[dadipentak]

There is more than one way to swing a cat... "Swing Your Cat Your Way"
and if you have never swung a cat before, practice.

Skuchee--here kitty, kitty...

[mickeyobe]

I am not inclined toward the technical/electronic aspects in this discussion.

I can only site my own experience for whatever it is worth.
I have a K100d. I usually shoot JPEG at 400 ASA/ISO.
I always spot meter.

I find that there is a considerable loss of detail in over exposed areas whereas the under exposed portions usually contain a wealth of detail that is not seen until the shadows are lightened.
Furthermore, the colours are richer when slightly underexposed. Increasing saturation in Photoshop does not give the same richness of colour.

Perhaps I am doing something wrong but it works for me.

Mickey

[dadipentak]

I find that there is a considerable loss of detail in over exposed areas whereas the under exposed portions usually contain a wealth of detail that is not seen until the shadows are lightened.
Furthermore, the colours are richer when slightly underexposed. Increasing saturation in Photoshop does not give the same richness of colour.

Perhaps I am doing something wrong but it works for me.

Mickey

I'm sympathetic to this approach but have found that I can get something close to the richness by adjusting Blacks (in ACR), levels (in PSE), Gamma (in FastStone) &/or some combination thereof. I sometimes suspect that these may all be the same thing but, not being technical, I don't think about it much ;~)

[krypticide]

If I understand what you are referring to (bit levels) then I consider that a urban legend based on Emil's data and others.
Naively it would seem obvious that the highest quality image data would arise from concentrating the image histogram in the higher exposure zones, where the abundance of levels allows finer tonal transitions.

However, the issue is not the number of raw levels in any given segment of the raw data (as measured e.g. in stops down from raw saturation point). Rather, the point is that by exposing to the right, one achieves a higher signal to noise ratio in the raw data. The number of available raw levels has little to do with the proper reason to expose right, since as we have seen the noise rises with signal and in fact the many raw levels available in higher exposure zones are largely wasted in digitizing photon shot noise (there will be more to say about this in a moment, when we consider NEF compression).
The fact that level quantization much finer than the noise is superfluous, since noise erases the perceptual impact of abrupt tonal transitions, means that many of the levels used to record higher exposure zones are unneeded and indeed wasteful -- photon shot noise is much larger than the level spacing in midtones and highlights on a typical DSLR.
That is, if the average photon count is 10000, there will be fluctuations from pixel to pixel of as much as sqrt[10000]=100 photons in the sample. Suppose each increase by one in the raw level corresponds to counting ten more photons (i.e. the gain g=10 photons/ADU); then noise for this signal is 100/10=10 raw levels. The linear encoding of the raw signal wastes most of the raw levels, since the noise is much larger than the quantization step.
In shadows, it's a different story. Suppose our average signal is 100 photons; then the photon fluctuations are sqrt[100]=10 photons, which translates to +/- one raw level for the supposed gain g=10. At low signal level, none of the raw levels are "wasted" in digitizing the noise.
Which means this is correct but NOT for the reasons stated:
Expose Right

I think it's a combination of both. Higher ISOs are just signals amplified by the camera. There is no physical change to the sensor. You can see this effect by shooting at ISO 100 with normal exposure and then ISO 200 one stop underexposed but pushed one stop. The highlights will look roughly the same. However, you will get more contrast in the pushed ISO 200 shots in the shadows due to less data in the shadows. It's pretty much an effect of posterization.

As far as SNR, you're also right because noise is added mostly by circuitry surrounding the sensor (ignoring hot pixels here and random photon fluctuations). At high gain (i.e. high ISO), given a constant noise provided by the circuitry, your SNR will be much higher. This is going to be more prevalent again in the shadows, due to the smaller real photon count (with constant noise) and thus higher SNR.

[FHPhotographer]

Peter, I'll leave your first question to the more experienced folks, but on the second issue... I've had some good luck in PS3 and PS4 with the Shadows/Highlights extended settings. I'm told it's not nearly as effective in earlier versions,
Brian

[JohnBee]

I've got the K7 and was wondering whether it would be more effective to increase the exposure of an image using Photoshop CS3 than to raise the ISO on camera. Is this a stupid question?

Interestingly enough, both methods(ISO Push vs PP) eventually share the same fate(almost). That is to say, that at some point down the sensitivity line, noise overcomes practical use.

Having said that, it is almost always more convenient to tackle sensitivity at the sensor level than that of PP as you gain the advantage of exposure in the areas that count the most. Which in turn facilitates your post processing tasks afterwards.

Another photoshop question: Are there any better ways to increase a photo's exposure than the usual Brighten/Contrast or Curves in terms of preserving picture detail?

Yes, you can shoot RAW(PEF,DNG), and gain access to the same image control measures that your camera applies when shooting JPG's. shooting RAW will give you exposure control as well as a number of other image control settings.

As for the question of which end(shadows/highlights) to aim for, the answer is always mixed. However, keep in mind that whatever it lost to overexposure(blow outs) can never be recovered. Whereas, shadows can always be recovered untils noise overcomes you. In my own experiences(blowouts aside), I've always fared better shooting lean(underexposed) and pulling detail out of shadows than the other way around. Which has been the beneficial path with Pentax sensor's since that of the K100D.

On the issue of shadow recovery, some quick tests between the K200, K20 and the K-x have shown that the K-x has almost 1 full stop of shadow recovery over that of the K20D(the K200D doesn't do well at all). Which I found to be most impressive!

PS. the only camera I've ever used to recovery highlights(accurately) was with a Fuji S5 Pro. Though the K-x seems to(almost) match that amazing camera with shadow recovery!

Don't forget that you CAN open tiffs and jpegs in raw. And get almost all the features of raw except white balance presets.