16 bit during editing process, then convert to 8 bit at the end

reason: every time you edit a picture a lossy transformation is likely to happen (except for a very few transformations such as 90� rotations / mirror / negative which are lossless and revertible);
every lossy transformation results in errors in the least significant bits; if you do all the editing at 16 bit and only convert to 8 bit at the end, all intermediate roundoff errors  are negligible; otherwise, if you do all the editing at 8 bit, you will likely end up with having only 7 or 6 actual colour bit depth, the rest being just random noise;

it's something similar to mixing music at 24 (or 32) bits before converting to 16 bits for the final cd master

If the image is exposed correctly and most of the adjustments are done in RAW converter (only some minor tweaks in PS afterwards) there is virtually no difference between 16bit and 8bit. If you are going to do strong adjustments in PS a 16bit file is preferable.

I usually convert to 16bit tiffs. It just feels more "safe" for me and the images can withold strong curve adjustments in Photoshop better. Often I'm not totally sure how the image files are going to be used, it's better to play safe with 16bit files.

And why not use 16 bit files? Storage and computing power is cheap nowdays and modern versions of Photoshop supports 16bit files well.

I worked in 16 bit for years.... about a year ago tried 8 bit and since then keep working 8bit.... their isn't any difference between the two end results.. at least not to my eyes.

Patrick.

I shoot in RAW, and work in 8 bit. Tho it's true that it's better to work in 16 bit and to convert it to 8bits in the end, I doubt it's so important. Also, it could happen than when you work in 16 bit and convert it in the end to 8 bit some color clipping ocures.

Regarding audio, I can clearly hear the difference between 32 and 16 bit audio, but only when it's played one after another. When you don't have something to compare to it's very hard, or to say if it's 16 or 32 bit sound.
Someone also asked if it's necessary to save files at maximum quality (level 12) in PS, or it could be done at level 10. I was comparing these two, and I could see very small differences at 400%, but again, only because I had two files saved at different levels to compare. Significant difference was in file size.
If I remember well, Mantonino said he is saving his files at level 10 always.

Whether it's a big deal or not is rather subjective.... but the difference is pretty obvious.

I made a simple example - well exposed image, not very much editing, not too many layers. There are 2 frames in the animated gif: one is the result of 16 bit editing, converted to 8 bit at the end (e.g. all layers flattened in 16 bit and then converted to 8 bit); the other frame is result of 8-bit editing - i.e. same file was first converted to 8 bit, then flattened.

In case you have deeper shadows, in case they are underexposed, in case you have higher ISO you will see much bigger difference. But even this example is sufficient reason for me to do all editing in 16 bit.

it is shown at 400%

I thought Sharply_Done was back for a moment.  Then I realised this was an OLD THREAD.