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Daniel-K

what the hell is this on my mirror??

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just followed this guy

lined the sink with a tea towel and used some instant foam detergent and gently washed it rinsed it a few times and stood it to dry had a few specks of dry water cause i never used distilled water. to be honest the dew in the air probably contains more Rubbish in then our tap water so i dont see the point in going through the effort of using distilled water for the mirror to be coated in dewy Rubbish stuff again. PLEASE DO NOT PUT YOU MIRROR THROUGH A DISHWASHER IT WAS A JOKE :grin:

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i just put it through the dishwasher on an eco cycle and used one of those finish tablets lemon flavor aswell came out as new :grin:

Excellent idea :eek:

I hand wash mine - really

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i just put it through the dishwasher on an eco cycle and used one of those finish tablets lemon flavor aswell came out as new :grin:

I cringed when I read that LOL .. wasn't sure if that was what you'd actually done or not, but glad to read otherwise further on :)

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While the mirror was removed from the scope, did you re-centre "the spot"

cheers

Steve

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Looks like what you had was an area of dew spotting on the mirror from where a patch of dew had dried out. It wouldn't have affected the view but it's cleaned now so fine. If you're doubtful about your centre ring then remove the mirror and find the centre by stretching threads across the mirror's diameter at angles to each other. Two threads will cross at the centre, a third provides a check that you're really crossing the full diameter. If you use a cheshire for collimation then put a self-adhesive paper spot at the exact centre and you'll be fine. The ring can be left since it's all in the shadow of the secondary anyway and does not contribute to light at the eyepiece. If you use a laser to collimate then you would need to remove and replace the ring.

Most likely your centre ring is fine - it's impossible to tell from your photographs.

Edited by acey

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its was over the entire mirror equally distributed, it must have been something in the air that night, but it wasnt on my finder? its all sorted now thankfully :)

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You mention a dessicant cap in your telescope. When was it last re-vitalised. With the wet weather we have had recently dessicants won't last very long before they loose their effectiveness. I assume that you have silica gel, is it coloured? If so the colour should tell you when the silica gel needs shoving in the oven for an hour or so at 150°C.

Nigel

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Dessicant caps are OK but they only absorb the moisture , not all the crud that was in the dew that builds up on the mirror unfortunately . . .

Steve.

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Sap from nearby trees? There's a sycamore in our garden and it chucks out all sorts of tat that ends up on the collector of my SCT.

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I just " Karcher " my mirror . . . . . . with distilled water obviously . . . :p

Damn. I was just about to write "You could use a power washer" :)

James

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...but I can't fit my SCT in the dishwasher... :grin:

You only need to put the corrector in. On the top rack, with the glassware, obviously.

James

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Dessicant caps are OK but they only absorb the moisture , not all the crud that was in the dew that builds up on the mirror unfortunately . . .

Steve.

Dew forms when the water vapour condenses onto a cold surface. It is essentially distilled water. Any dust/crud in the air will then stick to the wet surface. If you stop the dew forming in the first place the dust and other stuff in the air will not stick so well and can often be dusted off with a soft brush.

The best brushes to use are the cosmetic blusher brushes but don't use the other half's discards, they will be greasy, buy yourself a new one and keep it hidden from you know who.

Nigel

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Just out of curiosity... you don't happen to store it in a garage of sorts and smoke in the same room do you? I ask because, during last winter I smoked in my garage where my scope was stored, and had to clean it, since the ciggy smoke formed a haze on my mirror that looked just like the one in your pic.

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You dont happen to live near the ocean at all ?

I have seen similar on a friends mirror , it was salt in the air settling on the mirror , he has to clean his about every year , he has a great dark place to observe tho .

Brian.

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Either that or you've had some exceptionally filthy dew.

James

+1. I agree, looks like what I cleaned off mine this summer, when the dew drops there's enough crud in the air to dirty any mirror/lens.

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