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BMPCC Crop Factor question


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#1 Nik Aberle

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Posted 01 November 2016 - 02:55 PM

Hello all, 

 

Long time stalker, first time poster. So I'm hoping to invest in a BMPCC in the nest 12 months for personal projects and I've been having trouble understanding crop factor. 

 

From what I understand, putting an EF lens on the BMPCC will create a crop factor of 2.88 because the lens was meant for a 35mm camera. But what about lenses meant for the MFT sensor? Will the Vega-9 50mm on an MFT sensor look the same as the Canon 50mm on a full frame sensor? Or does the crop factor apply even when the lens was designed with the smaller mount/sensor in mind? 

 

Sorry if that has been covered before but I couldn't find any concrete answers. 

 

Cheers,

 

-Nik


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#2 Kenny Suleimanagich

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Posted 01 November 2016 - 03:45 PM

"Crop factor" is a confusing term that references field of view.

A 50mm on a 35mm still camera has a wider field of view by 2.88x than the 50mm on the blackmagic pocket (super 16). The reason why there are wider focal lengths for small image areas is precisely because of his.
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#3 David Mullen ASC

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Posted 01 November 2016 - 04:09 PM

A 50mm lens is always a 50mm lens whether it was designed for a Super-8 camera or an IMAX camera, though a lens designed for a smaller format usually cannot fill the larger format and you'll see vignetting. What changes is the field of view... a 50mm lens has a more telephoto effect as the format gets smaller, or has a wider view on larger formats.

So a 50mm made for a MFT camera will have the same view as a 50mm lens made for a FF35 camera if you put both on a MFT camera, but if you put both on a FF35 camera, the MFT 50mm would probably vignette.

If you want the equivalent view of a 50mm on a FF35 camera, you'd need to use an MFT lens that was 2.88X shorter (if that's the correct crop factor.)
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#4 Kenny N Suleimanagich

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Posted 01 November 2016 - 04:19 PM

Here is a helpful tool for understanding field of view. 


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#5 Nik Aberle

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Posted 01 November 2016 - 04:21 PM

Awesome! Thanks for the quick replies David and Kenny. 


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#6 Tyler Purcell

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Posted 01 November 2016 - 09:07 PM

The pocket camera magnifies your glass 2.88x.
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#7 Nik Aberle

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Posted 01 November 2016 - 09:20 PM

The pocket camera magnifies your glass 2.88x.

 

Tyler,

 

I see you've used the BMPCC in a few other shoots. Curious what you think of the MetaBones Speedbooster. I currently have no lenses so I'm not beholden to any mount style. I have a few photo lenses at work I'd have access to but that's it. I'm leaning towards MFT to use the krasnogorsk lenses as well as some other vintage lenses that have adapters due to generally cheaper pricing when looking at cine lenses. is the SpeedBooster worth the extra cash for an extra stop of light and reduced crop factor? I plan on shooting mainly with practicals and small lighting rigs indoors so I should have pretty solid control of lighting. My biggest fear is not having a wide enough lens for indoor shoots with the magnification.


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#8 Tyler Purcell

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Posted 02 November 2016 - 12:11 AM

There really isn't anything bad about the metabones speed booster for the majority of cinematographers. The difference isn't that great though, it maybe brings the 2.88x down to 1.88x maybe? I've done back to back tests and put the results into an editing program to see if it was worth owning one and in the long run, I didn't feel it was useful.

My biggest problem is that I'm old school, I light the crap out of everything and I use the sun for most of my lighting, so the camera is already WAY to sensitive for me. I run IRND .6, 200 ISO, 45 deg shutter and I still have over-exposure issues when shooting outdoors. The metabones just exacerbates that issue even more, increasing the amount of light hitting the imager by a stop.

So for people who need more sensitivity, the metabones adaptor will work great AND give you less magnification, which for some maybe nice.

In the end, you can't make the pocket have a S35 field of view, nothing will do that. The pocket looks like S16, which for some people like myself is great, that's what I'm use to shooting. For others, that look isn't as "cinematic", so the camera may not be the right choice in that case.

I mean, I think it looks great: https://www.dropbox....12-120.mov?dl=0
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