QHY294m ASI294mm mono

[alistairsam]

hi,

has anyone been using any of these mono cameras, looking for some reviews on their sensitivity given the 91%qe rating and 80% Ha as well as the larger pixels in the on-chip binned mode?

given the popularity of the ASI1600, i'd have thought these or the 2600m would've caught on pretty quickly, but couldn't find too many reviews.

There's a thread with reports of amp glow on the asi294m, but it has a better qe response in red and ha compared to the 2600.

Then there's reports of banding and driver issues as well.
appreciate some feedback from anyone using these.

Thanks
Alistair

[Camelopardalis]

Alistair, it's probably a combination of factors...

They've been hard to get hold of since launch (is that lack of supply, or high demand?)

For most folk, if they're happy with the 1600, why would they switch? Sure, there's an increase in QE, but is that worth the cost increase? The 1600 continues to work very well with minimal amp glow.

The specs of the 294m in 'bin1' mode look very similar to the 183 in most respects. FWIW, the amp glow on the 183 looks pretty horrendous if you look at a single dark, but it calibrates out well, which is what is most important IMO.

[Nikolas]

Glen I have the cooled 294mc pro and rarely if ever use flats, the issue was with a small number of those cameras, not a great scale issue, the reason there is not many reports on the 294mm is supply issues and that they are bloody expensive!

[alistairsam]

Hi,

I'll be using it with a 10inch F4, so the 4.6 micron pixel size, 80% QE in Ha, large well depth, seem a good match with the F4.

Price is actually not too bad especially if it means acquiring data faster given our super reliable cloudy skies in Melbourne.

The issue with the TEC cooling actually does explain the weird pattern as reported here with the Ha flat.
https://www.macobservatory.com/blog/2020/10/14/review-of-the-zwo-asi294mm-pro-camera.
Not sure how accurate reports are that the qhy version has better control of the amp glow.

Alistair

[The_bluester]

Actually, from what I have seen lately, the weird flats looks to be more like a diffraction effect from the microlenses rather than cooling. I have the ASI294MC (Which I am just about to sell as I replaced it with a 2600MC, and soon to arrive MM)


Apparently though the right filter a mottled patch in the same shape as the pattern on flats is visible if you take a photo of the face of the sensor.

[gregbradley]

I have a QHY294M. In 11mp mode it seems fine.

I haven't really used it in 47mp mode yet. I use a QHY600m mostly.

There was a driver update to correct banding in 47mp mode. I don't know how effective it was.

In 11mp mode banding was not really an issue.

Greg.

[alistairsam]

Thanks for the replies.

Do you see any patterns with flats in nb filters in 11Mp mode? is there a discernible difference with the high qe? what scope do you use it with.

Thanks

[gregbradley]

From memory (haven't used it for a while) flats looked normal. Because the scope illuminates a large field I don't recall much vignetting at all on the sensor.

AP Honders 305 F3.8.

I'll be using it again soon and i can dig out some flats which are on another computer.

I'll post an example tomorrow.

The main thing is accurately matching the darks to the exposure duration, temp, gain and offset settings.

It does have amp glow. A bit worse than an ASI183m. It does dark subtract out pretty cleanly but not absolutely perfectly.

Its very sensitive. I have not used it in 47mp mode but did take a test exposure. It would suit a shorter focal length refractor to use it in
47mp mode (2.3 micron like the ASI183m) which is even higher resolution than the ASI2600/6200 which has 3.76 micron pixels.

I like the 4.63 micron 11mp mode pixels as that suits my scopes better than 2.3 which makes them more susceptible to the poor seeing.

Small pixels are more effect of the seeing than larger pixels.

Greg.

[Robert_T]

I've been using the ASI294mm for a month now and have been very happy with the results.

I can't compare it to other mono cameras as until now I have only used OSC. It has more amp glow than other OSC cameras I've used, but i find nothing that doesnt calibrate out with simple flats. darks and bias - some people say you need to use flat darks instead of bias with this camera but I have tried both and no discernible difference so will stick with bias.

Ha and SII flats look wierd but work.

I've used it exclusively in narrowband (3.5nm) and no issues at least when using it in 2x2 bin mode and using exposures long enough to really swamp any pattern/read noise... 300s seems to do the trick. I think there's a lot of fiddliness than can add to variable experience and reports... i had a day scratching my head with some rubbish stacks when I realised that my flats (from NINA) had defaulted to 1x1 bin...that's something to watch for. Anyway proof is in the pudding ...here's a few from the last month.

https://astrob.in/5pkch9/B/
https://astrob.in/5te3pk/0/
https://astrob.in/t0wg2k/0/
https://astrob.in/qzgch0/0/