Tag Archives: 16-Bit ADC

Equipment, Gear Reviews

ZWO ASI6200 62mpx Full Frame Camera Review

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I recently wrote a review on the ZWO ASI2400 24mpx full frame camera, so I thought I would also do the same for the big brother which is the ZWO ASI6200 full frame camera with a mammoth 62mpx which I picked up from 365astronomy when returning the ASI2400 after the review. Looking at both of the cameras, there is no obvious difference from the outside except for the model number, both cameras are exactly the same size and feel roughly the same weight and the build quality is identicallyu exceptional.

ASI6200MC Pro One Shot Colour Camera

If we compare the specifications of the ASI6200 to the ASI2400 we can see where each camera has an advantage over the other:

ASI2400ASI6200
Weight700g700g
SensorIMX410IMX455
Sensor SizeFull FrameFull Frame
Pixel Size5.94um3.76um
Resolution24mpx62mpx
Full Well Capacity at 0 Gain100ke51ke
Qe>80%91%
ADC14-Bit16-Bit
High Gain Mode140100
Full well at High Gain Mode20ke18ke

So as you can see from the comparison on specification there are some differences, the ASI2400 has the edge on full well capacity, however the ASI6200 has a much more smaller pixel size as well as a higher Qe which to me gives the ASI6200 the edge over the ASI2400.

Now since both cameras are the exact same field of view due to them both being full frame sensors, the question is how does this affect resolution, clearly the ASI6200 has the upper hand having significantly more pixels than the ASI2400, but how does this translate to an image?

Iris Nebula taken with the ASI2400MC Pro, 82x150S at Gain 26, darks, flats and BIAS frames applied
Iris Nebula taken with the ASI6200MC Pro 48x150S at Gain 100, Darks, Flats and BIAS frames applied

As you can see, both cameras offer the exact same field of view, however when you zoom in on the images you start to see where the ASI6200 excels above the ASI2400 with the higher resolution

On the left is the ASI2400MC Pro and on the right is the ASI6200MC Pro

As you can clearly see from the above two images, the 6200 offers a much better resolution which will allow a much finer level of detail, however, depending on your sky conditions and focal length the ASI6200 might not be possible due to over or under sampling

You can see here, that on my SharpStar 15028HNT which has a Focal Length of 420mm the ASI2400 would lead to Under Sampling in my “OK” seeing conditions

But the ASI6200 shows in the green area:

If I increase the focal length to around 1150 the ASI6200 no longer becomes suitable and the ASI2400 is more suited to this focal length and sky conditions:

So as you can see, both the ASI2400 and ASI6200 is not a “One Size Fits All” scenario, you have to work out the best suitability depending on your conditions and equipment to be used.

From a price perspective, the ASI6200 is only slightly more expensive than the ASI2400, but both cameras offer the full frame capability and a fantastic field of view, but for me personally the ASI6200 beats the ASI2400 when using the focal length of my SharpStar 15028HNT. Just like it’s smaller version, the looks, feels, sounds and operates exactly the same way. Here is another image taken with the ASI6200 and then my Synthetic SHO version which I will be writing a tutorial on how to acomplish with Dual Band Filters.

North America Nebula – 60x300S at Gain 100 using the Optolong L-eXtreme Filter on the SharpStar 15028HNT
Synthetic SHO using the same data as the previous image

Either way, both ZWO cameras I have tested have been of awesome quality, and I would recommend either camera if you wish to go down the full frame route, but personally my favourite is the ASI6200MC Pro, more images to come since this is now my new camera.

Equipment, Gear Reviews

QHY268C APS-C Colour Camera Review – Part 1

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As many of you know, I have been using QHY cameras for a while, but with my plan to move to a RASA telescope next year and wanting to image with a bigger sensor than the QHY183M I decided to go for a bigger sensor but moving away from Mono, the latest addition to the QHY familly is the QHY268C Photographic Version. I had been talking to the QHY team for a long time about this particular camera, and finally I have one.

The QHY268C is a once shot colour camera based on the APS-C Sized back illimunated Sony IMX571 sensor, the camera has a true 16-Bit Analog to Digital Convertor (ADC), now there are a few camera models out there using this sensor, cameras such as the ZWO ASI2600, but one thing that sets the QHY268C apart from the others is the ability to have a 75ke full well capacity which is 25ke higher than the ZWO ASI2600. In my opinion, when imaging at fast focal ratios, a higher full well is desired to protect the colour around bright stars for example.

Opening the box I was greeted with a camera that was bigger and heavier than my 183M, but then the sensor is much bigger than the 183M anyway so this would be expected, but what I did not expect is the additional items that came with the camera:

Inside the box was:

  • QHY268C Photographic Version
  • UK mains plug for 12V AC adapter
  • 12V AC adapter
  • Car 12v power cable
  • Self locking power cable
  • 1.5M USB 3.0 cable
  • Dessicant drying tube
  • Self centering adapter plate
  • M54 to M48 adapter plate
  • M54 to 2″ nose adapter
  • A range of spacers to give you from 0.5mm to 13.5mm spacing
  • Associated screws for spacing adapters

QHY cameras have come along way since I bought my QHY183M, one of the things QHY has really worked on is amp glow, my early version of the QHY183M was renowned for was amp glow, which could be removed in image calibrations, but the QHY268C produces no amp glow whatsoever, below is a dark frame of 600S taken at -13.5C and you can clearly see there is no evidence of amp glow.

Single frame 600 seconds, Gain 26, Offset 30, -13.5C – Mono (Not Debayered)

Attaching to the telescope was pretty straight forward as I had already planned the imaging train before the camera arrived, since I will be using the SharpStar 15028HNT F2.8 Paraboloid Astrograph which has an M48 thread, I decided to keep the whole imaging train at M48 except for the camera of course which has an M54 thread, so I did not actually need to use any of the adapters that came with the camera, the reason for this is because I wanted to include a filter drawer, so my image train consists of the following (from telescope to camera)

  • TSOAG9 – TS Off Axis Guider (9mm)
  • TSOAG9-M48 – TS M48 Adapter for the OAG (2.5mm)
  • TSFSLM48 – TS 2″ Filter Drawer with M48 Thread (18mm)
  • M48AbstimmA05 – TS Optics 0.5mm Aluminium spacing ring (0.5mm)
  • TSM54a-m48i – TS M48 to M54 Adapter (1.5mm)
  • QHY268C with M54 Centering Adapter (23.5mm)

As you can see with all the above I reach my desired back focus of 55mm perfectly, if I was not going to be using a filter drawer (For my Optolong L-Pro and L-eXtreme filters), I would probably have stuck with the spacers that came with the camera. Below is a picture of the camera successfully connected to the telescope.

As far as settings go, after speaking with QHY on this at great length, I will be imaging in Mode 0 (Photographic mode) to avail of the massive 75ke full well, offset I will leave at 30, but Gain I will use two different settings, I will use Gain 0 for most bright objects with the L-Pro filter, but for the L-eXtreme, I’ll probably set a gain level of 26, luckily with SGPro I can set the gain level per object. From a cooling perspective I always image at -20C, one thing I have noticed is that this camera cools to exactly -35C below ambient, I tested this when the ambient temperature was 20.10 degrees, and the camera cooled down to -14.9C, it was always 25C lower until the ambient dropped below 15C and the camera remained at my setting of -20C.

The build quality of the camera is as expected having owned a QHY183M, one thing I did notice is that the fan in the QHY268C is much quieter than the 183M. Technical Details of the camera:

CameraQHY268CQHY183M
Image SensorSony IMX571Sony IMX183
Sensor SizeAPS-C1″
IlluminationBack IlluminatedBack Illuminated
Pixel Size3.76um2.4um
Effective Image26mpx20mpx
Full well capacity51ke
(75ke in extended mode)		15.5ke
ADC16-Bit12-Bit
Image Buffer Memory1GB/2GB128MB
Max Cooling Delta-35C-40C
Weight1006g650g

I can’t wait to get imaging with this camera, I have a very aggresive target list for this year in both RGB and Narrowband with the Optolong L-eXtreme filter, I will write part two of the review once I have some actual imaging data. Time to build my dark library.