As you probably noticed for the last 4 months now I have been mostly using a OSC CMOS camera from QHYCCD, namely the QHY268c . If you guys are still looking for the best astrophotography camera out there, I'm hoping my review can help shed some light on your final decision.
Sporting the 26 Megapixel SONY IMX571 colour sensor in APC-C format, 16bit ADC with 3.76um pixels, it is also part of a new wave of astrophotography cameras that brings new technology to the table. Zero amp glow, very low dark current and read noise with 3 different shooting modes, Photographic, High Gain and Extended Full Well. These new capture modes are a very interesting feature that QHY is exploring. To understand how it works I find it best to take a look at the charts available here. Other features worth mentioning are the 2GB DDR3 memory buffer, Anti-Dew Heater, AR+AR multi-layer anti-reflection coating and a Full Well capacity of 51ke in standard photographic mode.
First Impressions
This camera is HUGE! The early bird version that I got also called the Scientific version includes the infrastructure to use two 10 Gigabit fibre ports for 20Gbs file transfer speed.
This however makes the camera body long, 180mm long, like a CMOS Dachshund. The photographic version of this camera will end up shorter than this. The weight I found was pretty low on the other hand and mostly toward the sensor, so it should not cause any tilt issues for a good focuser. It comes with a female M54 telescope connection, which might be a problem since most people will use either an M42 or M48 corrector thread. So you will require an extra adapter for this unless QHY will add it to the package (hint hint). At the back we got the locking power screw, USB3, 4pin filter wheel connection and on this version the two 10 Gigabit fibre ports.
I was pleasantly surprised to see that QHY has really amped they game when it comes to accesories included:
12V power brick (6A)
Cigarette lighter power adapter
Locking power cable
5ft USB3 cable
Centrering/tilt adjustment ring
0.5 to 13.5mm spacer kit to adjust back focus (M54 size)
Desiccant tube
Metal M54 screw on camera cap
2” nosepiece to M54-Male adapter
A real bounty compared to my old QHY163m. My only complaint here is that for everyone not using a RASA, and requiring a corrector/reducer the M54 connection and accesories are not the ideal choice. A choice of step down adapters would be most welcome.
Testing the Giant
At the time the camera arrived we were in full winter mode here in Ontario, so I had the ample opportunity to play with it indoors. Driver install and getting it to run was a breeze, so really there was nothing crazy to troubleshoot. I used the ASCOM driver and SGP to run some calibration frames that looked amazingly clean and amp glow free even at 10min of exposure. I did find the TEC cooler less efficient than that on my 163m. I don't know if this is hardware related (size of the sensor, body construction) or something that can be corrected via software.
By the time clear skies arrived I have also received my new main telescope, an 8” Carbon Newtonian at f5 and 1000mm. I was originally going to start the test with my small and fast refractor but now I was too excited for high resolution imaging on some iconic winter targets.
I connected the camera to the Newtonian using a string of adapters starting at M54 and going to M48 (corrector side), adding up to a little bit over 55mm.
Again this can be a challenging task if one does not have a multitude of adapters and spacers. The conditions were poor, very cold and humid with poor transparency.
I shoot from my observatory in a suburbia at about Bortle 7 or more in winter due to all the extra lights and snow.
The Great Orion Nebula, M42 at 1000mm
110 min of exposure time with 20sec and 60sec frames.
Photographic mode, Gain 25, cooled at -20C.
I also shot 5sec exposures but ended up not using them since this camera has fantastic dynamic range.
The Rosette Nebula
4.8 hours of integration with a mix of 75 and 90 sec exposures
I was surprised at how much nebulosity got captured with this short integration and light pollution.
I think I could have gotten more if I would have used the High Gain mode.
Horsehead and Alnitak
1.8 hours of exposure with 60 sec exposures.
Super bright Alnitak resolved nicely with no reflections or halo.
Galaxy Season
Bad weather continued through February and March, by the time it got clear again Orion was gone and Galaxy season started. I don't use any kind of LP filter to maximize the signal.
I decided to switch the QHY268c into High Gain mode for galaxies. I settled at gain 0 and offset 25.
Heart of Virgo
401 x 75sec exposures
Sticking with short exposures due to light pollution.
The Pinwheel and friends
My favourite image using the QHY268c. I dreamed about shooting M101 properly.
The beauty of a big sensor like this is that even at long focal lengths you still have room to play with the framing.
I put 17.7 hours into this one, using 75sec exposures. Very happy how it turned out considering seeing was bad every night.
M81&M82
IFN in light pollution with a colour CMOS. Yes possible with the QHY268c.
Faint but it’s there, wish I had more clear skies for a longer integration.
This is about 15hours of data again with 75sec exposures.
Team work
As Summer approaches Nebulae targets are coming back. Because I don’t own a large 2” Halpha filter I am not able to test the 268’s narrowband ability. But I am sure that by pushing the gain up and using longer exposures one could easily capture faint nebulosity with this camera. For me the plan is to use the QHY163m+filter wheel and shoot Halpha while on moonless nights shoot RGB with the 268c.
NGC 6820
A very faint emission/reflection nebulea in Vulpecula
The RGB data was great with only 5 hours of integration. Emission part of the nebula was visible and nice star colours.
I added 8 hours of Halpha from the QHY163m to bring out faint hydrogen dust.
I am very excited to try out more targets this way, especially in Cygnus.
The ability to get great RGB data with no separate filter fuss is a real treat.
12bit vs 16bit
Compared to my 163m 12 bit mono camera, the raw frames coming out of the 268c are higher resolution, cleaner with minimal noise. No trace of amp glow. I have not Drizzled any of my images with the 268, and I was amazed by the details when zooming in or cropping.
M95
This is a huge crop since the galaxy is tiny at 1000mm.
Very smooth at native resolution, not drizzled.
Conclusion
The QHY268c is going to be hard to beat. I think the APC-C size sensor is a great balance between resolution and file size and to me it just might be the best OSC astrophotography camera out there.
Compared to the old generation of CMOS cameras it clearly solved the big problems like amp glow, reflections or halo’s. The super low read noise allows for short and clean exposures which make it ideal for fast systems like RASA, Hyperstar and fast refractors or lenses. I also think it shines at long focal lengths using Newts or Cassegrains because of the size of the sensor that will give you excellent resolution for galaxies or planetary nebulae and room to plan the framing.
Overall I think that this new generation of QHY OSC cameras are a game changer in the sense that they are incredibly sensitive with different capture modes and variable Gain to adapt to specific targets. Couple this with the arrival of dual, triple or quad band filters that bring narrowband imaging to a whole new level.