Blackmagic Forum

Forgive my ignorance but could I use this set up

c mount lens (adpator) to nikon speedbooster to mft?
I have the speedbooster now and love it but would like to get some c mount lenses also

Won't work.

First, the C mount flange focal distance (FFD) is 17.52mm. This much shorter than the Nikon FFD, which is 46.5mm. This means that even on a standard Nikon mount you won't get infinity focus.

Second, the SpeedBooster is a focal length reducer. It reduces the size of the image circle. So it needs a lens designed for a much bigger sensor that it is being used on. (Full frame on a ASP-C, ASP-C on MFT). If you fitted a lens designed for 16mm film onto the Speedbooster the image circle would be too small to cover the sensor in the BMPCC.

Thanks!

A C mount to M43 Speedbooster is what is needed!

Worzel Gummidge wrote:A C mount to M43 Speedbooster is what is needed!

But the second issues still remains. Most C mount lenses are designed for 16mm film or 1" sensors. So the image circle produced by the lens only covers a small area. Most will work fine on the BMPCC but if you mount most of them on a MFT camera you'll notice vignetting.

The SpeedBooster is designed to reduce the size of the image circle (x0.71). That is how it works. So reducing the image circle of a lens designed to cover a 1" sensor is not really an option as then the image circle would be too small for the sensor.

so I am best off with no speedbooster, just a regular adaptor it sounds like, you guys are awesome

16 mm and super 16 lenses start out as T/1.x fast lenses, and start at 5 mm! You do not need to boost them. They are pleantynfast, andvstartvverynwidevangles. S16 17 mm is a " normal" lens, and 8mm is a "super wide". Excellent adapters for both C mount and ARRI are available.

any recommendations? really looking for something with a lot of character

those are hot pixels, but jeez mine looked like someone sprinkled paramsean cheese all over my sensor

OK so one question here,
I got a c-mount lens for the bmpcc and a c-mount to MFT adapter
FFD for c-mount is 17.52mm and MFT is 19.25mm
Not sure what the math is, so how do I know if I can get infinity focus or not?

The C mount adapter is like a recessed lens board, setting the C lens to correct FFD, if it is a quality adapter. Not all adapters are made to the same standard. Get a good one like the Metabones. Cheap Chinese adapters do not always work correctly.

what does ffd mean?

Flange (focus) distance. The correct distance between the rear plate of the lens and the sensor.