Summary: All round great cooled astrophotography camera; super sensitive, supersonically low read noise, no amp glow, no dew problems and much cheaper than its bigger brother the QHY268 because it has a smaller 1” sensor. Affiliate Link: $1159.00 from High Point Scientific:
Settings: Gain:60, Offset 30, Xx300sec L, Yx 300sec R, G and B filters. Temperature -10 degrees.
INTRO I think the astrocams against which all other astrocams need to be judged are those with the IMX571 sensor ie ZWO’s asi2600mm and QHY’s 268m. They are the best sensors non millionaire nerds can reasonably expect to afford. These sensors represent the nail in the coffin to romantics like me who still believed old CCD sensors (like the KAF8300) had an advantage in narrowband astrophotography department. I’m going to compare these astonishing IMX571 sensor astrocams to QHY’s latest offering the QHY 533M.
CAMERA SPECS If you compare the specs sent to me by QHY of the QHY533M to those of the QHY268M in high gain mode you will see that they are virtually identical. This is fantastic. It means this camera is a great all rounder. It’s super sensitive which is perhaps the most important thing, it controls the dark current well which you need for good long exposures and has an astonishing low read noise which means we finally we have a camera which doesn’t cost the earth which is capable of delivering near 1 electron per pixel read noise. Heads up I am particularly interested in lucky imaging deep space as it is what Big Amateur Telescope is focusing on and having low read noise is particularly important for lucky imaging (or if your mount is a bit wobbly and short exposures mean you don’t have to throw away too many subs). On top that I am happy to report that this camera has no amp glow.
Here is my own read noise vs gain graph produced through sharpcap, Note that my results tally pretty well with QHY’s own results. Also note -and this is very exciting for me as a lucky imager – that the read noise drops to just over 1electon per pixel at a gain of 100, this particular reading is omitted from QHY’s own graph which is strange because it’s a major plus point as far as I’m concerned. QHY533M TEST RESULT On Thursday 24th March 2022 there was a clear night (don’t faint). I was at my mum’s place in Devon (Bortle4). I used the QHY533m with the QHY 1.25” filter wheel (loaded with baader LRGB ccd filters) in combination with an old and crappy looking 8” f4 Newtonian (don’t be fooled by the looks this is really my cheap version of the ‘wow’ scope I talk about half way down this page ) on my modest and brand new Skywatcher EQM35 mount.
The scarcity of clear nights forced me to kill three birds with one stone and test out the telescope, mount and camera on a single night. I can happily report that the mount worked fine and the telescope worked mostly fine (reviews to come) so we can concentrate on the camera. After 4 hours of imaging we got the above shot of the Sunflower Galaxy (which I am very pleased with). A few notes on the mount and telescope: The EQM35 did very well, able to carry the 10kg set up and putting in a very respectable 1.2arc seconds RMS wobble (which is slightly more than the pixel scale of 1arcseconds but nothing to write home about). My crappy looking scope did well too. It was a butchered 8inch f5 Celestron Newtonian which I chopped down (for reason’s that will become apparent in the next astrobiscuit video) and replaced with a GSO 8”f4 mirror – this mirror is at the heart of what I’m calling the ‘wow’ scope which members of Big Amatuer Telescope have used so successfully. Collimation wasn’t easy because the mirror cell was cheap, focusing wasn’t easy either because the focuser cost 40 quid but despite my collimation and focus being a touch off and the spider veins being slightly twisted I think the scope has punched well above its weight. PROBLEMS There isn’t much to complain about other than the sensor will be too small for folks wishing to produce hi resolution prints of their space pics but its fine for those of us who mostly upload to Instagram. The only other problem I had was that when paired with a zwo filterwheel my imaging program NINA bugged out. Bearing in mind I was using an early version of QHY’s sdk and the fact that it might not be anything to do with the QHY camera then I don’t think this is anything to worry about. The camera worked flawlessly with QHY’s own filter wheel which btw has a rather nifty alignment thing which helps getting your off axis in the right orientation. WHAT CAN YOU SHOOT WITH THE QHY533M Deep space: Great Deep Space lucky imaging: Awesome Planetary ; Great (Not tried it but surely it must be good) Lunar: Great (Not tried it but surely it must be good) Solar: Great (Not tried it but surely it must be good)