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So let me get all of this stuff straight (mono and OSC cameras)

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#1 DRK73

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Posted 19 September 2020 - 12:54 PM

So I've always been a mono-camera guy since I live in a orange/white zone and had more or less convinced myself that RGB imaging, and especially imaging with a OSC given light pollution and the moon. I defaulted then to narrowband assuming that if and when clear nights come up there'd be a good chance that I'd be contending with the moon, so it made the investment I had made in RGB filters seem pretty wasted. 

 

I primarily did Ha/OIII bicolor images, though (though I sometimes added SII) because I prefer "semi-RGB" to SHO palette.

 

I left the hobby a few years ago but am getting back into it - but before doing so I want to have a plan for what I'm going to be after (last time I didn't so I ended up buying and selling lots of cameras and telescopes to try out what I liked and ended up spending a stupid amount of money on endless tinkering/experimenting). So I want to really understand the advantages and disadvantages of mono and OSC cameras given the likelihood I'd be imaging under very bad light pollution and/or a bright moon. I also want to point out that while I do have processing experience and own a copy of PI, I'm ###### at processing. I also want to leave myself room for possible upgrading as I have barely tested my current mount (the AVX) and have no idea if it'll hold up to guiding for 10 minute+ subs. 

 

Anyway, here's what I'm trying to understand - particularly about OSCs: 

 

With OSC, I'd always accepted the conventional wisdom that narrowband imaging was, even though possible, not really advisable for quality imaging because of the Bayer matrix. But - now there are filters (tri-band and quad-band) that allow you to image in each of the RGB channels but using very narrow FWHM channels (including H-beta). I understand that this filter can be looked at as an extreme light-pollution filter, as well as a way to produce full color narrowband images of emission nebula using a OSC with the emission lines mapped to (more or less) their "true color." 

 

So depending on the target, with a OSC you could use a multi-pass filter for emission nebula, but for galaxies, reflection nebula, etc., you obviously DON'T use that filter...so you just flip in some kind of general light pollution filter such as the Astronomik CLS-CCD? 

So for OSC, two filters then is all you need for just about any DSO and you can do that with a simple drawer - or just a 1.25" filter holder (I have one from Scopestuff) that threads onto the camera's T-adapter?

 

Okay, for mono then is the advantage that you can set exposure times deeper for a particular channel? It seems like now though that to accomplish what a OSC camera can do with a multi-pass filter, for a mono you'd need each narrowband filter with a filter wheel (and have to refocus between each filter), AND you'd also need a set of RGB filters plus a light pollution filter for galaxies and reflection nebula? 

 

So for mono, you'd need three or four narrowband filters + RGB filters + a filter wheel to do what a OSC can do for a lot cheaper and with a lot less additional equipment? 

 

Yes I understand there will be arguments over resolution, but I'm not going to make poster sized prints - mostly just after "pretty pictures" that I can share with my kiddos or other astro-dorks. 

 

The reason I'm asking this is because I know the kinds of flexibility I want in my imaging set-up (my goals are to make pretty images of things like M42, Andromeda, the Iris, the Pleiades, , the Heart and Soul, the Wizard - which covers a fairly wide range of challenges as some are narrowband, some are RGB, some are a little of both). At the moment I've got an old CCD camera, no filter wheel, and a single H-alpha filter. Before I go and start buying more stuff to build out the capabilities of my camera, I guess I'm wondering, why should I? Wouldn't it just be cheaper, simpler, more economical, and more fun to instead pick up a cooled CMOS OSC and try to drive a bit further out of town? 

 

Thanks for reading! 



#2 bobzeq25

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Posted 19 September 2020 - 01:59 PM

Answering just your main points, concentrating on the bolded material.

 

For OSC, you need only one filter, and your best bet is one of the new duo or triband filters.   They're not "extreme" unless you count extremely effective.  <smile> They were designed specifically for OSC and are justifiably popular.  A compromise between the old broadband LP filters and narrowband.  Emission nebulae only, of course.  And they don't replace gradient reduction in processing, they supplement it.

 

Mono plus filters is better than OSC, but just how much is a topic of endless debate here.  The Bayer matrix, designed specifically for terrestrial use, is a more inefficient filter.  Particularly when you stack _another_ filter on top.  Mono is _way_ more expensive (pretty much its only drawback, but a big one).  People do lovely images either way, mono takes less total imaging time.  Just how much...  I image both ways, depending on circumstances.

 

The one place mono has a large advantage is doing broadband in light polluted skies, when you use the LRGB technique.  This clever trick takes advantage of the fact that our eyes are designed to see detail in black and white.  Using just an L filter (which doesn't block much, it's just a UV-IR block) for half your imaging time is a big advantage.  All the pixels are working all the time on all the data.  The gap to OSC narrows substantially in dark skies.

 

This is simply a personal choice, not universal right/wrong.

 

If you're unsure of your processing skills, I strongly recommend Astro Pixel Processor.  Both stacks and processes, has an excellent gradient reduction tool.  Pretty intuitive as processing programs go.  Capable of excellent results, especially the recent version.

 

It drives me crazy when people object to spending a small amount of money on something that's at least 50% of this hobby.   And then spend large amounts of time and effort trying to make DSS and a terrestrial editing program work.  "False economy" is the phrase.


Edited by bobzeq25, 19 September 2020 - 02:07 PM.

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#3 wrnchhead

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Posted 19 September 2020 - 02:12 PM

APP has really good support also, from it's creator and from really good and smart users. Tons of tutorials online. I had no questions about it that weren't resolved with a search. 


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#4 Bretw01

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Posted 19 September 2020 - 02:54 PM

I have no experience in LP as bad as yours. Also no experience with mono cameras.

 

In bortle 4 zone I use OSC and the L_eNhance filter. My subs are mostly 10 minutes, unless you have a very good AVX I doubt you can do this. (I own an AVX and 3 minutes is about as long as I go with it).

 

The worst LP I deal with is the moon. Here is an example with OSC and L_eNhance with average moon phase 97%. The full moon on 7-4 was about 60 degrees from target.

 

get.jpg?insecure

 



 

 

Mono plus filters is better than OSC, but just how much is a topic of endless debate here.  The Bayer matrix, designed specifically for terrestrial use, is a more inefficient filter.  Particularly when you stack _another_ filter on top.  Mono is _way_ more expensive (pretty much its only drawback, but a big one).  People do lovely images either way, mono takes less total imaging time.  Just how much...  I image both ways, depending on circumstances.

 

Bob I agree with most of this but question the part in bold type.

2.4 hours with OSC and L_eNhance. 

 

get.jpg?insecure

 

 


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#5 Bretw01

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Posted 19 September 2020 - 03:28 PM

Here is a comparison of the same target with the same amount of exposure time but different sky quality.

 

22.7 hours with mono and filters from bortle 6 skies:

 

https://astrob.in/dmsels/B/

 

22.8 hours OSC and L_enhance bortle 4:

 

NGC7293_22hr50min_PIPSv2_1w.jpg

 

Hopefully you find this useful.


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#6 bobzeq25

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Posted 19 September 2020 - 06:30 PM

I have no experience in LP as bad as yours. Also no experience with mono cameras.

 

In bortle 4 zone I use OSC and the L_eNhance filter. My subs are mostly 10 minutes, unless you have a very good AVX I doubt you can do this. (I own an AVX and 3 minutes is about as long as I go with it).

 

The worst LP I deal with is the moon. Here is an example with OSC and L_eNhance with average moon phase 97%. The full moon on 7-4 was about 60 degrees from target.

 

get.jpg?insecure

 

Bob I agree with most of this but question the part in bold type.

2.4 hours with OSC and L_eNhance. 

 

get.jpg?insecure

With LRGB, it's the L filter.  Sucking down _all_ the photons with _all_ the pixels is the advantage.  It's basically like 2 extra F stops in optical speed, compared to how the Bayer matrix uses the pixels.

 

Some people also bin the color 2X2.  The detail is provided by the L, so the RGB can be shot at lower resolution.  Also like a couple of F stops.  The practice seems to go in and out of fashion.

 

With narrowband it's less but you're still using all the pixels with each filter, and the interference filters have better efficiency than dyed glass.  With broadband you're also using only 33% of the time gathering G, the Bayer matrix devotes 50% of the pixels to green.  It's been optimized for terrestrial, which has a lot of green.  In astro you frequently have excess green, which needs to be removed.

 

All that is less important.  But the big deal is that some people use their intuition, and think that "gathering all the colors at once" has to be faster.  Because of how the pixels are used, and the low signal to noise ratio in astrophotograhy, it's not.  Gathering more total photons is the big deal.  It's very much like people overestimating the value of subexposure, and underestimating the value of total imaging time.

 

Again, people make fine images with both, and mono is _way_ more expensive.  But people who do mono are not being trendy, they're spending the money for good reasons.


Edited by bobzeq25, 19 September 2020 - 06:33 PM.


#7 DRK73

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Posted 19 September 2020 - 10:05 PM

 

 

All that is less important.  But the big deal is that some people use their intuition, and think that "gathering all the colors at once" has to be faster.  Because of how the pixels are used, and the low signal to noise ratio in astrophotograhy, it's not.  Gathering more total photons is the big deal.  It's very much like people overestimating the value of subexposure, and underestimating the value of total imaging time.

 

Again, people make fine images with both, and mono is _way_ more expensive.  But people who do mono are not being trendy, they're spending the money for good reasons.

 

 

 

I see what you're saying, and I've learned that there is no free lunch in this hobby - but that's not what I'm after. I just want to make images that I am happy with, and am willing to accept that every path has its own limitations, but want to pick the best path forward *for me*. Because I've been down the road before of buying lots of filters, etc., but seeing the work that folks are doing now with a OSC and a tri- or quad-band filter, I can't help thinking that I'm pouring more money than I should into doing things the "hard way." Again, I'm *not* trying to become a world famous astrophotographer - just trying to scratch an intellectual itch and use the camera to see what eyeballs on their own cannot. 


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#8 17.5Dob

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Posted 19 September 2020 - 10:21 PM

I see what you're saying, and I've learned that there is no free lunch in this hobby - but that's not what I'm after. I just want to make images that I am happy with, and am willing to accept that every path has its own limitations, but want to pick the best path forward *for me*. Because I've been down the road before of buying lots of filters, etc., but seeing the work that folks are doing now with a OSC and a tri- or quad-band filter, I can't help thinking that I'm pouring more money than I should into doing things the "hard way." Again, I'm *not* trying to become a world famous astrophotographer - just trying to scratch an intellectual itch and use the camera to see what eyeballs on their own cannot. 

$250 dSLR + L-Enhance filter +Bortle 5 skies + Full Moon

50298025528_35d7204742_c.jpg

 

50308874968_d92270488e_c.jpg

 

50292587982_648e6a43f4_c.jpg

 


And finally, with no moon

50343693447_eb35bdfb5b_c.jpg

 

50340369242_32bb84c9eb_c.jpg

 


Edited by 17.5Dob, 19 September 2020 - 10:22 PM.

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#9 bobzeq25

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Posted 19 September 2020 - 10:41 PM

I see what you're saying, and I've learned that there is no free lunch in this hobby - but that's not what I'm after. I just want to make images that I am happy with, and am willing to accept that every path has its own limitations, but want to pick the best path forward *for me*. Because I've been down the road before of buying lots of filters, etc., but seeing the work that folks are doing now with a OSC and a tri- or quad-band filter, I can't help thinking that I'm pouring more money than I should into doing things the "hard way." Again, I'm *not* trying to become a world famous astrophotographer - just trying to scratch an intellectual itch and use the camera to see what eyeballs on their own cannot. 

Sure.  OSC is not a bad way to go.  I do a lot of it myself.  You wanted to know the issues around mono and OSC, that was the only reason I went into it.  Not to try to talk you into mono.

 

We've discussed emission nebulae.  Here's Andromeda, Bortle 7, with OSC (a Nikon D5500 DSLR).  No (not so) magic light pollution filters.  A photographer friend of mine playfully accused me of faking it.  He wasn't serious, really was just paying me a compliment.  He lives a few miles away, knows that the sky looks like from here.

 

Next post shows a newer version, a mosaic with my C8RASA, and a 183 OSC camera.  Again, no filter.

 

I did spend a fair amount of time on gradient reduction, on both.

 

Attached Thumbnails

  • M31 SV70T small.jpg

Edited by bobzeq25, 19 September 2020 - 10:52 PM.

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#10 bobzeq25

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Posted 19 September 2020 - 10:45 PM

Click on this to see the detail, the dim extension.  Again, Bortle 7.

 

Better versions (than the required CN small jpgs) here, with data acquisition details.

 

https://www.astrobin.com/263253/J/

 

https://www.astrobin.../full/025umc/0/

 

 

M31 mosaic V6.jpg


Edited by bobzeq25, 19 September 2020 - 10:50 PM.


#11 17.5Dob

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Posted 19 September 2020 - 10:56 PM

Sure.  OSC is not a bad way to go.  I do a lot of it myself.  You wanted to know the issues around mono and OSC, that was the only reason I went into it.  Not to try to talk you into mono.

 

We've discussed emission nebulae.  Here's Andromeda, Bortle 7, with OSC (a Nikon D5500 DSLR).  No (not so) magic light pollution filters.  A photographer friend of mine playfully accused me of faking it.  He wasn't serious, really was just paying me a compliment.  He lives a few miles away, knows that the sky looks like from here.

 

Next post shows a newer version, a mosaic with my C8RASA, and a 183 OSC camera.  Again, no filter.

 

I did spend a fair amount of time on gradient reduction, on both.

 

attachicon.gifM31 SV70T small.jpg

16 min total exposure...NOT even a D5300...a really total junk stock dSLR camera...6 yr old photo, one from my very first 3 months imaging, Bortle 8, no filters

Don't let Bob scare you...

49659923742_0a514f1f25_c.jpg

 


Edited by 17.5Dob, 19 September 2020 - 11:07 PM.

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#12 terry59

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Posted 20 September 2020 - 05:20 AM

Hi Dan....things have changed since you left the hobby with the explosion of cooled CMOS cameras available. I'm really impressed with the OSC ones where images were taken from dark skies. If I lived in those conditions, I'd definitely go that route. The new tri band filters etc. have not impressed me and I would not go that way. With these CMOS cameras exposures are usually 5 minutes or less too. This is the latest from my SV70T/QHY183M, which should work well with your AVX

Attached Thumbnails

  • ic1848 sho.jpg

Edited by terry59, 20 September 2020 - 05:21 AM.

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#13 DRK73

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Posted 20 September 2020 - 08:59 AM

Hi Dan....things have changed since you left the hobby with the explosion of cooled CMOS cameras available. I'm really impressed with the OSC ones where images were taken from dark skies. If I lived in those conditions, I'd definitely go that route. The new tri band filters etc. have not impressed me and I would not go that way. With these CMOS cameras exposures are usually 5 minutes or less too. This is the latest from my SV70T/QHY183M, which should work well with your AVX

In a way I'd like to go the route of a modded DSLR, but like you said there are so many variants of cooled CMOS that (*to me*) buying a modded DSLR doesn't make sense (unless someone wanted to also use it for daylight photography, which is interesting to me but something I probably wouldn't do very much of). For astro though I feel like cooling is really the best way to go if for no other reason than to be able have proper darks. 

 

Regarding the AVX, I plan on using either a Nikon 300mm f/4 - or if that doesn't work on then I'll use my AT72 at f/6 (I have a FF for it). But I know my weak link is the mount and doing long exposures needed for narrowband with my ST8300 is going to be asking a lot of that mount and I'm not going to be shocked if I end up having to upgrade that soon. I picked it up when I thought myself unlikely to do DSO imaging again, but here we are...

 

That said, I see what a lot of people are doing with (esp) the OSC CMOS cams is a very large number of shorter subs, in which case I guess my AVX would be all right for. 

 

I'm going to take my time with this - there's a lot I feel like I need to understand a lot better.


Edited by DRK73, 20 September 2020 - 09:00 AM.

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#14 DRK73

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Posted 20 September 2020 - 09:12 AM

Sure.  OSC is not a bad way to go.  I do a lot of it myself.  You wanted to know the issues around mono and OSC, that was the only reason I went into it.  Not to try to talk you into mono.

 

We've discussed emission nebulae.  Here's Andromeda, Bortle 7, with OSC (a Nikon D5500 DSLR).  No (not so) magic light pollution filters.  A photographer friend of mine playfully accused me of faking it.  He wasn't serious, really was just paying me a compliment.  He lives a few miles away, knows that the sky looks like from here.

 

Next post shows a newer version, a mosaic with my C8RASA, and a 183 OSC camera.  Again, no filter.

 

I did spend a fair amount of time on gradient reduction, on both.

 

attachicon.gifM31 SV70T small.jpg

 

That's a really nice image and I'd like to be able to do something like that eventually. In all honesty my processing skills are that bad (though I'm more familiar with Photoshop than PI because I use that a lot more for regular photography) - I really struggled when it came to combining my H-a with OIII subs then I felt like I could never get the color right and usually hated the end result! I tried Andromeda recently and was really disappointed in not only the gradients I couldn't get rid of, but also a very strong green/orange pattern on the bottom right and top left of my frame...I didn't use darks because although I knew the temperature was dropping I didn't know what it actually was and couldn't have done anything about it, anyway. I was using a Nikon D610 with my Rokinon 135 @ f/2, ISO 800, and at even 30 seconds my skies were blown out. I managed to get my histogram back under control by going to ISO400 and just tried to grab as many subs as I could - ended up with 140 subs of mostly 15 seconds. 

 

The experience taught me that my skies were just too bad to allow for OSC imaging and a buddy loaned me his old ST-8300 so I could go back to doing narrowband - but now I'm seeing people post images taken with CMOS OSC taken under skies as bad as mine (or nearly as bad) and I'm blown away - and hence my question(s) :)


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#15 bobzeq25

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Posted 20 September 2020 - 10:07 AM

That's a really nice image and I'd like to be able to do something like that eventually. In all honesty my processing skills are that bad (though I'm more familiar with Photoshop than PI because I use that a lot more for regular photography) - I really struggled when it came to combining my H-a with OIII subs then I felt like I could never get the color right and usually hated the end result! I tried Andromeda recently and was really disappointed in not only the gradients I couldn't get rid of, but also a very strong green/orange pattern on the bottom right and top left of my frame

Have you tried the Gradient xTerminator plugin for Photoshop?  I use, and like PixInsight, but GxT is decent.

 

I've struggled with color in narrowband too.  My personal solution is to do one of two things.  Ha in black and white.  Combine narrowband with RGB, PI has a NBRGBCombination tool.  My first such took me about 50 hours, I'm now down to maybe 20.

 

But that's just my personal solution, there are many ways to go.



#16 Ballyhoo

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Posted 20 September 2020 - 12:01 PM

i also think that OSC can be really great with the triad filter. Proably a step up in strengh from like an L-enhance.

 

but then that requires investment. 


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#17 DRK73

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Posted 20 September 2020 - 12:32 PM

i also think that OSC can be really great with the triad filter. Proably a step up in strengh from like an L-enhance.

 

but then that requires investment. 

Looks like the difference between the L-enhance and the Radian tri-pass is that the Radian has a significantly narrower FWHM. Also about double the cost. 

 

The Radian quad-band strikes me as the kind of thing you hope your wife never finds out about...




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