Actually the information shown is only a very small part of the overall picture. Measuring at 50lpmm is measuring very fine detail and we need to know the 10lpmm and 30lpmm readings as well to pick up a more holistic view.

The graphs shown are actually suggesting behaviour more typical of a theoretically perefect lens, where the optimum resolution is obtained at or near open aperture. Stopping down reduces resolution because of diffraction effects.

It is much more usual for a lens to peak at middle apertures, older lenses at smaller apertures than more recent designs, so it makes me wonder how accurate the testing was.

Unless of course the 16-45mm behaves as a perfect lens. Perhaps it does.

In a generalised way, most prime lenses have an optimum aperture of maybe 2 or 3 stops down from open aperture. So your average f2 lens might perform best at f5.6. Older designs may be better at f8 or even f11.

Hgh quality zooms will be best around f8 or f11, but poor quality ones will continue to improve and may be at f16 before they are performaing at optimum.

This is all theory though, and it will depend on the decentering of the elements. A poorly constructed lens will not reach the potential of its design. Equally, a superbly centred low cost design could out-perform a poor example of a top design.

I don't think we need an MTF setting to know we need to stop down to f8 or f11 for best results...

My first one was fragile in the sense that the aperture ring fell apart. I understand this is a weakness in early samples of the lens.

My personal experience is that all my friends' Pentax kit has been fine (Samsung included) and none of these reported problems have been evident.

There is a problem in the skewed sample that we represent here - people with problems come here for help, so we see people with problems in a much higher percentage than the general norm.

Even so, of you add up the numbers it is not really particularly high, it's just reported everywhere at the same time.

I was looking at the AP test of the GX20 today and also musing on the rumour that Schneider are thinking of building a lens factory.

Starting from scratch, Pentax have a Vietnam lens factory. Then they build a second, buy new lens making kit, computers, and load up the software. Now they have two factories and also finish some of the lenses with Schneider written on them.

So what if they build a third factory, buy new lens making ket, computers, load up the software, but site it in Germany financed by Schneider? All these lenses might be marked Schneider. Are they still Pentax lenses? When do they stop being Pentax lenses?

Maybe one step further they run out of capacity, but nearby Canon have some spare capacity. They send over the computers and software and Canon make some lenses as a sub-contractor. Are these Pentax lenses?

I suppose where it leads me is that in the modern manufacturing world, potentially who knows who makes what any more. Does it matter? What do you think?

And all this train of thought came from AP continually calling Pentax cameras Schneider clones.

No hassle, no problem. Unfortunately it still seems to be too big (1024 pixels wide) but before I delete it again I'll see if i can see what the problem is. Is Photobucket set to resize automatically for you?

I've had a look and it's definitely too big, so please try again. You need to re-size before you upload to Photobucket - please see the post on how to post images.

Sorry to be pedantic, but the 800 pixel limit was decided on to prevent that irritating side to side scrolling. It makes the images difficult to view properly.

Please re-post in the Competitions thread, but the size does need to be reduced to 800 pixels on the longest side.

Thanks.

I'm not sure if this was supposed to be an entry for the "Blue" competition, but if so it should be reduced to 800 pixels on the longest side and also posted in the appropriate thread as the latest reply.

There are instructions posted at the top of the "Competitions" section that will hopefully explain the process.

If there are any questions, please ask.

It is asking you the focal length as it cannot read the info from the lens. The information is needed to enable the shake reduction to operate properly.

It may be that the contacts on your lens need a gentle wipe clean. perhaps there is poor contact causing an intermittent problem.

All the K10D's I have been awatre of personally through our own and other members of our camera club have been just fine.

We all use Pentax lenses (or the Samsung variants) and have had no problems whatsoever.

Personally I wouldn't expect to have to enter the engineering modes and would leave it to a repair house if it were ever needed.

I would buy with confidence.