# Difference Between Crop Factor and 35mm Equivalence



## Pauldanc (Sep 7, 2016)

Could someone tell me the relationship between crop factor and 35mm equivalence. I thought I understood these terms but now I'm not so sure. I have seen a ZenmuseX3 camera   with a 20mm (35mm equivalent) lens.  I thought that meant the crop factor was 1.75  (35/20). However the same camera has an image sensor of 6.17 x 4.55mm which I thought gives a crop factor of about 5.5 (43/7.6). Any help in clearing up my confusion would be appreciated. 
Thanks in advance


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## astroNikon (Sep 7, 2016)

Think of it as sensor size ==> DX Lens Focal Lengths

" I have seen a ZenmuseX3 camera with a 20mm (35mm equivalent) lens."  ==> do you have a link ?
I think they're just saying it's a 20mm lens.


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## Ysarex (Sep 7, 2016)

Your camera has a 3.6mm focal length lens, NOT a 20mm lens. DJI is causing confusion with their misguided labeling -- it's stupid.

Joe


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## Pauldanc (Sep 7, 2016)

Thanks for the replies. The quote I saw is at DJI - Zenmuse X Series Cameras Comparison
Is there an explanation for the 20mm quote?


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## KmH (Sep 7, 2016)

And 20 mm (35mm equivalent)/ 3.6 mm (actual lens focal length) = 5.5, the crop factor you expected.

The 3.6 mm actual lens focal length delivers the same field of view a 20 mm lens on a camera having a full size 35 mm image sensor would deliver.


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## Pauldanc (Sep 7, 2016)

OK that makes sense to me now. Thanks


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