I think I need to clean my filter!

Lee · #1 21-10-2007, 04:58 PM

Thought I'd do some flat frame testing this afternoon, concerned about the dust evident in shots I've done..... initially put down to dust on the CCD, which always looked spotless to me....
So I shot some flats through the UV filter, and also straight to the CCD too.....
Pretty clear where the dust is now!!!

Both are stacks of 5 0.02s shots at the blue sky, identical levels applied in CS2....

ballaratdragons (Ken) · #2 21-10-2007, 05:01 PM

Lee, here it is in negative.

Nice Open Cluster, pity about the focus

[1ponders] (Paul) · #3 21-10-2007, 05:28 PM

How does your ccd look with less of an exposure Lee? It's a bit hard to tell what state it is in with thjat image so strongly exposed.

Lee · #4 21-10-2007, 06:10 PM

Was the same exposure as the filtered one.... will do some more though.... my eyesight is pretty perfect and I'm buggered if I can see anything on it though, I'd be surprised if there was much.
The filter is pretty grubby though!

Lee · #5 21-10-2007, 06:27 PM

OK - quick trip outside (with less bright sky too) yields these....

I'll be buggered!
Are these THAT bad - will using flats fix this in images or should I clean it AND use flats???

mill (Martin) · #6 21-10-2007, 06:48 PM

Quote:

Originally Posted by ballaratdragons

Lee, here it is in negative.

Nice Open Cluster, pity about the focus

Ken you are a funny man

Got #^#^ tears in my eyes from laughing.

leon · #7 21-10-2007, 08:07 PM

Lee, yep by all means clean them, (The Filters), and don't be afraid, all this rubbish about not touching your filters, don't clean with this and don't do that.

I am proud to say i have an optical system that is always a spotless as possible, and have no dust or dirt issues.

I probably over do it, i admit that, but each imaging session i air blow the front and rear lenses of the system and also following the nights imaging, before the caps go on.

The filters can, and do get dust on them sometimes as well, and it is not a problem to take them out of the system, get a good quality cleaning cloth, something like you would clean your glasses with and go for it.

First blow the dust of as best you can, then just polish it between the fingers until it shines,

and put it back, the filter will survive,

I believe it is rubbish how people are so afraid to touch filters and clean them.

I have taken filters out of a 49mm frame and grinded some of the sides to fit a 48mm frame, polished it up, refitted it, and it is fine, with no visible
signs of damage.

I will shut up now and wait for the flack.

Leon

[1ponders] (Paul) · #8 21-10-2007, 09:23 PM

I thought you might be in for a surprise Lee

All of those that are clearly visible in your first image are on the CCD cover. You can tell by the size of them.

Don't worry about it, flats will remove them with np at all. Cleaning filters is one thing, they are easily replaced if you scratch them but the glass cover on a CCD is another story. Be very careful cleaning them. The suggestion I was given when considering cleaning my CCD cover was "Dont!!" unless it is really bad. Have a look at my SBIG thread and check out Dennis' SBIG flat.

and the dust mote on mine. The size of mine indicates to me that mine is under the class cover of the face plate. The actual CCD cover looks pretty good on mine.

ballaratdragons (Ken) · #9 21-10-2007, 09:33 PM

I cleaned my Toucam chip the way Paul Haese demonstrated at Camp. But done very delicately and ONLY if necessary!

With my Astronomiks IR/UV filter it can be cleaned with almost anything as it is rated as scratch resistant!!! I scrub it with tissues regularly and it is unharmed. I don't know about other filters though.