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View Full Version : GH2 A quick and dirty education in C mount lenses?



dishan
12-08-2011, 03:02 PM
I know one of the advantages of using a micro 4/3 camera is that you have a wider lens selection for cheap (*cough* Canon FD *cough*), but I had never heard of the C mount until recently.

This is very interesting stuff- they seem to be so wide and so fast and so #$%^ing inexpensive!

But the question is, are they actually any good?

I saw a few examples from some brand called "computar" (really? Did someone think that name would make them sound futuristic back in the 80's?), and the picture seemed kind of soft.
Then, upon further research, I see a lot of these are mostly 16mm lenses, causing severe vignetting. Sometimes that's cool, but other times folks end up zooming in with the crop tool to get around the soft edges, which then makes the "wide" part less enticing. At that point, is a 20mm F/1.7 lens cropped in really any more valuable than a 50mm F/1.8 FD lens?

Or are there some really good C mount lenses that I'm not aware of? Either way, there is some cool stuff there!

L1N3ARX
12-08-2011, 03:48 PM
If you decide to try out the cctv lenses... just make sure not to make the same mistake I did haha >> http://www.dvxuser.com/V6/showthread.php?269102-Anybody-try-the-computar-CCTV-12.5mm&highlight=computar+12.5mm.

ChipThome
12-08-2011, 03:58 PM
A few of the C mount lenses work fine with an adapter, as they are. Others you have to grind away a portion of the base. I purchased one C mount and adapter from Rainbow imaging and it works fine right out of the box. I then bought an 8mm f1.4 Cosmicar and that one will need to be ground down. Not having the metal working tools anymore, I just set the Cosmicar aside. IMO you can have some fun with these for not a lot of money, if you have the tools to make them fit.

tommyp
12-08-2011, 04:06 PM
I really dig the pentax 25mm 1.4 cctv lens. For stills mostly though.

http://farm7.staticflickr.com/6132/5983848636_a579593292_z.jpg

M. Gilden
12-08-2011, 04:08 PM
Tom, that looks excellent! Why only for stills? vignetting?

tommyp
12-08-2011, 04:18 PM
Tom, that looks excellent! Why only for stills? vignetting?

Yeah it hard vignettes if you stop it down. Its tiny so I don't have any ND's for it etc. Though that would be easy enough. I think mostly I like my footage clean then I could add the look in post rather than have it already done in camera. It is hard to cut the lens with anything too since the bokeh is so unique and it is only sharp in the center. It makes composition sometimes hard. It just seems easier to use fd's or nikons and worry about look later. That way I know it is sharp across the entire frame. In photo I can work around some of the issues better than in film.

dishan
12-08-2011, 05:06 PM
It just seems easier to use fd's or nikons and worry about look later. That way I know it is sharp across the entire frame. In photo I can work around some of the issues better than in film.

I hear that. Are there any good fast and wide FD zooms? I see so many on C-mount, but not so many other kinds of vintage glass.

tommyp
12-08-2011, 06:55 PM
fast and wide zooms? tokina 11-16?

dishan
12-08-2011, 07:06 PM
LOL- Ok, fair enough- but I was more interested in vintage glass and honestly wowed by the sub F/2 of these C-mounts. I mean, a wide zoom at F1.3? Where do I sign up! But I guess it seems too good to be true.
Isn't the Tokina F/2.8? Not that 2.8 is slow, but that seems pretty average for a versatile zoom. I've used the Tamron 17-50 on a Canon, and found it pretty average.

Meanwhile, weren't some folks in another thread saying modern glass is a problem because of aperture control? They don't make the Tokina in m4/3s, so how is everyone dealing with this?

I keep reading such conflicting information on this forum!

tommyp
12-08-2011, 07:23 PM
You need an adapter with an aperture ring on it and a nikon mount lens. It is kinda a pain. The hard part in all the vintage stuff is that it is all full frame so 20 was wide etc. you get into the old 14mm rectilinear fish and the lenses are huge. So you kinda have to look at the cmount or the DX lenses. Which are fine.

The cmounts may work. There are plenty of different ones. I haven't checked Seb Farges stuff lately but he had some really nice lenses figured. The lenses you want maybe out there. If I recall correctly one of the last ones he (Seb) was featuring was pretty nice. Here is the one I was thinking about http://vimeo.com/20788176.

http://www.bhphotovideo.com/c/product/573470-REG/Pentax_C60607KP_C60607KP_1_2_C_Mount.html

For $110 and a little machining it might be worth giving it a go. You are restricted to crop mode which means you want to keep the iso down so it might be a trade off.

ed_lee83
12-08-2011, 08:47 PM
I did lots of tests and demos with c-mount lenses here: http://www.youtube.com/edlee83 (starting from 7 months ago). Nearly all of them required some form of modification.
I also modified and sold quite a few Pentax (/Cosmicar) 8-48mm f1.0 c-mount lenses. You can still buy them new for about US$250. They vignette like hell but ETC covers the sensor fully. With such a fast aperture you won't need to jack up the ISO too much, avoiding the high noise issue - though I don't know if hacks made it better.
But it just hit me that I haven't shot any footage yet using the high bit rate hacks. I think Aquamotion works well with ETC right?