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first shots with ASI6200, M1 LRGB

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#1 prefetch

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Posted 27 October 2020 - 12:45 AM

i took this the same night i took M15, but this time i used 10 second subs.  280 frames per LRGB filter, and ended up throwing away over half of them in pixinsight subframe selector filtering for FWHM and eccentricity.  it ended up being about a 90 minutes of integration.

 

i used darks and bias frames.  i did a quick test w/ using just darks and a test with just bias, and it seemed to slightly better using both bias and darks in this instance.

 

this is the first time i've really used a cmos, and it's nice not having to worry about dead columns. (is that a function of cmos?  or maybe this is just a new chip..)

 

i think i might have taken too much green out of it.  i dunno - processing is hard.  i think this object looks better cropped, so this is a crop.

 

always looking for feedback on improvement, comments/criticisms are always welcome.

 

50535062878_76b8e001f6_c.jpg


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#2 maxsid

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Posted 27 October 2020 - 03:59 AM

Too much green. I just ran HLVG on your image (nothing else). Here's what I've got.

It's pretty good - congrats!

 

Untitled-1.jpg


Edited by maxsid, 27 October 2020 - 04:02 AM.

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#3 maxsid

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Posted 27 October 2020 - 04:04 AM

I actually never shot this target myself... Will try next new moon.

(Well, I did. When I just started two years ago. With a 180mm lens - it was just a blurry blob).


Edited by maxsid, 27 October 2020 - 04:07 AM.


#4 tjschultz2011

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Posted 27 October 2020 - 04:20 AM

What's the rest of your imaging setup? I'm imaging the same target this very moment with 10 sec subs and my 17.5" f4.5 dob. 


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#5 prefetch

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Posted 27 October 2020 - 08:44 AM

What's the rest of your imaging setup? I'm imaging the same target this very moment with 10 sec subs and my 17.5" f4.5 dob. 

i'm using a 1-meter F/4.25.  normally i'd probably do 60 second or maybe even 180 second exposures, but i've playing around with short exposures lately.



#6 prefetch

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Posted 27 October 2020 - 09:05 AM

Too much green. I just ran HLVG on your image (nothing else). Here's what I've got.

It's pretty good - congrats!

i think you're right - there is still too much green in my image even though i toned it down (via photoshop.) - thanks for pointing that out.  when you stare at an image for an hour messing around with it you start to get tunnel vision.

 

here's a new version after i've run pixinsight color correction.  i also added a smidge of vibrance via photoshop.

 

50536113873_df6f6e4911_c.jpg


Edited by prefetch, 27 October 2020 - 07:08 PM.


#7 Peter in Reno

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Posted 27 October 2020 - 09:42 AM

What gain and offset did you use?

 

Peter 



#8 prefetch

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Posted 27 October 2020 - 10:03 AM

What gain and offset did you use?

 

Peter 

zero gain, 50 offset.  since i'm new to cmos, i have no idea if those are appropriate or not for this sort of thing.



#9 Peter in Reno

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Posted 27 October 2020 - 10:18 AM

zero gain, 50 offset.  since i'm new to cmos, i have no idea if those are appropriate or not for this sort of thing.

That should be good for LRGB. Just expose a bit longer each sub and reduce total subs. CMOS does not automatically mean shorter sub-exposure times. The larger the gain the shorter the sub-exposure times but more total subs because full well capacity shrinks and dynamic range also gets reduced. Experiment with different sub-exposure times up to 5 minutes each sub. The longer the sub-exposure times the fewer subs.

 

Peter 


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#10 lambermo

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Posted 27 October 2020 - 05:04 PM

i'm using a 1-meter F/4.25.

Is that a 1-meter mirror diagonal or 1-meter focal length ?



#11 prefetch

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Posted 27 October 2020 - 07:07 PM

Is that a 1-meter mirror diagonal or 1-meter focal length ?

that'd be a 1 meter diameter.  smile.gif


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#12 tjschultz2011

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Posted 28 October 2020 - 08:45 AM

that'd be a 1 meter diameter.  smile.gif

That's some imaging scope. I thought mine was large at 17.5". How is yours mounted? Mines just a dob but it can track well enough for 10-20 second shots usually. I've been keeping it at 10 lately and boosting my ISO a little bit to increase the number of useable frames. 



#13 prefetch

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Posted 28 October 2020 - 09:10 AM

That's some imaging scope. I thought mine was large at 17.5". How is yours mounted? Mines just a dob but it can track well enough for 10-20 second shots usually. I've been keeping it at 10 lately and boosting my ISO a little bit to increase the number of useable frames. 

it's a planewave cdk1000, so it's mounted on an alt/az fork but it has a built in derotator so it tracks pretty well.  it's in a permanent observatory, so it's a pretty convenient system, although my biggest gripe is the FOV is relatively small.



#14 tjschultz2011

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Posted 28 October 2020 - 09:49 AM

Nice! That sounds like a pretty sweet setup. I'm experimenting with autoguiding on mine and if I can get it down good I'd like to add a derotator eventually. My FOV is also fairly small which can make finding and framing things difficult but can also provide unique close up views that you don't see too often on common objects. I just shot M42 the other night and it more than fills the whole frame while providing excellent detail. You can check it out on my astrobin account below if you want. I'm almost done processing my version of M1 that I was shooting the other night. Yours definitely has a bit more detail than mine but I can still make out the same structures and the color is pretty similar. 




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