Combining different pixel sizes and resolutions?

[Demonperformer]

I am looking at a dual rig set up. I would intend running one with a mono camera for luminance [4656x3520, 3.8um pixels = 5.8"/px, 340.2'x450'], and the other with a colour camera for ... well ... (one-shot) colour [1304x976, 3.75um pixels = 5.72"/px, 91.3'x124.4']. (These figures taken from FLO website, run through CDC Calc.)

First obvious issue is the smaller size of the colour image, but I could presumably crop the mono image down to size before combining them.

The other issue is the slightly different pixel sizes and resolution figures. Would this small difference cause problems when combining the colour image with the monochrome one (I use DSS & Photoshop v7)? I really can't afford to add another camera to the setup at this stage, so if it is going to be a right pain, it'll be best to abort the entire exercise.

Thanks.

[Droogie 2001]

I know the program Registar (not Registax) can deal with combining images from different focal lengths and image scales, so maybe worth a look. Doing the combining in PS or DSS will either be very difficult or simply not possible.

It only does this and does NOT offer any post processing options, it does however do this job very well. Its not free though there is a free trial, I think I paid around a £130?.

If it helps you acheive what you are looking for then maybe worth a look. You can download the free trial which stops you from saving an image but at least you maybe able to carry out some tests with similar data that you can find freely available on the Internet. This will help you before you even start spending any money to see if it is a viable option.

https://aurigaimaging.com/

 

[Demonperformer]

Thanks.

My initial thought is that, if I am going to have to spend out on more software, I could be better off waiting until I can afford another 1600 camera so that my results will match in DSS - but I will take a look at Registar and see what I think then. I'm not totally sold on the idea of a dual rig, but the thought that I could capture the LRG&B data all at the same time is rather appealing!

[Droogie 2001]

Certainly having the same spec camera will probably make things easier. Could you go for another mono and use the RGB filters across to the new one? I realise this increases costs but my concern would be the OSC data.
I guess it will work but not sure if the results will be as pleasing as combining seperate RGB data with LUM.

Have to confess I have no experience of Dual Rigs, managing just one OTA and camera is a challenge enough. I know there are alot of forum members who do run them so hopefully they can jump in with some suggestions.

[swag72]

I find that APP (Astropixel processor) matches different resolutions and scope well........ I have used it to match (perfectly I may add) some real different focal lengths and it's worked well.

I have found all sorts of potential issues with a dual rig.... certainly not as easy as Olly has made it look!! But I guess I've just been unlucky with 2 knackered cameras, a broken guide camera, broken stepper motor for focuser, useless cables, and now a broken PC, and I've not even mentioned flexure! Since November when I finally got it running (with a new mount) I've lost 2 months of imaging with my problems......  

[Demonperformer]

4 minutes ago, swag72 said:

2 knackered cameras, a broken guide camera, broken stepper motor for focuser, useless cables, and now a broken PC, and I've not even mentioned flexure! Since November when I finally got it running (with a new mount) I've lost 2 months of imaging with my problems......

and that would make it look less appealing - rather defeats the object of saving time by getting two lots of data at the same time

[swag72]

1 minute ago, Demonperformer said:

and that would make it look less appealing - rather defeats the object of saving time by getting two lots of data at the same time

But when it works well...... it's fabulous!! And that's not to say that you'd have to experience all of the broken stuff that I've been lucky enough to have 

[sloz1664]

I run a dual rig and apart from initial alignment issues it works very well indeed. I also use APP for calibration and image stacking and can't fault it.

Steve

[ollypenrice]

Honestly I'm not the technical type and all I did was bolt ours together and start shooting. It gives me no grief whatever. Alignment is via a Cassady T-GAD adjuster but FLO now do a good alternative. (The Cassady stuff is out of production.) We use a separate guide scope, no USB hubs, manual focus and two computers. 

Registar is a fabulous programme. I use it all the time, not just to combine the dual rig data but to blend long FL data with widefield, to align L to RGB, to re-align RGB when, very occasionally, Astro Art has got it wrong and so on. Also for mosaics, of course. Knowing that you have perfect channel alignment is very reassuring.

Olly

[tomato]

+1 for AstroPixel Processor, I have used it successfully to combine subs taken with an Atik 314 OSC and G2-8300 mono, albeit using the same scope.

[Stub Mandrel]

It isn't impossible or even hard to stack two images at different scale in Photoshop, just use the free transform tool to scale, position and rotate one image as a layer on top of the other one.

This (not brilliant) image combines data from a 150Pl at 1200mm f/l and a 130P-DS at 580mm f/l using the same camera.