I think I misunderstood what you intended.

Andrew

Photoshop cannot recover detail that just isn't there in a blown out sky - so, for scenes with excessive contrast, you have the option of either using a ND grad or reducing exposure so that the sky doesn't clip. For the latter, you can correct in post processing, but will increase noise in the darker tones.

Andrew

I think you might have to explain that comment a bit further, John.

If you navigate using "Shop by Category" to the "Lenses" subcategory on Ebay, there are presently 24,793 results. There are more Canon branded lenses for sale than any other marque (6292), followed by Nikon (4327), Sony(2563), Sigma(2389) and Pentax(2233).


Andrew

My goodness, you sound like PU is an AA meeting!!

I'm the only Pentax user in Oldham CC, but that's perfectly fine with me. The difference in image quality between camera marques is too small to worry about. I like using Pentax cameras, so I use them. Simples!

Andrew

The answer to your question varies with the lens make, model and condition. I'd be tempted to start with just one lens and see how you get on. Some old lenses are great - but many will be worse than the kit lens.

A Pentax SMC M (or A) 50mm f/1.7 manual focus lens is cheap and better than the kit lens at f/5.6 but not much different at f/8 onwards - a good sample is definitely worth the effort.

Pitfalls? Don't buy anything that's been in someone's loft for years. Fungus is your problem there. It may or may not affect picture quality, but there is the potential for passing it on to your other lenses. A lens with fungus is worth just about nothing - so avoid!

Andrew

I suspect that you can find moire in images from many digital cameras even if they do have an AA filter - if you look hard enough.

This is a small crop from an image taken by a K200D with a 18-55mm kit lens.




Andrew

I've hade a play around with RawTherapee and this is about the best that I've been able to do. One problem is that the best highlight reconstruction result screws up other parts of the photo. I think I'll have to spend a lot longer learning RT to be sure I've got the best out of it.




Andrew

Rawtherapee seems to do OK too. This was processed using auto CA correction. The blue fringing was removed in Photoshop Elements 8 using the Hue/Saturation tool.




This version was processed in PSE8, using ACR6.2 and PTLens to remove the CA.




The difference between this and the Rawtherapee version is probably down to the demosaicing algorithm and highlight reconstruction.

Andrew

I did have another quick whizz with a different (clipped) image of trees against the sky, using ACR 6.2 and alternatively, Rawtherapee (RT), tried the "High Quality" controls in RT - and got the reverse result - the RT image was much better.

I don't really think I can draw any conclusion so far - experimental error might well have a greater effect than the difference between the two raw converters. I'll try again in a more measured way, once I've fixed the central heating

Andrew

Yes.

I only spent a couple of minutes each with ACR6.2 (Elements 8 ) and Ratherapee V4.0 (already past my bedtime). I'll have another look tomorrow and see if I can do any better. Once I'm convinced there is no more to be had, I'll post some crops.

Andrew