oii subs - identical to the pixel B and G channel with 6d

[powerlord]

Hi chaps, is this normal ?

I took some h-alpha with my 6d and got what I expected - all the data in the R channel, none in the B or G. All good, grabbed that R data out.

When I did the same thing with my Oiii filter I expected to see none in R, and a bit in B and G probably.

What I actually got was pixel identical data in the B and G and none in the red. I stacked in APP, so maybe something up there, but it did work fine with the h-alpha.

I've attached the h-alpha and the oiii stretched, but as captured and stacked (RGB data)

When I mean identical I mean identical - it's same data in B and G. Put a layer style of difference on the G with B under it, and you get black.

If this was doing what it should be doing, ih-alpha.tifft can't be identical, so confused.

 

oiii data.tiff

[alacant]

Hi

Yeah. The sensor's sensitivity in gb @ 500nm is pretty much the same. Identical, I don't think so though.

6D; rggb

HTH

Edited June 19, 2021 by alacant

[powerlord]

Thanks, yeh I expected it to be similar on both but just down to noise alone they shouldn't be identical surely. Either the canon is doing summit funky or APP is doing something funky (wrong bayer mask or something surely ?

[alacant]

Not sure what the uploads represent. They seem to have been stretched.

  

 

[vlaiv]

1 hour ago, powerlord said:

Thanks, yeh I expected it to be similar on both but just down to noise alone they shouldn't be identical surely. Either the canon is doing summit funky or APP is doing something funky (wrong bayer mask or something surely ?

I think that your software for comparing channels is doing something strange.

Here is what G-B channel looks like when you do the math in ImageJ

Most of image is noise - but notice that we can identify some of the stars here - that means that G and B are not even the same - but very close (say 51% QE vs 50% QE from the graph alacant posted)

[powerlord]

Hmm. Thanks. OK ive screwed up somewhere then. I use affinity. I pulled each channel out as a bw layer, then set top one to difference for layer style.

Each is simply the stacked stretched image from APP.  One with halpha filter, one with oiii.

Affinity does have a bit of a weird way of separating channels. I'll try it in PS. Now I know it's me, I'll work out a process.

Thanks again.