Settings for ZWO ASI1600M

[wornish]

To date all my astrophotography has been done using a DSLR.  For most shots I have used ISO800 and simply varied the exposure times to get the lights I wanted.

I have just purchased my first dedicated astro camera a ZWO ASI1600M, and last night I went out for the first time to try some LRGB imaging using filters  and my target was M81.

I quickly realised this is  a new world because not only can I adjust the exposure time but also the gain and I had no idea what settings to use.  My mount was tracking and Guiding fine using PHD

My setup  is effectively F5.5 so quite fast.  Simplistically I assume its best to have as little gain as possible and long exposure times but how do you pick the right combination for a given target ?  Is it trial and error to avoid blowing the cores but catching the nebulosity, or is there some guide as to what settings to use.

I realise that something bright like M31 is different to M81 which is very different to a nebula but would welcome any advice.

 

Back to being a novice again.

 

 

 

[kens]

The most important thing is to expose sufficiently that the read noise is not dominant. After that you can adjust gain for either better dynamic range (lower gain) or for lower read noise (higher gain) which enables shorter exposures. A good starting point is a gain of around 75 for LRGB. I'll typically use 75 for LRGB and 200 for narrowband. I leave offset at 50 for all gain values.

 

[groberts]

This thread might help:

 

[souls33k3r]

Or without hurting your head too much with this information, use "Unity gain" (Gain 139 Offset 21) for nebulas and (can't remember the other option) Gain 0 Offset 10 for galaxies. 

[wornish]

5 minutes ago, souls33k3r said:

Or without hurting your head too much with this information, use "Unity gain" (Gain 139 Offset 21) for nebulas and (can't remember the other option) Gain 0 Offset 10 for galaxies. 

Thanks for the help I seem to be missing something as people keep talking about offset .

 

I have been using Sharpcap and I understand from the ZWO graphs  that unity gain is 139. but there is no mention of offset anywhere in the controls , what exactly is it?

Told you I was a newbie at this.

[souls33k3r]

2 minutes ago, wornish said:

Thanks for the help I seem to be missing something as people keep talking about offset .

 

I have been using Sharpcap and I understand from the ZWO graphs  that unity gain is 139. but there is no mention of offset anywhere in the controls , what exactly is it?

Told you I was a newbie at this.

I'm not sure how Sharpcap works but i'm sure if you click on the settings of the camera, a new ZWO settings window should pop up from where you can select these presets.

It will appear like this and you can choose the presets which will set up these values for you automatically.

[wornish]

1 minute ago, souls33k3r said:

I'm not sure how Sharpcap works but i'm sure if you click on the settings of the camera, a new ZWO settings window should pop up from where you can select these presets.

It will appear like this and you can choose the presets which will set up these values for you automatically.

Ah the now I see what people are talking about ?

 

Sharpcap doesn't give you access to this, no offset mentioned.  I will go and use the ZWO software

[souls33k3r]

1 minute ago, wornish said:

Ah the now I see what people are talking about ?

 

Sharpcap doesn't give you access to this, no offset mentioned.  I will go and use the ZWO software

We're all here to help each other mate

Also try ASICap if you haven't seen it already. It should work for you

[wornish]

5 minutes ago, souls33k3r said:

We're all here to help each other mate

Also try ASICap if you haven't seen it already. It should work for you

Yes I have got ASICap but it has no Offset control as far as I can see.

 

[wornish]

Just loaded the ASICamera Setup V6.0.3.18. which I guess is the latest version.

There is a Gain slider but NO Offset slider.  I guess something has changed ?

Thought I was going crazy.

 

My camera is the ZWO ASI1600MM Pro so that might be the difference.

[newbie alert]

I'm thinking of a camera along the same lines as a zwo 1600m or a qhy or altair 183..would anyone be so kind as to post either a single sub or stacked image up please..be interested to see as my heads scrambled a touch

[ngwillym]

ZWO removed the ability to alter the offset ( what used to be brightness in earlier versions of Sharpcap) in the latest version of their drivers - which is why its missing in the latest version of Sharpcap.

[wornish]

11 minutes ago, ngwillym said:

ZWO removed the ability to alter the offset ( what used to be brightness in earlier versions of Sharpcap) in the latest version of their drivers - which is why its missing in the latest version of Sharpcap.

Thanks I thought I was going crazy.