Does anyone still use hardware binned CCD?

[Demon]

As I've been thinking of a larger camera recently, it got me thinking sadly, so would love to here if anyone is still using CCDs for the following reasons...

Note: I have a ASI178MM (2.4um 9mm diag mono CMOS) and a QHY9C (5.4um 23mm diag colour CCD), also my focal length is 1.8m.

My mono camera is USB3 so nice and fast, its mono so more efficient using NB filters, its low noise, but its only got small pixels (2.4um) and a little sensor (9mm diag).

Conversely my CCD colour has high read noise, its less efficient and even less efficient with NB filter and its USB2 so is slow download, however its got large pixels (5.4um) and has a big sensor (23mm diag), it also has the ability to bin in hardware (CCD)!

If I hardware bin (x2) the RGGB pixels are merged to a mono output and it roughly goes from being 5.4um to 10.8um, but also the download time reduces with res reduction from 6.4MP to 2.1MP and crucially the read noise quarters from 8e to 2e (closer to CMOS).

I'm way oversampled currently with the mono so less bothered about reducing resolution as I'll end up sampling at 1.22"/pixel which is more appropriate, I'll still likely have to do at least 30-60sec exposures (I'm trying to get to lucky imaging but ignore that for now).

So I'm thinking I've got to have a go at this rather than buy the wrong camera.

My other big reason is that my calibration frames with my DIY cooler just arent what I need, however the cooler on the CCD is really well controlled and get to low temps easily.
I know all things are not equal and theres likely something else that will cause problems - however my mono is listed as roughly 1.4e noise per 2.4um pixel, while I'll effectively get 2e per 10.8um pixel with hardware binning. So if the efficiency was the same (its not) then the signal to noise would be much better as theres more area. As the 10.8um has 4x the area its getting roughly 4x the light. Oddly I can also x3 and x4 bin which does sound silly, but I am wishing this was a mono CCD now...maybe thats what I need a cheap old mono ccd!!! need to test it first as lots of ifs...

Any comments appreciated, especially those who have used hardware binning with CCD...

Edited March 19 by Demon

[TerryMcK]

I'm not using CCD Nick. I am however using an ASI294MM Pro (a mono camera). This uses the IMX492 chip just to be converse. Whereas the IMX294 chip is used in the ASI294MC Pro camera (a colour camera). Totally different chip but for some odd reason ZWO decided on this naming convention.

Going back to the original question my ASI294MM does 2x2 binning natively 4.8um as a default 4144*2822 pixels. This works as 14bit with 22MB subs. Really sensitive and it has a high gain mode very low readout noise in 2x2 too.

You can switch on 1x1 binning. The effect is only 12bit but mega huge subs of around 92MB with 8288*5644 pixels. So less dynamic range but more detail with its tiny 2.3um pixels. The high gain mode can't be used at 1x1.

 

The AstronomyTools CCD calculator seems to think it might be ok for your scope. I suspect

 

Altair also do a camera using the IMX492 chip too Altair Astro Hypercam 115M Mono camera

https://www.altairastro.com/altair-hypercam-115m-mono-tec-cooled-camera-7961-p.asp

 

You might get a deal of 10% off if you are going to the PAS show this weekend.

 

I suspect that calculator result really means 4x4 binning as you need to put the correct 1x1 CCD pixel size of 2.31 in as below and then apply the binning factor. So 3x3 and 4x4 both result in ideal resolution. I think somebody has entered the "ZWO - ASI294MM Pro (Bin2 mode)" entry incorrectly into their database. Hope this makes sense

 

 

[Demon]

Thanks Terry, Yep I like the look of the 115m and it looks to have a little nicer spectral response curve than an IMX571 particularly for Ha, however as you say its a little strange as its actually standard a 2x2 binned CMOS. My pockets arent that deep sadly hence me going round in circles. The question did pop up in my head whether on this CMOS this uses hardware binning or software binning. As I believe CMOS all pixels have their own separate read circuit which means you can only software bin and it doesnt reduce read noise, however the CMOS is already a low read noise camera. I think I'm grasping at straws with this colour CCD, I do wonder how it would compare if it was a binned mono CCD but again I dont have one so moot point...I'll keep going with what I've got for now and see what comes up second hand...thanks and appreciated.

[TerryMcK]

Yes CMOS cameras do use software binning. The values of a pixel are either summed or averaged out to make a larger virtual pixel.

[Demon]

Thats where this idea had some merit as binning reduces read noise/area on a CCD, plus smaller faster downloads - so trying to negate the downsides of CCD while getting to the big sensor that I already have.

I think I'd have a go if it was a mono CCD but with colour it would be wasting much of the aperture gain. I'd probably be better off just putting little 178mm on 80ED...

So many things I want to try but so few clear nights so help appreciated thanks...

[Carastro]

I still use Cooled mono CCD cameras.  I see no reason to change since they serve me well.  
i also bin the colour and Oiii and Sii data as the detail comes mostly from Lum or Ha with few exceptions. 
 

But don’t ask me anything technical l don’t do technical. Lol. 

Edited March 26 by Carastro

[Anne S]

I bin 2x2 when imaging through my 6 inch RC with my SX694. Image resolution binned is 1.4 arcs/pixel, perfect! I can also use much shorter exposures as natively it's a f9 scope.