Dark splodges - guesses anyone?

[Mel]

I'm wondering what these dark areas on this image are. I am putting my money on dew since I have persistent damp problems in my obs. The moisture seems to collect under my foam tiles and builds up until the humidity in the dome is >95% all the time pretty much.

The one on the right looks like a dust bunny to me -probably near the camera judging my the size - though not on a filter since it appears on all subs - maybe the camera glass?

Anyone got any thoughts? I'm new to the cooled ccd/filtered imaging scene since I just got a sxv-h9 (early chrimbo pressie to myself).

I don't really want to go as far as cleaning the refractor's objective yet although it does need it. I don't think these marks could be down to a few marks on the lens, but I could be wrong.

Feedback anyone?

(click to enlarge)

cheers

Iain

[RobH]

I would say they are dust bunnies and fingermarks Iain.

The closer to the chip, the smaller the mark.

They won't be on the objective....too far away to come up like that.

Get a dehumidifier....I have one switched on all the time when the roof is closed and it keeps it nice and dry in there.

Cheers

Rob

[Mel]

Yep - that's what I thought. Guess I got my little grubbies all over something...

:laughing3:

I know we're told not to clean anything, but the Megrez has been in the obsy for nearly a year now and even though its capped after use, it's picked up a load of crud while it's not been. The worst thing is flecks of fibre glass from the shutter opening and closing - it hangs in the air and sticks to the wet glass like the proverbial to a blanket...

Guess it might be time to get that lens/filter cleaning kit out. I normally just use a 'big bulb blower' to blow stuff off and wont even touch the glass with a camel hair brush as it leaves streaks/smears.

One thing I've learnt is never to use one of those aerosol compressed air sprays. Tried that on the LX and a load of propellant came out with the 'air' and stuck to the corrector plate leaving nice large frozen 'splats' everywhere...

Will have a search for cleaning tips before attempting anything. I know to my cost that anything you attempt to clean can be difficult to bring back to the same as it was before.

The dome is a serious wet site - I need to sort out the ingress before I even thing about dehumidifying - the seal between the outside wall and the concrete base is my first target. Gonna try pulling up the thin mastic bead that the installers (Pulsar - Gary Walker & co. - hi Gary :wave: ) put in place and redoing it with something more substantial first. It's been installed nearly 2 years now, so guess some maintenance is normal.

cheers

Iain

[RobH]

Hello Iain,

I clean my 14 inch corrector plate about twice a year, and cleaned the 80mm lens this year too.

As long as you're patient, there's not a problem. The coatings on these things are actually pretty tough!

I use pure isopropyl alcohol to start with, applied with lint free swabs, using a new swab per wipe (lots of tissues!)

I then apply a mix of distilled water and isopropyl, then finally pure distilled water, and carefully dry off with yet more swabs.

I probably use 80-100 swabs during this process, and it takes about half an hour.

I got all the ingredients from ebay....the distilled water was from 'cigar pleasures', it's not the stuff you top up your battery with as this is just deionized.

The exact quantities and proportions I can't remember, but it's Doc Clays solution. I made enough to last me for years very cheaply.

Cheers

Rob