[Alchemy (Clive)]

Disclaimer..., this is provided as a resource for those interested in the camera, not a commentary of processing or other equipment.

The QHY268C retails as of May 2021 for approx $3300 AU

I have been waiting for CMOS to reach a point where some of the limitations, in particular, banding and amp glow, to be resolved. this camera seems to have done that.

theres a lot of specifications, modes etc that i will not go into, its more of a practical limited real world test, without scientific analysis. WYSIWYG.

There are a number of modes (4) to choose from, each having its own dynamic range well depth and noise read. After reviewing the charts and with no other basis i chose high gain at 0 with an offset of 30, this made sure the signal was not clipped. this gives it a practical range of 14 stops, significantly more than my qhy8 and qhy9 mono.

Out of the box everything you need is supplied, although some of the spacers varied from the website information. for the simplest use, one can download the QHY package which includes a capture program and drivers, my experience was it worked, no glitches.

upon opening the capture program, you select the mode (high gain in my case) and once open set the offset an gain in the capture to your required level. note that if you select a different gain you will need to set it each time in the planner table.

temperature can then be set... of note qhy website suggests not to drop temperature too quickly, how reliable this information is i dont know, but with the qhy9 i just set it to -20 and auto temperature and left it alone without a care, on this one i set it around 30% power and leave it to stabilize, and if needed rise it again 10% , then if its stabilised around the temperature i want i set it to auto -10. the cooling on this camera is nowhere powerful as the qhy9 as i can drop it 50 below ambient.
with time used for focusing setting up guiding etc, by the time you are ready to image its all good. i chose -10 simply as most of the year thats achievable by the specs, and it lessens the required dark frame library.

other things of note, the glass screen has no UV/IR coating, it would appear more attention has been given to antireflective coatings, of note the one that came with the qhy9 was appalling and replaced quickly, i have found that on a star of magnitude .6 i was getting minor reflections on the 268, the assumption is reflections from the glass to the Astronomik uv/ir filter and back, i have not noticed it since on less bright stars. to fit the filter i have a ZWO filter drawer, of note i havent seen any light leaks as per other reviews.

the 3 screw adapter allows camera rotation, this seems like great idea unti you realise with the filter drawer the filter is rotated with respect to the chip, each time you move it you need different flats (found that out the hard way) it woud be nice if there was a callibration marker on the outside if you had this i mind.

onto the interesting stuff.... does it work? is it noisy? as they say a picture says a thousand words so.....shot through a FLT132 bortle 3.3 skies

PICTURE 1 centre of a 1:1 single 5 minute sub not debayered showing hot pixels and exposure range of M83 as by screen stretch in pixinsight. no further development.

PICTURE 2 the same sub now debayered in pixinsight and the screen stretch applied.

PICTURE 3 Stacked 13 frames of 5 minutes no dithering (heres where i worked out each night needed different flats if youve rotated the camera) sso just one nights frames (cloud rolled in as per melbourne), so stacked in deepsky stacker with color calibration, median for lights, 80 darks average, 20 flats average, 20 dark flats average. no bias files. then the autosave file histogram stretched in pixinsight and absolutely minimal processing. you could get more data and deconvolve etc for a better image. but this is something a beginner could achieve easily.

PICTURE 4 same as picture 3 but now stetched to show residual noise.

PICTURE 5 50 % resolution crop

PICTURE 6 25% resolution full frame with minimal cropping

so is it any good, for ease of use and the fact i could get a useable picture from an hour of data, its going to appeal to the time constrained cloudy skies dweller. (if i lived in a better location than Melbourne id get the mono version), time will tell and im interested in how it responds to filters etc. but for now im happy enough, in due course i may get the mono version as well, but i already have a mono camera and i moved the qhy8 on some time ago.

having had the opportunity to process some of martin pughs data, its something of an eye opener, and now im not overly fussed if mine's not the worlds greatest data, one can always spend more and more money in pursuit of excellence, and its out of my budget.

happy to answer any simple practical questions i can about the camera. i wont get into the technical level of detail some here can extract.