Recommendation for a CMOS mono camera to fit a C8 EdgeHD

Thanks all for your insights. I know have several options to consider.

I’ll also have a look at what other C8 users use for shooting, it could provide additional hints.

Thanks

Rodolphe

John Tucker · Mar 16, 2026, 11:47 AM

andrea tasselli · Mar 16, 2026, 09:41 AM

There are no good reason to buy a 12bit camera, me thinks. You can easily bin 2x and still get a better RON than that camera and full 14 bit (or 16 bit with an IMX571).

“RON”?

I don’t know a lot about cameras. The ratio of the square of the sensor sizes for the 432 vs the 571 is 5.9. If I’m doing the math correctly, that’s equivalent to dropping from F/10 to F/4 ????

I see a lot of conflicting opinions on the internet as to whether 2x binning increases the signal/noise ratio by a factor of 4 or a factor of 2.

I live in a place with a lot of light pollution and where it’s almost always cloudy, especially on new moons! So I’m a bit of a speed freak…

Sensor size has nothing to do with light gathering power of the detector. Pixel size, quantum efficiency and system noise are relevant.

CCD Binning increases SNR by a factor of 4, because CCD sensors do the binning before sensor readout, which then applies readout noise “RON”. So RON is only applied once to the binned “superpixel” consisting of 4 signal values from the single pixels.

CMOS pixels are binned after the readout, which means that every pixel has read noise already applied. Signal increases times 4 (because of four pixels) while noise increases by the square root of the signal, which is 2. You only increase the SNR by a factor of 2.

Tobiasz · Mar 16, 2026, 12:21 PM

John Tucker · Mar 16, 2026, 11:47 AM

andrea tasselli · Mar 16, 2026, 09:41 AM

There are no good reason to buy a 12bit camera, me thinks. You can easily bin 2x and still get a better RON than that camera and full 14 bit (or 16 bit with an IMX571).

“RON”?

I don’t know a lot about cameras. The ratio of the square of the sensor sizes for the 432 vs the 571 is 5.9. If I’m doing the math correctly, that’s equivalent to dropping from F/10 to F/4 ????

I see a lot of conflicting opinions on the internet as to whether 2x binning increases the signal/noise ratio by a factor of 4 or a factor of 2.

I live in a place with a lot of light pollution and where it’s almost always cloudy, especially on new moons! So I’m a bit of a speed freak…

Sensor size has nothing to do with light gathering power of the detector. Pixel size, quantum efficiency and system noise are relevant.

CCD Binning increases SNR by a factor of 4, because CCD sensors do the binning before sensor readout, which then applies readout noise “RON”. So RON is only applied once to the binned “superpixel” consisting of 4 signal values from the single pixels.

CMOS pixels are binned after the readout, which means that every pixel has read noise already applied. Signal increases times 4 (because of four pixels) while noise increases by the square root of the signal, which is 2. You only increase the SNR by a factor of 2.

Sorry, meant pixel size, not sensor size. The argument I’ve seen on the internet is whether read noise or sky noise (?) dominates in practice. Again, I don’t understand cameras well but the conclusion that the sky noise people reach is that for longer acquisitions you get more than a 2x improvement. I am not qualified to judge.

Tobiasz · Mar 16, 2026, 12:28 PM

John Tucker · Mar 16, 2026, 12:24 PM

Sorry, meant “pixel size”, not sensor size. Edited post to correct.

All other factors ignored: Yes, the bigger pixels of the IMX432 build up signal 5x times faster than the 3.76micron pixels of the IMX571.

Edit: If you ignore the resolution and just want to know how deep you can go with your telescope under your local conditions & stacking you can calculate it with the tool from Frank who developed MetaGuide.

https://smallstarspot.com/shiny/StackSNR/

There you can compare your f/10 edge with the noisier IMX432 with the big pixels against the IMX571 with the clean but small 3.76 pixels. I did a comparison and despite the high dark current of the IMX432 it will go about 1 magnitude deeper than the IMX571 with the same integration time. (SNR of 3)

Thanks!

Thanks Jan Erik,

I appreciate your comments and use cases: They resonate well with my experience on the C8 (with or without the .7x reducer). This telescope, if well collimated, is a joy to use.

I went to https://astronomy.tools/calculators/ccd_suitability to simulate the various combinations. It looks like the IMX571 would work well in most circumstances related to my real-life site conditions. It leads to oversampling in all but exceptional seeing conditions. But the KAF8300 as well!

The only main advantage of the IMX571, in my case, would be the increased QE/sensitivity. Is it worth the effort? I’m not convinced.

Fir the time being, I think I’ll stay with the G2-8300 as long as it keeps working: I’ve had it for almost 10 years and I’m still happy with it 🙂

On a side note, if you invest on the 0.7x reducer, watch out for the reduced back focus distance - I explored many options to accomodate the OAG and the CCD camera (55 mm BF) to make sure the sensor sits sharply at the 105 mm BF distance - I finally opted for the Moonlite CHL 2.5 focuser, which works perfectly for both my imaging setups (with and without the reducer).

All the best, Rodolphe

Rodolphe Goldsztejn · Mar 16, 2026, 03:37 PM

Thanks Jan Erik,

I appreciate your comments and use cases: They resonate well with my experience on the C8 (with or without the .7x reducer). This telescope, if well collimated, is a joy to use.

I went to https://astronomy.tools/calculators/ccd_suitability to simulate the various combinations. It looks like the IMX571 would work well in most circumstances related to my real-life site conditions. It leads to oversampling in all but exceptional seeing conditions. But the KAF8300 as well!

The only main advantage of the IMX571, in my case, would be the increased QE/sensitivity. Is it worth the effort? I’m not convinced.

Fir the time being, I think I’ll stay with the G2-8300 as long as it keeps working: I’ve had it for almost 10 years and I’m still happy with it 🙂

On a side note, if you invest on the 0.7x reducer, watch out for the reduced back focus distance - I explored many options to accomodate the OAG and the CCD camera (55 mm BF) to make sure the sensor sits sharply at the 105 mm BF distance - I finally opted for the Moonlite CHL 2.5 focuser, which works perfectly for both my imaging setups (with and without the reducer).

All the best, Rodolphe

No worries! I think that’s a very solid decision, as long as it’s working well and you’re happy, I wouldn’t switch in your shoes either.

As far as the reducer go I do own it, but it was unusable with APS-C cameras, it worked fine with my IMX533 camera a few years back. Here’s a thread about it that I now realise I never updated - Will do so now! As you can see there the reflections caused by the reducer were quite horrendous.

Clear skies!

Tobiasz · Mar 16, 2026 at 04:23 PM

Is this visible in LRGB exposures? I don't know.

Hi Tobiasz

Thanks for commenting.

I confirm that noise is very visible in LRGB exposures with the 8300. I also own a 571 camera, the difference is quite visible.

However, tools such as BXT and NXT help reduce their impact by a vast amount, in my experience. I have lately reprocessed old images using them, and they became quite pleasant and even easier to process.

Like you wrote it, the environmental conditions are the most important factor ultimately, and we have no control over them, unfortunately.

Clear skies,

Rodolphe