Thread: BMCC MFT and BMPCC Speedbooster sensor size equivalents

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  1. #31  
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    the (very common) confusion stems from the assumption that somehow the 35mm stills format is a sacred standard that everything else has to be compared to

    focal length is an absolute value - so a 0.58* SB does indeed turn a sigma 18-35mm into a 10-20mm in absolute terms

    the issue is then what FOV does that focal length give on a specific sensor size - this is where it gets confusing:

    lens focal length only gives a particular FOV on a specific sensor size - it doesn't have an intrinsic FOV in and of itself

    therefore a 35mm lens can be long on a small s16 size sensor, normal on a s35mm or aps-c camera, moderate wide on 'full frame' (urgghhh) 35mm stills and a proper wide on 'medium format'
    the stills 35mm (ie 'full frame') format is only the reference for so called 'crop factor' relationships because the vast majority of photographers were at one point using mostly 35mm still equipment - beyond that it has no special relevance

    in video it could be strongly argued that s35 (roughly aps-c) is a much better 'standard' for equivalence than 35mm stills - but it takes effort to retrain your brain into how you process FOV to lens focal length - its a bit like learning a new language

    as primarily a bmmcc shooter and also someone who generally does a a lot of of work at s35, but also having come from a stills 35mm BG, i have almost got to the point where i'm able to think in the native sensor size about what focal lengths represent in terms of FOV for all 3 systems (and m43 as well!) - but I found it ultimately easier to do that than to constantly try and 'equivalate' via crop factors back to one single reference. However, online you will find lots of references that do or don't and thus you also have to realize when a 'crop factor' equivalent is being used and when its not (generally 'crop factor' is mostly used to give an equivalent in stills 35mm but even that is not certain - its implied)
    Last edited by Stelvis; 08-31-2017 at 01:22 PM.
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  2. #32  
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    Feb 2016
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    just realised the original post is from 3 years ago - oh well never mind
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