5 replies to this topic

[DanB]

Hi Group,
I'm not new to imaging but not an expert. I guess I'm somewhere inbetween. I'm just getting back after about 10 years away though and some things are vague. My old QHY8CCD seems to have little to zero support anymore. I tried and tried to get my camera recognized the past 2 weeks and couldn't. After a lot of digging and reading similar posts I decided to get a new imager and shelf the old QHY8 for now.

So I ended up replacing the QHY8 with an ASI294MC Pro. Also bought an ASI120MM Mini Guider. Updated all Ascom and EQMOD software and drivers, got Cartes Du Ciel installed and PhD 2 and so far everything is talking. Also installed ASI Studio. I was out last night (yes, new equipment and still had stars but a few clouds) and everything worked great except for my lack of focus vigilance. Still, guiding was best I've ever had. Goto's are right on and the hardware all seemed to work great! I already built the Dark Library in PhD 2 for the Mini Guider as it prompted me to.

So now I need to build a Dark Library for the ASI294MC Pro and not sure where to start. I did a search and I still didn't see what I needed so here I am with a question that's probably been asked 200 times. With the QHY8 I don't think we even did darks so my experience with using darks is limited in the first place.

I guess the first obvious question is, should I build a Dark Library for the ASI294MC Pro?
Secondly, do I need to build a set of darks for everything from 1 second up to 900 seconds (for every possible exposure time)?
Third, how many darks do I need for each set?

I have not modified my Cloudy Nights profile information yet, it's many years old so please don't look at that. Some of it is obsolete now. I'll get that updated today.
Thanks ahead for any help.
Dan

 

[fmendes]

I have 20 sets of darks for each exposure/gain/temperaature I use. Since I only use -10degC and gain 120, only variable is the exposure. You don't even need to build the library at once, build as you go.

 

I have only my common exposures: 30, 60, 120, 180, 240 and 480s. On NINA, I make a sequence with all these configurations and leave it for a day.

 

Last, it's a lot of work, but inspect the darks if you have weird gradients. Seems a common issue.

[DanB]

I have 20 sets of darks for each exposure/gain/temperaature I use. Since I only use -10degC and gain 120, only variable is the exposure. You don't even need to build the library at once, build as you go.

 

I have only my common exposures: 30, 60, 120, 180, 240 and 480s. On NINA, I make a sequence with all these configurations and leave it for a day.

 

Last, it's a lot of work, but inspect the darks if you have weird gradients. Seems a common issue.

This helps a LOT!! Exactly what I needed. Thank you.

[hyiger]

I don’t have this camera, what I’ve been reading, taking proper flats and darks with this sensor can be a bit of a challenge.  Especially for flats it seems to require > 1s exposures with or without a filter. 
 

Like @fmendes I always keep my cameras at the same temp and gain so I only take darks for common exposures that I use like: 30,60,180,300 etc

Edited by hyiger, 04 June 2023 - 01:25 PM.

[AstroVagabond]

I have the 294MM Pro. I have a dark library based upon -5C and -10C cooling temperatures for 60, 120, 180, 240, and 300 second exposures.

 

Trivial to build.

 

Here is a video where I build the dark library using the ASIAir Plus:

 

https://youtu.be/CkPGjYrWVAk

 

Here is a video where I build the dark library using N.I.N.A.:

 

https://youtu.be/f_WA5nX9n9E

[fmendes]

I don’t have this camera, what I’ve been reading, taking proper flats and darks with this sensor can be a bit of a challenge.  Especially for flats it seems to require > 1s exposures with or without a filter. 
 

I never had the flats issue with the 294, but heard about it. Got recently an Ogma AP26CC, and had issues with callibration files. I believe the issue is comparable. With the Ogma, I noticed that some calibration files were ruining the stack. Carefully inspected all frames and found out that a few were broken. To make matter worse, PI only detects the issue as a visible pattern at 100% size. ASIStudio detects the defective frames at any zoom level.