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I've just finished my first ever astrophotography session with my new scope and as I was dismantling the equipment I realised everything was covered in condensation.  I'm leaving everything to dry off overnight indoors at room temperature but I'm wondering about the lens in my scope.  So, the silly question is, do I leave the optics covers off to allow them to dry or do I leave them on to avoid dirt or dust contamination?

Thanks in advance

Michael

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If you cover the objective, the condensation will be trapped inside and so it will not "dry off". If you are worried about contamination, wrap a tube of cardboard around that end to prevent dirt falling on the lens.

HTH

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Thanks Demonperformer.

Hi Jeff, the scope is great and I learned a lot last night.  I had a few issues with aligning my mount but that just needs experience.  I managed to get some nice shots of the Whirlpool galaxy before the clouds rolled in around 1am.

All the best

Michael

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19 minutes ago, Synchronicity said:

Thanks Demonperformer.

Hi Jeff, the scope is great and I learned a lot last night.  I had a few issues with aligning my mount but that just needs experience.  I managed to get some nice shots of the Whirlpool galaxy before the clouds rolled in around 1am.

All the best

Michael

Brilliant , glad you like it , good luck in your new venture , if you can please show us your images

 

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I've attached a crop of the original, it's 17 x 60 seconds, no darks or flats, stacked in DSS and tweaked with Pixinsight.  Bortle 8 skies with high cloud thickening - I had to discard another 24 shots.

The full image shows light from 5 other galaxies - to say I'm chuffed would be putting it mildly!!

All the best

Michael

Whirlpool2b.jpg

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1 hour ago, Synchronicity said:

I've attached a crop of the original, it's 17 x 60 seconds, no darks or flats, stacked in DSS and tweaked with Pixinsight.  Bortle 8 skies with high cloud thickening - I had to discard another 24 shots.

The full image shows light from 5 other galaxies - to say I'm chuffed would be putting it mildly!!

All the best

Michael

Whirlpool2b.jpg

What a neat little Galaxy... nice work.

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Hello Michael,

If you bring it indoors straight away, it is likely that you will have more condensation from the warm air hitting the cold equipment. It is best to let it dry in an unheated shed or garage, and then, when dry, bring it indoors, with the covers on, or in a sealed bag/case.

On the odd occasions that I use my DSLR for imaging, I put it straight in a zip-lock bag with a few sachets of silica-gel crystals. The sachets can be re-juvenated in an oven, for about an hour, at about 120 deg. C (as the oven cools after cooking the Sunday roast), and then stored in a screw-top jam jar.

Geoff

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I have a Dobsonian, and I usually put the dust cover on when I am finished viewing. Dobs have a larger space inside of them for the vapor to disperse, so should I still leave the dust cover off for a while?

I don't a garage to store the 'scope outside at outside temperature at the moment, but I will be moving house soon and will be getting a garage.

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Just how wet does it get while you are observing? As mentioned above, a lot of the problem is when the cold chunk of glass (mirror/lens) meets the warm (moisture laden) air inside and condenses the moisture out of the warm air (cold air cannot hold as much moisture in suspension as warm air and so the cold surface causes it to condense). If you cover the scope this before you bring it inside, that should not be a problem. All you are trapping in the tube is the cold non-moisture laden air.

If you are getting moisture forming on the scope while observing (it is "dewing up"), then you do need it to dry. If the tube is completely enclosed, the moisture can "disperse" within the tube, but the need is for it to get out. For that, there has to be some form of (for want of a better word) ventilation. If it is a solid tube dob and you cover the end, you are trapping the moisture in the tube (a truss dob is, of course, a different animal). If you are worried about dirt falling on the mirror while it is drying, I would suggest some form of light porous material draped over the end (a bit cut from an old sheet, maybe?) that will not trap the moisture, but will keep dirt and other nasty things from falling into it.

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10 hours ago, Demonperformer said:

Just how wet does it get while you are observing? As mentioned above, a lot of the problem is when the cold chunk of glass (mirror/lens) meets the warm (moisture laden) air inside and condenses the moisture out of the warm air (cold air cannot hold as much moisture in suspension as warm air and so the cold surface causes it to condense). If you cover the scope this before you bring it inside, that should not be a problem. All you are trapping in the tube is the cold non-moisture laden air.

If you are getting moisture forming on the scope while observing (it is "dewing up"), then you do need it to dry. If the tube is completely enclosed, the moisture can "disperse" within the tube, but the need is for it to get out. For that, there has to be some form of (for want of a better word) ventilation. If it is a solid tube dob and you cover the end, you are trapping the moisture in the tube (a truss dob is, of course, a different animal). If you are worried about dirt falling on the mirror while it is drying, I would suggest some form of light porous material draped over the end (a bit cut from an old sheet, maybe?) that will not trap the moisture, but will keep dirt and other nasty things from falling into it.

It doesn't get wet while observing, it gets wet when I bring inside and the inside moisture condenses on the cold mirror. I have an old sheet, I will try using that instead of the dust cover.

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6 minutes ago, xvariablestarx said:

It doesn't get wet while observing, it gets wet when I bring inside and the inside moisture condenses on the cold mirror. I have an old sheet, I will try using that instead of the dust cover.

Right. If the condensation is happening when/after you bring it inside you can fit the cover outside and this will stop the warm moist air from condensing on the mirror or inside the tube. Any condensation that forms outside can just be wiped off or left to dry naturally.

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My question was after my first session with my new scope.  The weather here has been poor for ages and it had rained quite a bit earlier in the day so there was a lot of moisture in the air.  The scope and mount were damp with condensation when I stopped for the night and I knew this would get worse when I brought them in. 

I hadn't thought about leaving it in the garage to dry off - but I'll need a skip or two before there's space in there for anything!!

All the best

Michael

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