reference is 9.54mm vs 36mm width for FF35.

jmarkham · Apr 22, 2011

mixedclimber said:
Does anyone know where I can purchase a m4/3 to c mount adaptor?

The best one I've been able to find is from hawks_factory in Taiwan...

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320675299245&ssPageName=ADME:X:AAQ:US:1123

I got a Fotodiox and I thought it was crap.

I use an old Zeiss Super 16mm 18-90mm and I think it's "specialty glass" .. you have to play with it ..
but you can get all kinds of interesting optical effects with it. For things like dream sequences or old
timey stuff, they work really well.

I would not consider them principle glass in any way ... as has been said, you're looking down parts
of the glass that were never meant to be imaged .. so the anomalies are many .. but some have
artistic merit.

But .. the old glass can look great.

jeff

biginvegas · Apr 26, 2011

dvbrother said:
You have a 25mm c-mount that covers the sensor? None that I have used will do that without a lot of vignetting. I have to go up to a 50mm before a c-mount lens covers the sensor without vignetting. Which 25mm c-mount do you use?

My Pentax 25mm 1.4 CCTV has zero vignetting at all apertures. On my GH1 it vignettes, go figure. I have a Pentax 12mm CCTV 1.2 that is surprising useful. Yes a heavy vignette but not the keyhole I get on the GH1. With a crop it will be fun creative lens for odds and ends, POV shots, music video's , night shoots when you only need the center of the frame . Both under $100 at BH.
The 12.5-75mm 1.8 Pentax zoom that I bought for my soon GH2 with ETC vignettes heavily but not unusable if creative.

Barry_Green · Apr 26, 2011

There's a difference between something that vignettes, and something that is usable. Most c-mount lenses 25mm or less won't cover the full sensor, but some will. But even if they do technically cover it, the edge sharpness might just be horribly soft.

The AF100's sensor is over twice as big as Super16 film, over 3x bigger than 16mm film, and 4x bigger than a 2/3" sensor. Most of the c-mount CCTV lenses out there were designed for a 2/3" chip or smaller. Most (if not all) of the c-mount movie lenses out there were designed to cover 16mm film.

As far as something vignetting on the GH1 but not the AF100, that's not unreasonable -- the GH1's sensor is slightly bigger than the AF100's (about 1mm bigger) so it's possible that if the coverage was extremely tight on the AF100, it might cover but on the GH1 it might reveal a bit of vignetting.

Evro · Apr 27, 2011

I want to add my experience with 16mm film zoom lenses and my advice is, forget it! The vignetting is unacceptable not to mention the infinity & back focussing issues you'll have.

I took the 17-69mm lens from my 16mm Krasnogorsk 3 film cam and mounted it to my AF102 using an M42 to M4/3 mount, this is how it looked:

I also tried a super fast Zeiss PL mount 10-100mm but the results were equally disappointing.
Just be wary of the claims that some sellers make on eBay.

Toddguk · Apr 27, 2011

I have been avidly experimenting with c-mount lenses since I got my first GH1 to find both primes and zooms that I could take along with me in my everyday kit. So far, I've been very disappointed in this regard, even after taking the 25mm and up approach. Here is a quick rundown of my own c-mount lens experiences:

Lens 01.) Wollensak f/2.5 Cine Velostigmat 1" Focus - to my amazement, this tiny little lens covers the entire sensor on both the GH1 and AF100. The drawback is that it is a fixed focus lens and if you simply attach it to an adapter and start rolling, you have to physically turn the lens in the adapter to focus. With the use of a 0.5mm spacer, you can get the lens to have a usable amount of focal depth without having to turn the lens. This area of focus is from approximately 4 feet away to 9 feet away. Any more than that 0.5 mm (using a 1 mm spacer for example) and the focal distance of the lens quickly shortens and becomes a macro lens. This is not altogether bad, but the need for spacers and the limited area you can keep in focus limits the everyday usability of the lens.

Lens 02.) Ampex Television Lens f/1.5 22.5 - 90mm (the particular model I have is NOT labeled as a Vidicon lens such as you often see on eBay).

This lens does not cover the sensor. It vignettes at the corners almost all the way through the zoom range, mellowing to darkened edges at full telephoto. The lens has an amazing circular blur and beautiful bokeh which makes it useful for specialty shots, but it's extremely heavy, weighing in at 3 pounds 12 ounces! So, either you hold up the camera by the lens, or you need to put this on rails with a proper long lens support. It is not useful for anything but a controlled shooting environment. I'm an even shooter, so I was bummed to discover this. Also, I had to file down the mount end of the lens with a Dremel because the lens was too wide at the bottom to fit in the c-mount adapter.
Below, is a sample photo taken with this lens.

Lens 03.) Canon TV-16 25-100mm f/1.8

This lens covers the AF100 sensor, but not the GH1 sensor. It does not focus to infinity when set at the wide end of the zoom, but it does focus to infinity when set at the telephoto end of the zoom. It is technically too heavy use without lens support at 2.5 pounds. Panasonic recommends lens support for lenses weighing 2.25 pounds or more to avoid damaging the mount on the camera body.

Lens 04.) No-name CCTV lens - 25mm f/1.2 off of eBay.

Covers the sensor when used at maximum aperture and vignettes as you stop down. Cheap, fast, and reasonably sharp CCTV lens that is probably the most useful for my shooting purposes.

General Observation: the c-mount adapters that are currently available are not of the greatest build quality and have a tendency to move around in the camera mount when attached. This is especially apparent with heavy lenses. This play between adapter and mount causes an intermittent connection between camera body and the lens, such that a black screen is invoked simply by twisting the focus ring! This is obviously frustrating and not acceptable for documenting live events where you get one chance to get things right.

In summary, I think I'm done experimenting with c-mounts. There really aren't many c-mounts out there that are suitable for use on the AF100 or GH1/2. The lenses either vignette or are too heavy. Edge sharpness definitely falls off in the ones I've tried, although in a special use or circumstance, this could be advantageous. My experiences leave me wanting Panasonic or any other lens maker to come out with fast and sharp zooms dedicated to shooting video.

Razz16mm · Apr 28, 2011

The Canon 25-100 is a model that was made for 1" tube cameras, so has significantly larger coverage circle than a 16mm or 2/3" lens. You could probably get one of these collimated by an optical shop so it would focus to infinity and maintain focus through zoom. Not a bad choice for a low cost relatively high quality fast zoom lens.

Toddguk · Apr 28, 2011

Razz16mm said:
The Canon 25-100 is a model that was made for 1" tube cameras, so has significantly larger coverage circle than a 16mm or 2/3" lens. You could probably get one of these collimated by an optical shop so it would focus to infinity and maintain focus through zoom. Not a bad choice for a low cost relatively high quality fast zoom lens.

Any specific recommendations for lens collimation shops? Your input is greatly appreciated.

Thanks.

mtigerpr · Aug 11, 2011

What can you say about the lens:
"APOLLO" ZOOM 1.8/18-90MM C-MOUNT LENS

etienne · Aug 11, 2011

I'm in no way an expert. Am using a Taylor Hobson Sopelem Rank f3.7 24-180mm.
Here some zoomed in and out grabs. I would post some video but am ashamed at my focusing skills.
Rgds,
Etienne

Richy Lacey · Dec 10, 2011

I've used the Pentax 25mm f/1.4 on my GH1 a bit.
It does vignette in the extreme corners but the main problem for me is the bokeh is quite ugly making it useless for any serious applications. The way it renders specular highlights isn't great either. It's good as an effects lens if you're looking for something interesting but not technically great.

c mount lenses?

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