Spots 'n stuff

Yes, Pentax has a sticky strip below the sensor to catch dust. Not sure for how long the strip keeps its stickyness, though.

Personally, I have used the Eclipse liquid cleaner a couple of times, with excellent result. It is specially made for sensor cleaning. The latest type of fluid is even safe for both types of sensors (CMOS or CCD).

John Riley was correct too: on much closer inspection it appears there are some marks on the inside of the SMC 50mm, how on earth do I get rid of them!

Likewise Gareth, the evening's fayre wasn't the best but it does help by planting ideas of different ways to photograph ordinary objects when you see someone else's work.
A couple of weeks back we had this guy at the club and it was just a wow evening.
http://www.marksissonphoto.co.uk/
http://www.natures-images.co.uk/

Now that was worth turning up for. See you soon

Thanks everyone, I am going to invest in an Arctic Butterfly very soon. And as for the dust spots inside the lens, for now I will have to clone them out. But I do have an old Auto Chinon 50mm f1.9 that I may practice stripping down and if I am successful I may have a go at the SMC A 50mm.
Again thanks everyone for the help and advice.

I've just this morning had problems trying to remove a dust blob. I took the lens off and gave the sensor screen a few blasts with the Giotto rocket blower, then had another look. Unfortunately although the original mark had gone, a lot more had appeared elsewhere so I then had a go with the butterfly only to find that some of the new marks that I had thought were dust had been smudged by the brush, so I reckon it was put there by the blower and is more than simple dust. Has anyone else had a similar experience and if so how did you cure it?

For sticky particles, a wet clean will almost certainly be needed.

Not only will the Arctic Butterfly not work for anything that is actually stuck, but it may smear what's there, and also contaminate the bristles with crap.

This will reduce its effectiveness for things it is good at, namely dust that is not adhered, and which therefore can be removed just by electrostatic attraction.

Sometimes it's hard to tell what sort of muck you have. It's just tough.. as the Visible Dust FAQ says:

[quote="visibledust.com"]
How can I tell if the contamination is dust or a stain?

Dust particles will come in many shapes and sizes such as specks and fibers. Stains will usually look fairly round and uniform, and sometimes cast a distinctive halo around the edges. Sometimes it is hard to differentiate between the two so the best course of action is to perform a dry cleaning. Best case scenario: clean, then you are finished. Worst case scenario: a smear is caused, a wet cleaning will need to be performed, followed by another dry cleaning (followed by cleaning your bristles).[/quote]

Yes, I've had a similar experience.

Have a look at my post here, and in particular at the 'before and after' shots.

I don't use the blower any more, except on lenses, for exactly this reason - it makes things worse as often as it improves things.

As I said in my earlier post, you'll probably need a wet clean.

Bite the bullet, get the swabs and fluid (RTFM so that you get the right materials), do it yourself.

It's very easy. Barely harder than the butterfly, in fact.

Thanks for the info, I've got the wipes you mention. Started with the dry sponge thing which just moves dirt around and I'm not sure what purpose it serves followed by two swabs then loads of dusts with the butterfly. Had to give the butterfly brush a wash & spin then let it dry first as I expect the muck left by the Grotty rocket blower had grease in it although where that came from I've no idea. Anyway, after lots of mirror up the sensor is now ok. I'll give the blower nozzle a wipe out on the inside with some Fairy & cotton buds before I use it again.