APS-C vs full-frame depth of field
QI use a Canon EOS M5 and a friend has an EOS 5D Mark II. Can my M5 give the same level of limited depth of field as his full-frame camera, with a subject framed head and shoulders? I use an 18-135mm f/3.5-5.6; he uses a 24-70mm f/2.8. I think I could stand further back using 135mm and this would at least match his 70mm. Fen Cable
AYou’re not quite correct. Let’s say you both stand the same distance from the subject, with both lenses at widest aperture and the 5D Mark II at 70mm and your M5 at 45mm so the framed view would be the same. Your M5 would produce about twice as much depth of field. You’d need to stand a little more than three times further away from the subject with your zoom at 135mm to maintain the same framing of the subject. But if you do the calculations, the depth of field will be hardly any different. That said, depending how far behind the subject the background is, that background could be significantly different. You’d see less of the background because of the narrower field of view and it would appear to be more out of focus. So, maybe, you’re half correct.