Mould in objective?

[huwbellamy]

Hi all,

I haven't used my C6R in a while and having a look at the objective there is a small spot in the mid periphery with feathery lines emanting from it. I'm guessing this is mould due to be being stored in a less than dry garage? The central dot is smaller than a pin head and the feathery stuff ocupies a space just smaller than a 5 pence piece. It doesn't appear to be causing any problems with viewing and I can't split the optics to clean it (I could but I'd need a fancy tool and some bravery). Do I just ignore it?

Thanks, Huw.

[Merlin66]

Yes.

Until you have the ability to remove and clean the objective, not too many options.

Just keep it dry in future.

Leaving it outside during the day with the cover off will let some UV light get it, which will help to "kill off" the mould. If left indefinately the mould will damage to coatings and possibly the lens.

( BTW This was a BIG problem for me when working in Thailand!! My mate lost a few good Pentax lens to severe mould growth - humidity and heat, a bad combination!)

[brianb]

If left indefinately the mould will damage to coatings

By the time you can see it the damage is done. Removing the fungus is not possible without stripping the coatings too. If you know someone who can recoat & recollimate objectives, it may be worth doing the job; otherwise, put up with, scrap if/when the impairment becomes too great.

[huwbellamy]

Thanks both, I have found this chap and wondered if anybody else has anything to report on his services: Astronomical Telescope Repairs and Servicing

Also spent some time stripping things and cleaning this morning - in the sun Merlin. The objective is certainly less dusty/fogged. I took some pics of the mould:

[huwbellamy]

To add - I took these through it last night so nothing horrendous happening: http://stargazerslounge.com/imaging-lunar-solar/84603-first-ever-imaging-dont-expect-much.html

Also, I've tried holding obstructions in front of the objective a few years ago to see what degradation a dirty lens may make - I had to get a fair amount of my hand in the way before things got worse. Do smears/dust/blobs make a big difference to viewing?

[dweller25]

Nice image of thr Moon.

I would just use the UV of the Sun to kill the mould, keep it dry and don't worry about the mark left on the objective - it will have no effect.

[huwbellamy]

Cheers dweller! I have been reading as much as google will give me on the "do dirty lenses make much difference?" issue and it would appear to agree with you. You need some pretty manky lenses/mirrors before cleaning/repair becomes worth the expense/risk.

If there was image degradation would it affect bright things like the moon most or faint DSO's?

Ta, Huw.

[dweller25]

Not sure but have a look through the scope at Jupiter - if you see nothing unusual (and I suspect you won't) then you are good to go.

[huwbellamy]

Thanks, I'll try it. Heres the prompt reply I got from Ade Ashford (edited to remove personal details):

"Anyway, to your C6R objective. I doubt that the mound/fungus would've

etched the coatings (unless you're really unlucky) as they're pretty

resilient these days. If it's not impairing the image (and a 5p-sized

obscuration would be unnoticeable) , I'd be tempted to leave well

alone for the moment -- annoying though the spot must look to you.

If it came to taking the objective apart, the retaining ring of this

Synta-made 'scope is not too hard to remove if you're methodical and

fabricate yourself a tool (a piece of ply with two small panel pin

nails does the trick). The two elements usually have registration

marks around the circumference that need to be realigned after

cleaning and reassembly; a simple pencil line on both will suffice if

none were there to start with.

With regard to cleaning, Baader Planetarium make an excellent 'Optical

Wonder' cleaning fluid (obtainable from David Hinds Ltd). Full directions come with the kit."

Good enough for me!