More ASI1600MM-Pro Questions!

[mikey2000]

Yep, me again.  Once again, I'm let down by the fast moving pace of technology!

 

I'm trying to work out the best settings for gain for this camera.  I found several cheat sheets but they all refer to Gain and Offset.  The lastest ASCOM driver from ZWO has removed the offset (apparently it is hard coded at 50).  Things have moved on it seems.

 

Last night I only managed one L frame (I struggled wih focus until I finally realised I had the wrong size spacer etc, then the clouds came)  I tried 120s at "Highest Dynamic Range" which I believe is Gain 0.

A quick screen transfer of the sub looks like this (ignore the coma - I had the wrong spacing for that too - oops)  It's M1.

The brighter stars here reached 62000 in K value, using the pixinsight 'readout tool (before any stretching at all).   I think that means they are very nearly saturated.  The unstretched sub only shows blobs where the very brightest stars are.  (That's more than I ever saw with an unstretched DSLR sub..!)

 

Does that mean that 120s/Gain 0 is pretty much spot on for me?    Or should I try higher gain, same exposure (and clip brighter details) or higher gain, shorter exposures?

 

I read so much contradictory stuff, I just can't work out what the best answer is.   I think it's maybe because I just don't understand all this business of Gain/Offset,Read Noise, etc etc.  On my DSLR (a6000, I'd just set ISO400 and expose as long as I could.  So simple!)

 

Any advice much appreciated!

[mikey2000]

PS - this camera is way more sensitive than my old A6000 DSLR!!!!!

[souls33k3r]

I would try with unity gain first. You just can't go wrong with that.

On a side note, you have spacing issues from what i can see from the above image. You're a bit too close, would need to move the camera a bit out but i'm sure you already knew that so i'll shut up

[Allinthehead]

Hi mikey. I've started to use 0 gain for lum and rgb, and unity for ha.

Exposure time depends on target.

What i like to do is let the brightest stars clip and i just ensure the medium stars are not saturated. I then take a few really short exposures for the bright stars. This camera is so sensitive and stars saturate so quickly that i have found the need to do this.

I also use a light pollution filter as an L filter this allows me to expose longer. I have found the dynamic range increase in using 0 gain has improved my images.

As always experiment as equipment/conditions are a big factor.

I bought my camera in September 2016 and i'm still experimenting.