ASI 120 MC color balance and exposure settings
Posted 05 January 2014 - 07:14 PM
1. Last time when imaging Mars, the red channel was overexposed and the least sharp, even though my histogram in Firecapture showed only about 50% when imaging. The unsharpness might at least in part have been caused by the inversion we were having at the time, however that would not explain the over exposure.
2. Jupiter had a slight blue/green tint and the moons of Jupiter also looked blue/greenish.
Posted 05 January 2014 - 07:16 PM
With this setup I checked different exposures and color balance.
Posted 05 January 2014 - 07:24 PM
Two things stood out to me:
1. Even though I was using a white piece of paper in sunlight ( I thought this to be the closest to the color balance I would need, as the planets reflect sunlight), the histograms were not superimposed, and the resulting image on the screen had a slight but definite blueish tint (confirmed by measuring RGB components in photoshop).
2. When increasing exposure time with gain set to 0, the red and green channel hit maximum at 50% (128 max) for green and 47% (120 max) for red. Further increasing the exposure time, resulted in a more pronounced blue tint of the image with finally blue hitting maximum at 84% (215 max). This was all done with the standard settings.
Posted 05 January 2014 - 07:26 PM
I actually opened the door for this, so that no color error would be introduced through the glass of the window. It changed the color balance slightly.
Posted 05 January 2014 - 07:30 PM
I will still image in non-debayer mode, however to set the exposure, I will turn on the debayer option and carefully checked the color histogram to ensure that non of the channels are overexposed (indicated by a single line or truncated bell curve in the histogram.
Please let me know your thoughts.
Posted 06 January 2014 - 04:42 AM
imaging Jupiter even with the RGB balance option in Registax
nothing changed anymore and the colors look ok to me.
This is the way to go I think.
Once done, sabe your settings into a file and when imaging
just load this settings file and done I think.
Posted 06 January 2014 - 11:17 AM
Posted 06 January 2014 - 02:14 PM
Please keep postings with how u use Firecapture with the ASI 120MC
Posted 06 January 2014 - 05:21 PM
From the log-files of Firecapture:
So Red 54 and Blue 86 in my case. ( mileage may vary
according equipment and conditions used )
Hope it helps
Posted 07 January 2014 - 09:56 AM
I have been happier with the adjusted settings and the greenish color of the moons of Jupiter seems improved, however, Saturn now seems to have a slight greenish tint.
Unfortunately, weather will force a delay in further investigation.
Posted 07 January 2014 - 03:34 PM
I normally check on the ceiling ( White ) with some lights
If out in the field, I use an empty "notepad" screen on
my laptop and let the camera look at this.
Then I merely adjust the sliders until the same color is
displayed on FC screen and as seen with my eyes.
It's not very scientifical but serves for me
When doing wavelets etc. in Registax you can use the
RGB-balance button and done with it, that's all I do
to it to obtain my final images.
Posted 08 January 2014 - 12:20 AM
That is why I decided to use sunlight, as that is the light that illuminates the planets. It actually made even a little bit of difference whether it was sunlight coming through the window, which does not appear tinted to me) or with window open.
I will try to compare the RGB curves with different artificial light sources.
Posted 02 April 2014 - 11:05 AM
Posted 02 April 2014 - 02:21 PM
I recommend waiting until you are looking at your target to adjust your color balance. Varying atmospheric conditions will require different adjustments. For instance the blue channel will need to be set higher if there is thin cloud cover. The elevation of the planet (which effects the amount of atmosphere you image through) also effects your color balance.