When you see a 'grainy' appearance through your viewfinder it's simply due to the smaller aperture of the lens. When you look through the viewfinder you're seeing the focusing screen which is make of clear plastic, but it isn't smooth, it's textured (not sure what the technical reason for this is, but I'm sure there is one). The smaller the aperture, the more visible this texture becomes.

To demonstrate the point, using your 70mm lens in Av mode, stop the aperture down (using the rear e-dial) say to around F8 or so. Then look through the viewfinder whilst holding the on-off switch on the DOF preview setting (the funny round symbol next to ON). This forces the camera to look through a smaller aperture than the largest the lens is capable of, and you should see the grain on the viewfinder appear as if you were looking through the kit lens (even a bit more so at F8 ).

Got my sensor all fixed up and shiny clean so I'll be seeing you all Saturday for sure. The wife is still a maybe.

I know Greynolds already offered but if anybody else still wants a lift from Edinburgh there are a couple of spots in our car. Last minute, I know, but didn't see the point in offering until my attendance was a definite.

Well certainly nothing lights up on a K-5 to tell you it's on.

Thanks! Good to know I have an emergency fall-back if necessary. Even in a worst case scenario if my K-5 is useless I have a Samsung WB550 compact I can use. It's a fairly decent little camera.

I don't know if everybody has seen the thread about the current state of my sensor but at this stage it isn't clear whether the cleaning kit I ordered to sort it out will be here in time for me to get it cleaned before the weekend. If not I'm a bit conflicted about whether to come or not because it really isn't in a usable state, and none of the camera stores around here seem to sell the wet cleaning solution.

It did occur to me that somebody else coming along might have the necessary materials and I could do it on the day... I really don't like to ask but I would hate to miss the meet because of a dirty sensor, and I would of course pay in full for any materials used.

So if somebody can help and really, truly doesn't mind please let me know. If my cleaning kit arrives this week it will, of course, be unnecessary.

Typical compacts are not dust sealed so this is probably quite common. There are a number of areas in the casing through which dust can enter, such as any of the buttons and controls, and small gaps between an extendible lens barrel and the casing. It's also possible there may already be dust inside the casing following the manufacturing process. Whilst the sensors themselves are manufactured in a dust-free environment, I very much doubt the camera bodies are assembled in one. The 'average' compact owner has no idea how to identify sensor dust so for the most part it likely goes unnoticed.

They have the 1.6 size on there too. Same price. Most likely I'll try them.

Well that's certainly reassuring. Did the Arctic Butterfly work okay on subsequent occasions?

[IMG]http://i1204.photobucket.com/albums/bb411/msitaylor/Dust/Dust.jpg[/IMG]

My sensor was showing a few spots of dust - not surprising since I have been changing lenses outdoors a fair bit. I purchased a Rocket Blower and a VisibleDust Arctic Butterfly SL700 sensor brush to attempt to rectify the problem. After a few blasts with the blower and a once over with the brush - all according to the instructions - the sensor looks like the above. About a million times worse than it was before, in other words.

My wife used exactly the same blower and brush to clean her sensor (on a Canon EOS 30D) before I did, and it worked perfectly on hers.

Does anybody know what on earth has gone wrong here and how I can get my sensor back to some semblance of normality?

She's had the Canon for 4 or 5 year but no, she does not have one of the big white lenses.