The Sigma 10-20 was the first APS-C lens I bought (other than the 18-55 that came in the kit) when I went digital and a couple of years on it's still the first lens I'd buy. Had the Pentax 12-24 not been twice the price I'd definitely have considered it however it's no better than the Sigma lens and therefore not (IMHO) worth any price premium over it.

The DA 16-45 F4 I also have and use a lot - it's my experience that it's massively better than the kit lens plus a more useful focal length range. It and the Sigma 10-20 are by far my most used lenses.

Of the others you mention:

Sigma 18-50 F2.8: The extra width of the Pentax 16-45 is worth more to me than the extra stop of this lens.

Sigma 17-70 F2.8-4: Sounds like a useful compromise lens and I've heard good things about it so probably worth a look.

It's also my experience that the Sigma 70-300 APO is a better lens optically and for flexibility than the 80-320. The 80-320 fetches more 2nd hand than the Sigma so personally I'd make the switch.

My, that's a big one...

When I lived in Hong Kong I remember seeing a huge lens for the 6x7 (might have been a mirror lens) that looked about the size of a dustbin.

I've not done a lot with it yet but I was quite surprised at it's sharpness wide open and the colour & contrast seem good as does the "bokeh" (I hate that term!). There always seem to be loads of them cheap on Ebay.

The Super Ozeck is a KR fit so once the problem pin is removed it functions like a KA mount although while the aperture info comes through fine the focal length doesn't. The Prinz Galaxy is a T-mount and the other two are M42.

Cheers. The Prinz Galazy isn't very good (quite soft even stopped down and with a bit of CA as well) but the others are decent enough especially as all those example shots were with the lenses wide open.

Difficult to say as they were shot on different days and in significantly different lighting conditions.

I've been playing about with some dirt cheap lenses recently:



K10D, Super Ozeck II 28mm F2.8 in KA/KR fit (£3.20)



*istDS, Carl Zeiss Jena 50mm F2.8 (£5.01)



K10D, Prinz Galaxy 135mm F3.5 (£0.99)



*istDS, Helios 44-2 58mm F2 (£2.40)

Me for one, as that answers all the other points (ok then whines) I'd make about affordable wide angle primes!

Just do what I did and hand out lots of commendations...!

Cracking opener from John for this theme.

I'll need to have a good think about an entry for myself because I doubt I've got anything for it at the moment.

*istDS, Tokina ATX-Pro 20-35mm F2.8