Last week I took a holiday near Aberystyth, mid-Wales. We found this rather cool tree which became the subject of a sunset photo shoot. Appologies if the colours are a little off, I still haven't ironed all the kinks out of my colour management.

[IMG]http://img.photobucket.com/albums/v68/thatguypinchedmyname/01-Sunday-003.jpg[/IMG]
Pentax *ist DL2 and 18-55 kit lens

[IMG]http://img.photobucket.com/albums/v68/thatguypinchedmyname/03-Tuesday-006.jpg[/IMG]
Pentax K10D and DA 55-300 cunningly pinched off my Dad

hope you like them, constructive comments always welcome.

lol the one on the right is giving the one on the left a real evil look!

good grief, I'm out of the picture for 2 weeks and the world ends!

the whole thing works just like a film SLR except that the film is a digital sensor. Unless you are talking about live view on the K20, the sensor is only active as long as the shutter is open (plus dark frame aquisition if activated).

I strongly suspect the shutter will wear out long before the sensor, but at the very least my K10D has taken 9500 shots with no visible ill effects so at your current rate you should be ok for at least 3 years.

My advice is stop worrying and start taking great photographs

oh and in answer to the actual question

I've been using my K10D and *istDL2 for astro photography ever since I've had them and neither shows any signs of ill effects.

One thing to watch though is that if you use a DSLR in place of the eyepiece of a Newtonian telescope then you are opening the sensor to the elements for the duration of the exposure. It will get very dirty that way. Dad and I eventually managed to construct a filter holder out of an old Vivitar 4 element TC, and this offers some protection.

for star trails reciprocity failure is actually helpful.

The stars are the subjects and are rather bright. Each point on the stars arc is exposed over the few seconds to a minute the star is in that position so reciprocity failure doesn't have any real impact. The problem with star trails is fogging of the sky in general which takes place over the whole length of the exposure. Reciprocity failure means that this is unlikely to be registered at its full intensity so you get a blacker sky than you otherwise would.

The important thing with star trails is either to print them yourself or use a lab which actually watches what the machine is doing rather than just letting it go nuts on auto, otherwise you'll end up with grey skys.

is there a UV filter on the lens?

My Tamron 90mm F2.5 dislikes UV filters and produced a similar fault to this when i was using one with it.

Hope it turns out to be something nice and simple.

what an interesting study on how the crop can change everything!

Sorry Dan, should have warned you against reading any more if you ever want to get any work done again!!

I remember this came up in a thread a few days ago and I can't find it now.

Anyway, I saw this on XKCD and I thought it might give one or two people a chuckle so

http://xkcd.com/394/

enjoy