Red WB on ASI071 and ASI1600MC with Idas LPS filters P2 & D1

donboy

I have experienced a consistent issue when using an Idas LPS D1 with the ASI1600MCC and the ASI071. And that is I can't get a WB due to the weaker Red channel. The D1 filter was created to combat the extra red sensitivity when a DSLR is modded and is suppose to be a better choice than the Idas LPS P2, per Hutech. I have both filters and I can only get a WB when using the P2. This is especially puzzling since the ASI071 is the same sensor in the Nikon D5100.

Please refer to this link to see histogram results using these filters with these two cameras:

Note the Red & Blue gain settings!

https://www.cloudynights.com/topic/564681-testing-asi071-for-eaa/#entry7774858

Don

lylver

I confirm there may be an issue with the red color, impaired WB and natural color rendering in red range

posted on CN too https://www.cloudynights.com/topic/570592-zwo-asi071mc-cool-color-issues/

I did a evening/night balance with a baader UV/IR cut filter (clone)

Got too much green when imaged a pure led red source

I removed this level of green with fitswork4 new G=-25%red 100% green 0% blue

Not a definitive fix but deep and bright red reappears.

Source image http://atom.lylver.org/AstroSurf/ZWO%20ASI%20185MC/capteurs/ASI071MC-Cool/RGB_org.jpg

Corrected green channel http://atom.lylver.org/AstroSurf/ZWO%20ASI%20185MC/capteurs/ASI071MC-Cool/RGB_-25.jpg

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I found informations here https://www.dxomark.com/Cameras/Nikon/D7100---Measurements

see at color response.

It appears hard to compensate red sensitivity (daylight)

White balance scales

R raw 2.5

G raw 1

B raw 1.76

It gives also a color matrix to regenerate the sRGB from the raw channels.

lylver

Hello, I worked a bit on daylight balance and color purity and I think I ended to a satisfying sunny day daylight balance with color correction.

setup : ES 80mm apo triplet + Kepler 0.75x reducer + IR-cut

My SharpCap .ini file http://atom.lylver.org/AstroSurf/Traitements/071-daylight-WB%20(ZWO%20ASI071MC-Cool(93826662)).ini

Unity gain

White Bal (B)=71

White Bal (R)=64

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Then I applied a color descramble matrix, using fitswork4 : http://atom.lylver.org/AstroSurf/Traitements/ASI071MC-color-matrix.fwf

Result :

http://atom.lylver.org/AstroSurf/Traitements/IRCUT+WB+XFORM.jpg

Not yet a night color balance, but I hope it helps.

Myriam

Sam@ZWO

the white balance of the camera is based on a limited range

the max WB_R can be adjusted to 2X of green

I think maybe this is the problem

lylver

Hi I worked further with narrow band led (cannot rely on my eyes only perhaps due to personnal high yellow + red sensitivity)

I realized all cam have a yellow deficiency even when white balance is done

First line is Ascom 5000K WB, numbers are led wavelength in nm.

I am color purist I guess ;)

Anyway got some nice unexpected results now, like with old imaging methods (film)

http://atom.lylver.org/AstroSurf/Traitements/M45color.png

http://atom.lylver.org/AstroSurf/lune/JUPITER/Jupiter2r.png