Originally posted by ziscwg I was thinking about getting that "budget" DA 50 mm 1.8 for my new K-50 to shoot a lot of indoor sports. Flash is not an option, so I need to use available light.
I mostly have to shoot around 3200 at f4.5 or so with my K-x kit lens 18-55.
At 3200 iso or higher, is the supposed increased sharpness of a 50 prime even worth it?
Or, is it needed to compensate some for the high iso?
Noise is a factor of signal. If the signal is stronger or clearer, the noise is less. Shooting on a sharper lens improves (in my mind, anyways, but also in my observation of my lenses) the detail being recorded by the sensor, and therefore the signal is stronger and less ambiguous (not as likely to be smudge by noise or NR algorithms). So theoretically, a sharp prime will generate less muddy pictures at high ISO than a softer zoom.
Also, you should judge the distance and the effect it has on DOF. The further your subject, the deeper your DOF. While you have been shooting at F4.5 because your kit lens limits you to that aperture, I find that F2.8 can often have enough DOF when shooting far enough subjects. That alone can either double your shutter speed or half your ISO.
One last thing, to reduce the apparent noise, overexpose a little. Again, noise is a function of signal. Saturating your sensor with more signal will reduce the apparent noise a little. How you achieve this is up to you.