Asi1600 or 8300ccd

[Allinthehead]

Just now, RayD said:

I think if you have a very good mount and guide very well, the benefit reduces to effectively just cloud dodging

Agreed and something i need to do often?

 

1 minute ago, RayD said:

I'll probably be looking at around the 3 or 4 minute mark.

Wise. At f5.5 i would guess you would be using the lowest gain setting for broadband.

[RayD]

4 minutes ago, Allinthehead said:

Agreed and something i need to do often?

 

Wise. At f5.5 i would guess you would be using the lowest gain setting for broadband.

Thanks, Richard.  I'm sure I shall be asking for plenty of advice on gain and offset settings when the time comes.

[wxsatuser]

CMOS..........Computer Mainly Overloaded with Subs. ?

[Laurin Dave]

I'd experiment with sub length Ray to avoid stars saturating badly.. I use 60s lum and 120s RGB ( 300 or 600s nb) and brightish stars saturate..   The Finn Nebula used 15s and 30s lum which I guess is one reason the stars are good .  

Dave

 

[Allinthehead]

2 minutes ago, Laurin Dave said:

I'd experiment with sub length Ray to avoid stars saturating badly.. I use 60s lum and 120s RGB ( 300 or 600s nb) and brightish stars saturate..   The Finn Nebula used 15s and 30s lum which I guess is one reason the stars are good .  

Dave

 

Yes saturation of the stars will occur even at the lowest gain setting. Nothing that 30 subs at 20 seconds or so won't cure.

[vlaiv]

Just a quick note - those short "filler" subs don't have to be dithered, and you don't need much of them if you are going to use only parts of them where long duration subs saturate.

In those places signal is already strong, like more than 12bit strong, SNR per long duration frame in those places is over 64, so if you use 16 times shorter fill in frames (and that would be around 18s for 5 minute regular subs), you will still have SNR of 16 per single fill in sub in saturation places - you need only 16 of them to get SNR back over 64, and that is total around 5 minutes of short imaging time. If you go for 10-20 minutes in short subs and you go from ~20s to 30s or 60s, you don't have to worry about SNR at all.

[Adam J]

On 30/11/2018 at 20:26, RayD said:

Nice.........But 1,733 subs and over 55GB of data for one image.............

Personally I am interested in the end result over and above the volume of data, even if it is a pain.

There will be a time in a few years when computers move on and we will wonder what the issue ever was.

[Adam J]

On 30/11/2018 at 20:45, RayD said:

Cheers.  I'm looking forward to possibly doing a side-by-side capture with this and one of my CCD's (dual Esprit 100's) and making the data available for everyone to have a look and a play.

For best results you need to dither the CMOS and so not sure how you could do a true comparison on a single mount.

[RayD]

42 minutes ago, Adam J said:

Personally I am interested in the end result over and above the volume of data, even if it is a pain.

There will be a time in a few years when computers move on and we will wonder what the issue ever was.

Go for it.  No one is going to stop you, certainly not me.

[RayD]

40 minutes ago, Adam J said:

For best results you need to dither the CMOS and so not sure how you could do a true comparison on a single mount.

Because whilst the OTA's would share a mount, I wouldn't be imaging simultaneously.  I would split the subs in to CCD/CMOS sections equally across 2 or 3 nights.