#21  
Old 15-10-2015, 11:24 AM
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Originally Posted by gregbradley View Post
My FLI Proline has a choice of download speeds, 1mhz and I think its 8mhz. The lower read noise figure for that camera is the 1mhz one. Do you use slower digitization rates on your Apogee and get the lower read noise?

I am wondering if I should shift over to doing that. 1 second downloads are seductive but a few extra seconds for lower read noise is not much to ask I suppose!

Greg.
I always use the slow digitization rate for image and calibration data, Greg. On the Apogee the fast rate is quite noticeably more noisy.

Cheers,
Rick.
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  #22  
Old 17-10-2015, 04:51 PM
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I should switch over to the slower rate. I did start to set it up at one stage.

Greg.
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  #23  
Old 19-10-2015, 06:21 AM
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Hi Everyone,
A test result and comparison of binning on a KAF8300 sensor cooled to -30 degrees:

The jury is still out.

This image was done by adding darks, flats & bias to 2 frames
& then showing that I went for a longer binned exposure.
Also shows the result of stacking 6 images.
Certainly when viewed straight off the camera the binned exposures seem to have more signal -
very important on a dim target - NGC 300.

cheers
Allan
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  #24  
Old 19-10-2015, 06:33 AM
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Stars tend to be fatter with 2x2 binning and detail in galaxies less clear with 2x2. That's why I tend to only use it for things like Ha in nebulas that don't have a lot of detail or Ha in galaxies where its really only little coloured blobs.
Colour in neb images may not be worth 1x1 and the extra time taken. Colour in galaxies or planetaries, globs etc is worth the extra time.

Greg.
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Old 19-10-2015, 06:40 AM
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Originally Posted by gregbradley View Post
Stars tend to be fatter with 2x2 binning and detail in galaxies less clear with 2x2. That's why I tend to only use it for things like Ha in nebulas that don't have a lot of detail or Ha in galaxies where its really only little coloured blobs.
Colour in neb images may not be worth 1x1 and the extra time taken. Colour in galaxies or planetaries, globs etc is worth the extra time.

Greg.

Hi Greg,
But you can see my results below -
even at 10 minute frames binned 1x1 -
only the center of NGC 300 was coming out.
Under dark skies I would have seen signal at 1x1.

cheers
Allan
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Old 19-10-2015, 09:40 AM
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Hi Greg,
But you can see my results below -
even at 10 minute frames binned 1x1 -
only the center of NGC 300 was coming out.
Under dark skies I would have seen signal at 1x1.

cheers
Allan

True. You have to use what works best for your conditions.
The good thing about the small pixels is they suit a lot of medoum length scopes.
Greg
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  #27  
Old 19-10-2015, 10:13 AM
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...They work perfectly well unbinned which is how I always use them...
Me too. I did a year or so experiment doing 2x2 on my colour subs and eventually found that doing 1x1 was the best with the KAF8300 sensor.

For the 11002 sensor I have been doing 1x1 all along. Being able to pick up lots of integration time affords me the ability to image at 1x1 with this sensor.
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  #28  
Old 19-10-2015, 01:26 PM
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Having colour data 1x1 gives a possibility of adding information to Luminance - just throwing in an idea...
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  #29  
Old 19-10-2015, 01:28 PM
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Having colour data 1x1 gives a possibility of adding information to Luminance
And often makes a nice improvement to the SNR.
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  #30  
Old 20-10-2015, 06:49 AM
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Originally Posted by Slawomir View Post
Having colour data 1x1 gives a possibility of adding information to Luminance - just throwing in an idea...
Yes - a good idea - I made a better picture of my NGC 300 doing that.
You need to make about 7 different stacks in DSS & blend in the best ones
to create a new luminance layer.
However - all my LRGB 15 minute subframes were binned 2x2 .


cheers
Allan
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