Blackmagic Pocket Cinema Camera 4k (crop factor)

[Tom S]

The crop factor is a mystery. It seems like the sensor is going to be just a smidge larger than the previous camera so the websites say "a reduced crop factor for a wider field of view." The original BMPCC is considered "slightly wide" meaning most zooms are 35 to 49mm wide which isn't great for indoor use.

Anyone know the exact crop factor of the new 4k pocket camera?

 

[AndreeMarkefors]

The effective sensor size is 18.96x10mm. It's listed on the Blackmagicdesign.com product page for the camera, under 'Tech Specs'....

My personal preference has always been to calculate crop in relation to the 'full frame' sensor size of 36x24mm. But since the aspect ratios aren't the same, you need to decide what the relevant comparison is: some use frame diagonal, but I use the width.

36/18.96 = 1.9x

But this only makes sense if you compare two systems with the same lens mount, like if the BMPCC had an EF mount. But it has an active MFT mount. While the FF system might use lenses like 24mm, 35mm and 50mm, the MFT system has 12mm, 17.5mm and 24mm. You can easily see how the difference in sensor size has been "taken care of" as part of the system design.

But... you CAN use FF glass on the BMPCC via a mount adapter. If you use a Speedbooster XL 0.64 you end up with 1.9x0.64 = 1.22x.

So, as an example, using EF glass on a BMPCC with a Speedbooster XL you end up with a 1.22x lateral crop factor compared to 'full frame'.

And as an additional example, when I take the Speedbooster setup above and compare it to my Canon 1Dx mkII, with a lateral crop factor of 1.34x, I can see that the BMPCC would actually see more of the light that the lens collects: 1.22x vs 1.34x.

 

[Alex.Mitchell]

Where’s the mystery? Like Andree said, both the original and new BMPCCs’ specs are listed on BMD’s website. The original BMPCC has a 12.48mm wide sensor and the 4KPCC has an 18.99mm wide sensor.

 

[Tom S]

Where’s the mystery? Like Andree said, both the original and new BMPCCs’ specs are listed on BMD’s website. The original BMPCC has a 12.48mm wide sensor and the 4KPCC has an 18.99mm wide sensor.

I didn't ask for the sensor size. I asked for the CROP factor. This is NOT listed on the BMD website and for some reason particularly difficult to find.

In practical terms, what I want to know is the effective focal length of an Olympus MFT 12-40mm zoom? So if the crop factor is 1.9x, the effective focal length would be 23-76mm?

 

[Noah Yuan-Vogel]

I didn't ask for the sensor size. I asked for the CROP factor. This is NOT listed on the BMD website and for some reason particularly difficult to find.

In practical terms, what I want to know is the effective focal length of an Olympus MFT 12-40mm zoom? So if the crop factor is 1.9x, the effective focal length would be 23-76mm?

Sensor size determines crop factor (I would just use the width). As does what you are comparing to. The sensor size is known the only thing that isn't known is what format you are comparing to as you haven't mention that. The rest is extremely simple math.

For example if you're comparing to FF35/VV 36mm sensor width then 36mm/19mm=1.9x. so yes a 12-40mm would have similar field of view on this camera to a 23-76mm lens on a 36mm wide FF35/VV sensor. I wouldnt call it "effective focal length" though because many other focal length characteristics don't carry over in such a calculation. It's just a field of view or "crop" comparison.