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Old 16-08-2018, 11:03 AM
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cometcatcher (Kevin)
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Mono or OSC?

Funds are almost there, about to make the purchase. It will probably be an ASI183 chip as I want that sensor size. I want narrower field than APS-C. It will likely be on the 10" F4 most of the time.

I have enjoyed my DSLR. I like the simplicity of OSC, a lot. But OSC will never match mono in resolution or be able to do narrow band. I know the pro's and con's of each but at the end of the day which one will I enjoy using the most? I feel like I'm being left behind with OSC. But.... so much easier! And for comets OSC rates very favourable. Mono is such a pain for comets.

I'm not likely to automate for a while with filter wheels on the mono. I may use a manual one to start with.

Just thinking out loud.

Any extra thoughts?
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Old 16-08-2018, 11:11 AM
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multiweb (Marc)
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Depends on your image scale and if the bayer matrix will hack details in your subs. Also if you want to do NB, an OSC will take a little longer but it can be done. For widefield imaging a mono will always be better but at long FL with an image scale under 1 or around 0.5 then an OSC will do as well IMHO. Unless your optics and mount are top end and your stars pinpoint there will always be plenty of pixels in any single star.
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Old 16-08-2018, 11:51 AM
glend (Glen)
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Kevin, it also depends on your health going forward. In the near term your going to be pretty weak for a few weeks, then cardio rehab will help rebuild your stamina. As I am going through the same sort of health issues, I have parked my astro activities while I work out how much of a hit my health has taken. In my case I am going to be downsizing my scopes at the very least. As I am mainly imaging, refractors are likely my direction, and light weight triplets like those up to my 115mm TS APO.
As far as the ASI183 is concerned, it is worth while reading Jon Rista's ASI183 Beta Test thread on CN. I am a fan of mono cameras (having an ASI1600MM-C), and narrowband. With narrowband it doesn't matter too much about where I end up living, I can still image. OSC really needs darkness unless your ok with shooting a lot of extremely short subs to beat skyglow. My dark site trips are probably out for life now, i can't risk being too far away from a treatment facility if i have another health emergency (thinking about my as yet unstented blockage). I have sold off my camper trailer this past week, and accepted that i have to work from my home observatory in the future.
Narrowband gives you options, that is my message. It also gives you great artistic expression opportunities.
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Old 16-08-2018, 12:50 PM
Imme (Jon)
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Hi Kevin
There is no doubt mono will give you better results, I'll never argue that. But how much worse will the OSC be and is it so much worse that it takes it out of the equation? I don't think so. Some of my recent pic's with a OSC have been, in my opinion, pretty good. I've had a few comments surprised it is OSC actually.
I have the same thoughts on telescopes........You can spend $10k on a top of the line scope that would give better pics than a $2k scope, but how much better are they? Can you and I as hobbyists tell the difference? Probably not.
If you're wanting the best pictures you can get then my advice would be buy a new mount for $20K, then put a scope on top of it worth $10K, then buy a mono camera/filter wheel combo for $5k (in that order). A good mono camera will give amazing detail......but that detail will be smudged and ruined by a cheap mount, inferior optics or poor guiding.

I guess it boils down to this.....

You don't put re-treads on a Ferrari, so why put top of the line equipment on a mediocre mount and scope?

My 2 cents.....
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Old 16-08-2018, 12:55 PM
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ZeroID (Brent)
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Re the manual filter wheel comment, get an electronic one, an EFW from ZWO or similar. Being able to manage remote from inside is much easier.
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Old 16-08-2018, 01:15 PM
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Some very good points from all.

Glen, I will be imaging from the backyard ROR observatory. I'm Bortel 4-5 here in some directions, maybe a 3 in others. I don't see a problem health wise strangely enough as the obs makes everything a bludge. The roof rolls off with 2 fingers and everything is already setup ready to go. I don't need to lift anything heavier than a camera.

Jon, what you said makes a lot of sense. I have a 10" F4 on a wobbly HEQ5 Pro. A mono will pick up the slightest wobble, making for no advantage with sharpness until I get a better mount. Even then it will only be an EQ6 of some sort. I can always use a smaller refractor on it I suppose. The ED100 and a mono camera on that mount should be fine.

Decisions decisions. I'll just get one of each.
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Old 16-08-2018, 04:59 PM
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As much as I like my mono ASI1600, it doesn't seem to make a lot of sense for comet hunting.

DSOs are a sure thing, long (=60-90s) exposures on a target that is only moving at sidereal rate.

Planetary too, where the frame rates are so high that short but separate R, G and B sequences can be pieced together and derotated.

Comets...sit somewhere in between prolly want the longer exposures as they can be faint, but that makes piecing the colour channels together more challenging because of any motion.

OSC might be the balanced solution...

But check out the amp glow and challenges with calibrating the 183. Given your focal length, I can't imagine that the 1600 is at a disadvantage, and calibrates neatly every time.
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Old 16-08-2018, 05:24 PM
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There's also the 294 Dunk, if I want to go wider. I can probably make use of just about anything I get. I need to save the DSLR from premature death by excessive shutter count!

I do want a lot of smaller objects, like PN's and small galaxies. I know nothing compensates for aperture, I'm just cheating.
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Old 17-08-2018, 04:52 AM
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Quote:
Originally Posted by cometcatcher View Post
....
I do want a lot of smaller objects, like PN's and small galaxies. I know nothing compensates for aperture, I'm just cheating.
That's why I bought the Mak 180 (f15), planetary and small targets. I use the 120mc for guiding through an 80F5 but it goes on the Mak for planetary, lunar and I guess comets. DSO's the 1600mm-c is on the Lunt (F7) for nebulae etc but it can also go on the Mak for small targets. Easier than having Barlows involved I reckon.

Just tossing up whether to get a cheap mono for guiding and have the 120 and 1600 just swapping scopes as required. What's the QHY5 like for guiding ? There's one in the for sale lists.
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Old 17-08-2018, 05:52 AM
glend (Glen)
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Quote:
Originally Posted by cometcatcher View Post
There's also the 294 Dunk, if I want to go wider. I can probably make use of just about anything I get. I need to save the DSLR from premature death by excessive shutter count!

I do want a lot of smaller objects, like PN's and small galaxies. I know nothing compensates for aperture, I'm just cheating.
I would avoid the ASI294, it's problems were fairly well documented during beta testing. My reading on it is despite having great well depth owners can't really take advantage of it due to terrible AMP glow and uneven chip cooling which causes colour patterns which cannot be calibrated out. Flats would always be needed, whereas something like a 1600 can be used without flats, and is easily calibrated.
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Old 17-08-2018, 08:19 AM
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Quote:
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I would avoid the ASI294, it's problems were fairly well documented during beta testing. My reading on it is despite having great well depth owners can't really take advantage of it due to terrible AMP glow and uneven chip cooling which causes colour patterns which cannot be calibrated out. Flats would always be needed, whereas something like a 1600 can be used without flats, and is easily calibrated.
Apparently the amp glow problem with the 294 has been fixed by the latest driver updates, although I think the TEC is still undersize. The 1600MC -C has been discontinued, leaving only the mono version.

I'm still leaning towards the 183MC-C or 183 mono cool at this stage. A mono 1600 is more $ and I haven't even factored in filters or accessories, which the OSC won't need.
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Old 17-08-2018, 08:23 AM
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Just tossing up whether to get a cheap mono for guiding and have the 120 and 1600 just swapping scopes as required. What's the QHY5 like for guiding ? There's one in the for sale lists.
There's a version 2 out now. I had a loan of a little DBK mono and it was great. Though I'm still using my 20 year old frame integration video camera for guiding at this stage! Still works like a charm. At least on the Win 7 computer.
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Old 18-08-2018, 07:32 AM
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Quote:
Originally Posted by cometcatcher View Post
There's a version 2 out now. I had a loan of a little DBK mono and it was great. Though I'm still using my 20 year old frame integration video camera for guiding at this stage! Still works like a charm. At least on the Win 7 computer.
Yeah, I know about the Vers 2, which is probably why the Vers 1 is reasonably priced but if it's good enough for guiding and if the software doesn't clash with the ASI SW then it's a good option maybe.
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Old 18-08-2018, 09:58 AM
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Hi Kevin,
I have enjoyed my QHY9 mono.
https://www.flickr.com/photos/247194...in/photostream

I've had no time to use it for more than 1 year but
I will get back to it when time allows.
Yes - it's a bit of a learning curve for taking pictures
as well as processing but in my honest opinion
if you're going to be up all night taking pictures
then you might as well get a mono & take the best data possible.
A 10" f4 on a wobbly HEQ5 Pro is a boy on a man's errand.
Even with my modified EQ6 pro
https://www.flickr.com/photos/247194...in/photostream
the image has to be stopped about 1
in every 10 to 20 frames & started again due to the guide graph
going more than 1 pixel out.


I need more time to get some great pictures & the mono
will really give me the best possible results.
Maybe my best pic is here
https://www.flickr.com/photos/247194...in/photostream
with my 10" f4 ONTC mirror carbon fiber Telescope with motorised focuser from TS in Germany.
https://www.teleskop-express.de/shop...oducts_id/5647

A 10" f4 is an ideal size for taking pics as long as it's collimated correctly
which took me a while to learn how to do.


So - you need a better mount & a mono camera
& you'll be amazed at what your results will be.
You may be able to pick it all up second hand which
could save you a lot of money.



cheers
Allan
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Old 18-08-2018, 10:49 AM
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Quote:
Originally Posted by cometcatcher View Post
There's also the 294 Dunk, if I want to go wider. I can probably make use of just about anything I get. I need to save the DSLR from premature death by excessive shutter count!

I do want a lot of smaller objects, like PN's and small galaxies. I know nothing compensates for aperture, I'm just cheating.
Seems like most(?) of the Sony-derived chips exhibit pretty shocking amp glow, if not dealt with correctly. The 294 looks great on paper though.

I hear you on the aperture front...I jumped in with a 178 for galaxy chasing with my Esprit 100 hence first hand experience with the dreaded amp glow it's no doubt exacerbated by small pixels on small scope syndrome, and given your penchant for 30 second subs on a bigger, faster scope, you'd probably be OK
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Old 18-08-2018, 07:50 PM
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Yes Allan a heavier duty mount is on the cards. It should probably be first on the list, but I can always downsize the scope to a refractor if it comes to that.

Your pics are great dunk. Was thinking of the 178 but the chip is just to small for me.

At present I am favouring a mono. I'm not fully setup for a mono, but as mentioned I do have a bunch of smaller scopes I can practice on until I learn the ropes. There are too many advantages to pass up. And I can shoot Ha in moonlight. (it's usually only clear here when the noon is out) For comets I'll probably continue to use the DSLR.
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Old 19-08-2018, 02:05 PM
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The 183 series being 12 bit, is that going to be a big disadvantage against 14 bit? Even my DSLR is 14 bit.
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Old 19-08-2018, 02:47 PM
glend (Glen)
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The 183 series being 12 bit, is that going to be a big disadvantage against 14 bit? Even my DSLR is 14 bit.
I don't think so. The 1600 is 12 bit as well.
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Old 19-08-2018, 03:05 PM
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I don't think so. The 1600 is 12 bit as well.
That's good then. The ADC on the 178 and 294 are 14 bit. Guess it helps keep the price down.
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Old 19-08-2018, 03:11 PM
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The 12-bit ADC makes no difference in the end. The modern mono chips generate good signal with such low noise that the preferred strategy is lots of shorter subs (I rarely go above 60s) that are sky limited...the resultant larger number of subs claws back any perceived loss of precision in stacking.
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