Mine doesn't do that. Have you formatted the SD card in the camera? Other than that, it may well be faulty and you would be entitled to a replacement from the supplier.

Thanks for that, very intersting!

I hear what you say, and you make a good argument.

It depends on what you need. I am amazed at the quality possible when shooting Macro on digital. It's far better than anything I ever did on medium format. Unfortunately I bought a Pentax 645n when really what I wanted was a 67 II.

So it also IMHO depends on what you define as medium format. 645 just was not a big enough quality jump from 35mm. 6x7cm is. 5" x 4" is even better, but the expense puts it right out of the question for me.

But at the end of the day it's the subject matter that's most important. I seem to make better images on DSLRs than i ever did. Partly maybe because of Photoshop, but maybe I've improved as well, helped by the ability to take so many more shots at no cost whatsoever.

Medium format has been hit very hard by DSLRs, full frame or APS-C, and I'm not convinced that other manufacturers are selling enough digital versions to make it worthwhile for Pentax. It ultimately depends on price as well as performance, but if the price ends up at Hasselblad levels, how many will buy?

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That just about sums it up! The results from the APS-C sized sensor are superb at this stage and that can only get better in the future.

As has been said, the 645D is the next logical step up, if there is sufficient demand for it. And that I suppose also depends on the final cost.

It helped enough for me to put in a bid on your lens Brian!

The dental Macro lens was sold in a kit with ring flash, for dental photography. It's a 100mm macro lens just like any other. Unless someone can tell me differently I don't think there are any special features. Using a 100mm macro is the classic focal length for dental photography.

Pretty much so far, apart from one SMC Pentax-A 50mm f1.7 (one of the early batch) where the aperture mechanism fell apart. I remember opening the lens up to try and fix it and finding all those interesting and unfathomable bits of metal and springs all over the carpet. This is why I always suggest professional repairs....

There has been no difference in reliability apart from that one glitch. To balance that, the only lenses with sticky diaphragm mechanisms have been M lenses.

I've come around to a similar point of view - no matter how good K and M lenses are (and they are very good indeed) it is much easier and more efficient to use A series and later lenses.

I reserve earlier lenses for use on the cameras that they were made for.

You didn't give me a "I'm thinking about it and I might" option, life isn't quite so black and white on this one.

Will the extra stop outweigh the massive increase in bulk? Will, indeed could, the quality be significantly better?

Time will tell.

Interestingly, the Tokina lenses mention the new water repellant coatings in similar words to the Pentax information release.