Quote:
Originally Posted by Max Vondel
And I have read online that a 75mm SLR lens is equivalent to a 50mm DSLR lens. So for example my old Pentax 50mm F1.4 will be equivalent to a 33.3mm lens on my DSLR body. Could anyone confirm that this is correct?
Secondly, what would be my F-stop for my 50mm if used at say full F1.4 be in equivalent 33.3mm.? And is there a simple way to calculate this.
Many thanks in advance
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What they mean is that if you use this lens on 35mm film and enlarge it to (say) postcard size, then use it on the DSLR and also enlarge it to postcard size, then an object on the DSLR postcard will be bigger than the same object on the film postcard. However the image on the film and the image on the sensor are exactly the same size. If you cut a 24 x 16 mm piece out of the centre of your 35mm film and enlarged it to postcard size it would look exactly like the DSLR postcard in terms of size of objects.
The focal ratio is not affected. An f4 lens is an f4 lens, no matter what sensor you put behind it.
Geoff