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Guided Horsehead exposure times...?

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I FINALLY managed to get all the pieces of my "new" imaging rig together (Synguided MN190/f5.3, modded Canon 40D, EOS clip LPR), BUT...

Althought I know the moonglow isn't conducive, I set everything up and thought I'd have a go a the flame / Horsehead nebula. I started with 10 mins exposures @ ISO 800 and the histogram was WAY to the right, so I reduced to 5 mins... which still clipped. I've ended up at 3 mins, and although none of the histogram is clipped, I was expecting longer exposures than that!

I know I COULD lower the ISO, but am I doing something wrong here, or is it simply the moonglow that's burning me out...?

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It's the moonlight! Unless you have a narowband filter the moonlight will swamp your detector. You can reduce the ISO and stop down a bit to take star cluster images otherwise you'll have to wait until the moon's out of the way.


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Well that's just typical - I've waited nearly 7 weeks for tonight... and it has to coincide with a full moon!!!

It's been a useful exercise anyway (it took me AGES to finally get everything setup correctly!), but I think I'll still see what I can get out of the 3 min exposures. I just hope that we get some clear skies in a couple of weeks time (and I'm not having to work late!)

Cheers Rob...!

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