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using filters and monochrome camera, or using a OSC and monochrome camera

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#1 countrybumpkin

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Posted 29 September 2022 - 10:26 AM

Sorry if this covered elsewhere, but I couldn't find anything that gives me a reasonable clear answer to my questions...

 

I know most imagers looking to achieve the best results use a Monochrome camera + filter wheel and filters, etc, but wanted to compare with one other method/approach that I'm aware of to achieve this. So my understanding is that one can either ...

  1. Use a Monochrome camera + filter wheel + filters , or ...
  2. Use a One shot colour camera then swap to an equivalent Monochrome camera - the former to gather colour data but the latter to gather high resolution Luminance data

I'm interested to try out method 2, as I potentially have access to 2 cameras which are the same in every detail except one is OSC and the other Monochrome. If I could use this approach, I could  avoid having to add a filter wheel and filter wheels - with the associated costs, weight, image train length, focusing per filter, calibration complexities etc, that comes with that method.

 

thoughts please ? Would 2 work ? Would I be able to use DSS to combine Monochrome and RGB Groups ? I don't have PixInsight

 

regards Dave


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#2 Tapio

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Posted 29 September 2022 - 10:33 AM

Yes you can do #2. Many do and I've done it too in the past.

So you get LRGB images.

But what is your light pollution levels.

If it's bad you may need to invest in NB filters - duo/trioband for OSC or normal NB filters for mono camera.


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#3 WadeH237

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Posted 29 September 2022 - 10:43 AM

Sure, you can do method 2, at least for broadband targets.

 

If you want to shoot narrow band, the most efficient way would be to use a filter wheel on your mono camera with appropriate filters.  You could also get a multi-band filter (like the Optolong L-eXtreme) and get narrow band data with the OSC camera.  This works fine for enhancing emission nebulae, or shooting in strong light pollution or moonlight.  The downside to the OSC with multi-band filter, is that it does not accommodate the Hubble palette well.

 

As far as logistics and complexities, I think that the differences between mono/filters and OSC is over stated.  I use a mono camera with filters on my main rig, and a OSC camera (optionally with a multi-band filter) on my wide field setup.  I actually find the mono system to be the easier of the two to use, both in data collection and processing.  I use NINA for automation, and it seamlessly manages the filters and wheel (including focus differences, etc.)  With the OSC system, I have a manual filter drawer.  When I want to switch between broad band and narrow band with the OSC setup, I have to walk out to the scope and manually change the filter. 

 

As for processing, I always debayer my OSC images into separate red, green and blue channels.  This is an extra step that I don't have to do with my mono camera.  On the flip side, I have to separate calibration for the different filters on the mono camera, but not the OSC, so I guess that processing is nearly a wash between them.


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#4 imtl

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Posted 29 September 2022 - 10:48 AM

You will need an L filter in both methods.

#5 Phishin_phool

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Posted 30 September 2022 - 06:08 AM

You will need an L filter in both methods.

I may be wrong but wouldn't that depend on the camera and whether the glass has AR/IR coating or not?



#6 F.Meiresonne

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Posted 30 September 2022 - 06:25 AM

I do it all the time using an DSLR, one unmodded for color and one monochrome (bayer matrix removed) with mostly an Ha filter,sometimes L-enhance. I used them on emission nebulale.

 

one example : https://www.astrobin.com/jo2f8m/


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#7 Phil Sherman

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Posted 30 September 2022 - 10:43 AM

Sorry if this covered elsewhere, but I couldn't find anything that gives me a reasonable clear answer to my questions...

 

I know most imagers looking to achieve the best results use a Monochrome camera + filter wheel and filters, etc, but wanted to compare with one other method/approach that I'm aware of to achieve this. So my understanding is that one can either ...

  1. Use a Monochrome camera + filter wheel + filters , or ...
  2. Use a One shot colour camera then swap to an equivalent Monochrome camera - the former to gather colour data but the latter to gather high resolution Luminance data

I'm interested to try out method 2, as I potentially have access to 2 cameras which are the same in every detail except one is OSC and the other Monochrome. If I could use this approach, I could  avoid having to add a filter wheel and filter wheels - with the associated costs, weight, image train length, focusing per filter, calibration complexities etc, that comes with that method.

 

thoughts please ? Would 2 work ? Would I be able to use DSS to combine Monochrome and RGB Groups ? I don't have PixInsight

 

regards Dave

You might want to investigate downloading the now free "ImagesPlus" (IP) from (its author) Mike Unsold's web site. It's a full function GUI interface astro image processing program that does both pre and post processing. Mike also has documentation pages on his site that show how to use many of the program's features. It's not quite Pixinsight (PI) but it also has a much easier learning curve. I started using (and still use) this program many years ago when it it was a purchase to use program and paid for many upgrades to it. Mike finally stopped developing the program and made it a free download when he was unable to obtain pre-release developer software for the DSLR camera manufacturer's new storage formats. When you feed the program DSLR raw files, it converts them to FITS then processes them.

 

IP has the capability of combining LRGB images but you might have to separate the RGB image into three separate color frames to do the combination.
 



#8 Alex McConahay

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Posted 30 September 2022 - 11:12 PM

I’ll start by saying you can combine the color of an OSC image with the luminance off a monochrome camera. Not difficult or uncommon.

But your logic for doing so strikes me as somewhat singular. You are in a weird position of having two similar cameras (although one is mono and the other OSC). I must say, you don’t need identical cameras. Substantially different optics, cameras, and other equipment can be used to produce the different channels of a picture. And then you can make a pic from them. But, let’s go with that thing about having essentially two versions of the same camera. That is unusual, and if you had to pay for it, you would be paying a lot more than me might for a filter wheel and setup.

Secondly, you are saying the LRGB is more complicated somehow. LRGB images are different, but not much “harder.” And consider the trouble you are about to put yourself through when you change cameras. It is a little complicated switching the software and cables ng, and even mechanically screwing the other camera into place. And then you have to re-aim the camera, including rotation to
make your data fully compatible. All that is a lot harder than just letting the computer gather a set of LRGB data.

So, yes it can be done. But I don’t buy your reasons for doing it.

Alex

Edited by Alex McConahay, 30 September 2022 - 11:15 PM.

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#9 Phishin_phool

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Posted 01 October 2022 - 11:09 AM

I’ll start by saying you can combine the color of an OSC image with the luminance off a monochrome camera. Not difficult or uncommon.

But your logic for doing so strikes me as somewhat singular. You are in a weird position of having two similar cameras (although one is mono and the other OSC). I must say, you don’t need identical cameras. Substantially different optics, cameras, and other equipment can be used to produce the different channels of a picture. And then you can make a pic from them. But, let’s go with that thing about having essentially two versions of the same camera. That is unusual, and if you had to pay for it, you would be paying a lot more than me might for a filter wheel and setup.

Secondly, you are saying the LRGB is more complicated somehow. LRGB images are different, but not much “harder.” And consider the trouble you are about to put yourself through when you change cameras. It is a little complicated switching the software and cables ng, and even mechanically screwing the other camera into place. And then you have to re-aim the camera, including rotation to
make your data fully compatible. All that is a lot harder than just letting the computer gather a set of LRGB data.

So, yes it can be done. But I don’t buy your reasons for doing it.

Alex

I have dual copies of the same camera 183m and 183c - there was a bogo 50%off sale on few years ago (QHY).  As you can see below changing the camera is as simple as loosening three screws remove and replace. It is not hard to line your camera up the same or many like my scope have a rotator on them.  (the big screws, the smaller ones are if you have a 1.25 adapter)

020113_3_695x695.jpg?v=1645539161


Edited by Phishin_phool, 01 October 2022 - 11:11 AM.


#10 choward94002

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Posted 01 October 2022 - 11:17 AM

I have dual copies of the same camera 183m and 183c - there was a bogo 50%off sale on few years ago (QHY).  As you can see below changing the camera is as simple as loosening three screws remove and replace. It is not hard to line your camera up the same or many like my scope have a rotator on them.  (the big screws, the smaller ones are if you have a 1.25 adapter)

020113_3_695x695.jpg?v=1645539161

It's not quite that simple ... anytime you change anything in your optical path you need to take new flats, since you introduced new dust motes and moved around the existing ones since you rotated the field.  As an aside, having thumbscrews anywhere on the optical path is a bad idea; you'll get tilt errors when the camera shifts and pivots on those screw points



#11 Drothgeb

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Posted 01 October 2022 - 02:32 PM

I have a 294MC and a 294MM. I use the 294MC on a C8 w/Hyperstar for color data, and the 294MM on my much sharper SVX80T w/.8x reducer for luminance. I’m just getting started, but so far it looks very promising. The scopes are very different, but the way they are configured, focal lengths are less than 2mm apart. 

 

I just bought another mount, so I can image with both at the same time. My main motivation was that good imaging conditions are so brief, I want to collect as much data as possible between the clouds. 



#12 Phishin_phool

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Posted 02 October 2022 - 02:22 PM

It's not quite that simple ... anytime you change anything in your optical path you need to take new flats, since you introduced new dust motes and moved around the existing ones since you rotated the field.  As an aside, having thumbscrews anywhere on the optical path is a bad idea; you'll get tilt errors when the camera shifts and pivots on those screw points

yes you do need new flats- The camera 'presses flat' on the filter wheel then is secured by the screws - not ideal burt the way the cfw3 works - has not caused me any noticeable issues


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#13 countrybumpkin

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Posted 05 October 2022 - 04:32 AM

thank you to all of you for your helpful comments. So, it seems that what I'm proposing can be done, and many people adopt this method. I would also argue that swapping out an MM camera for it's equivalent  MC camera, still feels easier than using swapping filters. I only have to re check focus and take flats per camera. Software and cables all stay the same.

 

my next question then is : how would I initially register and stack, say using DSS ? Would I for example upload all my Colour data to DSS as say Group 1, do the same for Monochrome , call that Group 2, then let DSS do it's magic and bring both groups together ?

 

many thanks



#14 imtl

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Posted 05 October 2022 - 04:52 AM

I may be wrong but wouldn't that depend on the camera and whether the glass has AR/IR coating or not?

Most do not have any. And AR does not mean proper UV/IR cut. And definitely not to the same transmission as a proper L.

ZWO have these options with transmission curves.



#15 F.Meiresonne

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Posted 05 October 2022 - 07:41 AM

thank you to all of you for your helpful comments. So, it seems that what I'm proposing can be done, and many people adopt this method. I would also argue that swapping out an MM camera for it's equivalent  MC camera, still feels easier than using swapping filters. I only have to re check focus and take flats per camera. Software and cables all stay the same.

 

my next question then is : how would I initially register and stack, say using DSS ? Would I for example upload all my Colour data to DSS as say Group 1, do the same for Monochrome , call that Group 2, then let DSS do it's magic and bring both groups together ?

 

many thanks

No , you make 2 stacks. One monochrome and one OSC color stack. You can use then the mono as luminance.

In Startools you have a slot for Luminance and 3 slots for color, Red,Green and Blue.

 

Also you will have to align the 2 stacks



#16 Mike7Mak

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Posted 05 October 2022 - 08:50 AM

I've only done this once, by accident. I recently shot about 7hrs of L on ngc7331 only to discover when processing it that I had taken 7hrs of OSC on the same target 2 years earlier with a different scope. Saved me the trouble of spending 2 more nights collecting RGB. Both cameras have the same chip but the scopes were slightly different image scales and the two image sets were also slightly rotated with respect to each other.

 

I preprocessed both image sets with their respective calibration frames. But before stacking I aligned all the subs of both sets using Nebulosity's 'align, rotate and scale' routine. After that it was simply a matter of separately stacking the L and OSC and using StarTools to post process each stack and then combine them with the 'layer' module using a brightness mask. Never did it before or since so I was pretty much winging it and learning along the way.

 

As 'easy' as it was to do I don't think I'll ever deliberately set out to do it again. The OSC data for this image was essentially 'found footage' that I'd abandoned for reasons too long to explain, and mildly embarrassing to boot. My rig is set up in an obs and I generally do very little taking things apart. And being lazy I try to get as much use out of flats as I can before having to take them again.

 

The only way I can see this technique making sense is if you can have two separate rigs capturing the L and OSC at the same time.

 

get.jpg?insecure



#17 countrybumpkin

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Posted 06 October 2022 - 02:37 AM

I don't have Startools, just DSS and Photoshop ...so what would my workflow be using those 2 Apps ?

 

Also, with the idea of using 2 rigs to capture L and OSC at the same time, I can see how that would save time - but I don't have 2 rigs, just the one... so can instead just swap camera's



#18 psandelle

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Posted 06 October 2022 - 10:11 AM

I don't have Startools, just DSS and Photoshop ...so what would my workflow be using those 2 Apps ?

 

Also, with the idea of using 2 rigs to capture L and OSC at the same time, I can see how that would save time - but I don't have 2 rigs, just the one... so can instead just swap camera's

Of course you can just swap cameras, and despite a mono camera and filter wheel usually being more efficient in this case, sometimes people want to use what they have (or just not buy MORE stuff...grin.gif), and, sometimes, the rig won't allow for filter wheels (RASA/hypestar, or, like me, other types of faaaaaaaaaaaaaaaaaaast scopes where backspace is at a premium). Try it! Have fun!

 

Paul



#19 unimatrix0

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Posted 06 October 2022 - 10:22 AM

I don't have Startools, just DSS and Photoshop ...so what would my workflow be using those 2 Apps ?

 

 

Youtube is your friend (if you have ad-blocker installed)

 

fast forward to 19:17 to see how to process using DSS and Photoshop
https://www.youtube....h?v=pXcRKoxTPVg



#20 F.Meiresonne

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Posted 07 October 2022 - 02:01 AM

I don't have Startools, just DSS and Photoshop ...so what would my workflow be using those 2 Apps ?

 

Also, with the idea of using 2 rigs to capture L and OSC at the same time, I can see how that would save time - but I don't have 2 rigs, just the one... so can instead just swap camera's

It takes at least 2 sessions , difficult to change that...allthough it crossed my mind to use 2 rigs. I have to rigs,it should be possible but not tried it sofar.

 

I don'tknow the workflow in photoshop. I do now eg 'The Elf' does it in PI. Actually i took over the whole idea from him. We use even thesame camera's but different scopes and processing software.

I do have PI, use it for stacking, and aligning the stacks or evaluation of subs. But i don't use it for processing.


Edited by F.Meiresonne, 07 October 2022 - 02:03 AM.



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