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Julian

Blackmagic Pocket Cinema Camera c-mount lens compatibility list

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x2.6 !

interesting that changes the list of lenses that will work !

recalculate!

 

Come one guys... Don't make it harder than it is. The numbers are there. The sensor size is known (in the specsheet on the Blackmagic website), so is the crop factor! There is no doubt about it.

 

Of course the cropfactor is measured from fullframe camera's, because the term cropfactor comes from the photography world I suppose. We all know what the cropfactor of 2x means for MFT, or what the cropfactor of 1.6x means for our Canons (and 1.5x for Nikon dslrs).

 

So lets stick to the standard that a fullframe camera with a 36x24mm sized sensor has a cropfactor of 1x.

The cropfactor is determined by the diagonal of the sensor. In video mode the aspect ratio is 16:9 instead of 3:2, so the active sensor area is 36 x 20.25mm for fullframe.

 

The math:

 

Fullframe (5D Mark III): Active sensor area 36 x 20.25 mm, diagonal of 41,30mm.
Blackmagic Pocket: Active sensor area 12,48 x 7,02 mm, diagonal is 14.32 mm.

 

Divide 41.30 by 14.32 = 2,88. So the cropfactor (in relation to a 35mm fulframe dslr) is 2,88x. Fact.

 

his data is what the test is based on and I don't have any reason to believe it is incorrect. Science just prohibits from Blackmagic from changing anything to this fact. Or the Pocket must have a built in a Speed Booster... but it doesn't.

 

Lets just accept that the cropfactor is 2.88x, at least till someone can prove otherwise. The people mailing answers like 'we don't know the technical details yet' aren't very technical I suppose. I'm not a professor either, but this is all very basic stuff and the sensor size is in the spec sheet, so the cropfactor is know.

 

Sorry, It just frustrates me that people get all confused over this.. The way Blackmagic is answering to those questions doesn't help a lot either.

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I totally get the math and sorry I kept bringing this up...I was simply trying to figure out what their answer was based on...clearly and as you said it's based on non-technical people answering a technical(but very simple) question.

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Ive not ready any final spec sheets on this camera at all Im just reading whats on this forum ...

confusing when they have said  2.6 recently to someone!!  I would prefer it if it was 2.6

We have a good relationship with Blackmagic we built a cool rig for the BMCC the other month

http://www.eoshd.com/comments/gallery/image/180-tecnoir-blackmagic-anamorphic-cinema-rig-lores/

 

When we spoke with them last week regarding the pocket camera they said the specs were not finalised for the pocket camera yet....

so lets wait and see......

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Nice find Andy! Shame it doesn't say if it actually covers m43. Some of the lenses have samples but it doesn't specify if it's in EXTC or not. There is a 1.9mm f/1 with some samples that just vignettes a bit, but that must be in EXTC...

 

There are some big wide angles though that look like they cover quite a wide image circle, like this Computar 6mm f/1.8:

http://us.c-mount.passion.pro/article/Computar+6mm+f1.8.html

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Hey guys,

 

I noticed in the top thread that you calculated equivalent FOV for each of those C mount lenses, but you also calculated equivalent aperture? I have never heard of this. Does aperture also change with crop factor? All my research seems to suggest otherwise.

 

Some more info on this would be great.


Thanks guys,


Adam 

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The crop factor is not less, they're just not comparing it to full frame, they're stating the crop factor compared to super 35 or micro 4/3, depending on the situation.

My advice is don't worry about it, it's filmmaking, not maths, treat it like a super 16mm camera and you'll be fine.

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Actually it is a bit of 'math' to figure out if certain lenses will work on it. That's what the topic is about :)

 

No other GH-shooters with c-mount lenses here? There must be more!


I might to find some footage on Vimeo/Youtube as well that isn't shot in EXTC. We can do the same calculation, just in lower resolution though.

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Thanks Brucker. That is a great list! Everything with a 16mm image circle or larger should work on the pocket. 

I'll work on an update for the list with these results. Still would be nice to have some confirmation with images though :)

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IMHO the exact ratio of BMPCC to Full Frame is 2.88

 

Full Frame Active sensor area for full HD video is 36 x 20.25mm

diagonal = sqr(36)+sqr(20.25)=sqrt(1706.0625) = 41.30

BMPCC active sensor area 12,48 x 7,02 mm

diagonal = sqr(12.48) + sqr(7.02) = sqrt(205.0308) = 14.3189

 

41.30/14.3189 ~ 2.88

 

Which is the same if you simple divide the long sides - 36/12.48 ~ 2.88

 

Most C-Mount lenses cover 2/3'', 1/3'' and 1/2'' inch sensor sizes. Probably only 10 to 15% of all C Mount lenses cover the 1'' sensor size needed for BMPCC. So most will vignette heavily on BMPCC and among those which do cover correctly the 1'' sensor size there may be  still problems. Like:

                1. Will the lens work without modification on a C- Mount to m43 adapter. Some don't. Can't focus on infinity and need some rework.

                2. Is the image quality good enough. Most of those are surveillance camera lenses not optimized for high quality photo/video/film work. From what I've seen image quality on GH2 (tele converter mode) doesn't look good. It doesn't make sense to buy BMPCC which is supposed to give great image quality and stick a poor soft lens in front of it.

 

My hopes are in Metabone Speedbooster for m43. 

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You are right about the math, I fucked some things up :) changed the numbers... thanks.

 

The thing with the EXTC mode is that you magnify everything to a 100% view. Lens errors get more pronounced. This might be less on the Pocket. I don't want C-mount lenses as my only solution, but I love the idea of having a set of 3 very small lenses and the BMPCC in a small bag. Could carry it around everywhere :)

 

Even if the lens doesn't have the greatest quality, the funky bokeh and softness can be desirable sometime. Adding sharpness and correcting lens distortion/vignetting is easier in raw too.

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Carl Zeiss Tevidon 10mm f/2 should work fine.

I found a sample image on a NEX-7, calculated the BMPCC sensor area, this is the result:

 

post-20742-0-26826000-1366299474_thumb.j

 

Source: http://verybiglobo.blogspot.nl/2012/03/nex-7-carl-zeiss-jena-ddr-10mm-f2.html

 

There's a test of the CZ Tevidon 35mm f/1.9 as well, covers the whole Sony NEX-sensor:

http://verybiglobo.blogspot.nl/2012/04/sony-nex-7-carl-zeiss-tevidon-35mm-f19.html

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If it has not been mentioned, the bm pocket camera + speed booster + iscorama = widest taking lens of 25mm before vignette.  which is the same as a 35mm taking lens on aps-c or s35.

 

this maxiumum taking lens width changes to around 35mm for longer anamorphics like the sankor/eiki types.  

 

I just picked up a distagon 25mm to add to the rollei zeiss collection for this exact purpose.  

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Is it true that you will get a black circle around the image for C-mount lenses that have a focal length less than around 25mm? I was eyeing some Fujinon TV zoom lenses (such as the 10.5mm-147mm) particularly for the wider end. Would these give a full picture?

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while I can't speak from experience I don't think this is true...if a lens is designed to cover a specific senor format it doesn't matter what FL it has...unfortunatly it seems like most of the ones designed for 1"/S16 are 8mm or higher...at least that's  the widest I could find that covers 1"(I believe it was a Canon PL zoom lens...very expensive).

Is it true that you will get a black circle around the image for C-mount lenses that have a focal length less than around 25mm? I was eyeing some Fujinon TV zoom lenses (such as the 10.5mm-147mm) particularly for the wider end. Would these give a full picture?

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