One Shot Colour, sound technique?

[ollypenrice]

A nice new Atik 4000 OSC has come my way for a colour-mono shootout piece for AN but I know nothing about OSC as yet. Does this sound like a decent workflow, please? All help geefully absorbed.

-Shoot the light frames.

-Open them in Artemis RGB, do the pixel offset to get sane-looking colour and save as 48 bit Fits.

-Stack them in AstroArt. (When I do real images as opposed to indoor tests I will here apply darks and flats as well.)

-Open in Ps and, in Levels, set the black and white points for each colour in turn.

Doing this has given me a very convincing result on a simple tri-colour test card I have imaged, with the colours coming out nearly spot on. But I could be missing a few tricks, of course, which is where SGL comes in!

Thanks,

Olly

[steppenwolf]

That is a reasonable start and (although you don't have any I suspect!) item 3 will resolve some light pollution issues into the bargain. Obviously, there is tons more to do but much of this applied to LRGB combined images too.

[ollypenrice]

Thanks Steve. No light pollution, no, or none to speak of. It is really just a question of getting to the stage with which I'm familiar in mono imaging. Alas the variable in this mono-colour shootout is little me so I want to minimise my effect on the whole thing.

I have to say that if, when the moon goes, this colour camera does as well by night as it has done by day I will be hard put to send it back...

Thanks again,

Olly

[NickH]

I think for narrowband work Olly, and general sensitivity against the mono 4000, you will ...

We did a pseudo mono shootout with the 314E's in Spain...the mono cams just beat them hands down... but...OSC has a lot going for it...as Greg Parker proves continualy...so will be interested in how you get on

[harry page]

Hi

Of course you do know that calibration should be carried out before debayering ! which if you use AA4 does automatically

Flat in a OSC are harder work

Here is how I make and use them In AA4 with my sx m25 camera

http://www.harrysastroshed.com/AA4flat.html

Good luck and look forward to seeing some work

Harry

[Tim]

Olly, which telescope are you going to use with it?

I went at it the other way round, OSC to mono, and using the mono camera has really highlighted that the varying OTA's I have bring the colours to focus at different points. Your kit is higher end than mine, but it may be worth watching for that.

[ollypenrice]

Indeed, this is one of the things I'm interested in. The Tak is almost colour perfect, the Meade triplet rather less so. It will be interesting to see what effect this has. However, using good parfocal Baader LRGB filters, the interferometric ones, I don't usually have to refocus in the Meade 127 between colours so I hope it will prove to be okay. The other thing will be the risk of undersampling the Bayer Matrix at very short focal lengths. I probably won't be able to run the colour camera in the reduced Tak (f3.9) because I won't be able to get the spacing right without a huge expense in adapters so 450mm will be the shortest focal length on test.

Olly

[Tim]

I have those filters Olly, plus the narrowband ones. The OIII is usually the one which stands out as being most out of focus, especially if focus is obtained through the red or Ha filters. I use a bahtinov mask to see exactly how much and which way the focus alters.

Got a link to info about undersampling? New to me that.

Looking fwds to the results

[ollypenrice]

Hi TJ, it was a piece by the mighty Deitmar Hager but I can't remember exactly where, I'm afraid. I'll look into it.

Olly