[HSV]

a) Assuming that I'm shooting in a low light situation (K-5 shooting in JPG, with highlight and shadow correction off)...and that my shutter speed and aperture are predetermined (only ISO varies), what would be better for dynamic range and noise performance:

1) Shooting at a lower ISO, therefore significantly underexposing the image, and then pushing exposure in PP, or
2) Shooting at the appropriate ISO to get the desired exposure?

Two other related questions:

b) About the highlight and shadow correction (both of them are pushing exposure selectively), will these significantly increase noise and decrease dynamic range?

I've done a bunch of experiments, but so far I haven't concluded anything because I have no way of objectively measure. I cannot pinpoint the exact problem with those 2 features but the images just look very unnatural and muted.

c) About the highlight correction and the famous "bounce flash overexposure" problem, I got away from it by using wireless P-TTL always...but I'm curious to know, why is it recommended to have highlight correction ON when bouncing flash?

[chesebert]

The third option would be to increase ISO and ETTR. But with limited high ISO DR, ETTR could be challenging. I don't think intentionally underexposing and bump in post is such a good idea from a pure S/N perspective.

[JJJPhoto]

There are MANY variables here, but the short answer is that using a high ISO is better than underexposing and pushing in post.

Yes, lower ISOs have greater dynamic with the K-5 (and with almost all image sensors) and lower ISOs are better for fine details, but the more you underexpose the more image data in the shadows gets clipped which usually isn't as ugly as overexposed/clipped highlights, but it's still lost image data. Also, the more you push the exposure in post the worse the visible noise gets ... particularly in the shadows and you effectively lose fine details.

Exposing to the Right
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[HSV]

Good, thank!

Basically, it's better to expose as much as possible without clipping...makes sense.

[wildman]

Been thinking about how I would actually do a very low light shot...

....shot in RAW, TAv, ETTR. and run it through ACR and PS.

Single 7 watt florescent desk lamp about 8 feet away. handheld full frame. The EXIF should tell you what you need to know.
I'm pretty much at the limits of the technical quality of the gear (especially the sensor) and software at least for me.
Beyond this and I wouldn't personally go unless I just wanted a snapshot for the record.

[vonBaloney]

If you are shooting in JPG, I'd use the correct ISO to get the exposure. If shooting in RAW where pushing is easier, keep in mind that above ISO 1600 all the camera is doing *is* pushing so the question is do you like the job it does or would you like to push it yourself manually with tools like Lightroom, etc. Generally I choose the latter and don't shoot above ISO 1600. Of course casual shots are an exception -- just get it. But if I want to work on it later to get the best out it, then 1600 max and then push as needed....

[HSV]

If you are shooting in JPG, I'd use the correct ISO to get the exposure. If shooting in RAW where pushing is easier, keep in mind that above ISO 1600 all the camera is doing *is* pushing so the question is do you like the job it does or would you like to push it yourself manually with tools like Lightroom, etc. Generally I choose the latter and don't shoot above ISO 1600. Of course casual shots are an exception -- just get it. But if I want to work on it later to get the best out it, then 1600 max and then push as needed....

That's an interesting fact...why is ISO1600 the most that the K-5 can go before "digital" pushing?

I have been pouring over pages of pf and dpreview about this topic, how did folks discover that the highest analog gain for the K-5 is ISO1600?

[vonBaloney]

That's an interesting fact...why is ISO1600 the most that the K-5 can go before "digital" pushing?

I have been pouring over pages of pf and dpreview about this topic, how did folks discover that the highest analog gain for the K-5 is ISO1600?

Because they are smart and did lots of technical testing I don't understand. But I believe them -- apparently up to 1600 the sensor is actually able to "be more sensitive", i.e. it is at least partly a hardware solution (partly because some software-based pushing is involved there too, I think), but beyond 1600 it is pure software, and so you can get the best results with manual post-production, using the various tools available from Adobe, Topaz, etc. But if the marginal improvement from doing it yourself isn't necessary for your needs, then it is certainly easier just to dial-in whatever ISO it requires and shoot that way.

[HSV]

Thanks for the info!