How do I take and process LRGB for planet's?

[Nigella Bryant]

Hi all, I'm about to install my 11xlt in my obsy and want to do LRGB imaging of Mars in the coming months. Never done this before. I've a mini zwo filter wheel, RGB filters, a zwo ASI 178mm and 2.5x power mate. I think I've all the equipment needed but never ever done LRGB on anything. Also would the 685nm IR filter be an advantage? Also what software do you use, pre and post capture? I've only ever used sharpcap for solar imaging. I've Photoshop cs2 as well. Are there better software for combining LRGB? Thanks for looking. 

Edited August 4, 2020 by Nigella Bryant
Correction of content.

[CraigT82]

Regarding the questions about LRGB, Damian Peach has a good article on imaging Mars and the various colour combination methods:

http://www.damianpeach.com/marscolour.htm

As for software, sharpcap will be great for capture. I use autostakkert 3 for stacking, registax for sharpening, winjupos for derotation (can add lum channel in winjupos) and PS cc for final edits 

[Nigella Bryant]

Thanks, also what would the optimum amount of time per channel be for Mars, I was thinking 2mins per channel or would this give significant rotation?

[CraigT82]

If you are using winjupos I think the standard quoted time for capture is a maximum of 6 minutes per sequence, ie. 2 mins per RGB channel, but this is dependent on the resolution, at finer pixel scales you should do shorter times and coarser scales you can do longer times.  You could calculate the rotational smearing using the pixel scale, apparent size and rotation speed if you were so inclined.  The key is to shoot RGBRGBRGB... etc. rather than RRRGGGBBB. That way you can derotate each colour channel to the exact same mid point time.

[Nigella Bryant]

10 minutes ago, CraigT82 said:

If you are using winjupos I think the standard quoted time for capture is a maximum of 6 minutes per sequence, ie. 2 mins per RGB channel, but this is dependent on the resolution, at finer pixel scales you should do shorter times and coarser scales you can do longer times.  You could calculate the rotational smearing using the pixel scale, apparent size and rotation speed if you were so inclined.  The key is to shoot RGBRGBRGB... etc. rather than RRRGGGBBB. That way you can derotate each colour channel to the exact same mid point time.

Thanks, that was helpful. So taking a two min sub in each channel of RGB resulting with six minutes and use winjupos for derotation.

[CraigT82]

Yes that's it. Load up all the sharpened stacks of the red channel and derotae them to the mid point of the entire session. Do the same with the green and blue, using the same mid point times and then you can combine the channels (however you like), with each final channel being at the exact same moment in time.

Even if you can't manage to get each channel derotated to the same midpoint time (ie if you do shoot RRRGGGBBB - no motorised filter wheel?) you can do a second derotation of the RGB channels to combine them into the final colour image, as long as the total session time wasn't too long for winjupos. I'm not entirely sure what the total session time limit is currently for Mars as winjupos has been recently updated to handle longer times (60 mins for saturn & 20 mins for jupiter) will need to find this out and get back to you. 

Edited August 4, 2020 by CraigT82

[CraigT82]

Just found out for Mars you can go up to 60 minutes total capture time for winjupos derotation... plenty! 

[Nigella Bryant]

3 hours ago, CraigT82 said:

Just found out for Mars you can go up to 60 minutes total capture time for winjupos derotation... plenty! 

Many thanks, yes that's more than enough, lol.