C-mount lenses on Micro Four Thirds
One of the great things about the micro four thirds format is that you can simply mount anything on these. It’s just a matter of finding the right adapter, among the variety of available offers. In this particular case, the C-mount to M43 one pictured above is indeed well made, but there are cheaper ones starting from just a few bucks.. Fotodiox comes to mind.
C-mount lenses are still in use, no longer as 8mm or 16mm cinema lenses as they used to be but as security devices lenses, namely closed circuit television lenses. Normally they are pretty fast lenses as they need to work 24h and they come under the commercial term of TV lenses (from the CCTV acronym).
This is why some may be interested in the vintage C-mounts on a cropped sensor. Fast glass is expensive and C-mounts are not.
Bolex cameras were very popular in both the 8mm and 16m world, that much the guys over at Digital Bolex thought it could be commercially viable to financially venture into a revival.
I myself have been tempted by the whole C-mount business, best thing is always hand on. Names like Angenieux and Cooke do appear in c-mounts variants, as in old movie lenses, and suddenly you start thinking how nice it would be to have them on you next shooting session not for too much money …or at least nowhere as much as a Cooke S4 or an Angenieux Optimo. I had my fair bit of C-mount knowledge from experience .
There are some things that have to be said thought.
First issue relates to the focal length. You cannot go any wider than 22mm as the lens will indeed vignette at best or porthole in worst cases scenarios. Actually the term vignetting is not technically correct, we should say there is a the mismatch between the original intended mount and the real mount. On the micro four thirds format the sensor is nearly a super 35mm, close in size to the Aps-c format, anyway horizontally and vertically bigger than the 16mm format those lenses were originally designed for. We could say that the Micro 4/3 sensor is 20% wider than 16mm.
You can refer to the below summary that I found on a Google Spreadsheet as a reference between focal lengths and sensor coverage, compiled by some good soul
|MANUFACTURER||MODEL||FL||MAX AP||SENSOR COVERAGE||DETAILS|
|Schneider||Cinegon (silver)||10||1.8||No||~14mm IC|
|Schneider||Cinegon (black)||10||1.8||No||~17mm IC|
|Elgeet||Cine Navitar||12||1.2||No||~16mm IC|
|Schneider||Cinegon (black)||16||1.4||~18mm IC|
|SOM Berthiot||Cinor||20||1.5||No||~16mm IC|
|Schneider||Cine Xenon||25||1.4||No||~15mm IC|
|Schneider||Cine Xenon RX||25||1.4||16:9 ~20mm|
|SOM Berthiot||Cinor||25||1.8||No||~19mm IC|
|SOM Berthiot||Cinor||25||1.9||No||~19mm IC|
|SOM Berthiot||Lytar||25||1.9||No||~19mm IC|
|Taylor & Hobson||Cooke Kinic||25||1.5||full>22mm|
|Taylor & Hobson||Bell&Howell||25||1.9||no||~18mm IC|
|Taylor & Hobson||Cooke Filmo||25||1.8||no||full>22mm|
|Computar||25||1.3||Yes||very slight vignette|
|Kern||Macro Switar||26||1.1||no||slight vign|
|Schneider||Xenoplan||35||1.9||No||very slight vignette|
|Kern||Vario Switar||18-86||2.5||No||~16mm IC|
Now, a vignette fx can be nice. In fact. It’s even a preset on after effects and popular in some packages like Red Giant Magic Bullet.. it can work well on a music video but I would find it a bit awkward in a narrative piece.
Given the above table, probably as wide as 35mm would be what most would recommend as a general safe area and a good focal length on the m43 machines (giving you an effective 75mm focal in 35mm terms, a general portrait/medium close up focal length), you can add vignettes in post if you feel so and have full control over it.
Another thing to consider is that a typical lens design is sharper in the center and less sharp in the corners. Resolution and possible contrast drop may happen at the same time. While this can be corrected on modern lenses design, this issue would be ever-present for any C -mount lens. Depending on the real lens you can get some corner smearing too, which again is a non removable effect. Below an example
This is it. When shopping for old c-mounts bear go mind that you are not paying for full lens coverage. These days 26mm Switars are going for crazy $450 minimum, they are indeed very fast but almost unusable wide open.
Bokeh. Forget about creamy and smooth out of focus areas, most of these glasses will have a swirly background.. which you might like or not. To me it’s an interesting effect and you’re not always buying a lens because it is technically perfect, the swirl is something you would only do in post with time-consuming rotoscoping techniques or with carefully planned ahead green screen work.
I would recommend Kern Paillard Switars, you will be amazed how sharp these old beauties are and the color rendition. Possibly I would go with the AR versions, the RX ones were meant to be used with a prism and might lead to potential issues. You can go for the Yvars too, they will be very good but the top of the line were the Switars back then, with the Pizars positioned further below at the entry-level line. Best to avoid the zooms, quite likely they will all porthole all along the scale or to a certain focal lengths.. unless you opt for the ETC mode but to me it’s not an option, too fuzzy, no external HDMI output and issues with some hack patches.
The 50mm Switars are going for a minimum of $500, they are very sought after. Down to you to decide if you want to spend that money on a 30 years old lens with limited design.
There a couple more cons I would line to draw your attention to. Namely the grease on these lenses tends to dry out so either aperture or mostly focus are stiff. Luckily enough they are self -serviceable so with some extra care you can work around this.
The other issue will be even more present and that is due to the C-mount design itself. Pretty much like the M42 design, C-mounts have to be screwed in like a bulb lamp, there is no lock so if ANY ring is stiff, the lens will pop out.
Even if well lubed the lens might unscrew and that fact alone is a pain in the neck if you ask me. Never mind follow focus, put it in the wardrobe and let it collect dust.
One solution would be to glue the mount to the lens base, adapters come really cheap so you could. In this case a resale is quite unlikely going to happen though..
As a Director of Photography (or DP as it’s quite popular to say) is part of learning curve to try lenses on and I tested Kerns 3633 and 75mm, Bell & Howell 3″ Angenieux, Rank Taylor & Hobson Cookes Anastigmatic 75mm, Pentax Cosmicar 25mm and others memory might have left behind but I ended up selling them on.
Kerns were indeed intriguing. Kodak Cine Ektars are meant to be good as well and quite the same league but I cannot swear by that. Generally speaking all old 16mm Bolex stuff is worthy a look.
My personal advice is to try them on if you can find them cheap, it can be funny or you can discover some real gems but overall I would not bother too much.. there are better alternatives out there.Even for the forthcoming smaller sensor Blackmagic cinema camera or Digital Bolex I would not find them too appealing, I know they will be soon hunted for but I feel that ARRI PL mounted super 16mm lenses would be better performers.