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Old 12-10-2020, 07:33 PM
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multiweb (Marc)
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ASI462 MC Color Balance

I'm struggling with the color balance with that camera. I don't know if I should use longer exposures or if my gain is too high. When I do an auto colour on the histogram I almost get a monochrome picture. Here's an example on Mars.
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Old 12-10-2020, 07:56 PM
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Not sure about that camera or method. The recommendation on EAA live stacking with my ASI183mc is to manually set the histogram peaks . Seems to be be all wrong in auto in some settings but ok in others.
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Old 12-10-2020, 07:58 PM
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Marc, I find that Jupiter gives a much better guide to a more natural colour balance, so you can port the settings you use for Jupiter over to Mars.

I prefer to capture using image settings 50:50:50 (R:G:B) and colour balance in processing, but I did experiment with getting natural colour out of the camera and it was approx. 64:50:93

FWIW your gain looks fine, those histograms look well exposed to me
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Old 12-10-2020, 08:03 PM
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I think I know what I did wrong... The SER files are RGB. Somehow when I switched to FireCapture from Sharpcap it started recording in RGB. I must have stuffed the settings. Problem is between the keyboard and the chair
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Old 13-10-2020, 09:50 PM
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I always struggled with colour setting, it is possible that your first image maybe OK, just increase the saturation. Not sure it will work but worth a try.
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Old 14-10-2020, 01:47 PM
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multiweb (Marc)
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Thanks for the feedback guys.
Here's a funny one I've just noticed in Registax 6.

There is a significant difference if you strecth the histogram levels before or after doing an automatic color balance. So it might be better to do the color balance before playing with the levels/blackpoint.

Maybe somebody can chime in and explain why.

Then again is Saturn yellowish including rings or blueish with more color variations as in the right?
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Old 14-10-2020, 04:39 PM
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I think the one on the right is closer. If you bump the saturation a bit the planet should go a bit sandy coloured with a dash or reds/browns.

I’ve read that the rings are slightly off-white because of dust particles tainting the ice, with the outer rings being whiter because they’re younger and less “dirty”
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Old 14-10-2020, 04:57 PM
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Quote:
Originally Posted by Camelopardalis View Post
I think the one on the right is closer. If you bump the saturation a bit the planet should go a bit sandy coloured with a dash or reds/browns.

I’ve read that the rings are slightly off-white because of dust particles tainting the ice, with the outer rings being whiter because they’re younger and less “dirty”
I'm trying different things for the colors, zeroing in on a routine and taking notes. It's going to be different for each planet and also dependent on the number of usable frames I have collected. Once I have the camera settings downpat I should get some kind of repeatability in the results as well.
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Old 14-10-2020, 09:17 PM
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Hi Marc, based on a previous colour balance test on Jupiter, I reckon the white balance values to use (in Firecapture) are Wred=69, Wblue=86.
https://www.cloudynights.com/topic/7...tc/?p=10376048

Also, you can't use Registax to "auto-balance" predominantly single colour planets like Mars, Uranus and Neptune (and probably Saturn), as it tries to equalise the colour channels (which these planets are not). Jupiter works pretty well.

Saturn has a yellow hue - we might try to "correct" it out to make a nicer looking image, but it's yellowish/green in real life.
https://solarsystem.nasa.gov/resourc...rthern-summer/
https://www.cloudynights.com/topic/7...-final-report/

Andrew
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Old 15-10-2020, 07:37 AM
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Thanks for that Andrew. I also took note of the colors of Mars in the other thread and catching up on all your posts on CN. A treasure trove of good info. Kudos to you.
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Old 15-10-2020, 09:27 AM
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Yeah it's hard to know what's right, as you see so many different renditions.

The thing to take care with the nasa imagery is that their filters may have different bandpass to ours.

On top of that, our atmosphere creates a perception too...
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Old 15-10-2020, 09:52 AM
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Quote:
Originally Posted by Camelopardalis View Post
Yeah it's hard to know what's right, as you see so many different renditions.

The thing to take care with the nasa imagery is that their filters may have different bandpass to ours.

On top of that, our atmosphere creates a perception too...
I guess in the end if you have a color palette that approximates the real thing while still having a clear separation between features, clouds, etc... then you win.
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Old 15-10-2020, 09:58 AM
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Quote:
Originally Posted by Camelopardalis View Post
Yeah it's hard to know what's right, as you see so many different renditions.

The thing to take care with the nasa imagery is that their filters may have different bandpass to ours.

On top of that, our atmosphere creates a perception too...
Absolutely, fully agree there. The Cassini filters are similar to ours (you can read about them in the link below, Fig 20), Hubble's are not.
https://www.researchgate.net/profile...-At-Saturn.pdf

The atmosphere will also remove some of the blue from the planets, especially at lower elevations.
https://www.cloudynights.com/topic/7...ees-elevation/

Andrew
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Old 16-10-2020, 06:51 PM
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Yeah the subtle blue in the Martian clouds could get a little challenging for the next few years
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Old 12-11-2020, 07:06 AM
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What was your final verdict on colour? I recently picked up the QHY version of this sensor and am curious too. Using the below graph the sensitivities in each colour translate to 1:1.23:1:28 but that's at wild odds from what's been recommended here, so obviously that's not how it works. Also firecapture 2.7β is giving me 0-255 ranges instead of 0-100. The manual says you have to white balance it but only gives example numbers without saying if that's a recommendation, citing 161:128:255, which should like the ballpark ratios more in line with what I'd expect based on other camera usage. Poor English in the rest of the manual makes it hard to understand just wtf they mean about biasing colour.

https://www.qhyccd.com/uploadfile/20...0050933812.png

https://www.qhyccd.com/index.php?m=c...atid=30&id=316


I'm having all sorts of other troubles with capturing in firecapture on linux, but that's another story, and almost certainly related to it being the QHY camera...

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Old 12-11-2020, 10:40 AM
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Good day Con, still getting some data on this. I used the settings in FC beta that Andrew recommended. Wred 68 and Wblue 86. Using a UV/IR cut made a big difference on Mars. Jupiter is easier to color balance.

I also started using the camera for deep sky at 1:1:1 in Nebulosity.

I measured the int mode in CCD Stack and after doing a quick pixel map ended up with those ratios:

Red: 1:00
Green: 0.98
Blue: 1.27

I have to get a wider FOV as this is far too close to get a background readout so I will try with the FSQ later on which gives me a nice field and an image scale close to 1asp.
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Old 12-11-2020, 11:26 AM
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Thanks Marc. I wouldn't dream of using this without an IR filter as all channels would always be washed out with IR signal and effectively black and white in that range which it's more sensitive to than the visible range. That's why it's always sold with filters by QHY for example.
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Old 12-11-2020, 01:12 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.
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Old 12-11-2020, 01:39 PM
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Meanwhile the QHY linux sdk for the 462c is rather flaky and errors out madly with firecapture so I can't really use it to its full capability, but the QHY dev has said they're looking into it. Considering QHY normally charge more for their hardware than ZWO, I find ZWO's software side far more mature by comparison.
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Old 12-11-2020, 06:38 PM
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Quote:
Originally Posted by Ittaku View Post
What was your final verdict on colour? I recently picked up the QHY version of this sensor and am curious too. Using the below graph the sensitivities in each colour translate to 1:1.23:1:28 but that's at wild odds from what's been recommended here, so obviously that's not how it works. Also firecapture 2.7β is giving me 0-255 ranges instead of 0-100. The manual says you have to white balance it but only gives example numbers without saying if that's a recommendation, citing 161:128:255, which should like the ballpark ratios more in line with what I'd expect based on other camera usage. Poor English in the rest of the manual makes it hard to understand just wtf they mean about biasing colour.
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 ...

Andrew

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