Put in a reply summarising the changes now available.

If the image looks shapr in the viewfinder and isn't on the sensor, then something is physically out of alignment. The mirror could be displaced or the focusing screen not seated correctly. If all is well, the manual focus image will be sharp and the viewfinder image will be sharp at the same time.

AF is not and never has been perfect. It will be fooled by low light, low contrast and it only knows where you want it to focus if you tell it.

I find the best way is to use centre-point focus only. lock with a half press on the shutter release, recompose and fire. If it's worked you can see it snap in on the focusing screen (I never look at the green hexagon) and if it won't lock then use MF. The DA lenses can be tweaked manually after AF has locked if you're not happy with the precision.

There are lots of other things that can go wrong with the focusing of SLRs, but they need proper repairs, such as to reset the mirror position. This is Critical, so mirrors should never, ever be cleaned by wiping or touched in any way.

You can switch off the writing to new folders on each date - have a look in the camera menus.

To expand on that, Sigma as I understand it "reverse engineer" their lenses. That is, they take a camera such as the K7 and then make their lenses work with it.

The consequence is that the K9, K5 or whatever replaces the K7 may not work in the same way so the lens will have anomalies in its function. The lens may be able to be re-chipped, but sometimes not.

A genuine Pentax lens can be expected to work without any hitch.

You can pretty safely assume that all the Pentax 50mm lenses will give similar results from f8 onwards. At wider apertures the different characteristics will begin to show.

The f1.7 and f2 designs are the best for the sheer ability to (optically) abuse them by adding close up devices and using bellows, extension tubes and so on.

The f1.4 has more contrast as suits its reportage and low light functions. It does have lower resolution so this is not for you if copying or ultra fine detail is what you need.

The f1.2 is brilliant for those who need it, and wonderful for those who desire it.

In general terms, if you are using the images for the web and maybe up to A4 prints you'll be hard pressed to say which of the lenses is better.

Preferably use A series or later on digital for the covenience in operation that it brings. Having said that, I'm offering an M series f1.7 on eBay now, currently at £10, which is in brilliant condition.

I've corrected the title for you.

My first camera was my Grandmother's Kodak Brownie Junior 620 box camera. I still have it.

That makes me sound much older than I am!

Hope you all have a fantastic 2010!

It puzzles me that someone would want such high ISO settings as for example the new Nikon D3S. 102,400 seems ridiculous, apart from the fact that probably the metering isn't accurate enough in the dark anyway.

We can make images in the near dark with 100 ISO and a tripod, or, as george points out, we can add light as needed.

Surely photography is about painting with light, not with darkness?