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Old 26-11-2007, 05:50 PM
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Question What went wrong???

Thought analysing a dud image (or at least one sub) might help some people out.... I've always found learning from disasters quite effective.....

This is a 5 minute sub at the Helix in Ha taken last night. 100mm f/5 achromat scope, DSI Pro II, guided by PHD on G-11. Outback cooler at 18degC. Dark subtracted only processing - only slight stretching to show the problem.
The dark subtracted .fit for the really interested.

Can anyone suggest what is going on, what's going very wrong in this??? I eventually worked it out, then went to bed early!
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Old 26-11-2007, 06:19 PM
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Is it fogging on the chip from the cooler?
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Old 26-11-2007, 06:24 PM
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Hmm, you left a Hartmann mask on the scope?
(Been there, done that!)

Cloud moved in front 30 seconds in?
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Old 26-11-2007, 07:15 PM
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There seems to be some of the same at the left of the images as well, could there have been some electrical interference, just a thought.

leon
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Old 26-11-2007, 07:19 PM
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I vote for fogging, although you could have been shooting through trees.

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Old 26-11-2007, 07:31 PM
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OK - the foggers have it - the right hand side of the frame was fogged (with an angular section on the left end clear) when I pulled the camera off. The left looks so white from the histogram stretching to bring helix out of the fog I believe.

Topped off a crap night really, with average guiding as well....

I initially thought it must have been a light leak around the silly filter holder on the DSI. I have usually checked the chip for fogging by looking down the objective with a torch - but the Ha filter is a tad hard to see through!

Seriously though - people - post your duds too - there is a lot to be learnt from others' wasted hours!
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Old 27-11-2007, 01:22 PM
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You want to see real serious (and obvious) fogging....
Try this sequence from my ST7 from a few nights back while I was starting a set of flats.
Images were about 30 seconds apart, at -10C.
Decided to call it a night as the clouds rolled in shortly thereafter anyway.

Will be baking the desiccant shortly!

Turbo
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Old 27-11-2007, 05:50 PM
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Then there is always this thread.
http://www.iceinspace.com.au/forum/s...ad.php?t=24960

with this animation of fogging http://www.iceinspace.com.au/forum/a...6&d=1192838628

Dem ST7 can get frustrating at time, turbo.
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