Darkness Became Light! ... A Quantum Leap in 36 x 24mm at 61.1MP?
In recent years, color cameras have become increasingly popular. A reversal of the trend is not to be expected. One reason for this is the ability to capture weak structures in deep-sky objects even with moderate exposure times. Developments in CMOS sensors and recently the BSI sensor technology have played a decisive role in this. In addition, both quantum efficiency (QE) and full-well capacity increased, noise was reduced, pixels became smaller and smaller, and dynamics increased with almost every new sensor generation.
What happens when all these developments see the light of the stars in a new camera like the QHY 600M with a black and white sensor?
I had asked myself the question: Which camera is really the new reference camera?
What is the true meaning and relevance of all the terms that manufacturers are now using, emphasizing and promoting, or sometimes just simply sweeping under the carpet as if they didn't even exist?
Well, lets take a jump back to the year 2015 / 2016. Back then I bought my first RASA 11" and used it with a DSLR-camera: the Nikon D810A. This combination made astronomy really exciting. It was crazy what could be captured from my backyard with an extremely short exposure time of 60 to 90 minutes. This was my first contact with the Sony CMOS age – and it was very promising!
Is the leap today, in 2020, an even bigger one?
When I summarize all my experiences, I deliberately do not want to describe it as enormously! (Read the way I went, and decide for yourself.)
I have used many new products myself in recent years, but certainly not everything. Although I was convinced of the principle, and the direction and tendency of the technology are clearly visible, the "WOW – that's AWESOME!"-moment was still missing, when I tested new equipment. I was still waiting for this experience.
And then came the day when the QHY600M EB was on my desk - in the Early Bird version with the Pro Option. Baader Planetarium also shipped the last adapters for my RASA 11 to connect the QHY600M to the UFC filter changer. In the last years I did a lot of work with the RASA 8", RASA 11" and RASA 36cm astrographs. Especially exciting were the new Baader Ultra Narrowband f2 Highspeed filters, although I am not a "narrowband guy"!
With the RASA 8 and the Baader FCCT + QHY 163M (a small but very fine monochrome CMOS-camera)became my highlight of the summer of 2019. I think the combination is really a lot of fun: See my M31 picture in only 4,5 hours - with full story.
Why the QHY600M EB? (Not only because full frame works on RASA 11 and 36)
The IMX455 SONY-Chip chip is also available in a cheaper "packages", but that was not the important point for me. What is interesting for me is who gets the most out of this chip – and who supplies me with the highest quality version of this chip. And after extensive research I ended up with the QHY 600 EB – with a built-in industry grade chip.
I have known the QHY Brand for almost 15 years and have worked with its products several times, with different experiences - and for more than a year I have only had very good experiences. During the whole years of existence QHY had gained experience and optimized the numerous camera models and their electronics for the interaction with the Sony sensors. You cannot buy this knowledge!
What do I expect from the new QHY600M EB camera?
Simply: That it does everything better and shows even more in a single frame than any other camera before! And I'd compare it to any hardware on which I have ever gotten my hands on. My expectation was nothing less – but also nothing more.
Basic preparations: First I had to translate everything from the fact sheet of the QHY page into a "What does it mean for me?" language. That is, I had to find out the true advantages that will really be useful for me in the end - for every image I'll take.
At first, I wanted to use the QHY600M with the Sony IMX455 CMOS-BSI sensor on the RASA 11" (279/620mm f2.2). It was exciting that for the first time I would attach a camera with 61.1 megapixels to a fast f2.2 system – is that possible? (Spoiler: Yes, it works, and really well).
For me, the interesting points of the QHY600M were:
- QE at 87% – over a huge range of the spectrum, no "sugarcoating"
- Connect the filter wheel via the camera – this was not an issue for the first use, but it is possible!
- QHY makes a clear statement regarding the QHY600M that the 1GB or 2GB DDR3 memory can really read out the chip immediately, unlike practically all other cameras, which only have 256MB of DDR3 RAM. This was one of my most important criteria, because a CMOS BSI is exposed until it is read out to 100% – otherwise this leads to irregularities in the image..
- The IMX 455 Sensor Grade is indicated as Industrial Grade. As I found out after a very long search on the Sony website and through linked information, a better image can be achieved with it compared to consumer grade sensors.
- The Extended Dynamic Range option (Of all the IMX-455 models on the market, only the QHY600 series can do this!) is not a new technology and has been used successfully for a long time – if the manufacturer can use it properly. The method is also used by another, very well-known manufacturer - there the 12Bit AD signal is added to 16Bit. The QHY 600M is already a real 16Bit camera - delivers dynamic from head to toe or light to shadow. But, this must be understood: Extended Dynamic Range (EDR) not only increases the dynamic range, and this is equal to the full well capacity of over 51,000 to just over 80,000 at 3.76mü small pixels. With the EDR I can also use a wider range of gain values without reaching saturation! So I can get extremely deep Lum and RGB data, with full drawing and details, and display extreme dynamic differences in one image - without tricks and cheating.
Of course these were all theoretical considerations before the first First Light. (Funny what I read about this technology when I posted it - all in all the answers were: It's all fake!)
In the Bin 2x2 18Bit are output, and the full well explodes in sizes that were almost unthinkable. Since I like to record with long focal lengths, the option Bin 2x2 resulting in 7.4mü pixels is ideal! The binning is offered in DSO 16Bit mode as well as in EDR mode – now I almost get stress, what do I try next? 🙂
I thought about cooling for a while - how cold should it be?
I finally went for -10°C. I was able to measure a slight advantage at -20°C, but not enough to be willing to run the cooling with full power in the coming summer months.
Driver and Installation:
Everything on GO – no problems and running smoothly since day one. Just load the ASCOM-plugin into Maxim Dl, and off we go.
PC-Connection for now with USB 3.0 – the fiber optic connection I bought is "on hold" for now, and I want to wait for further development.
Because: Fiber optic will come - not only can you bridge a much longer distance with it, but you also get a much more stable connection. USB is known to react to interactions and influences from outside (PC, interferences...) with stripes, dropouts and all possible and impossible artifacts. The higher speed of the fiber optic connection is another future development possibility. So I will still be "up to date" in three or five years.
Preparation for the first night at RASA 11
I recorded bias and darks at -10°C with 16Bit DSO and the EDR mode. Other settings: Download speed: Normal // Gain: 26 // Offset: 60
The Master Dark has awakened and intensified my curiosity about what can "come" now. I call it "Noise Floor", when the maximum accumulation of noise is in a range that barely exceeds the 10ADU range. What does this mean for the image? The weak signal is not only visible after averaging many recordings, no: the single frame should already show it!
The first light - so far, it was only hinted that a big leag is imminent...
I couldn't wait any longer, although it was only two days before full moon – but clear weather was possible until about midnight! And darkness from about 22h... Anyway – for a test and checking the picture it was okay.
I had also bought a better USB cable, but it had a thicker cross section. This causes a thicker spike. The original power cable from QHY is a bit wavy and thinner, so its spike is thinner and maybe not quite sharp. I'll take care of that one day, but that's not important now. What was important to me was that the cables were aligned at 90° to each other.
The QHY600M has an adapter which is attached to the UFC filter slider through a thread. The camera is then fixed in the adapter with three screws.
These three screws allow a very precise rotation and centering of the camera to the optical path. The alignment of the adapter fits very well with the camera housing. It is important that the camera is really in the center of the field and on the optical axis. The heads of the three screws protruded about 2-3 mm into the beam path and were still original shiny in the first night. But this was also their last shiny night - now they are black!
1st Light and almost Full Moon!
With the Baader UFC and the DSLR I had collimated the RASA 11 over a year ago with 16.7MP full frame. To my joy the adjustment was almost good even at 61.1MP. I only had to optimize / adjust very little, and I knew from the RASA 8 and the FCCT what has to be done and so – YES – everything is fine, I can leave it like this!
The RASA 11" can handle the 61.1MP without any problems and that at f2.2 – that's great! What kind of optics can do this without batting an eyelid?
On the top of my list of test objects was M13, because I had started the camera in EDR mode. So don't start by getting to know it first - NO, I go to 101% right away! In the UFC filter drawer the Baader UHC-S in 50,4mm was inserted.
Surely everyone who takes pictures knows M13. Because M13 is 5.8mag bright, I chose 120s as exposure time at almost full moon because of the fast f/ratio of f2.2 of Rasa 11 and the 87% QE of the camera. What do you expect as result?
So, 117 seconds, 118, 119, 120 - and downloading the image...
What? How? M13 clear resolution, and the background at 3000ADU?? Crazy – so lets try 180 seconds – there is even more to come! So, finally, 300 seconds at f2.2 with UHC-S filter, and then I get to see an EDR-download where the brightest stars in M13 are just reaching saturation. (The ADC of the background is now at about 7900). But the globular cluster remains totally resolved and without overexposure of the core. In the same picture you can already see the faint outer regions – that's DYNAMIC!
The next test object is Abell 2219. 180sec with UHC-S on Abell 2219: Check, the galaxy cluster is clearly visible and already shows a large number of galaxies in this very distant cluster.
There's no stopping now: Next is Draco Dwarf with 180sec and UHC-S. The brightest stars shine at about 19mag or even less! And this at almost full moon – and the same success as in Abell 2219...
My checklist would have been even longer, because I also wanted to test the behaviour of the RASA 11 + UFC with the 61.1MP resolution, but... THAT'S IT, high cirrus clouds at almost full moon and increasingly worse conditions unfortunately meant the end of the first light night.
After this experience, the pictures were still before my eyes, the following days and nights, which finally brought the long awaited rain, seemed much longer.
The Quantum Leap – the Night from May 17th to 18th, 2020.
What did I change compared to the first night? I switched from EDR mode to DSO 16Bit – I wanted to see the simpler 16Bit dynamic.
My plan was first ABELL 2219 in Lum (depending on seeing), then Draco Dwarf in L and / or RGB, and finally at about 2:40AM a quick look at the North America Nebula NGC7000 in H-alpha – it would be high enough in the sky by then that it can judge the image. The weather forecasts for the coming night were also good, so I just wanted to decide spontaneously what I'd to do.
The results at Abell 2219 and Draco Dwarf were like in the first light night – everything went as usual. The data is collected, I will show the picture in the future.
But at 300 seconds at H-alpha with the new Baader 3,5nm Ultra Narrowband f/2 Highspeed Filter, I could really see what a revolution was happening. Very real on the PC – without marketing blah-blah: This is the future! I felt like I was 5 years old again, excited and even more excited... I don't know how many times I looked at the data, and there were too few frames in H-alpha I could take at night.
So the plan for the coming third night lay clearly in front of me: first H-alpha and then O-III... I wanted to see the picture as a bicolor, because I know the object really well.
Data stacking was done in PixInsight as usual.
The darks alone are enough for the QHY600M, because the data is extremely smooth, as already mentioned! I can count the hotpixels, and I only have one pixel for which the 65535 ADU is reached completely – 1 hotpixel!
Depth, dynamics, signal and an insignificant noise in bicolor! As weighting I used red = H-aplpha (factor 1.0) : green = (H-alpha x 0.5) + (O-III x 0.5) : blue = O-III (factor 1.0) The processing was designed to maintain the dominance of the H-alpha and to give O-III the importance it really has.
The image processing was exciting and was done in PixInsight and Adobe Photoshop CC 2020. After a few days on the PC, the dynamics of the H-alpha image had finally arrived in the BiColor version of NGC7000 + IC5070.
The contrast is – I would describe it like this – endlessly brilliant, with only 620mm focal length the resolution was very fine and the gradations of the tonal values were grandiose – no noise, nothing, just an image! No kind of noise reduction was used! No flats were used and no bias was subtracted, only darks were used to calibrate the single images (I didn't schange the camera settings)!
But now have a look at it yourself and think about my details of the picture. Such a result is possible today with 75 minutes BiColor in Ultra Narrow Band with the setup as described. (Baader Ultra Narrow Band f2 - H-alpha 7x 300s and O-III 8x 300s at -10°C).
What's next? Just marvel, click on the picture and enjoy it in high resolution!
Your Christoph Kaltseis
About the author: Christoph Kaltseis
Christoph is not only an Adobe Photoshop specialist and as Nikon Professional touring for Nikon, but also an experienced astrophotographer. He is one of the founders of the Central European DeepSky Imaging Conference (www.cedic.at), which is held every two years in Linz since 2009.
In addition to his various projects, Christoph has developed an innovative image sharpening process called APF-R (Absolute Point of Focus)in recent years. The procedure is not always the same, but is adapted to the combination of lens and camera. Therefore, a flexible method was necessary to achieve the desired results.
In his career as an astrophotographer Christoph has also created several APODs (NASA Astronomy Picture of the Day), e.g. the APF-R-processed image of the M33 Galaxy or the Heart of the Orion Nebula (M42).