Post by Dragon Man on Mar 9, 2017 4:35:54 GMT
To discover the performance quality of the cheaper Rising Tech 224 camera I did a comparison between it and the ZWO ASI224, both using the same IMX224 sensor.
Dark Frame captures were carried out with the ZWO ASI224 in SharpCap and the Rising Tech 224 in RisingSky.
All Dark Frame captures are single frame, with matching settings in both softwares in Brightness, Contrast, Hue, Saturation etc.
Both cameras were placed into an ED80 Refractor to take advantage of the Heatsink properties of a Focuser Barrel, no extra glass added (Focal Reducers or filters), and the temperature only wavered by 0.5 degree from the Ambient of 17 degrees Celsius throughout the testing time of 1 hour.
I have done separate comparison images of:
ZWO ASI224
8 seconds - zero gain
8 seconds - quarter gain
8 seconds - half gain
30 seconds - zero gain
30 seconds - quarter gain
30 seconds - half gain
Rising Tech 224
8 seconds - zero gain
8 seconds - quarter gain
8 seconds - half gain
30 seconds - zero gain
30 seconds - quarter gain
30 seconds - half gain
and combination frames of:
8 seconds - zero gain
8 seconds - quarter gain
8 seconds - half gain
30 seconds - zero gain
30 seconds - quarter gain
30 seconds - half gain
The results show not a lot of difference (if any) at 8 seconds at all 3 gain settings.
There was little difference at 30 seconds with no gain.
BUT! the difference became noticeable at 30 seconds once gain was raised to quarter and half.
Here are the resultant comparison images: (all labelled)
The full frame images show the noise and amp glow better.
This is both cameras at 8 seconds with NO gain
and both cameras at 30 seconds with 50% Gain
What these results seem to show (and the preliminary statistics of the images confirm) that at shorter exposures, the Rising Tech camera is actually less noisy than the ZWO camera. Only a little, but it is there visually and in the stats.
On the other hand, at 30 seconds, with any level of gain applied, there is a clear difference, with the ZWO camera being "cleaner". If there is no gain applied, then the RT camera is still less noisy, even at 30 seconds.
It might be that whatever ZWO does to clean up the image runs constantly, and thus induces some very low level of constant thermal glow. But the RT camera doesn't run this fix, and thus you don't see the noise associated with the fix. Only when you apply some level of gain does the RT image start to degrade.
At shorter exposures and low gain, the Rising Tech camera is cleaner. But as its exposures and Gain are increased there is no 'clean up' happening.
Whereas the ZWO version appears to have a fixed level, starting above the Rising Tech but remaining as the Rising Tech quality decreases from adding exposure and Gain.
This isn't a very scientific graph but it shows what I mean:
I hope this helps someone.
Both cameras can be purchased through these links:
RISING TECH GPCMOS01200KPC (US$168) - www.aliexpress.com/store/product/NEW-USB-colour-CMOS-astronomical-telescope-camera-with-Sony-sensor-for-Lunar-Planetary-deep-sky-and/1918400_32722953617.html?spm=2114.12010612.0.0.Oa6sJb
ZWO ASI224 (US$299) - astronomy-imaging-camera.com/products/usb-3-0/asi224mc/
Dark Frame captures were carried out with the ZWO ASI224 in SharpCap and the Rising Tech 224 in RisingSky.
All Dark Frame captures are single frame, with matching settings in both softwares in Brightness, Contrast, Hue, Saturation etc.
Both cameras were placed into an ED80 Refractor to take advantage of the Heatsink properties of a Focuser Barrel, no extra glass added (Focal Reducers or filters), and the temperature only wavered by 0.5 degree from the Ambient of 17 degrees Celsius throughout the testing time of 1 hour.
I have done separate comparison images of:
ZWO ASI224
8 seconds - zero gain
8 seconds - quarter gain
8 seconds - half gain
30 seconds - zero gain
30 seconds - quarter gain
30 seconds - half gain
Rising Tech 224
8 seconds - zero gain
8 seconds - quarter gain
8 seconds - half gain
30 seconds - zero gain
30 seconds - quarter gain
30 seconds - half gain
and combination frames of:
8 seconds - zero gain
8 seconds - quarter gain
8 seconds - half gain
30 seconds - zero gain
30 seconds - quarter gain
30 seconds - half gain
The results show not a lot of difference (if any) at 8 seconds at all 3 gain settings.
There was little difference at 30 seconds with no gain.
BUT! the difference became noticeable at 30 seconds once gain was raised to quarter and half.
Here are the resultant comparison images: (all labelled)
The full frame images show the noise and amp glow better.
This is both cameras at 8 seconds with NO gain
and both cameras at 30 seconds with 50% Gain
What these results seem to show (and the preliminary statistics of the images confirm) that at shorter exposures, the Rising Tech camera is actually less noisy than the ZWO camera. Only a little, but it is there visually and in the stats.
On the other hand, at 30 seconds, with any level of gain applied, there is a clear difference, with the ZWO camera being "cleaner". If there is no gain applied, then the RT camera is still less noisy, even at 30 seconds.
It might be that whatever ZWO does to clean up the image runs constantly, and thus induces some very low level of constant thermal glow. But the RT camera doesn't run this fix, and thus you don't see the noise associated with the fix. Only when you apply some level of gain does the RT image start to degrade.
At shorter exposures and low gain, the Rising Tech camera is cleaner. But as its exposures and Gain are increased there is no 'clean up' happening.
Whereas the ZWO version appears to have a fixed level, starting above the Rising Tech but remaining as the Rising Tech quality decreases from adding exposure and Gain.
This isn't a very scientific graph but it shows what I mean:
I hope this helps someone.
Both cameras can be purchased through these links:
RISING TECH GPCMOS01200KPC (US$168) - www.aliexpress.com/store/product/NEW-USB-colour-CMOS-astronomical-telescope-camera-with-Sony-sensor-for-Lunar-Planetary-deep-sky-and/1918400_32722953617.html?spm=2114.12010612.0.0.Oa6sJb
ZWO ASI224 (US$299) - astronomy-imaging-camera.com/products/usb-3-0/asi224mc/