#21  
Old 27-07-2020, 05:33 PM
echocae (Brian)
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If you are shooting widefield you should be fine with the 183.
cool.. yes i ony interested in dso on widefield.. thrn ok I wont listen to my friend. .
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  #22  
Old 27-07-2020, 06:37 PM
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The 183 is a pretty versatile camera and should work well with your scope. You will likely need a field flattener, as short refractors are notorious for their field curvature. You’ll get lots of detail out of a 183 under the right conditions. Calibrating is easy once you get the hang of it, it’s just a step in your processing.

Personally, I wouldn’t bother swapping it out. There’s always something out there that’s “more, better”, but the 183 is already pretty excellent at what it does. The challenge will be honing your technique. At this stage, I think that’s more important, but it’s your choice of course!
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Old 27-07-2020, 07:35 PM
echocae (Brian)
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Originally Posted by Camelopardalis View Post
The 183 is a pretty versatile camera and should work well with your scope. You will likely need a field flattener, as short refractors are notorious for their field curvature. You’ll get lots of detail out of a 183 under the right conditions. Calibrating is easy once you get the hang of it, it’s just a step in your processing.

Personally, I wouldn’t bother swapping it out. There’s always something out there that’s “more, better”, but the 183 is already pretty excellent at what it does. The challenge will be honing your technique. At this stage, I think that’s more important, but it’s your choice of course!
Thank you... I decided to keep my 183, and what you said is correct regarding "Honing my technique" is better get ugly now.. so later one when I decided to get serious I understand the process without cheating (with no-amp glow camera), btw Do I have to make Calibration library?

If I do need to make make calibration library (DARK) for 183 what gains, exposures,temperature that I should focus on.. is that any series/sequence that I need to concentrate... eg. -5, -10, -15 ... gain 0,10,20,70,100,150 and exposure 10 sec, 30sec, 60 sec, 90 secs... etc2?
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Old 27-07-2020, 09:30 PM
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Hi Brian,

With my 294 I do a dark library once a year. As I tend to only image at gain 120 as this is the lowest read noise for this sensor that gives a gain to keep exposures low.
I do a library for 30 sec, 60 sec, 90 sec, 120 sec, 180 sec, 240 sec and 300 sec. I don't use bias masters apart from calibrating flats.
The reason for stopping at 300 sec is that for my location longer exposures start to get more light pollution and my equipment may start to run into guiding issues etc. You may want longer if you go narrowband but I would use a broadband or light pollution filter first if you are in suburbs or metro urban areas and probably none in a dark sky site.
You will need to do say 30-50 frames for each then integrate each set into masters that are used in the calibration process.
You will need to do bias frames, darks and flats all integrated into masters that attempt to remove as much from your light frames that is not related to the signal that you want. That is, intrinsic chip noise, general thermal and other noise and problems with the chip (cold and hot pixels) finally the dreaded amp glow. Then there is the imaging train stuff like dust on your optics and vignetting that are removed with flats. Oh also don't try to get the temp down too low as the advantages are less in CMOS and it causes a lot of current draw in cooling. I try to stick to -10 as this is unlikely to lead to cooler power more than 60%.
Here is a reference article that will help to familiarise you with how the calibration works especially if you use pixinsight but are still relevant for the other calibration and stacking software. https://pixinsight.com/forum/index.p...bration.11547/
I really would encourage you to read it as it contains great insights in regards to calibration and the videos from Robin Glover that I referenced in a previous post.
Remember to stick to the same temp (I use -10 degC), gain 120 would be a good start "so called unity gain", unlike the 294 there is not a sudden change in read noise that makes a particular gain perfect but 120 is middle of the road. I am not sure about offset as this may be fixed in the driver. If you change any of these parameters in your lights you will need a new set of calibration frames especially if for any reason you change offset as this can lead to clipping in the calibrated light frames. Also avoid using automatic white balance values. In the 294 these auto values in the native driver can lead to problems. Check for the best values (in the 294 this is WB-B 50 and WB-R 50). Check online for advice.
Let us know how you get on. Generally users of this camera get pretty good results and there is a lot of information on common problems and their solutions. This is the advantage of getting a camera that has been released for a few years.
Good luck and clear skies
Mike
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  #25  
Old 27-07-2020, 09:40 PM
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I have a 183MC. First camera I have ever tried using for Astrophotography. Managed to get my first subs on Saturday night.

I messed up my flats and was unable to use them. The image below is using my darks only. I am not even 100% certain I got the darks right to be honest. I asked some questions elsewhere regarding my flat frames and I was told that if I get them right I will be able to get rid of the amp glow. Have seen plenty of pictures taken with the 183 cameras that do not have amp glow present so I am confident it is possible.

Once again bear in mind that these are the first photos I have taken with the camera so by no means are they anywhere near perfect. I just felt it was a great opportunity to give an example from a very novice user.
Correct darks remove the amp glow not flats. Flats handle uneven illumination of the sensor like vignetting and dust donuts.
Don't use Biases.
Amp glow is a hassle to a point. You need to have exactly correct darks otherwise it does not remove it. With the various combinations of settings you need a lot of different types of darks to match the light exposures.

When properly matched the amp glow seems to disappear.

Greg.
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  #26  
Old 27-07-2020, 10:02 PM
nsavage (Nick)
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Originally Posted by gregbradley View Post
Correct darks remove the amp glow not flats. Flats handle uneven illumination of the sensor like vignetting and dust donuts.
Don't use Biases.
Amp glow is a hassle to a point. You need to have exactly correct darks otherwise it does not remove it. With the various combinations of settings you need a lot of different types of darks to match the light exposures.

When properly matched the amp glow seems to disappear.

Greg.
Thanks Greg.

I clearly misunderstood the information I was given regarding my darks and flats but as you probably saw later in this thread I was able to work out what I had done wrong with my darks (which I then tested by integrating my subs and darks only and can confirm that this got rid of my amp glow) and then integrate my subs, darks, flats and dark flats which resulted in a corrected image.
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  #27  
Old 28-07-2020, 05:54 AM
echocae (Brian)
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Originally Posted by Spartacus View Post
Hi Brian,

With my 294 I do a dark library once a year. As I tend to only image at gain 120 as this is the lowest read noise for this sensor that gives a gain to keep exposures low.
I do a library for 30 sec, 60 sec, 90 sec, 120 sec, 180 sec, 240 sec and 300 sec. I don't use bias masters apart from calibrating flats.
The reason for stopping at 300 sec is that for my location longer exposures start to get more light pollution and my equipment may start to run into guiding issues etc. You may want longer if you go narrowband but I would use a broadband or light pollution filter first if you are in suburbs or metro urban areas and probably none in a dark sky site.
You will need to do say 30-50 frames for each then integrate each set into masters that are used in the calibration process.
You will need to do bias frames, darks and flats all integrated into masters that attempt to remove as much from your light frames that is not related to the signal that you want. That is, intrinsic chip noise, general thermal and other noise and problems with the chip (cold and hot pixels) finally the dreaded amp glow. Then there is the imaging train stuff like dust on your optics and vignetting that are removed with flats. Oh also don't try to get the temp down too low as the advantages are less in CMOS and it causes a lot of current draw in cooling. I try to stick to -10 as this is unlikely to lead to cooler power more than 60%.
Here is a reference article that will help to familiarise you with how the calibration works especially if you use pixinsight but are still relevant for the other calibration and stacking software. https://pixinsight.com/forum/index.p...bration.11547/
I really would encourage you to read it as it contains great insights in regards to calibration and the videos from Robin Glover that I referenced in a previous post.
Remember to stick to the same temp (I use -10 degC), gain 120 would be a good start "so called unity gain", unlike the 294 there is not a sudden change in read noise that makes a particular gain perfect but 120 is middle of the road. I am not sure about offset as this may be fixed in the driver. If you change any of these parameters in your lights you will need a new set of calibration frames especially if for any reason you change offset as this can lead to clipping in the calibrated light frames. Also avoid using automatic white balance values. In the 294 these auto values in the native driver can lead to problems. Check for the best values (in the 294 this is WB-B 50 and WB-R 50). Check online for advice.
Let us know how you get on. Generally users of this camera get pretty good results and there is a lot of information on common problems and their solutions. This is the advantage of getting a camera that has been released for a few years.
Good luck and clear skies
Mike
In Australia, What temperature setting u guys are using on Summer and winter?

i was thinking -5 to -10 for summer and -15 to -20 for winter..
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  #28  
Old 28-07-2020, 07:46 AM
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Brian, for cooling, refer to the manufacturer data...

https://astronomy-imaging-camera.com.../DCvsT-183.jpg

Multiply the value by the exposure time and you get an estimate of the thermal noise contribution.

You should be good for -5 or -10 all year round.

Which brings me onto darks...IMO experiment with the camera first before worrying too much about a dark library...you can always create that afterwards - the light frames don’t self-destruct without it!

Typically, folk find they settle on a given gain, temperature and exposure time for certain types of objects (for example, deep sky) and stick to it. That also makes it easier when you want to create a dark library
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  #29  
Old 28-07-2020, 02:38 PM
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Thanks Greg.

I clearly misunderstood the information I was given regarding my darks and flats but as you probably saw later in this thread I was able to work out what I had done wrong with my darks (which I then tested by integrating my subs and darks only and can confirm that this got rid of my amp glow) and then integrate my subs, darks, flats and dark flats which resulted in a corrected image.
Not sure what you mean by this. But you only subtract darks once not twice.

You open all your light exposure files. You dark subtract and apply flats to each one of them.
Then you combine them into one image. I don't bother with flat darks but it may make a very minor difference. The cameras are so clean its probably not needed.

Greg.
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Old 28-07-2020, 02:49 PM
nsavage (Nick)
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Originally Posted by gregbradley View Post
Not sure what you mean by this. But you only subtract darks once not twice.

You open all your light exposure files. You dark subtract and apply flats to each one of them.
Then you combine them into one image. I don't bother with flat darks but it may make a very minor difference. The cameras are so clean its probably not needed.

Greg.
Yes sorry I was not real clear.

I worked out what I was doing wrong with my darks so I did a test run just using the darks with the corrected setting as a test. Once I realised that my correction had worked I did a brand new stack using my lights, darks, flats and dark flats.

In regards to the dark flats I was just following a suggested workflow. No idea how much of a difference they make if any but given your comments I may experiment with them a little to see fi I think them worthwhile.
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  #31  
Old 28-07-2020, 04:11 PM
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Regards a dark library, I am in the middle of shooting one for my new camera at the moment. Once you settle on a gain and a temperature you expect to use commonly you can shoot darks more profitably, there should not be a need to shoot darks for loads of different temperatures, just pick one you can probably achieve all year and shoot both lights and darks (And flats depending on length of flats) at that temp. It looks like my new ASI2600 will comfortably hold -10 sensor temperature in any reasonable ambient temperature so I am shooting 30, 60, 120, 300 and 600 second darks while I wait for some more gear to arrive. If I find that I want to use a different gain or there is a hole in my list of exposure times, I will shoot darks to suit later.
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  #32  
Old 28-07-2020, 04:59 PM
echocae (Brian)
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Hi Brian,

With my 294 I do a dark library once a year..
Do u have to do the dark library once a year? what if u dont do that.. is that any significant changes?
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  #33  
Old 28-07-2020, 06:39 PM
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I actually shot one about every six months with mine. If you notice hot pixels creeping through calibration it might Be time to think about it. I mostly used 300 second subs so it was only one new mater dark to shoot Most of the time.
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  #34  
Old 30-07-2020, 07:36 AM
echocae (Brian)
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Hi guys... I done the dark library of GAIN 120 with 30 sec, 60 sec, 90 sec, 120 sec, 180 sec, 240 sec and 300 sec.

I forgot to tell, I have a tri-band Narrowband filter for OSC that work on Bortle 5 - 9 skies... should I make more than 300 secs exposure (eg.500 secs, 600sec or more)? or the 300 secs should be enough with triband narrowband filter usage?
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  #35  
Old 30-07-2020, 03:46 PM
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I haven't used the 183MC Pro but I find the 533MC Pro to be a pleasure to work with. The only way it could be better is if they offered it in a mono version like the 183MM.

No amp glow, extremely clean files, and have had no issues with calibration so far (touch wood.)

I'm sure the 183MC Pro will serve you well, though. The pixels are smaller so in theory you will need to expose longer, but on the flipside, you will gain more latitude to crop your files in post, something that the 533MC doesn't offer much of.
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  #36  
Old 30-07-2020, 04:10 PM
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Brian,

I use a duo band filter in similar skies and 300secs is the longest I use. Best thing is try it and see if it is enough for your intended target. Mind you I rarely go for really faint targets from my backyard and make these a focus for my dark sky trips. You can always do longer darks if needed. Just do your flats using the same filter on the night and you should be good to go.

Mike
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  #37  
Old 31-07-2020, 07:23 AM
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Yeah ultimately you only need to expose long enough to overcome the read noise. This helps keep the stars from blowing out also.

The read noise is very low with this camera - 1e at gain 100. I’d be surprised if you needed long exposures...although the filter may kick the ball down the road.
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