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Galaxies far away....

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#1 Danoglide63

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Posted 22 April 2021 - 05:03 PM

Hi everybody!

I got started about 2 years ago and have worked my way up to a David H Levy 152mm MakNewton, ASI533MC pro and an AVX mount. I’m guiding with an ASI 120mm mini and a 50 mm guide scope. Medium size DSO’s have been great and I’ve enjoyed parts of the bigger ones but now it’s Galaxy season and what I’ve came across lately are rather small. I have a 2x 2”Barlow I’ve had for years I’ve been trying to grasp onto how to use it but the exposures are really long like 3-4 minutes and not very productive. Sooooooo.......without buying another OTA what can I do? I used to have an ASI224MC that looked pretty good for the money but I let it go. Now there’s the Asi178mc “The ASI 178 camera has extremely high sensitivity. It is suitable for the Moon and planets, but also for deep sky objects, making in universally applicable!” Sounds good to me but is it? 
 

What’s a good solution? I’m not requiring Hubble quality.

 

Thanks,

Dano



#2 ChiTownXring

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Posted 22 April 2021 - 05:18 PM

I am in the same boat with my 714 FL APO and I am new to the hobby so I am just taking my subs and then crop and resize the image. I really don't think we can do anything else besides buying a big Schmidt-Cassegrain..


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#3 rj144

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Posted 22 April 2021 - 05:24 PM

Try Virgo and go wide field to get many galaxies in the same frame.  It's pretty cool.


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#4 Stelios

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Posted 22 April 2021 - 06:03 PM

Start by PLEASE forgetting about using a Barlow for DSO! All you will achieve is quadrupling (yes, 4x) your acquisition time and adding a possible degradation to clarity not to mention possibly introducing tilt. You will also make guiding much harder. And for what? 

 

Your Mak Newt has a 731mm F/L. Your ASI533MC-Pro has a 3.76um (micron) pixel size. This makes your image scale 1.06"/px. This is pretty much ideal. 

 

A Barlow would halve this to .53"/px. You are unlikely to have the seeing to support this, even if you could guide as well (almost impossible with an AVX) at that focal length. You would get a bigger image, sure--but it would have about the same detail you would get by just zooming in on the image obtained with your 1.06"/px image scale. 

 

You are much more limited in your ability to image DSO by your mount. What's your guiding RMS? You would be surprised at how good images of galaxies can get with a 1.06"/px image scale when you are able to guide at sub-arcsec RMS consistently. This is an image of NGC 7331 (a fairly smallish galaxy) and the *small* Stephan's quintet, taken by a scope and camera pretty similar in specs to yours. And my processing at that time was sub-par.

 

The cameras you mentioned are planetary UNcooled cameras. They will result in far worse images than the ASI533MC-Pro. Yeah, everything is universally applicable. Any camera that can keep the shutter open for more than five seconds can be used to image DSO. But the noise will kill you, the FOV is smaller.

 

The COOLED version of the ASI178MC (the -Pro) does have smaller pixels than your camera (and significantly smaller FOV). The ASI183MC-Pro is a larger sensor with small pixels. Both those will give you 0.677"/px image scale with your current camera. This will be THEORETICALLY better than what you have now--but I doubt if you would be able to track well enough to take advantage of either of those with an AVX. 

 

Bottom line: 

1) Do the best you can now. Optimize your guiding. You can get very nice shots with your current equipment.

2) Improve the MOUNT first. This will "magically" make your images better by improving your guiding, unless you have an exceptional (and largely fictional) AVX copy.

3) With a better mount, check your seeing. If it's normally above average (average for the US is around 2"-3"), like in the Florida Keys, then you may benefit from an ASI-178MC-Cool (if they still make them) or an ASI183MC-Pro or an ASI294MC-Pro (which can be used in 2.3um pixel mode). 


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#5 Midnight Dan

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Posted 22 April 2021 - 06:09 PM

+1 for everything Stelios said. wink.gif

 

-Dan


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#6 Birddogoby

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Posted 22 April 2021 - 08:34 PM

Just a quick follow up to the excellent advice of previous replies. I have a EQ6-R and use one of two full frame cameras that produce image scales of .89, 1.11, 1.23, 1.57, defending on whether I'm using a reducer or prime focus on my Tak TSA-120. The mount tracks very well (typically .2-.5 RMS) but even with those numbers, I'm pushed to the limit with my QHY600M at an image scale of .89. I have to be very careful about my exposure length, guiding and atmospherics at that small image scale. I can't imagine trying to manage imaging with a Barlow at an even smaller image scale at .53 or whatever.

Maybe I have a good copy of a EQ6-R but you don't have to spend $10k on a mount to produce good images. Spend money up front for a nice mount and good things will follow with patience, experience and the advice of others, all things being equal.

Sent from my SM-G960U using Tapatalk
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#7 TelescopeGreg

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Posted 22 April 2021 - 11:36 PM

Piling on here, and totally agreeing with Stelios, but perhaps with a different time line in mind.  How long have you been using the MacNewt / 533 / AVX combo?  Personally, I'd stick with what you have right now, and work on your technique; his #1.  Timeline to #2 may be longer than you are thinking.

 

Deep Sky AP requires a bit of patience and practice to get the most out of your equipment, otherwise you're looking at over-killing the solution to make up for it, and that gets really expensive, really fast.  Instead, get your balance adjusted in a way that your AVX likes it (they each have their own personality); tweak and optimize PHD2's parameters.  You might upgrade the guide scope and camera, but you're not totally out in the weeds with what you have, as long as it's properly attached.  Get really good at polar alignment, to keep the AVX's Dec motor quiet.  If possible, mount your equipment to keep it as low, balanced, and compact as possible.  Remove anything that doesn't absolutely have to move, away from the stuff that does.  Watch the cable dress.  Fine tune the focus (certainly my challenge!).  Understand proper exposure, and the proper use (and not) of filters.  This is all hygiene.  Go for more data (hours) to bring out the fine detail.  It can be there.

 

I've spent (only) 4 years at this hobby, making upgrades and adjustments in equipment, yes, but mostly learning how to use what I have.  I started with an 8" f/5 Newtonian on that AVX mount.  I kept improving, but also kept getting advice to dump the AVX and get a better mount.  I might do that some day, but it keeps surprising me as I've made other changes to the system and how I use it.  I still have it, because I keep finding it's not the weakest link.  I am.

 

After hitting this month's Challenge target (Markarian's Chain), I stumbled across a cute little galaxy that was just begging to be imaged.  I imagine it's the sort of target you're going after.  This is NGC 4535, the Lost Galaxy, and it's about the same size as the one Stelios imaged, also with 4hrs integration.  My scope is longer in focal length than your MacNewt (not necessarily an advantage - it makes it much harder to control), the camera pixels are the same 3.76u as your 533, and it's all on top of that same AVX mount. 

 

To be sure, I could spend "500 Lattes" on a better mount, that would probably reduce the star size a bit, and improve the detail in the galaxy, but the limit in Seeing is what it is (it's not great here), and I expect doing a better job at (re)focusing would go a long way to closing that gap.  Doing that won't require me to spend money on anything, but just get better at using the tools that I already have.  And all that skill will directly apply to any mount, scope, camera, and processing that I do in the future.  Stelios is much more experienced at both imaging technique and processing than I am.  Imagine what he could do with my (or your) equipment?

 

So I'll work on my focusing, THEN I'll consider upgrading the mount.  Maybe.  No promises...  Maybe after a reducer / flattener first?  Markarian's chain was just too big to image.  That said, mosaics can be free, too, and that's another skill I don't yet have.

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  • NGC4535 Lost Galaxy 3 nights 4hrs DSS ST old process sharp (reduced).jpeg

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