IMX492 (Mono) sensor in today's world

What is the general opinion on the IMX492 (mono) sensor in today’s world?

This sensor is already quite old by technology standards, shows amp-glow, is 12-bits (in the bin-1 mode), can be tricky in calibration, etc.

On the other hand it is the only sensor of reasonable dimensions that has significantly smaller pixels than the traditional 3.8 micron. Especially for telescopes in the 300-500mm range, 3.8 micron is pretty big. Thinking about a good pairing for my FSQ85 with 330/450mm (reducer/flattener) focal length and on paper the IXM492 seems like a good match.

There’s good reports on the IMX585 of course, but that sensor is much smaller, so field of view significantly smaller.

Any thoughts on this? Worth going for it, or would an IMX571 be a better choice, and drizzling your way to lower pixel-scales?

The 585 and 492 are very efficient sensors with very high QE in the red spectrum, which is important for H Alpha because it does the heavy lifting in emission nebulas. The 571 gives you more FoV, but has much worse QE in the reds. With the others you can even shoot in NIR if you want.

As you said the FoV can be altered with a reducer, but in the end it depends on the targets you want to shoot.

I attached the QE graphs of the 492, 571 and 585.📷 23716.png📷 21474.png

I have used the 585 both color and mono for a long time now and it’s a a great chip. The 2.9 micron pixel pitch is perfect for avoiding under sampling with smaller refractors. The camera has great sensitivity in the near IR, high frame rates for lunar/planetary. If you get a version with has drivers to take advantage of HDR mode you’ll get a dynamic range of over 15 stops at 16 bits. I use it on a 6” F/6 Newtonian, sometimes even with a Barlow because I’m a lot more interested in actual resolution than wide fov.

Tony, can you please elaborate on the process you used for calculating the stops number?

You can do a sensor analysis with Sharpcap and the result will tell you the dynamic range in stops.

If you divide your full well capacity with the read noise you receive the amount of brightness levels your camera is able to detect.

12 stops dynamic range are 4096 brightness levels for example. The IMX585 reaches in HDR a FWC of 26k electrons with 1 electron read noise.

26k divided by 1 are still 26k, so 26k brightness levels can be detected, which are around 14,7 stops of dynamic range (two to the power of 14,67 = 26k).

lunohodov · Mar 27, 2026, 01:52 PM
Tony, can you please elaborate on the process you used for calculating the stops number?

It’s in the data sheets in the manual:

📷 585 hdr.jpg

Thank you both!

Generally, for the sensors I own, I found Sharpcap’s analysis to disagree with manufacturers’ data sheets. Hence my question.

Anyone further insight into the IMX492 sensor, as per the original topic?

My advice is to move on and just get a 571 chip camera, in either color or mono. The price gap simply doesn't justify the smaller size and technical obsolescence.

Just FYI talking about the IMX492 getting old. The IMX571 is at least 1 year older (Sony adding the datasheet to the product portfolio in 2018). From a business standpoint the IMX571 has higher chances to reach End of Life sooner than the 492.

Tobiasz · Mar 28, 2026 at 12:31 PM
Just FYI talking about the IMX492 getting old. The IMX571 is at least 1 year older (Sony adding the datasheet to the product portfolio in 2018). From a business standpoint the IMX571 has higher chances to reach End of Life sooner than the 492.

Thanks, that’s interesting to know. This helps explaining why Moravian has only recently added the IMX492 in their line-up, in both their two hardware configurations.

Rafał Szwejkowski · Mar 28, 2026 at 12:09 PM
My advice is to move on and just get a 571 chip camera, in either color or mono. The price gap simply doesn't justify the smaller size and technical obsolescence.

It’s not about size or price. It’s more that the pixel-size of the IMX492 fits wide-field scopes better.

Tobiasz · Mar 26, 2026 at 08:43 PM
The 585 and 492 are very efficient sensors with very high QE in the red spectrum, which is important for H Alpha because it does the heavy lifting in emission nebulas. The 571 gives you more FoV, but has much worse QE in the reds. With the others you can even shoot in NIR if you want.
As you said the FoV can be altered with a reducer, but in the end it depends on the targets you want to shoot.
I attached the QE graphs of the 492, 571 and 585.📷 23716.png📷 21474.png

I did not realise this, but it means that the IMX492 has 30% more sensitivity in red/Ha/SII than IMX571. That is quite significant.

Willem Jan Drijfhout · Mar 28, 2026, 12:43 PM
Tobiasz · Mar 26, 2026 at 08:43 PM
The 585 and 492 are very efficient sensors with very high QE in the red spectrum, which is important for H Alpha because it does the heavy lifting in emission nebulas. The 571 gives you more FoV, but has much worse QE in the reds. With the others you can even shoot in NIR if you want.
As you said the FoV can be altered with a reducer, but in the end it depends on the targets you want to shoot.
I attached the QE graphs of the 492, 571 and 585.📷 23716.png📷 21474.png
I did not realise this, but it means that the IMX492 has 30% more sensitivity in red/Ha/SII than IMX571. That is quite significant.

Yes, that's something that is hard to ignore, especially in narrowband.

I did a comparison with your FSQ85 with and without a reducer.

IMX571@450mm has a slightly smaller FoV than the 492@338mm.📷 25555.jpgI did that to achieve a somewhat similiar sampling (571 → 1.71”/px, 492@BIN1 → 1.41”/px).

If you calculate the pixel signal with this calculator

The 492 collects the same amount of photons per pixel, but with better resolution (because of the much better QE). If the sampling rate is the same (hypothetically), the small 2.35 micron pixels collect 40% more photons. That is quite a difference.

The lower bit precision can be offset by stacking more subs and the lower fullwell is not that much of a concern with shorter subs.

Simply saying the IMX571 is better is not really precise. It has it's advantages, but not in every aspect.

Tobiasz · Mar 28, 2026 at 12:59 PM
this calculator

Thanks @Tobiasz , this is very helpful. So you would end up with more and shorter subs, which is fine as you collect 40% more photons per pixel. In the end you just have to push through more data (higher pixel-count and more subs) and end up with slightly smaller FoV, but with a higher resolution image as the result.

Willem Jan Drijfhout · Mar 28, 2026, 01:14 PM
Tobiasz · Mar 28, 2026 at 12:59 PM
this calculator
Thanks @Tobiasz , this is very helpful. So you would end up with more and shorter subs, which is fine as you collect 40% more photons per pixel. In the end you just have to push through more data (higher pixel-count and more subs) and end up with slightly smaller FoV, but with a higher resolution image as the result.

With the 492 you have a slightly bigger FoV.

More subs, bigger stacks, more food for the pixel rejection algorithms.

Just came across this thread as have been looking into the 492 and wondering the same thing (especially as Moravian didn’t seem to have this sensor). But seeing on this chat that they are bringing one out (C1+46000) is v v interesting indeed. Their cameras are great, so if they think its worth making a camera with this sensor, that bodes well.

And I didn't;t appreciate the difference in sensitivity either (I knew the difference in full well). V interesting - thank you!

Vin · Mar 28, 2026 at 02:08 PM
Just came across this thread as have been looking into the 492 and wondering the same thing (especially as Moravian didn’t seem to have this sensor). But seeing on this chat that they are bringing one out (C1+46000) is v v interesting indeed. Their cameras are great, so if they think its worth making a camera with this sensor, that bodes well.
And I didn't;t appreciate the difference in sensitivity either (I knew the difference in full well). V interesting - thank you!

That was exactly my thinking!

Willem Jan Drijfhout:
Tobiasz · Mar 26, 2026 at 08:43 PM

The 585 and 492 are very efficient sensors with very high QE in the red spectrum, which is important for H Alpha because it does the heavy lifting in emission nebulas. The 571 gives you more FoV, but has much worse QE in the reds. With the others you can even shoot in NIR if you want.

As you said the FoV can be altered with a reducer, but in the end it depends on the targets you want to shoot.

I attached the QE graphs of the 492, 571 and 585.📷 23716.png📷 21474.png

I did not realise this, but it means that the IMX492 has 30% more sensitivity in red/Ha/SII than IMX571. That is quite significant.

It always had.. people underestimate that sensor because is "old" and full of ampglow, but I dare to say despite that, that is one of the few last sensors that can beat even the 571. His worst nightmare is the ampglow, but in you can live with that, the QE in the reds is astonishing, in BIN 1, he have more resolution than the 571 for example as well the pixel size drops to half, and at his 4/3 size is compatible with 1.25" filters, as well other sizes. At his native BIN 2, he works without any problems with the 14bit, which helps a lot with the high QE. I use to say, to have the perfect sensor/camera, was to have this sensor at APS-C size without the ampglow but retaning those IMX492 features.

Despite been "old" I'm planning to acquire this camera/sensor for mono imaging.. For me she's perfect.

I have and use the same sensor in the ASI incarnation (and both the OSC and Mono) as well IMX533 and IMX571 sensors. In bin1 the amp-glow is hardly noticeable in a 3 min integration and only becomes apparent in 5+ min integration and its response is just fantastic in BB. They might be old design but they still pull a lot of signal and the possibility to switch between bin1 and bin2 (in hardware mode) is a bonus. If you need signal bin2 and if you need resolution bin1. My next monochrome sensor will still be an IMX492 (but not from ASI!). I can't give a rat's arse about the IMX571 extra pixel count for what use I have of the camera. Signal is king, period.

I was also pleased to see Moravian include the IMX 492 in its catalog, but it's a shame they did so so late compared to Asian manufacturers. Personally, I've never felt the need to upgrade to the IMX 571, even though I recognize its undoubted qualities. Calibrating with dark frames eliminates the amp glow problem, and you essentially have two cameras with different modes for use with short and long focal lengths. If I were to ever switch to the IMX 571 out of curiosity, I'm sure I'd keep the QHYPro as well...

For anyone who is in the market right now, beware of the IMX492 offering from Touptek. They are the only vendor selling this sensor with extreme amounts of amp glow instead of the amp glow we know from the others. I honestly don't know why their cameras have it like that.

Tobiasz:
For anyone who is in the market right now, beware of the IMX492 offering from Touptek. They are the only vendor selling this sensor with extreme amounts of amp glow instead of the amp glow we know from the others. I honestly don't know why their cameras have it like that.

They are not particularly cheap either. My heart is set for the PlayerOne's, with all the extra bits in it.

andrea tasselli · Mar 28, 2026, 06:48 PM
Tobiasz:
For anyone who is in the market right now, beware of the IMX492 offering from Touptek. They are the only vendor selling this sensor with extreme amounts of amp glow instead of the amp glow we know from the others. I honestly don't know why their cameras have it like that.

They are not particularly cheap either. My heart is set for the PlayerOne's, with all the extra bits in it.

Agree, I would also buy the PlayerOne variant, but I try to snap one IMX492 on the used market (anyone?).

But the price of the PO cameras are without taxes and duties. Touptek is with everything included already.

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