09-24-2011, 03:41 PM
[quote name='Brightcolours' timestamp='1316872907' post='11817']
So if you had a 2x crop (compared to 135 format) film, and you shot with a 50mm f2 lens, and on 135 format you shot with a 100mm f2 lens, the 100mm lens would let through a lot more light for the same exposure duration.
[/quote]
And it would have to expose a much larger film area (and therefor need more light). But, what's more important and what ISO really is about: it would take the same exposure time in both cases.
That's all relevance the ISO number has to me as a photographer. Same ISO, same aperture -> same shutter speed. Regardless of the sensor size.
-- Markus
So if you had a 2x crop (compared to 135 format) film, and you shot with a 50mm f2 lens, and on 135 format you shot with a 100mm f2 lens, the 100mm lens would let through a lot more light for the same exposure duration.
[/quote]
And it would have to expose a much larger film area (and therefor need more light). But, what's more important and what ISO really is about: it would take the same exposure time in both cases.
That's all relevance the ISO number has to me as a photographer. Same ISO, same aperture -> same shutter speed. Regardless of the sensor size.
-- Markus
Editor
opticallimits.com
opticallimits.com