on the computer, or on the camera itself?

something which had my Dad and I foxed for a while recently was that we had turned down the screen brightness on the camera for some reason, then forgotten about it. Everything looked underexposed.

I find that my Sigma 530 does underexpose a little, +1 flash compensation seems to be needed.

In general Pentax metering tends to bias towards underexposure to avoid blowing the highlights. You may find you just prefer the results with +0.5 or +1 stop compensation. Personally I let the camera do its thing and pull it up a bit in RAW conversion, but this approach can increase noise.

By diffraction limited, I mean limited only by diffraction. By F22 I would be surprised if anything else makes much difference because the physical limit on placed on resolution by diffraction renders other considerations meaningless.

Obviously at F8 there are large variations between lenses, by F22 I doubt you could see the difference even if it's measureable.

Matt, it deppends on how good the lens is.

A Perfect lens would perform best wide open, with angular resolution given by theta=arcsin(1.22*(lambda/aperture))


where theta is the minimum angular separation of two bearly resolved objects and lambda is the wavelength of light.


Even the best lenses are imperfect, so performance degrades wide open, but since imperfections tend to be worse at the edges of the lens matters usually improve for the first couple of stops as you stop down.

At some point the benefits from cutting out imperfections in the lens are outweighed by the diffraction limit and performance decreases.

I don't use Lightroom, but I agree with justgetoutandride. I use the automatics to give me a place to start, then tweek until I'm happy.

In most cases the baseline doesn't look as good as the camera JPG, but by the time I'm finished tweeking it usually looks better.


The beauty of RAW is you can always scrap what you've done and start over without any fear of having damaged the original file. Don't understand what a particular slider does? grab it and pull! There's nothing like experimentation to show you what will happen.

I can see the smallest amount of noise in those images, but I had to zoom in to 200% to see it.

I know what you mean, I feel the same way!

if that's true, then the shot is no fluke, it was played for and got. Do you get every one you play for? probably not, but then I doubt there's a single person here who does.

by F22 I would expect all modern lenses to be diffraction limited and therefore to perform almost identically.

Interesting, I had often wondered if that would work. I have tried it a couple of times with my K10D + FA80-320 without a lot of success, but the 80-320 isn't the fastest focusing lens in the world and has a habit of hunting. If/when I get my hands on some better long AF glass I'll give it another try.

TAv changes the ISO automatically in acordance with the meter, it's manual with Auto ISO.

I'm finding it more and more useful, but it's not an everyday mode by any means.