The new QHY268C-Review

I am thinking of buying a one-shot-camera and I am extremely excited about this new CMOS camera.

QHY268C TEST REPORT

The QHY268C is the latest APS-C sensor camera from QHYCCD, featuring the color-only IMX571 back-illuminated CMOS sensor. It features a native 16-bit ADC and a 3.76um pixel size for 26 megapixels total with zero amp glow. The camera produces very low dark current (0.0005e/pixel/sec @ -20C and 0.001e/pixel/sec @ -10C) and read noise (0.7e- to 5.5e- depending on mode and gain choice). It also features an extremely high full well capacity up to 75ke-. The quantum efficiency of the sensor is not confirmed but tests suppose it is close to 90%. This combination of high fullwell, high QE%, and native 16-bit ADC allows for an unparalleled dynamic range response not available in other CMOS sensors offered currently in this price range. These features set it apart from the current pack of 12 and 14-bit one-shot color cameras available in today’s dedicated astronomy camera market.









GENERAL FEATURES AND PHYSICAL DIMENSIONS

The version of QHY268C I have received is the early bird version of the camera. Like the early bird version of the QHY600, the larger full frame companion to this camera’s sensor, it features a longer body (approx. 180mm) and scientific features. It contains the infrastructure to use two 10 Gigabit fiber ports for up to 20Gbs file transfer. This feature is currently disabled and will require a PCIe capture card, an addon that QHY will make available later. If one chooses to enable this feature later (which will most likely be quite costly) file transfer speeds can reach up to 2000MB/s, compared to the typical USB 3.0 speed of 300MB/s.

It is slightly heavier than most of the QHYCCD medium size format cameras at 990g (1065g with tilt/centering adjuster). For comparison, my QHY367C weighed in at 770g. A standard photographic version will be available from QHY and not be quite as long as the early bird version, but will still be a bit longer than other current offerings. Most of the weight is up near the sensor half however and I don’t think it should present any tilt problems on good focusers. However, it is something to keep in mind.


INCLUDED ACCESSORIES

Included accessories with the QHY268C

Aside from the camera, the box contains the following items:

• 2″ nosepiece to M54-M adapter

• Desiccant tube

• 6-hole 0.5-13.5mm spacer kit for adjusting fine backfocus

• Cigarette lighter power adapter

• 12V power brick

• Locking power cable

• 5 ft USB 3.0 cable

• Centering/tilt adjustment ring

• M54 screw on metal camera cap







I was happy to see that they are now including a spacer kit with their cameras; backfocus and spacing is a continued frustration in this hobby for a lot of people. The included spacers have six holes that attach directly to the camera body via M3 screws. It’s worth mentioning that depending on how much space you require, you may need to purchase different length M3 screws. If you are using a QHY OAG these spacers can be used easily in conjunction with it, but would require longer M3 screws.

My one complaint about the included accessories is that it’s still not quite ready to go out of the box for most users who require the typical 55mm backfocus for many reducers and correctors. The camera itself has a backfocus of 17.5mm, or 23.5mm when using the centering/tilt adjustment ring. With the included spacer kit, the maximum total available out of the box is only 37mm. The user must still make up 18mm with other spacers, filter slider/wheel, or OAG. One thing I would like to see QHY do in the future is offer a “ready out of the box” solution for the standard 55mm backfocus. However, most users will need a customized solution anyway and the reducer connections vary, so I can understand the case against this.

DRIVER INSTALLATION & USE IN IMAGING SOFTWARE

I’ve heard several people on forums say they have had driver issues with QHY cameras. I want to be clear that this is something I’ve never experienced in the nine different QHY models I’ve used over the past few years. The camera itself was quite easy to get setup and I had it running in a matter of minutes. I am using a Windows 10 64-bit installation on a Surface Pro 4. From the QHY268C download page on QHY’s website, you’ll need to do the following:

• Download and install the QHY System Driver – unzip and run the executable file.

• Make sure you have the latest ASCOM platform installed (if not, get it from ascom-standards.org) • Download and install the QHY ASCOM Driver from the same page. This will allow you to connect via ASCOM in imaging software.

If you are going to be connecting through ASCOM, you’re done. You can now connect to the camera in your software application (I used Sequence Generator Pro) and adjust the gain and mode in the settings. Make sure “Remove OverScan Area” is checked or you will end up with black lines on the edges. P.S. I do not recommend using the gain and offset settings shown here!

NEW CAPTURE MODES

One of the most interesting features of the QHY268C is that it has three available capture modes that you can choose from which offer varying performance and trade-offs. The charts which show fullwell capacity, system gain, dynamic range, and read noise in these varying modes are available from QHY here. A brief overview of the three modes follows:



M42, The Great Orion Nebula – 1.1 hours (66×60″)







#0 PHOTOGRAPHIC MODE

This is the standard “default” capture mode. There is a high/low conversion gain cutoff point between gain 25 and 26 where you will see the read noise drop from about 5.2e- at gain 25 to around 2.5e- at gain 26. The read noise response is quite constant from gain 0 to gain 25, and again from gain 26 to about 60. Due to this, most users will probably want to use either gain 0 or gain 26 and nothing in between, as you would only be losing fullwell capacity and dynamic range in the middle. I mainly image at fast focal ratios of f/2.2 so for me it makes more sense to use gain 0. Users of slower focal ratio telescopes, or in dark skies, will most likely want to use gain 26 to take advantage of the lowered read noise. Increased exposure time is going to be recommended over increasing the gain into the “middle ranges.”

#1 – HIGH GAIN MODE

This mode features a consistently lower read noise throughout its response, with the tradeoff of a slightly lowered fullwell capacity. Like #0 Photographic Mode, there is high/low conversion gain cutoff point. For this mode the cutoff is between gain 55 and gain 56, where the read noise drops from approximately 3e- to 1.5e-. I like this mode the most for narrowband imaging as you can take advantage of the extremely low read noise at gain 56 without having to worry much about fullwell capacity. For most of my standard broadband imaging, I also prefer the lower read noise of gain 0 and still relatively high fullwell of 60ke-. Unless I am shooting a field with very bright stars in it where the higher fullwell capacity of Photographic Mode may be a better choice, this mode is my main choice for imaging with my RASA. This mode also features the best dynamic range at 14.26 stops.

#2 – EXTENDED FULLWELL MODE

The name pretty much says it all for this mode. It offers the most potential fullwell, and a higher fullwell capacity through the entire gain range. It has the most consistent response of all three modes as well. The read noise stays around a constant 5.2e- and it has a smoother drop in both fullwell capacity and dynamic range, with more fullwell available at higher gains. I haven’t done much testing with this and I’m not sure of a case where this would be better than the other two modes.



IC434/Barnard 33 Horsehead Nebula – 2.1 hours (129×60″)




PUTTING IT TO THE TEST

When I first got the camera, the weather was not cooperating so I was limited to shorter integration times during windows of clear sky, which wasn't a big problem for my f/2.2 RASA 11. The following tests were all performed in my Bortle 5 backyard (approximately 19.70 average measured SQM) with an Astronomik L2 UV/IR Cut and Astronomik 12nm H-alpha.




My first target test was the Great Orion Nebula. The main goal of my testing was to see how the dynamic range performed. I also wanted to try out the different modes so captured part of the frames in High Gain mode (30×60” at gain 0) and Photographic Mode (36×60” at gain 0). I really couldn’t discern a huge difference between the two modes at f/2.2 other than the diminished fullwell showing slightly more saturated stars in the High Gain Mode. I combined these frames for a total of 1.1 hours (66×60”) and processed it for the result shown on the previous page. Not bad for just an hour!






In addition to M42, I also did some testing on the Horsehead Nebula (above). For this I chose to only test with Photographic Mode at Gain 0, Offset 30. The total integration before being stopped by cloud cover was 2.1 hours (129×60″). Several nights later, continuing my trend of not having ideal conditions, a 30% moon was up so another bright object was in order. I chose another popular target, the Pleiades star cluster. I obtained 1.9 hours (115×60”) before clouds rolled in and stopped me in my tracks. The processed result is shown below.








The next step was to try out some narrowband Hydrogen alpha and a fainter target. I’d been eyeing an area in Orion featuring Cederblad 51, with a combination of reflection, emission, and dark nebulae. This perfectly fit the bill.

The moon was 60% illuminated on my next clear night so it seemed the perfect time to capture the Hydrogen alpha. I used the High Gain mode set at gain 56, and managed 3.1 hours (62×180″) through the Astronomik 12nm H-alpha filter. Most people don't think of one-shot color cameras as their first choice for narrowband imaging but the QHY268C can clearly hold its own. Despite all logic of “only using ¼ the pixels,” the resolution is still quite good. A few weeks later I finally managed to get another clear night to add some regular broadband data to this image. I captured 3.6 hours (215×60”). Both results of Ced 51 are shown above.



M45 The Pleiades – 1.9 hours (115×60″)


QHY VS. ZWO COMPARISON


Many wanting to purchase a new one-shot color camera will be debating between this camera and ZWO’s ASI2600MC counterpart so I thought I’d cover some of the differences I’ve noticed. Having not tested the ZWO version personally, these are based off the specs from their website.

1) The QHY has a 2GB DDR3 memory buffer – the ZWO has 256MB DDR3 memory buffer. This may matter for those who want to do EAA or any kind of video capture.

2) The QHY has 3 different readout modes which offer varying performance and tradeoffs. It appears that the ZWO camera only has one which most resembles the Photographic Mode.

3) The QHY has an M54 interface, the ZWO has M42 interface. This may not matter to some, but it may have ramifications for those who use fast setups such as Hyperstar or RASA, where the steep light cone can cause extra vignetting.

4) Physically, the ZWO body is much shorter at 97mm compared to the 180mm of the early bird and an unknown, but certainly longer than 97mm, length of the standard QHY268C.

CONCLUSION

I think it’s safe to say the CCD era is just about over. As far as color cameras go, this is it. Gone are the old problems of CMOS like amp glow and low native 12 and 14 bit ADCs. The lower read noise and dark current of the QHY268C allows for much shorter exposures, offering much more sensitivity and flexibility. In my opinion this color camera rivals the performance of some of the monochrome sensors in terms of resolution and how clean the images are. If an APS-C sensor like this is offered in monochrome in the same price range, it is pretty much over for CCDs in amateur astronomy. Read Jarrett's complete review and update at: http://cosmic-colors.com/gear-reviews/qhy268c-review/

Article - Gibraltar Magazine March 2020


Gibraltar Magazine Article - March 2020





Reach for the Stars

Speaking to Charles Duarte, MAstro (Masters in Astronomy), Fellowship Member of the Royal Astronomy Society (UK) and head of the Gibraltar Amateur Astronomer’s Society.

By Sophie Clifton-Tucker

 March 1, 2020

 


What is the Gibraltar Amateur Astronomers Society, and who was it founded by?

After obtaining a Master’s Degree in Astronomy, I decided to create the GAAS back in 2013 with the help of a small group of fellow astronomers. The aims were and are to provide a forum for discussion of astronomy matters and share knowledge, as well as to meet other fellow stargazers, whether just getting started in astronomy or as a seasoned observer and/or astrophotographer. It’s also a great way to learn about telescopes, eyepieces, cameras, and the Universe.

How many members are there? When/where do you meet? What do you do?

Since its founding in 2013, membership in the society has been limited to members interested in astrophotography, and currently, we meet in Spain at least once a month. We have a Facebook page of nearly 700 followers, and Facebook groups of over 2000 members. I would like to establish a club locally to develop and create awareness of the sky above us, bring together local people from our community to share our passion for astronomy and the wonders of the Universe. I receive many requests from local parents asking how their children can join the society, but without premises, it’s difficult.

I REMEMBER THE EXCITEMENT I FELT SEEING IT.

 

When did your interest in astronomy begin?

When I was in school from a very young age, I was interested in all kinds of science things. There weren’t many books on astronomy at the time, but I read all the ones in John Mackintosh Hall library. TV series like Star Trek and Lost in Space when I was growing up did influence me quite a bit. I do remember the first trips that were made into space, like the Gemini and Apollo missions. It wasn’t until later in life when I could afford a telescope, that I saw for the very first time a close-up of the Moon; I remember the excitement I felt seeing it.

What do you love most about it?

I had to think about this for a long time. But I think the best thing is being able to share what I have learned about the Universe with others and enjoy their enthusiasm and amazement.

What has been the most significant/exciting discovery, in your opinion?

There have been many significant discoveries, mostly in the past fifty years. Still, I will stick with last year’s breakthrough and one in particular, which proves a theory going back decades. I am talking about the first image of a black hole, taken using Event Horizon Telescope observations of the center of the galaxy M87, published in April. This shows the supermassive black hole at the center of the Messier 87 galaxy, which is about 54 million light-years away from Earth. The black hole’s mass is equivalent to 6.5 billion suns.

Scientists struggled for decades to capture a black hole on camera to prove it exists, since black holes distort space-time, ensuring that nothing can break free of their gravitational pull — even light. That’s why the image shows a shadow in the form of a perfect circle at the center.

How do you see our knowledge of the skies advancing over the next decade?

In the next decades, we will see a global competition between nations and the private sector to reach the Moon and Mars to establish colonies within the next twenty years. India will send astronauts into space in the next few years. Late this year ESA with Roscosmos aims to discover life in Mars. SpaceX by 2024 plan to send a crewed spacecraft to Mars. China expects a spacecraft landing on the far side of the Moon. We mustn’t forget the USA and Russia, whose sole interest is in the Moon’s minerals.

Would you take part in the Mars mission, given the opportunity?

Sure, wouldn’t you? I can picture a special tour: First a stop on the Moon, wearing spacesuits and exploring all its splendor. Second stop, Mars. There are lots of places to visit there — the Grand Canyon of Mars, the ice caps, strolling along in the morning in the ice fog. Our imagination has no limits. Even if there are no tour ships yet, it will come, but we will need to wait for some years before this is a reality. I would also like to mention that space is a dangerous place, from cosmos radiations to super-speedy dust grains that can damage spacecrafts and astronauts, to gravitation forces that affect our bodies.

WE WILL SEE A GLOBAL COMPETITION BETWEEN NATIONS TO REACH THE MOON AND MARS.

How much of the observable Universe do we know about? What is it comprised of? What do you think lies beyond?

Ahh, the million-dollar question. Of the many ideas that have been discussed over time, the one theory that I feel is most likely is that outside this Universe, there are a bunch of others all expanding just like ours, or contracting.

The Universe is expanding. Space itself is expanding. That much we know from the cosmic redshift of distant galaxies in every direction and which is measurable. The fact it is expanding means it was once smaller, and carrying that to its finality is to recognise that it must have at some point been unified in some form or way. Although I have read a lot about this subject, there is no concrete answer yet.

Now, to make everybody aware of how little we know about the Universe. All the stars, planets, and galaxies that can be seen today make up just 4% of the Universe. The other 96% is made of stuff astronomers cannot see, detect, or even comprehend.

What planets/constellations are best seen from Gibraltar/Spain, and in what spots?

Gibraltar’s uniqueness makes it difficult for seeing. We have a big rock and quite a lot of light pollution, and there are only a few places you can appreciate the cosmos with your naked eye; one spot is on the top of the rock, but only if you’re lucky. Remember the night sky changes throughout the year and constellation position changes as well. If you look towards the North (North Star-Polaris) you will see Constellations like Perseus, Cepheus, and a few others rotating around Polaris. Spain is a vast country, and there are quite a lot of pitch-dark sites nearby. My observatory, for example, is in Istan (Malaga) mountainside with a night sky reading of 21 SQM.

What equipment would one need? Or where can we borrow it/use someone else’s?

The simple answer is minimal to get started.  A clear night and a star chart are enough.  Star charts can be bought from most of the larger book shops online, such as WH Smith. As you gather sky knowledge, buy a reasonably low budget telescope with a GOTO mount. This will be your starting point, and remember, do not run before walking, or it will cost you eventually.

Do you have a favourite constellation?

Not sure, I suppose Orion given its spectacular colorful nebule images once processed. I have been observing and imaging the night sky for years. For me, the Universe is my favorite space.

Do you have any advice for someone who is interested in getting into the field of astronomy?

Amateur astronomy should be calming and fun. If you find yourself getting wound up over your eyepiece’s aberrations or a planet’s invisibility, take a deep breath and remember that you are doing this because you enjoy it. Take it only as fast or as slow, as intense or as easy, as is right for you.

 

Flip-Flat Equipment


I purchased the Flip-Flat for my FSQ-106 and like it a lot. It’s well-made, and it's a necessary for my camera images, thou I found the included plastic strap for mounting is a bit loose, I can replaced it with a large metal “hose clamp.” if necessary. Using with SGP for automation while I sleep, it’s very handy that it will record flats and close to cover the scope at the end of the night. As others have said, I don’t trust it for bias or darks in daylight, because it seems light will leak in, so I simply record those with the camera unmounted and capped during the night.

This equipment can be a bit over prices I disagree that it is a luxury item... any more than filters, reducers/correctors or PixInsight.

Good quality flats are a requirement and anything that makes taking good flats consistent and reliable is worth every penny. Look at the hundreds of posts on CN about problems processing lights with flats, the majority of which have to do with the quality of the flats in the first place. High quality, astro-dedicated like the Flip Flat eliminate that problem. iPads, cheap LED panels from Amazon and the like are NOT valid substitutes.


New Shed for Small Scope

Observatory

Observatories/ Sheds are highly individualistic; they reflect the interests, equipment, and personalities of their owners. Unfortunately, this also means that one individual's dream observatory might be a white elephant for someone else. As a result, the more specific observatory plans become, the less useful they are.


To store my telescope I used  PVC/Aluminium walls with an insulation foam between the internal and outside walls. to move the shed I connected four wheels with brakes, the front of the shed has a rolling shatter that lifts with a cable, this way its easy to just move back the shed from the semi-fixed mount/telescope.


Having the shed will safely guard my equipment from the elements better than the previous telescope covered that I had 




      






Calibrating a CMOS - ZWO 1600mm with Pixinslight



I've been using my ASI1600MM for last month or so, along with the PixInsight BatchPreProcessing script.

I've read multiple posts to try to understand what should be the proper settings, and at this stage my conclusions are:

1600MM-C

1- All exposures should be longer than 0.2 seconds, as the sensor is not consistent under that.
2- Take light frames as usual, at lowest temperature reasonable (-15C for me these days), with proper gain and offset (gain 200 and offset 50 for me, as I do narrowband), and for me exposures are determined using help from the tables in this post.
3- Take matching dark frames: same length, same gain, same offset, same everything as the lights.
4- Take flat frames: adjust gain as needed so that exposures of over 0.2s are achieved, giving a SGP ADU readout of around 12,000-16,000
5- Take dark flat frames: same gain and offset as the flat frames, and same length. For me, this means one set of dark flats per filter.
6- No bias frames
7- In BPP, put Dark Frames in Darks, Dark Flat frames in Darks, nothing in Bias, Lights in Lights, Flats in Flats. Dark Optimization set to OFF. What I understand this does is:
    a. Create a master dark of same length as light frames
    b. Create a master dark flat of same length as flat frames, for each filter
    c. Flat frames for each filter are calibrated with the master dark flat that corresponds to the length of each filters' flat exposure
    d. Flat frames for each filter are calibrated into a master Flat
    e. Light frames are calibrated with Master Dark (from step a.) and Master Flat (for each filter)
    f.  Light frames are star aligned/registered
    g. Light frames are integrated into a Master Light
8- If needed, manually perform a drizzle or Local Normalization integration


Flats

For flats I am using a technique using the daylight instead of a light panel, tests have proven that the quality is much better then a light panel, and its easy to do.

Cover the telescope, Filter Wheel and camera to avoid light penetration to the sensor.


You need tin  paper, tee-shirt and an elastic band










In SGP I set the ADU level to 25000 with 1000 tolerance.
















First CMOS Camera

Modern CMOS Sensors Are Often Superior to CCD Sensors

CMOS sensors have undergone significant upgrades in recent years, in many cases surpassing CCD sensors. Their high speeds (frame rate) and resolution (number of pixels), their low power consumption and, most recently, their improved noise characteristics, quantum efficiency, and color concepts have opened them up to applications previously reserved for CCD sensors.

The improvements to CMOS technology and the strong price/performance ratio in these sensors make CMOS sensors increasingly attractive for industrial machine vision. In particular, the very high frame rates that can be achieved, almost without any compromise in image quality, are one of the primary hallmarks of the current generation of CMOS.


CMOS development over taking CCD



  1. High speeds (frame rates)
  2. High resolution (number of pixels)
  3. Strong dynamic performance
  4. Low power consumption
  5. Improved noise performance
  6. Improved quantum efficiency
  7. Improved color concepts
  8. Good price/performance ratio
What is a CMOS sensor?


There are two types of image sensors for industrial cameras on the market: CCD and CMOS sensor. The right sensor for any given job is a case-by-case question. At the same time, the trend seems to be toward CMOS sensor technology as the wave of the future. This should come as no surprise, as CMOS sensors have made major strides in recent years in two important parameters for area and line scan cameras, namely image rate and noise level. Since the beginning of 2015, it has become official that CMOS technology will be the future technology.


My New CMOS Camera


ZWO 1600MM PRO







One beautiful thing about the 1600MM pro is it's huge size chip. The MN34230 CMOS sensor comes with a resolution of 4565*3520 and has a 3.8um pixel size, which makes it a great camera for imaging widefield objects with my 105MM refractor. Another important reason for me to buy this camera is that it also contains DDR3 256MB memory, which should help to improve data transfer reliability and minimize amp glow caused by a slow transfer speed when using a USB 2.0 port on your laptop or computer to connect the camera. Moreover, the camera has a low read noise of 1.2e.


Testing noise and ampglow levels

You can guess that the first thing i did was taking some dark frames and checking the amount of noise and amp glow at various shuttertimes, while cooling the camera at -25 degrees celcius (77 degrees fahrenheit) at unity gain (139) setting. I went as far as 5 minute (300s) frames.















GM2000


My new mount 10Microm GM2000  replaces my old AP 1100, my motivation for the upgrade grew out of the realization that my astrophotography quality needed a with dual decodes which lack the replaced mount. Two things matter to me: avoiding wasted time during an overnight session (caused either by images thrown away due to tracking errors or by time spent repeatedly trying to properly frame the desired variable star), and image quality (which affects photometric – brightness measurement – accuracy). This is a personal expression, but never got the reliability to the point where I could trust it to work during unattended overnight sessions.

What made the GM2000 so attractive is that it uses absolute encoders on both the declination and RA axes, which virtually eliminates periodic error. The company claims that tracking error is routinely less than 1 arcsecond,  What appealed to me is that 10Micron doesn't sell any version of the GM2000 without absolute encoders, which has permitted them to optimize the entire control system around the use of the encoders.
Installing the GM2000 onto my pier was straightforward, just requiring a few holes and bolts. The most difficult part of the installation was wrestling the 30 KM of mount up onto the pier. The image below is a picture showing the new mount, telescope, and camera.
It then took a couple of weeks  to finish upgrading my software to handle the computer interface to the GM2000 and to build a "mount model" in the GM2000 firmware.
To build a mapping points model there are third parties software , this are ModelCreator or Mount Wizzard. It a be tricky to setup the communication channel , but once you connect it a great program.
The firmware has a very nice polar alignment tool, eventually 5 arcseconds away from perfect. 

This time I used Polemaster to assist me , thou you need first to do a three stars alignment followed by the polar alignment and if you use the mount PL you would need again to do the three stars alignment.

The general "feel" of the mount is wonderful. The GM2000's firmware seems solid. When you execute a goto, the mount does it quickly and accurately, the same every time. When things go wrong, you don't need to cycle power to get the mount working normally again; instead, just fixing the problem makes the mount happy again.

The mount performs "two-axis tracking," with both the declination and RA motors involved in the tracking process. The mount's pointing model is translated by the firmware into both a declination tracking rate and a RA tracking rate. Thus, the two-axis tracking is able to compensate for all of the known elements of small misalignment. I've run the mount last week for the first time given that when setting up the connection to SGP  it platesolving was not aligned with the mount RA/DEC coordination. The issue was the mount software memory stick firmware version, thinking that it was latest in reality its was old, quite old (1.22) when the current update with 1.5. After realizing this and quite annoyed that they sold me a nearly two year old mount (new , but old if you know what i mean) I did a fully automates of five hours overnight sessions, connected and sync to the dome. 
For my exposures (up to about 6 minutes), there is no visible tracking error. Typical star images have FWHM widths of about 1.9 pixels.



Mount in action