Thread: BMCC MFT and BMPCC Speedbooster sensor size equivalents

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  1. #21  
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    Quote Originally Posted by rick.lang View Post
    Brian, a correction for the first post in the thread:

    Canon APS-C on 7D camera
    22.3 x14.9mm
    I just got the numbers from the APS-C Wiki page that I have linked to in the first post.
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  2. #22  
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    This should be a sticky.
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  3. #23  
    Thanks Ecking - I've been curious about purchasing a 2nd speedbooster & I own a pocket and 2.5. I own the regular m43 speed booster so this is really helpful to know that to match them pretty closely would be a matter of purchasing the bmpcc specific one!
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  4. #24  
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    Can you all help me understand these numbers because they don't add up to me. I read in different places the original crop of the bmpcc is 3.02x and then other places say 2.88x . So I may be doing the math wrong but if I take 3.02x * .58 = 1.75x effective crop or 2.88x * .58 = 1.67x (which is APS-C I think). Now with that being said if I take the Sigma 18-35mm f/1.8 * 1.75x = 31-61mm f/1.0 true or false?

    If true how can Metabones claim the 18-35mm becomes a 10-20mm f/1.0? It seems they are applying the .58 reduction to the focal length is this the correct way to gauge the applied focal length with the adapter. I also notice Andrew from EOSHD said the first version of the metabones speed booster gave a 2.1x crop and made the Sigma 18-35mm a 38-75mm f/1.2. However according to Metabones and their math, with the original SB then the Sigma should be a 12-24mm f/1.2.

    So which way is the correct way ?


    Edit: I might have answered my own question but still would like some insight. So I applied the .58 reduction to the focal length of the Sigma and got 10-20mm, multiply that by the original 3.02x crop of the pocket and we get the 31-61mm f/1.0 or 2.88x is 28-57mm f/1.0. So technically its does make the Sigma a 10-20mm f/1.0 but its rather misleading as its not actually that wide on the pocket(could be wrong I dont own either yet). I just like to research and know these things before hand.
    Last edited by Abstrak; 04-04-2014 at 08:59 PM.
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  5. #25  
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    Quote Originally Posted by Abstrak View Post
    Can you all help me understand these numbers because they don't add up to me. I read in different places the original crop of the bmpcc is 3.02x and then other places say 2.88x . So I may be doing the math wrong but if I take 3.02x * .58 = 1.75x effective crop or 2.88x * .58 = 1.67x (which is APS-C I think). Now with that being said if I take the Sigma 18-35mm f/1.8 * 1.75x = 31-61mm f/1.0 true or false?

    If true how can Metabones claim the 18-35mm becomes a 10-20mm f/1.0? It seems they are applying the .58 reduction to the focal length is this the correct way to gauge the applied focal length with the adapter. I also notice Andrew from EOSHD said the first version of the metabones speed booster gave a 2.1x crop and made the Sigma 18-35mm a 38-75mm f/1.2. However according to Metabones and their math, with the original SB then the Sigma should be a 12-24mm f/1.2.

    So which way is the correct way ?


    Edit: I might have answered my own question but still would like some insight. So I applied the .58 reduction to the focal length of the Sigma and got 10-20mm, multiply that by the original 3.02x crop of the pocket and we get the 31-61mm f/1.0 or 2.88x is 28-57mm f/1.0. So technically its does make the Sigma a 10-20mm f/1.0 but its rather misleading as its not actually that wide on the pocket(could be wrong I dont own either yet). I just like to research and know these things before hand.
    Crop factors are a curse, and only seem to lead to needless confusion. When comparing the BMPCC to 35mm still format you have the complexity of comparing two different aspect ratios in addition to two different format sizes. The BMPCC has an aspect ratio of 16:9, while 36x24 format has an aspect ratio of 3:2 (or 13.5:9). So if you compare diagonals the crop factor of the BMPCC is 43.27/14.319 = 3.02. On the other hand, if you compare the horizontal dimension you get 36/12.48 = 2.88.

    The 0.58x Speed Booster reduces the focal length and f-number of a lens by a factor of 0.58x. Pure and simple. The 0.58x S.B. plus the 18-35/1.8 Sigma really does become a 10.4-20.3mm f/1.0 lens, and there's nothing misleading about it once you get used to how focal lengths translate to field of view on the BMPCC format. Note that a 10.4-20.3mm f/1.0 lens is *very* different from a 20-58.5mm f/1.0 lens because the latter would have a much larger entrance pupil diameter and correspondingly shallower depth of field.
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  6. #26  
    Senior Member rick.lang's Avatar
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    Quote Originally Posted by Brian@202020 View Post
    I just got the numbers from the APS-C Wiki page that I have linked to in the first post.
    Well wiki is crowd sourced just like our input. I am not aware of an APS-C sensor that is wider than film S35 as this Wiki entry apparently claims. The APS-C Nikon sensor is wider than the APS-C Canon sensor such as the 7D but it's still smaller than film S35 I believe.
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  7. #27  
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    Thanks for the explanation Brian!
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  8. #28  
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    Guys can some one point me in the right direction on how to figure out what my lens becomes after adding it to a particular speed booster. I am trying to figure out what my BMCC + bmcc SB with 58mm and 2x Anamorphic becomes? thanks
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  9. #29  
    Senior Member Tim Hole's Avatar
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    It's also handy to have the diagonal length which will tell you what your normal lens is for that sensor. Maybe not directly translatable to film but the photographic rule of thumb for range is: half the normal focal length for landscape, 2x for portrait, 4x for sports and 8x for wildlife.
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  10. #30  
    Quote Originally Posted by Brian@202020 View Post
    I started this thread as a reference for the Metabones Speedbooster when added to the BMCC MFT (Blackmagic Cinema Camera Micro 4/3) and BMPCC (Blackmagic Pocket Cinema Camera) will give you in equivalent sensor size.


    BMCC
    Sensor size:
    15.81mm x 8.88mm
    Equivalent sensor size after adding the MFT (.71) Speedbooster:
    22.27mm x 12.51mm
    Equivalent sensor size after adding the BMCC (.64) specific Speedbooster:
    24.7mm x 13.88mm

    BMPCC
    Sensor size:
    12.48mm x 7.02mm
    Equivalent sensor size after adding the MFT (.71) Speedbooster:
    17.58mm x 9.89mm
    Equivalent sensor size after adding the BMCC (.64) specific Speedbooster:
    19.5mm x 10.97mm
    Equivalent sensor size after adding the BMPCC (.58) specific Speedbooster:
    21.52mm x 12.1mm


    Other sensor sizes for a frame of reference
    Super35 sensor size (film):
    24.89mm x 18.66mm
    Super35 sensor size (Blackmagic Production Camera):
    21.12mm x 11.88mm
    APS-C:
    25.1mm x 16.7mm (3:2)
    Micro 4/3 sensor size (AF100 and most other Micro 4/3 camera's):
    17.8mm x 10mm
    Micro 4/3 sensor size (GH2 16x9):
    18.8mm x 10.6mm

    Let me know if there are any inaccuracies and I will fix them.
    I have this bookmarked and come back here for reference a lot. So I wanted to add one more comparison. There is another speed booster type adapter available that is like a wireless follow focus device called DEC Aperture LensRegain. The reduction is just .75 so won't get as much improvement as the Metabones but the addition of wireless follow focus is something to think about. Not to mention that on the BmCc with the passive MFT, this adapter lets you use all the canon lenses and IS you want since it controls the iris, focus and power to the lens.


    BMCC = 15.81mm x 8.88mm
    BMCC + DEC LensRegain (.75) adapter = 21.08mm x 11.84mm
    BMCC + MFT (.71) Speedbooster = 22.27mm x 12.51mm
    BMCC + 'BMCC' (.64) Speedbooster = 24.7mm x 13.88mm

    BMPCC = 12.48mm x 7.02mm
    BMPCC + DEC LensRegain (.75) adapter = 16.64mm x 9.36mm
    BMPCC + MFT (.71) Speedbooster = 17.58mm x 9.89mm
    BMPCC + 'BMCC' (.64) Speedbooster = 19.5mm x 10.97mm
    BMPCC + 'BMPCC' (.58) Speedbooster = 21.52mm x 12.1mm

    Blackmagic Production Camera = 21.12mm x 11.88mm
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