Maybe the answer to that conundrum is in here - http://www.kenrockwell.com/tech/lens-sharpness.htm

Andrew

The 18-55mm MK2 kit lens (same optically as WR, I think) is pretty good at 50mm from f8 onwards. I've tested it a couple of times against a 50mm prime and although it's outclassed at f5.6, there is very little difference at f8. I've also tested the kit against a 28mm prime and again, it is bested by the prime up to f5.6, but holds its own at f8 onwards.

Andrew

I use RawTherapee also. I've yet to download the new alpha version. Does it seem stable yet?

Andrew

Sorry, but I don't see any "huge" differences either between the lenses or between shots taken at different apertures. Can you explain where you see them?

Bearing in mind that the lighting/exposure is slightly different from one shot to the next, I don't think it is really possible to discern differences that you can definitely atttribute to the lens. Much more testing with different subjects would, I think, be needed to do that.

I think the photos taken by dougf8 confirm that the kit lenses do amazingly well at 19mm wide open and at f8 when compared with a more expensive and highly regarded lens, even if you pixel peep.

Andrew

Very interesting results dougf8, thanks.

On my monitor, the full frames are close to identical, apart from slight variations in lighting. The 100% crops seem to show a *slight* advantage to the 16-45mm. I may be wrong, but I bet the differences seen on screen would not survive printing the whole image at A4 and possibly even larger.

My wallet still isn't twitching.

Andrew

I don't use Picasa, so don't know its limitations. Can you make a fixed size crop (e.g. 600x400 pixels)?

Even with the cropping problem, it's an interesting result. I was expecting it to be close at f8 - but not so close as this at f4. I cannot feel my wallet twitching.

The image size for the WR lens is smaller. Was it taken at a different focal length?

I have and use an 18-55mm lens and it's amazingly good. I keep trying to justify buying a "better" lens like the 16-45mm but in the end fail because the "better" lenses aren't much (any?) sharper than the kit at f8 and beyond.

You should definitely be able to get "a viewable level of sharpness" from any of the Pentax kit lenses by f8.

Andrew

Congratulations to the winners and especially to Stefan. I think flocks of birds fly in apparent formation by a process that involves each bird maintaining proximity to its nearest neighbour, without any consideration for the direction of the flock - a bit like squaddies on drill, but without the benefit of a drill sergeant to keep them directed.

I also liked Mike's photo. A jigsaw puzzle arrives as a bag full of complete disorder. The whole purpose of the puzzle is to impose order on the pieces and ultimately achieve a state of complete order. Mike's photo was a colourful exposition of a stage in that process. Brilliant.

Looking forward to seeing Stefan's "easy" theme for the next competition.

Andrew

Under a blue sky at Loch Lednock




Taken 04/04/2010 with Pentax K200D with 18-55mm MK2 kit lens @ 28mm, f8 1/250 ISO 200.


Andrew