High ISO Noise Reduction

[Colin Southern]

Thoughts?

Hi Brian,

The only thought I had to be honest, is how it's impossible to draw any conclusions since 97% of the noise will have been sampled out when the image was reduced for inline display. The only way you'll be able to see the difference is if you pixel-peep the originals, although having just said that, I'd eat my hat if the shot that was exposed +2EV didn't have noticeably less noise.

Photo 1 is a classic example of grossly under-exposed in terms of what's needed for best signal to noise ratio for a high ISO shot.

[speedneeder]

Colin, I agree completely! Which is what you already said a few posts up, that the high iso 'noise' is overrated for a typical 4x6 print or something you look at on the computer screen. If anyone is interested I will take the time to do some 100% crops of the +EV photos for a closer look. Not surprisingly, the +2EV photo looks remarkably like an ISO 1600 photo
This answers my question about higher iso for hockey pics. Again as you noted above, it will be a trade off between shutter speed and noise. It seems to me that 'exposing to the right' only means that shutter speed slows and I'm probably better off just picking the lower ISO to begin with?

[Colin Southern]

It seems to me that 'exposing to the right' only means that shutter speed slows and I'm probably better off just picking the lower ISO to begin with?

Hi Brian,

I think you'll need to do some experimenting (should be easy enough) but really what we're aiming for here are shots where the highlights are pushed as close to blowing as you can tolerate. The LOWER the ISO you can do that at will give you best SNR (signal-to-noise-ratio) (due to the greater dynamic range of the sensor), but of course you have the added complication of shutterspeed to worry about (in terms of action stopping) - so first and foremost, PUSH the exposures - and after that, worry about the actual ISO / shutterspeed combo that best meets your needs.

As a "case in point" - in terms of noise (assuming a purely reflective scene) - you'll probably get similar noise from a 6400 ISO shot where the exposure is pushed to the max, as you would from a 1600 ISO shot where the metering has been conservative and left a 2 stop safety margin (which is pretty typical).

Personally - if it were me - I'd Max the camera ISO out (excluding HIGH range(s) that just digitally manipulate the file - and not change the analog gain) knock the exposure comp up at least 1 stop - and see how you're looking for shutterspeed. If the shutterspeed can be tolerated lower then lower the ISO.

Just remember though that the image you see on the review screen isn't a RAW image - it's a JPEG produced by the camera and they typically show areas that are blown when there's still wiggle room in a RAW exposure, but the actual amount varies -- hence the reason one needs to experiment