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  #21  
Old 01-03-2021, 10:04 PM
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Nikolas (Nik)
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Hi Nik,
Sorry, the reply was meant for Gordy.

Chris.
Cheers mate
I also agree with Peter mono is king but again time is of the essence and I have produced some great images with the osc.
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  #22  
Old 02-03-2021, 10:34 AM
SB (Chris)
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Originally Posted by Peter Ward View Post
If you are seeking excellence, mono is the ONLY way to go.
The laws of physics make them the obvious and only choice.

Suffice to say, JPL/NASA/ESO/JAXA don’t fly colour cameras.

If you are time poor/just want some fun/technically challenged, then the new colour cameras can give great …in fact occasionally…award winning results.

But for sheer depth and breadth of intrinsic data…. mono wins every time.
Hi Peter,
You omit in your list the two things that slow me down moving to Mono which are $$$$ and clear sky time. Mono is substantially more expensive.

I also ponder about the time taken up in focussing between filters and repeating this when the temperature changes. DSO targets transverse quickly in the sky and time is of the essence. Also potentially if Mono imaging starts at altitude 50Deg on Red filter and the next filter is at 65Deg (for example illustration) then filter at higher ALT will be a better image. With OSC all the colours are balanced at each ALT imaging range.

Chris.
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  #23  
Old 02-03-2021, 11:34 AM
jahnpahwa (JP)
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You missed my point I think
I personally use an osc camera because of my limited time for image acquisition and the crap weather Melbourne serves up. No time to acquire 4 times the time to acquire an image with different filters, what takes me hours would take me weeks with a mono camera.
Nik (and Chris), I have to chime in and say that I really don't believe this to be the case. I think imaging time for colour images is roughly equal (perhaps even quicker with mono), especially when the Luminance layer is well developed. A good set of filters (even my basic ZWO ones) are parfocal, or close enough to parfocal that it doesnt matter for 99% of people.

I'm not saying this because I'm team mono and want everyone on my team, but to let people know that this is a non-issue. The way it goes (if I am imaging a galaxy from the backyard) is I focus in Lum, I set an imaging routine in APT and press go and walk inside binge watch something on tv. I almost always set the routine to run vertically, ie, switch filters each sub (which is less than 1 second), so even if clouds come over an hour or two in, i still have a complete dataset to play with. This also negates the differing seeing as the targets moves through RA, metnioned by Chris below.
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  #24  
Old 02-03-2021, 12:00 PM
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Originally Posted by Nikolas View Post
You missed my point I think
I personally use an osc camera because of my limited time for image acquisition and the crap weather Melbourne serves up. No time to acquire 4 times the time to acquire an image with different filters, what takes me hours would take me weeks with a mono camera.
Same exposure time OSC versus Mono and the mono will be less noisy, especially in the dim areas.

Its not less time for OSC and its not 4X time for mono. You simply spend less time on each of the LRGB components.

For these CMOS sensors that are so very sensitive, 30 minutes each for RGB is enough and say 30-60 minutes of Luminance is plenty for many objects so 2:30 total exposure time. That is within the time you are doing for OSC.
The OSC image would be nice on a bright object and where they usually fall short is in the dim, dusty areas. At least that was true with the older OSC CCDs. Probably not as true with the latest CMOS with 80-90% QE.

As you say you can produce great images with OSC and the gap has narrowed between OSC and mono over the years. But 4X more time for mono is not true. It could even be less time because its more efficient.

Having said that I wouldn't mind a OSC CMOS to complement my mono's. Thomas Davis used to use an SBIG OSC and a mono camera and combine them to great effect. Best of both worlds. He was hampered by a narrow imaging window and made the best use of available time. The OSC was on an FSQ106 and the mono on an AP RHA. So long as the OSC was a wider field scope that would work well.

Greg.
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  #25  
Old 02-03-2021, 12:38 PM
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Originally Posted by jahnpahwa View Post
Nik (and Chris), I have to chime in and say that I really don't believe this to be the case. I think imaging time for colour images is roughly equal (perhaps even quicker with mono), especially when the Luminance layer is well developed. A good set of filters (even my basic ZWO ones) are parfocal, or close enough to parfocal that it doesnt matter for 99% of people.

I'm not saying this because I'm team mono and want everyone on my team, but to let people know that this is a non-issue. The way it goes (if I am imaging a galaxy from the backyard) is I focus in Lum, I set an imaging routine in APT and press go and walk inside binge watch something on tv. I almost always set the routine to run vertically, ie, switch filters each sub (which is less than 1 second), so even if clouds come over an hour or two in, i still have a complete dataset to play with. This also negates the differing seeing as the targets moves through RA, metnioned by Chris below.

Don't agree sorry Mono easily doubles acquisition time for the amount of data collected.
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  #26  
Old 02-03-2021, 12:47 PM
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Originally Posted by Nikolas View Post
Don't agree sorry Mono easily doubles acquisition time for the amount of data collected.
Citation needed.

If you're concerned about focus time when changing filters, Voyager for example can do a focus routine in about 1 minute. That's not much to add.

You can also "cheat" if you've got parfocal filters and just focus on one filter, reducing the focusing time further.

As for the data itself, math that's out there already shows what has been already said - it doesn't cost more time.
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  #27  
Old 02-03-2021, 02:26 PM
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let's agree to disagree ok?
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  #28  
Old 02-03-2021, 02:33 PM
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Quote:
Originally Posted by gregbradley View Post
Thomas Davis used to use an SBIG OSC and a mono camera and combine them to great effect. Best of both worlds. He was hampered by a narrow imaging window and made the best use of available time. The OSC was on an FSQ106 and the mono on an AP RHA. So long as the OSC was a wider field scope that would work well.
Greg, are these the same OTAs you have? And if so, is it a coincidence?
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  #29  
Old 02-03-2021, 04:16 PM
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Originally Posted by Peter Ward View Post
If you are seeking excellence, mono is the ONLY way to go.

the new colour cameras can give great …in fact occasionally…award winning results.
These two points contradict each other.

Mono is wonderful. So are OSCs.

Pick your poison folks, do what's right for YOU, and don't be swayed too much by either side, because rarely you'll see someone say "I made a mistake"... instead you'll see a natural expression of Post-Purchase Rationalisation or Confirmation Bias.
These are completely normal things for the human brain to do, but it's the reason why people make bad witnesses.
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  #30  
Old 03-03-2021, 01:09 PM
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What as great number of interesting comments and observations. Thanks everyone.

Cheers, Gordy
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  #31  
Old 03-03-2021, 01:48 PM
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Originally Posted by jahnpahwa View Post
Greg, are these the same OTAs you have? And if so, is it a coincidence?
I have the RHA but not an FSQ although I have had 2 FSQ's in the past - lovely scopes. I have a CFF105 F6 and an AP130GT upgraded with the 3.5 inch GTX focuser and 3.5 inch flattener and a CDK17 F6.8 for small objects.

I haven't run 2 scopes at the same time on the same object one with OSC and one with luminance. Although my observatory has 2 piers and was designed to run 2 at once.

One is usually enough of a handful but I could run 2 at once.

I've had quite a few scopes over the years but settled on the above and finally don't feel any need for more. Each is excellent in its own class. Its a matter then of extracting that performance.

With regards to OSC I think the game as changed as these new CMOS sensors like the ASI2600/QHY268 are so sensitive. Nik's Eta Carina image for example is a good example. A superb image and the OSC has shown very good Ha and O111 performance. It looks to be about the same as a previous mono CCD where typical Ha and O111 sensitivity is often 30%- 50% or less. Usually less for O111.

Greg.
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  #32  
Old 03-03-2021, 02:11 PM
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To be honest the HA performance of my ASI2600MC surprised me. I have a fliter wheel on order and am in theprocess of selecting filters. I will go on to mono when money permits, but the FW may well be full of filters by the time I can afford the $3K or so for a mono ASI2600.

It would be interesting to compare NB data shot via both a mono and OSC cam (Better still, the mono and OSC versions of the same camera) to see the quantifiable difference between native resolution and interpolating from one pixel in four of a bayer matrix.
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  #33  
Old 03-03-2021, 02:15 PM
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Originally Posted by The_bluester View Post
To be honest the HA performance of my ASI2600MC surprised me. I have a fliter wheel on order and am in theprocess of selecting filters. I will go on to mono when money permits, but the FW may well be full of filters by the time I can afford the $3K or so for a mono ASI2600.

It would be interesting to compare NB data shot via both a mono and OSC cam (Better still, the mono and OSC versions of the same camera) to see the quantifiable difference between native resolution and interpolating from one pixel in four of a bayer matrix.
If anyone has both the 294mm and 294mc they could do a comparison
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  #34  
Old 03-03-2021, 02:34 PM
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I think it would be great to see a head to head comparison with the same optics and (somehow?) the same exposure. I suspect we'd be looking deep zoomed in to the image to see differences, but I love being wrong.

Best
JA
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  #35  
Old 03-03-2021, 02:59 PM
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If anyone has both the 294mm and 294mc they could do a comparison
I hope this year to have both versions of the 2600. As before, my plan is to gather the bits up over time so with any luck I will have a filter wheel full of filters. It would make an interesting experiment to shoot NB data on the same target with both versions of the camera to be able to see a quantifiable difference.
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  #36  
Old 03-03-2021, 08:39 PM
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You missed my point I think
I personally use an osc camera because of my limited time for image acquisition and the crap weather Melbourne serves up. No time to acquire 4 times the time to acquire an image with different filters, what takes me hours would take me weeks with a mono camera.
I am in a light-polluted area. As a result, I don’t try for OSC or LRGB images. If I want to achieve reasonably sharp images I have to use NB filters. The price is that I have to spread image acquisition over multiple nights. That’s just the way it is. It also means I can’t hope to get decent galaxy images. So it’s nebulae only or planetary. And each has it’s own season. Winter and Spring. The rest of the year is just a waste of time.
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  #37  
Old 05-03-2021, 11:29 PM
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There is no doubt most people who do AP long term started off on colour and then progressed to mono. In fact, I would say most of us started with a DSLR as 10+ years ago there wasn't the variety of OSC cameras available today. But today OSC colour cameras are high tech imaging units which are cooled and for anyone starting out and allow incredible detail to be captured very quickly and this can suffice for many years.

So to answer the OP's question, sure at a personal level absolutely no regrets, and once you have cycled through all the well known objects in the sky with a OSC camera and master processing you will long for more detail etc. and eventually go to mono. In light polluted skies in a city of 5 million people I am totally amazed what a Ha B&W camera can capture.

Do I miss some of the instant gratification of OSC? Not any more as Ha and L in B&W provide this and exceed the detail that OSC cameras provide. Would I like the simplicity of OSC processing rather than LRGB? Sure!

Just my 2 cents worth.

Clear skies.

John K.
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  #38  
Old 08-03-2021, 01:13 AM
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Do I miss some of the instant gratification of OSC? Not any more as Ha and L in B&W provide this and exceed the detail that OSC cameras provide. Would I like the simplicity of OSC processing rather than LRGB? Sure!

Just my 2 cents worth.

Clear skies.

John K.[/QUOTE]





Well said John.
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  #39  
Old 08-03-2021, 02:42 PM
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The price is that I have to spread image acquisition over multiple nights. .
And that's the crux of my argument, in my current lifestyle I don't have that luxury
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  #40  
Old 08-03-2021, 03:22 PM
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And that's the crux of my argument, in my current lifestyle I don't have that luxury
+1
If astrophotography was my only hobby, or major call on my time, then mono would make more sense for me.
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