16 bit/14bit nefs opening in P/S from camera raw 5.2 as 8 bit images

Question

I am downloading 16 bit nefs (D300) from card reader with cs4 bridge. In bridge I can check the meta data and see that they are 16bit but when I open in camera raw 5.2 then do the open file in photoshop form there they open as 8bit files instead of 16bit as I expected. I tryed the convert to dng on the import and get same 8bit results. I am using windows xp pro. Any ideas what I am doing wrong? I have slow dial up here so do not have my work photoshop computer hooked to net for help files from bridge and photoshop. Also have Shewes new real world camera raw and his deal with Martin Eweing preordered from amazon but don't know when they will come.

Answer 1

>I'm having trouble understanding the jargon though. Are you saying that the sensor data is read more slowly in 14-bit, which reduces the noise floor? and that is is only of any benefit when used at the lowest noise ISO (ie 200)?
Yeah that is basically the idea. A different read-out path or set of amplifiers is used or it is simply "read slower" which can, in principle, reduce noise. Not something that is inherent to 14 vs 12 bits but more to the way the data is read. If the noise stayed the same and it is in the lower 2 bits of the 12 bits converter, there is no point as the only thing you're doing is more precisely imaging the noise. If however, the noise goes down a little going to the 14-bit readout method, you might get better signal to noise ratios and hence more shadow detail. This is all theory, and if you actually do the test with your camera, you'll see there is no difference in real world photos. The shadows would need to be really deep to see any of this. Basically you need to be boosting exposure by 3 or 4 stops AND applying shadow fill near 100. Not a realistic situation. To see it, you indeed need to be at a situation where the noise floor is significantly low, which means low ISOs on most cameras. At high ISO, there could be a difference because of differences in amplifiers, etc, but in practice that is not the case either on this camera. Other sources of noise drown it out completely.
>Is there no other benefit to post-processing? I'm not clear where the extra 2 bits go; is it increased resolution over the same dynamic range, or is the dynamic range extended? Is this not also a factor in choosing 14 over 12?
There could be some benefit if the noise characteristics were significantly different. Lower noise means higher dynamic range and therefore better capability to extract detail from shadow areas. However, from my testing, in practice this does not happen on the D300. Other cameras might well show higher dynamic range and better detail in shadows at 14 bits. You can see some of this by looking at the dynamic Range charts on DxOmark.com where sensors of different cameras are tested. You need to be significantly above 11 to 12 EV for 14 bit capture to make a difference.
>Sorry if this is a bit off-topic, but you have to grab experts when you find some
The easiest thing is to test it. In realistic scenarios, I just cannot see any difference. If you contrive a completely weird case, such as underexposing an entire image by 8 stops, or pushing up shadows by as many stops, you can get into the range where it might make a difference. Those are just not real situations though.