ASI1600MM-C on Celestron EdgeHD 8" setup

[Geordie mc]

I don’t know enough about it to be honest, but he definitely said you cannot bin a cmos chip. It’s done in software and you don’t get the same increase in sensitivity you get with CCD’s. I’ll try and find the link to the video. It was an Astro imaging channel livestream. 
 

The 1600mm cool has been fine on my Hyperstar. The issue for me has always been focus at F2. Such a narrow zone. Hoping the new Celestron focus motor will improve things. I only shoot narrowband with it as I have no LRGB filters for the Baader filter drawer system. I’m using the 2inch F2 narrowband  filters from Baader. I have some 1.25 inch filters in LRGB in my QSI but don’t want to keep taking it apart to swap to the 1600. I may invest in the 5 position filter wheel later in the year and give them a try on the Celestron with focal reducer but I’m not splashing out for new filters for Hyperstar use. 
 

I will try to post images when I can, but I’ve moved house (and country)  twice in 14 months and am finding time for Astro rather tight. I’ll just get things sorted and we’ll be at the point where it doesn’t really get dark here. I’m at 46 degrees latitude now. I think another 2-3 weeks and I’m done until August. On the plus side I might have my pier concreted in place by then. Depends on when I’m allowed out. Rules very strict in France.

[JamesF]

2 minutes ago, Geordie mc said:

I don’t know enough about it to be honest, but he definitely said you cannot bin a cmos chip. It’s done in software and you don’t get the same increase in sensitivity you get with CCD’s. I’ll try and find the link to the video. It was an Astro imaging channel livestream.

My understanding is that with CMOS sensors, it doesn't happen "on sensor".  So whereas with a CCD you read the value for the "super pixel" and get one lot of read noise, with a CMOS sensor each pixel is read, giving four lots of read noise and that data is then added together to give the value for the "super pixel".

James

[Geordie mc]

Thanks James. That is exactly right. I’ve just watched the video again. 
 

The sensitivity increase seems to be somewghat cancelled out by the read noise. It’s discussed starting at about 1hour 7 minutes into the video. The whole video is interesting though. I suppose some of it comes down to how well the software/firmware carries out the binning. I only use my 1600 cmos on Hyperstar where I can get frame and focus data with very short exposures without binning so I never use it. I’m happy with it and clearly a lot of others are too as it’s a very popular camera. I think one point that doesn’t seem to come across in the video is cost. My QSI660wsg-8 was more than double the cost of the ASI1600 even allowing for adding a filter wheel and Off axis guider. The pixels are a similar size but there’s a lot less of them! If the 1600 had been around 10 years ago I wouldn’t own the QSI. On the other hand I’ve had 10 years of very reliable use from the QSI. It’ll be interesting to see if the 1600 proves to be as reliable. 
I think it’s a great time for Astro imagers. There are more affordable cameras and scopes with better guide camera choices. Some great scopes and mounts. I’m even thinking of eventually getting a OSC like the ASI294mc pro so I can do colour on Hyperstar in one unattended session and maybe add Ha from the 1600 another night. If I was still looking at £3000 plus for a good OSC that would never be a justifiable option. 
‘That said, someone please stop me buying gear! What is it with this hobby? There’s always something else you “need”.

[Gina]

Binnning: The differences between CMOS and CCD  by Atik describes the difference between CCD and CMOS sensors very succinctly IMO.

With read noise being very much lower on CMOS sensors as produced by ZWO, binning is definitely worthwhile on very faint targets.

Edited April 17, 2020 by Gina

[Geordie mc]

On 13/04/2020 at 20:17, Rocket Stars said:

Id be very interested of the results!

How do you like the 1600 on the hyperstar? Pondering about that for my hyperstar c8hd rig. 

Clear skies!! 

 

I’m just getting used to it so it’s early days. I’m happy so far with most aspects but focus at F2 is hard to get really sharp. I’ve just added the Celestron motor focus so hoping that makes things easier. I need to get the correct step size and backlash sorted to make best use of it. Early attempts with SGP have not produced good V curves but it’s improving each attempt. I might try my old FocusMax V3 with it and see if that does any better. I did the calculations for step size so I think it’s a backlash issue. It’s hard finding clear nights here right now to get time to experiment. 
im using the Baader filter drawer system with their F2 filters (2inch) in Narrowband which seem very good if rather expensive. Still, if I can get it all working properly then the ability to get a lot of data, wide field etc will be worth it. Trouble is, if I get a clear night it’s hard not to just stick the QSI660 on my TSQ65 which is so reliable and gives great results.