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Going to try EAA @ F10....

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#1 Jeff Lee

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Posted 14 July 2021 - 11:11 AM

I've been using everything from F3.3 to F6.3 and now want to try @ F10. I understand that requires about 2.5 times the exposure time (easily done on the AZ-EQ even in AZ), not so sure how the C5/SE setup will work.

 

Anyone have any tips for EAAing at F10?  Thanks.



#2 jerahian

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Posted 14 July 2021 - 12:05 PM

I assume you will be using your ASI294?  If so, crank up the gain to 300 and you will still be able to keep your EAA exposures to a nice, short 20-30s.

 

This image of mine, which I know is now fully processed (EAA police, please don't shoot me), started off as an EAA live stacking experiment on my EdgeHD 8" at f/10 (no filter, Bortle 5 sky).  I wanted a FOV that could capture galaxies well during the Spring months at our club's electronic star parties.  So, to keep the exposure times very low in order to have an interactive presentation, I decided to jack the gain up to 300 and it worked really well.  During the presentation, with just 15 minutes of total live stacking, I had a progressively beautiful Needle Galaxy on a 12' project screen wowing our local astronomy club members with my little experiment.

 

I think you will be pleasantly surprised...

 

CS, Ara


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#3 Jeff Lee

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Posted 14 July 2021 - 12:34 PM

Thank you that is what am looking for, but since I just try for what I would see in a larger scope in the EP at a dark site I will be some what shy of 3 or 4 hours:). I am think that 10 minutes @ 450 gain should do that....



#4 dcweaver

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Posted 15 July 2021 - 12:25 AM

Jeff,

   

Don't know if you are set up to use SharpCap Pro's recommended exposure times, but the math behind it shows you may be able to get away with 5-10 sec exposures and 120-60 subs for 10 min total exposure.  This assumes the following:

   

Bortle 7.5 sky (if darker expose longer)

f/10

ASI294 color camera

4.6 micron pixels

1.2e read noise

0.75 QE

   

If you try 10 sec or less, let me know how it works out.  Would like to see the raw math behind SharpCap's engine put to a good field test.  I'm out of action for a while and can't check it myself.


Edited by dcweaver, 15 July 2021 - 12:57 AM.


#5 alphatripleplus

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Posted 15 July 2021 - 06:57 AM

It will be interesting to see what the maximum length sub-exposure the  tracking on the SE mount at the full 1,250mm focal length of the C5 can handle before stars start to trail (assuming you are going unguided). 



#6 Jeff Lee

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Posted 15 July 2021 - 08:15 AM

It will be interesting to see what the maximum length sub-exposure the  tracking on the SE mount at the full 1,250mm focal length of the C5 can handle before stars start to trail (assuming you are going unguided). 

More a test of how many images SharpCap PRO can stack and align before the crop becomes unacceptable. I've done up to 20 minutes and still the main subject and surrounding space was ok after a crop. It seems to me that 8 to 10 seconds (I have a limited sky view and normally am pretty high in the sky when doing EAA) is my max. But I'll post my results here with data.


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