OSC data combined with Ha data - Next step

[Z3roCool]

Hi there, I currently only shoot Narrow band with my 1600MM camera. I have tried RGB but I get terrible results compared (Using the 1.25" ZWO filters). I have been looking at getting a OSC camera (294MC) and a LP filter to get quick colour data and then combine with Ha data collected from the 1600 camera for increasing the depth and detail of the image.

I cannot see a way of getting natural RGB data with my current setup (Canon 400mm lens) with no easy way of implementing an LP filter. With the 294MC I could add an LP filter into the EFW to get quicker RGB data. Just trying to work out a path forward, wondering what others would do? Going between getting the OSC or swapping the lens with a proper scope (Esprit 100 or WO GT-81...)

*Sorry, realised this is in the wrong topic but cannot work out how to delete*

Edited June 10, 2020 by Z3roCool

[Knight of Clear Skies]

I'm not sure what to advise really, as shooting RGB with the 1600MM should work better than using an OSC camera. Could you post an example please? We may be able to diagnose the problem.

Personally, I've had much less trouble with colour balance shooting through RGB filters on the 1600Mm cool than with OSC.

Edited June 10, 2020 by Knight of Clear Skies

[wimvb]

My first guess is that it's the post processing that needs addressing. Which ever software you use, colour calibration should be your first order of business. In PixInsight you'd use background neutralization and colour calibration for that.

[carastro]

Perhaps if you could post up some files done with both ha and RGB and let us have a go to see whether it is your processing that is the problem or to agree with what you say.

I have added Ha to DSLR data in the past and it does work well so long as you have something like Registar (or similar) to re-size the images.  All done from Bortle 8.

Examples from 2011

DSLR

Ha added to the DSLR image above from Mono camera in 2012

Carole  

Edited June 12, 2020 by carastro

[ollypenrice]

There's no reason to believe that OSC would be quicker than RGB. The term one shot colour can be misleading because a more accurate term for these cameras would be quarter of a shot red, quarter of a shot blue and half a shot green - though I'll grant that this doesn't roll of the tongue!  If you judge the exposure by counting photons per colour per unit time you'll find they are pretty much equivalent in both systems.

On the other hand the RGB might benefit from an LP filter. I don't know much about LP since I'm lucky enough not to have it. I would make this the key factor in your consideration and ask for specific advice on the utility of LP filters when shooting colour.

I'd also be careful about adding depth and detail with a colour image. Colour without luminance is slow going, and that's why L-RGB is faster than OSC. Going deep in colour is pretty difficult - or time consuming. Also going for detail involves sharpening and sharpening requires deep signal, so again LRGB will beat OSC. Be aware, also, that your Ha data will be considerably sharper on the hydrogen regions than anything you will capture in red or luminance.

As the others have said, giving us a look at the problem RGB would be helpful.

Olly (ex-Derbyshire myself.)

 

[carastro]

Have to agree with Olly.  Though constantly cloudy skies I agree can be very frustrating.  

Carole 

Edited June 13, 2020 by carastro

[Ken82]

3 hours ago, ollypenrice said:

On the other hand the RGB might benefit from an LP filter. I don't know much about LP since I'm lucky enough not to have it. I would make this the key factor in your consideration and ask for specific advice on the utility of LP filters when shooting colour.

 

This is a dilemma I had pondered for years before changing to a mono camera earlier this year. 

I’ve found it’s perfectly acceptable to achieve LRGB images under light polluted skies (bortle 5-6) without using a LP filter. 
 

The one notable difference which I believe Whistlin Bob has also noticed is that taking HA and adding this into the red channel is very important to bring out these nice areas of colour. Im not sure why that is but my OSC was excellent at bringing these areas out without using a HA filter. 

 

[ollypenrice]

14 minutes ago, Ken82 said:

 

The one notable difference which I believe Whistlin Bob has also noticed is that taking HA and adding this into the red channel is very important to bring out these nice areas of colour. Im not sure why that is but my OSC was excellent at bringing these areas out without using a HA filter. 

 

I'm surprised by this. At one time I used two Atik 4000s, one a mono with Baader filters and one an OSC. I didn't see much difference in Ha sensitivity. However, the point about Ha filters is not that they pass more Ha than a red filter. (I doubt that they do.) Rather, they block everything that isn't Ha signal, so emphasizing the contrast in the cloud structures. Let's not forget that we all shoot a lot of Ha, too. Usually far more than we shoot in any colour.

Olly

[Ken82]

21 minutes ago, ollypenrice said:

I'm surprised by this. At one time I used two Atik 4000s, one a mono with Baader filters and one an OSC. I didn't see much difference in Ha sensitivity. However, the point about Ha filters is not that they pass more Ha than a red filter. (I doubt that they do.) Rather, they block everything that isn't Ha signal, so emphasizing the contrast in the cloud structures. Let's not forget that we all shoot a lot of Ha, too. Usually far more than we shoot in any colour.

Olly

I’m not sure it’s about the sensitivity of the HA as by all accounts my ASI6200MM is much more sensitive than my OSC. Perhaps it’s because it’s more sensitive to the other wavelengths that it drowns out the HA ?? 
 

It could also be down to Pre processing And combination. I know Whistlin Bob noted this to me and he uses the same process of combination although he’s using the asi 1600. 
 

I haven’t got a like for like comparison Unfortunately but in my m33 image I know for sure I’d need to take some HA images and combine this with my RGB to bring out the nice areas.  
 

[Whistlin Bob]

You're right @Ken82- I am having the same challenge with the Ha.

To respond to the OP I went from OSC to Mono at Christmas (Canon 600d to ASI1600mm) and my experience under Bortle 5 skies has been that Mono is at least as quick as OSC to gather a similar set of data. When I was experimenting to start with on LRGB I used an IDAS D2 filter because this had been massively helpful on my Canon (to the point that when they fitted LED lights on my street I feared I may have to give up until that filter saved the day), but it did not seem to help at all on the Mono and I now just shoot with the LRGB filters in the wheel. I use ZWO filters which seem to be par-focal and I set it running on an APT plan to get all four channels and then cycle round them. It's at least as fast to gather the data this way as it was on the DSLR (although it takes longer to process afterwards) and also frees me to observe whilst its running- that's critical because I remain in love with visual astronomy (I'm just two-timing it sometimes with my imaging rig!!!). 

The frustration I was sharing with Ken was that in order to bring out star forming regions in galaxies I need to capture an Ha channel as well. To demonstrate below are 2 M81/82 shots- one from last year with the Canon and one from this year with the ZWO. Different scopes were used giving different FOVs but from other shots with scopes it's not the source of the problem. The Canon clearly picked out the Ha regions, the ZWO doesn't unless I add an hour or two of Ha in. Even then I really have to push the data to get the same effect.

 

For some reason the second picture has compressed badly, but hopefully you can see the point about the Ha regions. Both images are around 2.5 hours of data, and I would say that except for that and the processing time, there is no other advantage to the OSC.

[Annehouw]

@Z3roCool

You have received some good input here, but it might be wise to direct your efforts at the root of your problem.

 

"I cannot see a way of getting natural RGB data with my current setup" is that correct?

 

I could not find a description of your image processing pipeline, so a bit blind in in helping you in that respect:

As has been mentioned earlier, correcting for Light Pollution (and gradients) and  getting a "correct" colour balance is  something that a lot of post processing software is very good at. I see no principal problem with your camera, filters or your lens. There are a lot of people producing fine images with a set-up like that, also from a light polluted environment.

Doing this systematically:

1) Look at your image processing pipeline first as a way of tackling the RGB color and light pollution problem. AstropixelProcessor, Pixinsight or Startools are popular choices. 

2) The effectiveness of OSC vs LRGB is a nice conversation  topic while emptying a few bottles of whisky, but either will work well.   I do not think this is at the heart of your problem. You already have the mono + RGB filter set, so.....

3)  A light pollution filter just maybe  gets you a bit less light pollution in your shots, but gradients and residual LP will still be present and so it is back to item (1) and if you master item (1), there is no need for a LP filter.

 

 

Maybe you could share your workflow and the natural RGB colour problem in a bit more details, with images? 

 

 

 

 

 

 

Edited June 13, 2020 by Annehouw

[carastro]

Since the original poster has yet to respond to any of our comments, I don't think we can really help any further without seeing some of his data.   I hope he/she is well at this difficult time. 

Carole 

[Z3roCool]

16 hours ago, carastro said:

Since the original poster has yet to respond to any of our comments, I don't think we can really help any further without seeing some of his data.   I hope he/she is well at this difficult time. 

Carole 

Hi all, thanks so much for the replies and helpful input! I have been snowed under with personal things and work going through threat of redundancy (Just found out 10 mins ago all is okay for now!). I will have a read through and respond...sorry for not being on the ball.