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m15 from white zone

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#1 corpusse

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Posted 12 July 2013 - 11:29 AM

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Took this last night from home. 5 minutes x 20 then windows updates decided to update the computer. I finally turned automatic updates off. I've lost so many nights due to this.

What's amazing about this picture is no light pollution filter. With the QHY8 gain set to 0 its not very sensitive at all. Over 2 minutes with an SLR will blow out the image.

Should be clear this weekend so I can shoot a few more objects. It will be at least a couple weeks until I get back up to my other site and continue work on the grey zone observatory..

#2 CounterWeight

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Posted 12 July 2013 - 12:28 PM

Andrew, that is quite impressive :) No IDAS and 5 minutes from my yard all you would see is some gradient with impressions of things. way to go - push that envelope! :bow:

My first response was "we are not supposed to be able to do that!"

#3 Jeff2011

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Posted 12 July 2013 - 12:51 PM

I finally turned automatic updates off. I've lost so many nights due to this.



I had this happen to me the other night. Fortuantely it was before I started imaging, but it did delay my start. There is an option to automatically download the update, but allow you to choose when to apply them. I just had forgot to set mine that way.

Great pic. I use a DSLR and around 2 minutes at ISO400 with my F4 scope seems to be the limit for in my red/white zone with a sky glow filter.

Your results bring up an interesting question. Is it better to reduce the sensitivity (gain in your case and ISO in mine) and take longer subs, than increasing the sensitivity and take shorter subs? I am sure this has been debated to death before.

#4 Magellan

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Posted 12 July 2013 - 03:55 PM

shoot for 1/3rd to 1/2 of the histogram, shooting anymore above this is pointless. If the maximum you can shoot and the sky limit is limited to 2 minutes than only shoot the 2 minutes. Just shoot many more subs to get the same SnR as the ones with the longer subs. your results will be the same and with more subs that you can shoot you can stretch the data more.

The only issues with shooting shorter and many is:

1.) More wear and tear on DSLRs due to many mirror actuations. My T1i that I use for daytime only is at 10500 mirror actuations and still works fine.
2.) Longer to process the images in DSS.

#5 Jeff2011

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Posted 12 July 2013 - 04:27 PM

At 130 seconds, it is right at 1/2 the histogram when my target clears the worst of the light pollution. That is at 400 ISO. Would it make sense to drop my ISO to 100 and try for the longest that I can get with that setting, or just keep it at 400 ISO around the 2 minute duration?






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