Red tinted images with ASI533-ASIAir Pro

adamsdp

I have been trying to figure out why my images obtained while live stacking with my ASI533 camera and ASIAir Pro have a red tint to them. The long story is in the thread below
https://www.cloudynights.com/topic/814718-red-tint-to-images-with-asi533/

The short story is that when I do subs of 30 sec length and auto white balanced on, the images have a red tint. The red tint is not present when doing a shorter exposure like when I took light flats. The histogram when live stacking shows a stronger red signal but in preview mode, the red, green and blue signals curves are nicely overlapping each other.

Histogram in preview mode showing red, green , blue levels matching

Histogram in live stacking mode (1 sub) showing red signal stronger than green and blue

It doesn't make sense to me that the red signal changes relative to blue/green when switching from preview to live stacking mode. I have seen others post images using the ASI533/ASIAir combination without red tinted images.
Below is an example of the red tinting after stacking 15 subs

If anyone has any idea why this red tint is occurring while live stacking and not in preview or while taking flats, please let me know. Thank you!

Dave

w7ay

adamsdp If anyone has any idea why this red tint is occurring while live stacking and not in preview or while taking flats, please let me know.

Did you have Auto White Balance turned on in the Main Camera's Advance Settings? That would explain why your Preview images have a neutral white point in RGB space.

Turning it off will show the actual colors that the camera sees; and will also preview an image faster on a slow tablet.

Chen

Tech@ZWO

adamsdp Could you save the image to ASIAIR? and check it in the image manager, can you see the red tint?
You can send us the fit files you shoot in the preview mode and live mode to analyze, if possible, please use the same parameter. you can share the fit files with us via google drive if the files are too large.
Thank you.

adamsdp

Hi Chen,

I do have the auto white balance turned on. If you have any ideas why the images are red tinted, please let me know. Thank you,

Dave

w7ay

adamsdp If you have any ideas why the images are red tinted, please let me know.

The Sony sensor R, G and B sensitivities try to match the CIE Standard Observer sensitivity of the human eye.

But they also respond the the IR region (see the curves for your camera).

If your UV-IR cut filter cuts too much of the UV region and not enough of the IR region, you can get a red-weighed image since the IR light will hit the pixels that are behind the red filters.

Equally likely, your skies are polluted by streetlights that are more predominately on the longer wavelengths (although newer LED streetlights tend to peak more in the blue-green region).

Just let the post processor balance the color result for you. AstroPixelProcessor, for example has a nice tool to match the color of stars to match the stars along the Hertzsprung-Russell curve; its author's day job is astrophysics -- the result is colors as your eye will see the night sky, were it sensitive enough. ASIAIR live stacking is just a beginner's toy.)

Chen

adamsdp

Hi Chen,

Thank you for the helpful information. I have been using the Optolong UV-IR filter for star clusters and Optolong UHC for galaxies. I was seeing more of the red shift effect with the UHC filter and my understanding is that it passes a portion of IR so that would go along with your information about the camera responding to IR.

I did try imaging without a filter and still was getting some red shift so was thinking as you mentioned that maybe the light pollution where I image has a red tint. This would seem to explain why the red tint is only showing up in longer exposure subs and not in the shorter subs like when I image the moon or take flats with a light panel. The only thing that seems confusing is why in preview mode the red, green and blue levels all match up nicely even at 30 sec exposure length while in live stacking at the same gain and exposure length, the red is elevated. In the second picture I posted of this thread, it shows the red peak much wider than the blue and green peaks while in live stacking mode.

I will check out the post processing software you mentioned and they both sound like good tools. My main interest is EAA and am hoping to find a way to have the images appear on the Ipad without color tinting without having to post process. If light pollution is the issue, I am thinking this is not possible. If there is some other reason, causing the red to be elevated while live stacking such as a software issue than maybe it is possible. I greatly appreciate your insights as I am just learning. Thank you!

Dave

adamsdp

I saved the final stacked images using the save icon in the lower right side of the ASIAir app as displayed on the Ipad. I think this saves to the usb memory stick (which I selected as the save option). I don't know what the image manager is and sorry for the basic question but is it a way to view the image on the Ipad in a different way then how it shows up after live stacking?

I didn't save the preview files but will do so the next clear night. After saving the preview and live mode files should I where should I email them to? Thank you!

Dave

w7ay

adamsdp the ASIAir app as displayed on the Ipad

Dave,

Take a look in the Photos album of your iPad.

Chen

adamsdp

Chen,

Thanks and the images saved to the Ipad in the photos album of the Ipad show the red tint and look like the images as they appear within the ASIAir app.

Dave

adamsdp

To tech@zwo,

I submitted an email to ZWO with files showing the red tint and stronger red histogram signal in the live stacking versus preview mode. If you need any additional information, please let me know. In answer to your earlier, question, I saved the files to the ASIAir and checked them in the image manager and the red tint did show there as well with the live stacked files. Thank you,

Dave

LovelyNights

I have the same issue.
In my case if I apply a Dark for livestacking, the image has red tint. If I do not do pre- processing the image has natural color. I'm using 533mc pro/ L pro filter.
Anyone resolved this issue?

735z4pr0

Hello. I know this is a old thread... but in my system is happening the same problem.
Live stacking using dark library I did with Asiair results in very reddish images.
Asiair Mini updated to the last version, iOS app updated to the last version, ASI533MC as the camera.
Has this nasty problem ever been solved? How?
Thanks...