flat frame question

[diurnal]

here is my old flat frames in rgb. this was shot with an EL panel.


here is greyscale.


here is my new flat. this was shot with a light box with LEDs and white tshirt.

here it is in greyscale

Questions:
the mean is an ADU measurement right?
Does Pixinsight use the greyscale image or the RGB image?

Is my new flat any good?

Thanks

[pfile]

calibration is done when the OSC images are still in bayer format. so the flat is really a mono image with all 3 channels interleaved with one another at the time it is divided into the light. i believe 3 different scaling factors are computed; one for each channel.

are you using a CLS filter? the red channel is weaker than the blue and green…

rob

[diurnal]

rob,

im not using a cls filter. i just have a canon 60DA, which has an increased sensitivity of hydrogen-alpha. so would that be a reason the red so low?

how could i increase the red?

i have some frosted acrylic on order, to see if that helps out.

the ultimate reason for all of this is a red gradient keeps cropping up on my final images and i think my subs are too dark in the corners. ive not got a chance to use the new flats you see.

mick

[pfile]

hmm, with no filter i'm not sure why the red would be so low, in truth it should be higher with a modified camera or the 60da.

unfortunately the only way to get your channels balanced in the face of color casts like this is to modify the color of the light you use to make the flats. when i was using a CLS filter with a modified 50d, this meant using a slightly pink t-shirt for my t-shirt flats.

rob

[Phil Leigh]

The EL panel is producing light which is too blue. Most of them do. Which panel are you using?

[diurnal]

With the new flat, i got these results:
This is using old flat


This is new flat.


i was amazed at these results.

hmm, with no filter i'm not sure why the red would be so low, in truth it should be higher with a modified camera or the 60da.

unfortunately the only way to get your channels balanced in the face of color casts like this is to modify the color of the light you use to make the flats. when i was using a CLS filter with a modified 50d, this meant using a slightly pink t-shirt for my t-shirt flats.

rob

i tried a pink shirt but it was too red. I spent about 5 hours trying to make a good flat box. best i could do is R channel= 25000 ADU G = 28000 ADU and B= 31000 ADU.
I'll have to try a couple more things , then I'm done with it. I'll just buy a professional light box or something.

The EL panel is producing light which is too blue. Most of them do. Which panel are you using?

12x12 inch electroluminescent panel with lead wire and connector. http://www.glowhut.com/12quot-by-12quot-electroluminescent-panel-with-lead-wire-and-conne1212.html

[Phil Leigh]

your 25/28/31 balance should work fine. The channels do not have to be perfectly balanced. Just so long as the levels are all in the linear region for your sensor (which for a DSLR is pretty easy)