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Where do I start with DSO imaging?

Astrophotography Beginner
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#1 tita

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Posted 22 April 2021 - 01:17 AM

I am looking for some advice on what is the best approach to learn AP for someone who has zero experience with it. My goal is to learn the basics and take some okay photos as I learn. I am not expecting anything amazing, just looking forward to enjoying the journey. My question is what DSOs would be the best ones to start with given my lack of experience?

 

In terms of equipment I had purchased months ago the EQ6-R and placed an order for an Edge8. I got the mount right away but Celestron was not delivering anything.Afetr waiting for six months I gave up on the Edge8 and decided to split what I would spend on it on a Sky Watcher 10" Dobs just for visual and get a small entry level refractor and camera to get started on AP. I just purchased an AT72EDii and a ZWO120MC-S, I expect them to arrive this weekend just in time to the scheduled rainy week.

 

I also wonder if I have all I need. Besides the equipment I listed above, is there anything else that is essential? Does the camera attachs directly where the EP would go on the refractor or I need some extension to attain focus? I will be doing most of my imaging in my backyard (Bortle 7).



#2 ravenhawk82

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Posted 22 April 2021 - 04:00 AM

Welcome! Congratulations, it sounds like you're off to a good start :D

You may need an extension tube to achieve focus. I don't know about that scope for absolute certain, but my AT80ED stops just shy of having enough focus travel for the camera to go into the tube directly and I'd assume the AT72ED has similar backfocus.

One thing to keep in mind though, the ASI120 series cameras are intended more for either autoguiding or planetary imaging. DSO photography really isn't their strong suit so you'll be limited to brighter objects that don't require very long exposures. Since you don't have any way to guide right now you'll be limited to shorter exposures anyway. To get started, I'd aim for bright globular clusters like M13 and see what you can manage out of them. You should be able to achieve 60s unguided subs over most of the sky if you practice getting your polar alignment as spot on as possible. It's a little late for Orion now, but in a couple months you can try for the Lagoon Nebula and other bright objects along the galactic plane.

Aside from DSOs it also makes a great planetary imager. If you put some rings and a barlow on your 10" newt later this year you can mount it on the EQ6 and get some photos of Jupiter and Saturn at their oppositions in Summer! That's a bigger scope than I'd trust for reliable DSO imaging on that mount but it'd be doable for shooting some planetary video, and the 120MC is a good tool for doing that.

As long as you have reasonable expectations of this camera's DSO capabilities I think you'll have a blast with it. If you ever decided to upgrade to a cooled chip down the line you can use it as a guide camera to get much longer exposures!



#3 mayhem13

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Posted 22 April 2021 - 06:39 AM

Personally how I started my AP journey just a year ago was with the same refractor and imaging the Moon. The large target offered me soooooo much hands on experience with working on the sky in the dark in regards to exposure time, ISO, setup stability, color rendering.....but most important proper focusing and the challenges it presents from a screen instead of objective lenses. I’d first get the .8 reducer for the AT72 for flatter images and a full frame view of the Moon with your ZWO 120.

 

The moon will allow you some basic hands in time with the EQ6 as well....understanding slew control, vibration reduction and get comfortably familiar with polar mount setup and proper alignment. The ONE major lesson I learned is that this hobby is FOUNDATIONAL on a proper and stable....well.....foundation...that being the mount.......so proper setup is crucial. Master the process of mount setup, alignment and slewing?.......the rest will fall into place quickly and allow for you to concentrate on the artistic side of the hobby.

 

Start with the upcoming Super Moon this Monday evening and then work on the phases every few days as you’ll start to pickup all the awesome contrast the Moon has to offer as it dims. Trust me when I say the lunar AP experience is invaluable as you approach an attempt at deep sky where the learning curve is vicious!

 

Best of luck and enjoy!



#4 TelescopeGreg

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Posted 22 April 2021 - 12:43 PM

Recommended reading are books on Deep Sky Imaging.  There's one by Charles Bracken ("Deep Sky Imaging Primer", 2nd edition), and another by Allen Hall ("Long Exposure Astrophotography").  I use them as a reference, looking stuff up when I have a question or puzzle, but reading either of them front-to-back isn't a bad idea.  It depends on how you learn - some do by reading, some by doing.  (I'm in the later group...)

 

The hobby is one of a bazillion little details, none of which are really all that hard to understand or deal with, but when taken as a whole it can seem overwhelming.  #1 lesson for me was that microns count, and that one needs to be precise in their technique and strive for repeatability in what you do.  Every image you take contains a record of all the things that went right as well as wrong while the shutter was open.  Study them and let them teach you about what is going on, as well as enjoy them for what they reveal about our night sky.

 

As noted by others, the 120MC is best for really small, really bright objects - the planets and small bits of the Moon.  Definitely grab the Moon as a test target, since it's handy.  Coming up this summer will be M13 and M57, which were my first DSO AP objects.  I took them with a planetary camera, too, before realizing that Celestron had led me astray with their marketing.  Huge upgrade, and frankly a breath of fresh air, was to find a DSLR at a local swap; that and a simple "T-ring" adapter netted me several years of imaging.  If you have a DSLR, I highly recommend that approach.  It doesn't need to be anything special. 



#5 tita

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Posted 22 April 2021 - 01:21 PM

Welcome! Congratulations, it sounds like you're off to a good start laugh.gif

You may need an extension tube to achieve focus. I don't know about that scope for absolute certain, but my AT80ED stops just shy of having enough focus travel for the camera to go into the tube directly and I'd assume the AT72ED has similar backfocus.

One thing to keep in mind though, the ASI120 series cameras are intended more for either autoguiding or planetary imaging. DSO photography really isn't their strong suit so you'll be limited to brighter objects that don't require very long exposures. Since you don't have any way to guide right now you'll be limited to shorter exposures anyway. To get started, I'd aim for bright globular clusters like M13 and see what you can manage out of them. You should be able to achieve 60s unguided subs over most of the sky if you practice getting your polar alignment as spot on as possible. It's a little late for Orion now, but in a couple months you can try for the Lagoon Nebula and other bright objects along the galactic plane.

Aside from DSOs it also makes a great planetary imager. If you put some rings and a barlow on your 10" newt later this year you can mount it on the EQ6 and get some photos of Jupiter and Saturn at their oppositions in Summer! That's a bigger scope than I'd trust for reliable DSO imaging on that mount but it'd be doable for shooting some planetary video, and the 120MC is a good tool for doing that.

As long as you have reasonable expectations of this camera's DSO capabilities I think you'll have a blast with it. If you ever decided to upgrade to a cooled chip down the line you can use it as a guide camera to get much longer exposures!

I will look for an extension tube. Are they standard,meaning they should work for most refractors as long as I match the diameter? 

 

I do realize that the camera is not good for DSO but my expectations are really low. My goal is just to learn the basics and I am sure I will take many low quality photos for some time. I am patient, so that will work on my favor.

 

Adding the 10" to the mount! What a wild idea, that would never crossed my mind. I will look into that possibility.



#6 tita

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Posted 22 April 2021 - 01:26 PM

Personally how I started my AP journey just a year ago was with the same refractor and imaging the Moon. The large target offered me soooooo much hands on experience with working on the sky in the dark in regards to exposure time, ISO, setup stability, color rendering.....but most important proper focusing and the challenges it presents from a screen instead of objective lenses. I’d first get the .8 reducer for the AT72 for flatter images and a full frame view of the Moon with your ZWO 120.

 

The moon will allow you some basic hands in time with the EQ6 as well....understanding slew control, vibration reduction and get comfortably familiar with polar mount setup and proper alignment. The ONE major lesson I learned is that this hobby is FOUNDATIONAL on a proper and stable....well.....foundation...that being the mount.......so proper setup is crucial. Master the process of mount setup, alignment and slewing?.......the rest will fall into place quickly and allow for you to concentrate on the artistic side of the hobby.

 

Start with the upcoming Super Moon this Monday evening and then work on the phases every few days as you’ll start to pickup all the awesome contrast the Moon has to offer as it dims. Trust me when I say the lunar AP experience is invaluable as you approach an attempt at deep sky where the learning curve is vicious!

 

Best of luck and enjoy!

okay, I'll add 0.8 reducer to the shopping list.

I certainly need to learn to polar align well. I can do it but I am not sure how good my alignment actually is. I am planning to take photos of moon and planets for sure. I will follow your advice and start with the moon. 



#7 tita

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Posted 22 April 2021 - 01:39 PM

Recommended reading are books on Deep Sky Imaging.  There's one by Charles Bracken ("Deep Sky Imaging Primer", 2nd edition), and another by Allen Hall ("Long Exposure Astrophotography").  I use them as a reference, looking stuff up when I have a question or puzzle, but reading either of them front-to-back isn't a bad idea.  It depends on how you learn - some do by reading, some by doing.  (I'm in the later group...)

 

The hobby is one of a bazillion little details, none of which are really all that hard to understand or deal with, but when taken as a whole it can seem overwhelming.  #1 lesson for me was that microns count, and that one needs to be precise in their technique and strive for repeatability in what you do.  Every image you take contains a record of all the things that went right as well as wrong while the shutter was open.  Study them and let them teach you about what is going on, as well as enjoy them for what they reveal about our night sky.

 

As noted by others, the 120MC is best for really small, really bright objects - the planets and small bits of the Moon.  Definitely grab the Moon as a test target, since it's handy.  Coming up this summer will be M13 and M57, which were my first DSO AP objects.  I took them with a planetary camera, too, before realizing that Celestron had led me astray with their marketing.  Huge upgrade, and frankly a breath of fresh air, was to find a DSLR at a local swap; that and a simple "T-ring" adapter netted me several years of imaging.  If you have a DSLR, I highly recommend that approach.  It doesn't need to be anything special. 

I do learn both ways but I lean more towards hands on. I think the book will provide background to explain what I am doing and why. I like that aspect of the hobby as well. Thanks for the tip.



#8 Juzwuz

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Posted 22 April 2021 - 01:58 PM

https://astronomy.to.../field_of_view/

 

Take a look at the field-of-view calculator in the Imaging Mode (2nd tab). You can select different targets, telescope, and camera and it will show you the field-of-view. It can help you choose the best target for your equipment or help choose suitable equipment for your target. 



#9 jonnybravo0311

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Posted 22 April 2021 - 05:36 PM

One thing to note - you might not be able to use that 10" for imaging. Unless it's been designed for imaging (like the Orion 10" astrograph), chances are extremely good you'll never be able to achieve focus with a camera without performing modifications like moving the primary mirror up the tube.



#10 tita

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Posted 22 April 2021 - 06:28 PM

One thing to note - you might not be able to use that 10" for imaging. Unless it's been designed for imaging (like the Orion 10" astrograph), chances are extremely good you'll never be able to achieve focus with a camera without performing modifications like moving the primary mirror up the tube.

Don't give me ideas, lol. I have a flex tube so in theory I could move the secondary closer to the primary. I need to freshen up my knowledge of optics to calculate the right distance.

 

Actually when I extend the tube, there is a click halfway that I have no idea why it is there. The manual does not mention anything about it.


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#11 TelescopeGreg

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Posted 22 April 2021 - 09:02 PM

One thing to note - you might not be able to use that 10" for imaging. Unless it's been designed for imaging (like the Orion 10" astrograph), chances are extremely good you'll never be able to achieve focus with a camera without performing modifications like moving the primary mirror up the tube.

Ooh, good catch!  At f/4.7 (if I'm finding the right model), it will certainly need a coma corrector as well.  A Paracorr-2 will fix that, and also likely get a DSLR to prime focus.  I used one on an 8" f/5 Newtonian.  A small chip / short back-focus planetary camera might work without either.

 

But, that scope was for visual use...  Imaging with a non-motorized Dob is pretty much limited to Lunar and planetary anyway.  Don't distract them!



#12 tita

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Posted 23 April 2021 - 04:33 PM

Ooh, good catch!  At f/4.7 (if I'm finding the right model), it will certainly need a coma corrector as well.  A Paracorr-2 will fix that, and also likely get a DSLR to prime focus.  I used one on an 8" f/5 Newtonian.  A small chip / short back-focus planetary camera might work without either.

 

But, that scope was for visual use...  Imaging with a non-motorized Dob is pretty much limited to Lunar and planetary anyway.  Don't distract them!

It is f/4.7

I bought from my local shop but here it is on Astronomics site

https://www.astronom...r.html?___SID=U

 

I am enjoying it a lot for visual. All jokes aside, the tube is heavy and I would be worried about overloading the mount. I think the tube alone is around 33 pounds! It is unlikely I can lift it to place on the mount anyway. I am a short old lady and mounting the head of the EQ6-R is my limit.


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