The adapter fits entirely within and flush to the K mount. Ther's nothing for the usual lens release button to push.

The Pentax Adapter K is the only one of choice. To remove, make sure that the camera is pointed downwards and use a pen point or small screwdriver to depress the small spring in the adapter. It should then turn easily and just drop out into your hand.

It's just a knack and with very little practice should be fine.

Have fun with the K10D.

The f1.7 lenses are actually better than the f1.4 versions, especially up close. You can certainly abuse them more!

I don't know how they choose what to test, it's going to be the wrong choice for someone whatever they do. I imagine the Canon owners will be miffed this week.

The test is in the new AP, out yesterday for subscribers, but not in the shops until Tuesaday.

The new issue of AP (out Tuesday) features a test of three macro lenses:

SMC Pentax D-FA 100mm f2.8
Micro Nikkor 105mm f2.8
Sigma EX DG 105mm f2.8

The Nikon and Pentax are very closely matched, with the Sigma just a whisker behind. The "scores", for those who like scores are:

Nikon 92%
Pentax 90%
Sigma 87%

Geoffrey Crawley writes an interesting piece about the lenses and clearly likes the Pentax very much. The quality of all the lenses is very high in any event.

The 80-320mm is one of the (few?) lenses I have not used, but the reviews in the photo magazines were generally very complimentary.

I've been looking out for one to try, but so far the prices on eBay have been far too high. That in itself suggests that the lens is well regarded and sought after.

I wouldn't worry too much about the gap. It's not essential to have a continuous spread of focal lengths. The difference can be made up by two low-tech solutions: walking backwards and forwards to change position and cropping the final image.

The camera selects the optimum aperture for the lens in use. This really implies that we use Pentax lenses, the information for which will be recognised by the camera.

I thought that's what you were getting at, but it isn't really mystical. It's just a very complex subject and in photography we are talking about a creative process that requires certain characteristics from lenses.

The proof of the pudding is in the final creative image, be it a fine landscape, an emotive portrait or whatever else.

Lens testing can end up as a fruitless process of photographing test charts, maps, or even teddy bears, but in the end all lenses with proper use should these days be sharp. Especially with digital imaging, sharpness is the least of our worries as we have sharpness beyond all 35mm film standards.

As you are clearly interested in getting under the skin of the subject, perhaps this book would be a good start:

The Lens Book by Roger Hicks and Frances Schultz ISBN 0 7153 0149 7 David & Charles 1994.

This explains in a readable way much of what we are talking about.

Fair comment George.

It usually takes a while to get to know a lens and really be sure it's doing the job. Favourite lenses are held onto very firmly, less good ones reveal themselves in time and get discarded.

It's a tough world for a lens.