flats with ha data?

[blink138 (Pat)]

hello members just still trying to get my head around shooting ha with my 60da
i have just shot 8 15min subs of the tarantula just in ha, with the same darks and this morning shot 8 flats, however looks especially awful when combined in dss
here is the raw (resize) dss
any help?
regards
pat

[blink138 (Pat)]

this is it with just the ha data stacked and it looks better but very noisy!
pat

[blink138 (Pat)]

and finally this is a single ha sub
how are they supposed to combine for goodness sake?
this single looks good to me!
pat

[alpal]

Hi Pat,
Try stacking them without using bias frames, darks or flats.
Then stack again each time adding one of the above.
You might find that it stacks OK with just flats & darks but no bias frames.

You could also play around with the bayer- debayer settings under

Settings
Raw/FITS DDP Settings

cheers
Allan

[blink138 (Pat)]

thanks allan for the reply
i have not used a bias frame and really do not know much about them to be honest
once the lights have been stacked how then do you add a dark or flat to them in dss allan? i would of thought that could not be done and the program would not allow it?
i really do need to learn a bit more about this!
pat

[alpal]

Hi Pat,
it's only a matter of opening the files when selecting: darks, flats & bias frames - top left hand column.
You then can see them & tick them.

This video might help:
https://www.youtube.com/watch?v=J96e9HRbi-A

It's hard to do Ha with a Bayer matrix camera - as you have.
You'll need to play around with the settings as below.
Remember only one pixel out of every 4 will detect Ha.

cheers
Allan

[blink138 (Pat)]

thanks allan very helpful
pat

[LewisM]

H-a with an OSC/DSLR is not a quick process.

As Allan pointed out, only 1 in 4 pixels register the H-a. You can minimise the noise/gaps by binning it 2x2 (but lose resolution).

Alternatively, you can extract the red channel alone in software (PS, PI, MaxIm, AstroArt etc). Save each of these extracted images and combine them instead of the RGB conglomerations.

It's a long process, but in the end, yes, you can get an OSC to be VERY similar to mono.

[blink138 (Pat)]

ta lewis, when you know little in the way of processing anyhow the task is even harder!
pat