Greedy for data...dual rig?

[gazza]

Hi,

I've now - finally - got a setup that is working perfectly after years of frustration with lesser gear. This comprises Mesu 200, Esprit 100, QHY9S/filterwheel loaded with a full set of Baader filters.

In addition I have an ASI071 pro OSC camera that is to be used as a portable system on an HEQ5 Pro with a 130PDS.

A trial with the OSC camera showed quite decent results even though I am located in a city of 250k people and only 1.5km from the centre. It is classed as an orange zone. Due to site restrictions I have to image to the east right over the city centre. Despite this the gradients in my test were not too bad, and certainly appear manageable in the OSC. 

I wondered therefore about setting up a dual imaging rig using the OSC for rgb and the QHY9 for narrow band.

Has anyone tried combining data from a newt with that of a refractor? If this is a no go, what about a small refractor - ZS61? Would the difference in pixel scale be any great issue? Much as I'd like, another Esprit ain't gunna happen :-(

Alternatly RGB with the Esprit, and perhaps an MN190 for narrow band?

Is this doable?

Suggestions/gotchas?

cheers

Gary

[steppenwolf]

6 hours ago, gazza said:

Has anyone tried combining data from a newt with that of a refractor?

Yes I have, using  an SXVF-M25c for the colour and an SXVF-H9 for the mono (12nm Ha filter). You would ideally use Registar to align your images as this does the alignment in a non-linear manner which is important when using disparate optical systems.

The Butterfly Nebula in Cygnus captured as described.

[alexbb]

Food for thought: it might be easier and more efficient if you would see the same area with the OSC and the mono. The APS-C sensor is quite larger than the 4/3 one and this will be even more apparent putting the large sensor on the short FL and the smaller sensor on a longer FL.

The QHY9s on the Esprit 100 and the ASI 071 on the 130PDS at its native FL will cover about the same area. If the colour result from the 071 and the 130 is not satisfactory, you could shoot some L also with the mono and the Esprit, create a synthetic lum from the RGB, combine the lums and then apply the colour. That's how I would approach this in the beginning, you don't even need to buy anything for now. I'd also use both mounts if possible and point the scopes in the same direction.

http://astronomy.tools/calculators/field_of_view/?fov[]=48||438||1|1|90&fov[]=227||71||1|1|90&messier=42

[gazza]

Thanks for the replies guys - I did have reservations about using the 130PDS/refractor combination but it is worth a try. Over Christmas I'll mount both scopes side by side and do a trial. I anticipate using the OSC for RGB, and replacing its L channel with Ha data from the mono - Sound doable? I'm trying to maximise my imaging time and will be automating the obs using an AAG Cloudwatcher awaiting delivery - at my age - pushing 66 I need my beauty sleep. I tried 2 nights in a row until 3 am and was a zombie after....

cheers

Gary

[alexbb]

3 minutes ago, gazza said:

I anticipate using the OSC for RGB, and replacing its L channel with Ha data from the mono - Sound doable?

Doable? Yes. The outcome could be good if the target is predominant in Ha. I would still make a synthetic lum from the RGB channels (turn the RGB image in a grayscale image) and experiment with adding the Ha to the L and/or to the R.

[ollypenrice]

21 hours ago, gazza said:

Thanks for the replies guys - I did have reservations about using the 130PDS/refractor combination but it is worth a try. Over Christmas I'll mount both scopes side by side and do a trial. I anticipate using the OSC for RGB, and replacing its L channel with Ha data from the mono - Sound doable? I'm trying to maximise my imaging time and will be automating the obs using an AAG Cloudwatcher awaiting delivery - at my age - pushing 66 I need my beauty sleep. I tried 2 nights in a row until 3 am and was a zombie after....

cheers

Gary

Absolutely not. Well, it is perfectly doable but you can get far better results by working otherwise. I believe in starting from first principles and luminance = the full visual spectrum while Ha lies in the deep reds, slightly magenta. Why would you illuminate your whole image in deep red/magenta light?

No, I would shoot OSC for colour and use the mono side for a bit of luminance and a lot of Ha and/or OIII. I would then add Ha to red and OIII to green and blue using Photoshop's Blend Mode Lighten. This way you are respecting nature's colours, at least so far as is possible in this game.

Olly

[gazza]

Thanks Olly,

I had thought about using the Halpha as L as I am in a light polluted zone and figured that I could get better detail using it rather than shooting straight luminance. Your suggestions make perfect sense so I'll give them a trv- have the whole summer here to experiment. Planning mods to obs to allow roof automation now. Sleep is a wonderful thing and whilst I love the night, can't do what I did 20 years ago.

cheers

Gary