Pocket Cam - C-Mount Lens Compatibility

Hello, I'm posting on behalf of a good number of folks over at Personal-View.com who are extremely interested in the Pocket Camera, but are unsure of the availability of affordable, fast, wide-angle lenses. There are of course MFT lenses like the Panasonic 7-14mm that would certainly be wide enough for most uses, but they are rather slow -- F/4, in the case of the Panny 7-14.

One of the more interesting options I've found are C-mount lenses by Kowa designed for 1" sensors (13.2mm x 8.8mm), which should cover the Pocket cameras Super-16 sensor (12.48mm x 7.02mm). However, I'm not sure whether these will focus to infinity, or have any flange-related issues.

Fortunately, the spec sheets are available:
Kowa 6mm f/1.8: http://www.rmassa.com/specsheets/LM6HC.pdf
Kowa 8mm f/1.4: http://www.rmassa.com/specsheets/LM8HC%20.pdf

See a full list here: http://www.rmassa.com/manu/kowa.htm. There are several families of lenses listed for 1" and larger sensors. The 2-megapixel family is the most appealing to me, for the low cost.

Can anyone comment with knowledge about these questions?

Thank you!
Sangye Ince-Johannsen

hmmm very interesting indeed.

I'm hoping the same. If the sensor is truly a S16 size, and BMD has been pretty mum on the sensors, then c mount glass should cover it. Which means, the flood gates will open!

Nikon 1 lenses can also cover the same dimensions and are very cheap, but there are no N1 -> M43 adapters.

I'm fairly new to the cinema camera world, and I am also interested in options other than Super 16 for 'native crop', because as far as I can tell those Super 16 lenses are fairly rare and quite pricey (for me, as a hobbyist anyway).

Any additional C Mount compatibility info would be great to know - expected crop factor and general lens quality info (suppliers to look into, adaptors etc).

I've pre-ordered the BMPCC, and I know I can get a variety of good, modern MFT lenses, but I am a bit worried about the crop factor for attempting to shoot anything wide. My worries may be misplaced, as frankly I don't know enough.

Thanks in advance - Very excited about the BMPCC.

Crop factor is very close to 3.0x.

Crop factor is very close to 3.0x.

Yes, for MFT - is that also the case for C-Mount lenses?

Thank you.

Crop factor is very close to 3.0x.

Yes, for MFT - is that also the case for C-Mount lenses?

Thank you.

Crop factor is based on the sensor size, not the lens. So as long as the C-mount can be attached with the proper adapter and has the proper flange focal distance to the sensor (and covers the entire sensor area), it will work, and the crop factor will be the same (3.0).

As Erik says the crop factor is 3x. Focal length has nothing to do with the sensor size. Only the crop factor does which affects the Field of View.

C-mount lenses are designed for different size sensors. Not all will work on the BMPCC. Any lens designed for a 1" sensor should work fine on the BMPCC. Lens for 2/3" and smaller sensors will probably vignette.

Those 2 Kowa's both look like they will work based on the specs (says they cover 12.8 x 9.6) but you'll need to test.

The 6mm would give you a similar FOV as using an 18mm on Full Frame DSLR
The 8mm would give you a similar FOV as using a 24mm on Full Frame DSLR

Don't forget, too, that when looking at a lot of lenses they'll list an F-Stop which is not the same as a T Stop. Cine lenses are marked in T stops, or Transmission Stops (true stops as I call them) which actually means it's letting through x amount of transmitted light. F stop is just a mathematical relationship between iris size and lens element size; which is used for Depth of Field calculations, not Exposure.
For example, you may have a F2 lens which is really a T2.8 (this most normally happens on zooms.)

things to keep in mind.

As for C Mount. Some may cover. i'd avoid zooms in C-Mount. They're cheap and plentiful and there are MFT to C Mount Adapters on Ebay for a few bucks. I picked one up for my GH2 and I'll play with it when it eventually ships in (granted a GH2 sensor is not S16mm in size in the least; but I have some musty old fungused up C-Mount lenses I want to put to work for "special effects.")

Thank you all for the replies. I guess I was confused about the C-Mount size being appropriate for the Super 16mm sized sensor in the BMPCC - but doing some more research last night I also realize not all C-mount lenses are created equal (or, for the same size sensor/film) .

I understand crop is introduced due to the lens being designed for a specific sensor (or film) size. Thanks again for the explanations.

So many variables with this ****.

Meh; just look for one made for the same size or larger imager than you've got and you should be ok.
It can seem overwhelming, but in truth; I highly recommend renting out lenses until you know what you'll need so you don't fruitlessly spend money on things which don't do i for you, or the client.
I know this seems expensive; but just bill it on, at cost, don't mark it up (or do if you want, I don't normally).
'Course if it's just for you, just play 'round. Best way to figure out a camera IMHO.

Are there any specs on the Pocket Camera's flange focal distance? Maybe around 17.5mm?

Are there any specs on the Pocket Camera's flange focal distance? Maybe around 17.5mm?

Hmm? I would think it would be M4/3 which is 19.25mm but that's a good question. 17.5mm would be for c-mount, but I believe the C to M4/3 adapter recedes into the mount a little bit.

I've had good results using a passive C to MFT adaptor on my GH2... all my C-mount lenses focus to infinity on the GH2 but obviously most of them don't cover the entire sensor.

I've ordered a BMPC purely for use with my C lenses...