Originally posted by derekkite Fstop of the lens is a fixed number arrived at by measuring the focal length and the aperture size. It doesn't change with the sensor size. If I put a 45mm 2.8 lens on the Q I would get roughly the same field of view as the 06 lens. And if I could adapt the Q 06 lens to the K3 it would be like a 45mm except it wouldn't cover the sensor. Or I could crop a shot made with a 45mm 2.8 lens on the K3 down to the size of the Q sensor to get an equivalent field of view. The f stops of the lens don't change. They are fixed in hardware. The equivalency numbers represent the field of view.
That is pretty impressive for such a small body. I was disappointed with the iq of the original Q, and have been eyeing the Q7 or later for improvements.
That's very true but as you say it is valid for both focal length and apperture. That was is written on the lense.
If you start using equivalence, this is to understand what setting you should have on a different body to get the same result. You can't apply equivalence only on what setting and keep the other setting unchanged. So you'd get the same looking image at 207mm f/13, iso2000 on an FF than 45mm f/2.8 isos 100 on Q. And there no issue going f/13 because well the apperture is not fixed in hardware, only the min/max apperture are fixed and so an f/2.8 lense can typically be closed down to f/13.
This is very important to know what to expect, understand what is possible on different systems.
I'd say you can see it as a game, try the Q @ f/2.8, then try a shoot at equivalent focal length but keeping f/2.8 apperture on a larger format camera or going f/13 on FF or f/8 on APSC iso 800. Maybe 207mm for FF f/2.8 is not practical so why not try a shorter focal length on APSC at f/2.8 and f/8 and see what setting look the most similar to the Q @ f/2.8 ?
You can even print the different photos and ask your friend what photo look the most similar to them.
You are all amazed by this f/2.8 because you map it to what f/2.8 does on FF on APSC... On theses systems f/2.8 is for high end zoom and the "pro" standard. The lenses are big and expensive So when you see f/2.8 on a smaller body you continue to think the same way. It should be big, heavy and expensive. If it is not it must be a fantastic achievement. But f/2.8 become average... RX100 III has an f/1.8-2.8 variable apperture, Fuji X30 f/2-2.8. and Canon G7X has f/2-2.8.
Even through the number are the same, f/2.8 everywhere, they do not translate in the same engineering effort or the same possibilities in term of shooting low light or deph of field.
Last edited by Nicolas06; 12-28-2014 at 04:09 AM.