#21  
Old 12-11-2020, 07:09 PM
Ittaku (Con)
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Originally Posted by Tulloch View Post
Hi Con, as far as I know, FC treats ASI and QHY cameras differently due to the driver file it comes with. On ASI cameras you only get to choose Wred and Wblue, but in FC 2.7 Torsten added a Wgreen "offset" as a multiplier. Whereas (I believe) QHY allows you to set a value for all 3 colour parameters, which can be varied between 1 and 127 with a midpoint of 64. This is just my best guess, based on what I've seen on CN.

So, assuming that the ASI462MC's values are Wred=69 and Wblue=86 with the Wgreen offset of 0, then the QHY462 values might be
Wred = 88
Wgreen = 64
Wblue = 110

Torsten replied to this assumption of mine here
https://www.cloudynights.com/topic/7...er/?p=10595485

Hope this helps, unfortunately I cannot help with your Linux issues though ...
Hi Andrew. The camera is working somewhat and it has sliders that go up to 255 for all three colours. My issue are clearly timing overruns due to a broken SDK they distribute with linux for what it's worth - the QHY dev himself said he'd look into it. As for the green offset when there is no real green control for ZWO cameras, I found that a risky thing to use - the reason is it offsets what it's getting but can't prevent clipping. So if you set it to say -30 you could easily be clipping but it only showing 70 maximum value - I've seen the huge spike at the right end of the green histogram when you do that. Positive offset is okay but I found that's rarely required with green in particular. I'm hoping the true fine grained control of each colour in the QHY camera comes in useful.
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  #22  
Old 12-11-2020, 07:25 PM
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Tulloch (Andrew)
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Yep, I've never used the green offset on my ASI224MC, even though I'm probably the reason why it's there. When I was trying to achieve "correct" colour balance (whatever that is ), I found that I couldn't get the Wblue value high enough, so ended up setting Wblue to 99 and adding a 1.1 multiplier in Registax to the blue channel. I believe that the Wgreen value in FC 2.7b modifies the green channel so that the blue level could be higher by comparison.

Since I don't have a QHY camera, I don't know how FC balances the colours using the W values - I had seen in another post on CN there the "default" values for the QHY cameras was 64,64,64 which I assumed was the halfway point for 0-127. I reckon the ratios from above are correct (or at least close), but I don't know what actual values you need - might be a case of trial and error?
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  #23  
Old 12-11-2020, 07:28 PM
Ittaku (Con)
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Originally Posted by Tulloch View Post
Yep, I've never used the green offset on my ASI224MC, even though I'm probably the reason why it's there. When I was trying to achieve "correct" colour balance (whatever that is ), I found that I couldn't get the Wblue value high enough, so ended up setting Wblue to 99 and adding a 1.1 multiplier in Registax to the blue channel. I believe that the Wgreen value in FC 2.7b modifies the green channel so that the blue level could be higher by comparison.

Since I don't have a QHY camera, I don't know how FC balances the colours using the W values - I had seen in another post on CN there the "default" values for the QHY cameras was 64,64,64 which I assumed was the halfway point for 0-127. I reckon the ratios from above are correct (or at least close), but I don't know what actual values you need - might be a case of trial and error?
It's okay, based on the manual I should be running blue at 255 and scale everything down from there... if and when the skies clear up and this stupid SDK bug is fixed. I see no sign of hidden clipping occurring with green when experimenting at home with daylight objects which is reassuring!
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Old 12-11-2020, 07:43 PM
Ittaku (Con)
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Here's something that demonstrates the problem with green offset being negative without true green control. This is looking at a bright green card. The colour values aren't equivalent so ignore the histogram peak discrepancies. First is with ZWO green offset to very negative. Second is with QHY and the green set so low that it registers only about as much as the blue channel, yet it's still a smooth graph without the abrupt cut off. I picked this up the hard way on the ZWO the first time with a whole lot of stuffed Mars captures.
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  #25  
Old 12-11-2020, 09:08 PM
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multiweb (Marc)
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Another thing I have noticed is that the 462MC will not connect to Neb 4 with the native drivers. Only ASCOM. No such issue with 120MM which connects fine both ways.
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  #26  
Old 13-11-2020, 08:14 AM
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Quote:
Originally Posted by Ittaku View Post
Here's something that demonstrates the problem with green offset being negative without true green control. This is looking at a bright green card. The colour values aren't equivalent so ignore the histogram peak discrepancies. First is with ZWO green offset to very negative. Second is with QHY and the green set so low that it registers only about as much as the blue channel, yet it's still a smooth graph without the abrupt cut off. I picked this up the hard way on the ZWO the first time with a whole lot of stuffed Mars captures.
Not knowing exactly how you tested this it's difficult to comment, but I would have expected that the green signal would be very high if your were imaging a bright green card. However, it appears to me that the gain on the ZWO ASI224 is set too high if you are seeing clipping in the green, and no amount of offset in FC can fix this. A better test would be a colour checker chart (if you have one) or a colourful shirt (even the old ABC test pattern ).
https://www.redbubble.com/i/sticker/...23011194.EHVJB
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  #27  
Old 13-11-2020, 08:17 AM
Ittaku (Con)
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Originally Posted by Tulloch View Post
Not knowing exactly how you tested this it's difficult to comment, but I would have expected that the green signal would be very high if your were imaging a bright green card. However, it appears to me that the gain on the ZWO ASI224 is set too high if you are seeing clipping in the green, and no amount of offset in FC can fix this.
I guess you missed the point then? That's exactly what I'm trying to say, the offset can make you set the gain too high if you try to compensate for there not being enough blue. The offset is entirely artificial and green is maxing out at 82%. To me that means the whole negative offset feature is useless.
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Old 13-11-2020, 09:39 AM
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Oh sorry, I did miss the point

My understanding of the offset is to help get a correct white balance direct from the camera during imaging, similar to the way commercial digital cameras have a "white balance" feature. The issue with the ASI224MC in particular is that the sensitivity in the blue region is too low, even with the offset set to 99, I find I still have to increase the blue level in post processing to get the colours to look "correct". In the ZWO cameras, there is no ability to set a "Wgreen" in the driver, the blue and red levels are set relative to the green level. I believe that what the Wgreen offset in FC does is perform a software reduction in the green channel, so that the red/green and blue/green ratios can be increased (above 99/50) because now the ratio is (say) 99/45 so the blue cannel is effectively higher straight out of the camera.

With the QHY cameras, all three colour components can be set individually so the white balance setting is slightly easier.
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  #29  
Old 13-11-2020, 09:41 AM
Ittaku (Con)
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Yep, you've just described one of the reasons I bought a QHY camera.
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  #30  
Old 13-11-2020, 10:20 AM
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Interestingly, the 462 doesn't need any Wgreen adjustments, the ASI462MC's values are Wred=69 and Wblue=86.
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  #31  
Old 14-11-2020, 09:58 AM
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Are you using an ircut filter? I found the ircut filter when used with my 224 mc sorted out a lot of the colour balance issues, especially for planetary and some deep sky
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Old 19-11-2020, 09:19 AM
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Are you using an ircut filter? I found the ircut filter when used with my 224 mc sorted out a lot of the colour balance issues, especially for planetary and some deep sky
Good day Nik, yeah definitely use an UV/IR cut when doing straight RGB. Only in IR do I equalize all channels visually then work out the gain not to saturate anything.
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  #33  
Old 11-12-2020, 12:33 PM
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Here's an RGB and an IR/LUM blend. Response of the camera in IR is certainly a lot better than my QHY9. These are 12x5min in IR and 27x2min in color. It would have taken me a lot more integration time to get the noise down. Although it's perfect for planetary the pixel size and the field are too small for that FL (~2.6m) but on my FSQ at prime I should get an image scale of ~1asp and a really nice field, not too tight, not too wide. That will be my next test.
I did some IR on the flame the other night then slew to the horse head. The SNR was so bad on the HH that I didn't get much at all even after 12x900s.

These are 15x600s with an FSQ106N at 540mm FL. So it is a fast scope. Captured in Neb4. The camera is very noisy for long exposures as it is uncooled. I don't think if it's practical to do IR with it. Lot of walking noise as in uncooled DSLRs. Ambient temperature was around 19c. Camera temp as registered in ASCOM was 29c. Maybe if they do a cooled version of that SONY sensor one day it will be a viable IR camera.

The crop is stacked as is.

The full field was calibrated with darks which helped with walking noise mostly due to hot pixels.
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Old 11-12-2020, 01:25 PM
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Nice effort Marc

QHY have produced a 4K version of the 462 (which is basically 1080p), so 4x the area but basically the same technology and, presumably, characteristics.

That'd probably be an interesting candidate for cooling too.

My suspicion is that the camera makers are more interested in selling us their larger chipped cooled cameras with greater margins...
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