Getting Ready for Deep Sky Imaging

[Mandy D]

I'd like to do some deep sky imaging alongside my lunar and solar and could do with some advice.

My proposed setup is an Evoguide 50ED and ASI178MM on an AZ-EQ5GT mount. Obviously, the mount is adequate for this setup. I will be getting the Evoguide field flattener later, but for now I just want to get set up. I'm not worried about over/under-sampling right now, so let's not talk about that, beyond which it is at the moment. That can be discussed later. What I am concerned about now is getting this lot set up and working. I need to get a longer USB3 cable for the camera, as I don't have a laptop set up yet, so will be viewing the camera output from my living room about 2-3 metres from the imaging rig.

I have ASI Studio for capturing images and would like to stick with that for now, if that is sensible, even though better options may be available. Likewise, I use PIPP and AS3! and only wish to add anything to this mix that is absolutely necessary or if these are going to make life difficult.

My planned target for starting is M42, as it is an easy one to begin with.

So, here are my first questions:

1. Is my choice of kit suitable and do i need anything else? I'm not considering colour imaging, yet.

2. How do I best set up the mount, as I have never done this before? I have the instruction manual.

Let's leave the questions around actual imaging and processing for now and come back to those later, once I know how to get set up properly.

[vlaiv]

35 minutes ago, Mandy D said:

1. Is my choice of kit suitable and do i need anything else? I'm not considering colour imaging, yet.

Make sure you have IR/UV cut filter. You camera is mono and it has only AR coated window and you will be using that with refractive optics (even if it is a well corrected one - you still want to filter out IR and UV parts of spectrum to remove excessive bloat/blur).

Other than that - nothing special.

Setup your mount in EQ mode, do decent polar alignment and start of with shorter subs (15-30s) - see how you get on with those.

[StevieDvd]

First thing I'd do is to get a rough focus during the day, on a distant landmark, aerial etc.  Use ASIStudio (or SharpCap if you have it) and of course for daytime use very short exposures.

Next step is to try the same at night but on a reasonable target (the moon perhaps).

For the mount you'll need a polar alignment method to get a reasonable unguided image - later you might consider a guide scope/software.  Polar alignment is down to your preferences, either manula or software/hardware assisted. If you have a good North view then the paid for add on in Sharpcap may be suitable. The free ones that come with other software can be daunting as part of a full astro package.

Steve

 

 

 

[Mandy D]

2 minutes ago, vlaiv said:

Make sure you have IR/UV cut filter. You camera is mono and it has only AR coated window and you will be using that with refractive optics (even if it is a well corrected one - you still want to filter out IR and UV parts of spectrum to remove excessive bloat/blur).

Other than that - nothing special.

Setup your mount in EQ mode, do decent polar alignment and start of with shorter subs (15-30s) - see how you get on with those.

Good point on the UV/IR. I only have a 2" one, so will order a 1¼" one.

[Mandy D]

5 minutes ago, StevieDvd said:

First thing I'd do is to get a rough focus during the day, on a distant landmark, aerial etc.  Use ASIStudio (or SharpCap if you have it) and of course for daytime use very short exposures.

Next step is to try the same at night but on a reasonable target (the moon perhaps).

For the mount you'll need a polar alignment method to get a reasonable unguided image - later you might consider a guide scope/software.  Polar alignment is down to your preferences, either manula or software/hardware assisted. If you have a good North view then the paid for add on in Sharpcap may be suitable. The free ones that come with other software can be daunting as part of a full astro package.

Steve

I'm clear to the north and can see Polaris on a clear night.

I have a rough daytime focus, already. I'm going to hit the Moon, shortly.

Given the mount I have, I think a software assisted 3 star alignment is my first choice.

I'm not even close to considering a guidescope, yet and the 50ED will become my guidescope at some point in the future.

Given the software I listed as my preference for a starting point, is there a good reason to switch to Sharpcap?

Thanks for the pointers.

[Elp]

If you've got good eastern skies M45 Pleiades will just about fit. You can then use the data later once you get colour data as your luminence (via lum filter or UV/IR cut). You'd be essentially imaging stars (so can check your tracking), a fairly open cluster which just about fits (so can keep an eye on your framing, as it's also naked eye visible, especially over multiple nights) and broadband nebulosity.

If you don't already, it will also be a good time to learn about, how to take and apply calibration frames and stacking via software like Deep Sky Stacker or Siril (both free). Siril is more involved, but just using it's background extraction on your images to remove light pollution gradients will transform them, you can also perform some post processing within the same program.

Edited September 7, 2023 by Elp

[Mandy D]

21 minutes ago, Elp said:

If you've got good eastern skies M45 Pleiades will just about fit. You can then use the data later once you get colour data as your luminence (via lum filter or UV/IR cut). You'd be essentially imaging stars (so can check your tracking), a fairly open cluster which just about fits (so can keep an eye on your framing, as it's also naked eye visible, especially over multiple nights) and broadband nebulosity.

If you don't already, it will also be a good time to learn about, how to take and apply calibration frames and stacking via software like Deep Sky Stacker or Siril (both free). Siril is more involved, but just using it's background extraction on your images to remove light pollution gradients will transform them, you can also perform some post processing within the same program.

East is the one direction I just cannot get from home. I have Siril, but no idea how to use it, yet. Right now, I just want to get set up and grab a few trial images. Processing them comes later and is a long way off at the moment. As soon as I have a long USB cable, I will point it at the Moon and see what happens.  I have chosen M42 as my first deep sky target, as it is now moving into my late evening sky and I can easily get it.

What I could do with at the moment is some pointers to get me set  up. The advanced stuff can come later.

As both you and Vlaid have indicated I need a UV/IR cut filter. My current one is 2", so no good for this setup.

I wonder if I ought to step back a bit and focus on the mount, getting it set up and running with the A105M on it as a visual only setup, then come back to the imaging part as a separate entity.

Thanks for the thought provoking input.

[Elp]

Up to you. I started with just a compact camera on a fixed photo tripod. Then a cheap eq1 mount and respective telescope. Then an azgti in alt az mode. Then upgraded it to fully autoguided eq. And more mounts followed etc.

You just need to practice, EQ mode isn't really any different from alt az, in fact for imaging I'd say its even easier as you only need to polar align, your goto should do the rest (with a slight nudge to get target in centre). You can image in alt az but exposures need to be kept very short depending on focal length (I did do M42 and M31 with 9s exposures through my Z61).

If the front of your evoguide is threaded you may be able to front mount the filter, or even DIY a mount with an m48 thread for it to screw into.

Pointers depend on how you want to start. The first frustrating things you'll encounter from experience:

1. Mount shaking/vibrating inconsiderably (you shouldnt have this issue with yours),

2. Very fine focusing (it gets easy through experience),

3. Finding an effectively invisible target (again a lot of experience), plate solving is a very good thing to get working in this regard.

4. Getting camera backspacing right.

Your evoguide is fairly short focal length so wideish FOV so will be more forgiving for finding and framing.

Alt az, or EQ polar alignment, similar process of finding and alignment to a star (EQ will need either a manual polar scope, or computer with software (acquire or setup) and a camera (which you have)) so start with either, you'll know if you're getting good alignment if A. Your scope doesn't decide to point to the ground in a depressed state (does sometimes happen when goto in alt az and something including alignment isn't setup right), and B. When targets appear in the FOV after a goto.

You can kind of test A during the day using a stellarium to roughly guess if your scope is pointing at a target, your daytime practice will be spent on levelling the tripod and aligning to true north.

Edited September 7, 2023 by Elp

[Mandy D]

@Elp I'm begining to think that I might do what you did and use the DSLR for the first stage of learning this.

Sadly, no threads on Evoguide, so I'm back to rear filter.

The 178MM on the Evoguide has a similar FOV to my D800 on the 300PDS, so that should help. But, shouldn't the mount be finding the targets, anyway, rather than me doing it all manually?

[Swoop1]

@Mandy D We are on a similar journey- I jus started a little before you!

My first suggestion- get your Polar Alignment right (or at least as close as you can) first. This will help prevent one of the causes of star trails. There are lots of videos and tutorials for polar alignment. Do you have a polar scope in your mount?

I was lucky in that my polar scope was perfectly collimated to my mount out of the factory.

My second suggestion- play with your mount in visual mode to get used to how it operates/ moves. I still get caught out when framing by moving the scope in the opposite direction to that intended!

My third suggestion- consider an RDF such as a TELRAD as I find this invaluable on my larger scopes for ensuring the scope is pointing ath the right general sky area. With my RVO Horizon 72ED the short dovetail on top of the tube rings acts almost as accurately as a rifle sight- crouch down behind the scope and squint along the groves in the dovetail and my target is often somewhere within the FOV.

Re SIRIL, Sky at Night magazine had an article a couple of months ago about using SIRIL on saved TIFF files from stacks to start drawing out detail- https://www.skyatnightmagazine.com/advice/siril-software-processing-dslr-astro-images

This is how I got my first jump for joy moment when processing the first light deep sky from my above scope.

Finally- don't get dispirited. I regulalry have Doh! moments when going toprocess data and finding I forgot to set exposure speeds etc. so I'm trying to process a whole host of 0 secon exposures....

Meatware problems rule😀

[Elp]

If your goto is off, unless you're familiar with the starfield it's looking at, or if you're not using plate solving, some manual nudging/minor slew will be required. I've found my gem28 gotos work fairly well confirmed with a 30mm eyepiece, but if I use say a 10mm or less, not so much. A mount will only know if it's on target if you've got it fully automated with plate solving and software controlling the image acquisition and plate solving process.

I've found my Rigel Quikfinder works well if confirming alignment visually as it has two quantified circles in the reticule, so you can visually see/measure/judge the angular distance between stars. Using your dslr, or any camera, you can always take an image, upload it to astrometry.net for it to plate solve, no software setup needed.

Edited September 7, 2023 by Elp

[alacant]

2 hours ago, Mandy D said:

advice

Hi

By far the easiest way to get started is by having someone with deep sky imaging experience by your side. Your local astronomy club will be sure to be able to supply you with such. Everything becomes less of a frustration that way and you'll be underway in minutes rather than hours. Or months!

Cheers, good luck and HTH.

Edited September 7, 2023 by alacant

[Mandy D]

29 minutes ago, Swoop1 said:

@Mandy D We are on a similar journey- I jus started a little before you!

My first suggestion- get your Polar Alignment right (or at least as close as you can) first. This will help prevent one of the causes of star trails. There are lots of videos and tutorials for polar alignment. Do you have a polar scope in your mount?

I was lucky in that my polar scope was perfectly collimated to my mount out of the factory.

My second suggestion- play with your mount in visual mode to get used to how it operates/ moves. I still get caught out when framing by moving the scope in the opposite direction to that intended!

My third suggestion- consider an RDF such as a TELRAD as I find this invaluable on my larger scopes for ensuring the scope is pointing ath the right general sky area. With my RVO Horizon 72ED the short dovetail on top of the tube rings acts almost as accurately as a rifle sight- crouch down behind the scope and squint along the groves in the dovetail and my target is often somewhere within the FOV.

Re SIRIL, Sky at Night magazine had an article a couple of months ago about using SIRIL on saved TIFF files from stacks to start drawing out detail- https://www.skyatnightmagazine.com/advice/siril-software-processing-dslr-astro-images

This is how I got my first jump for joy moment when processing the first light deep sky from my above scope.

Finally- don't get dispirited. I regulalry have Doh! moments when going toprocess data and finding I forgot to set exposure speeds etc. so I'm trying to process a whole host of 0 secon exposures....

Meatware problems rule😀

Polarscope is optional for this mount, but the software can handle it via three star alignment, which should be good enough for now.

I fully intend to use it in visual mode, first. I have a Vixen A105M that I am going to stick on it for that purpose. I still move my Skytee the wrong way, so it's not just you!

The 50ED is so small and has nowhere to mount a finder or Telrad. I might have to find some proper tube rings for it so I can do this stuff, better. I never use a finder with any of my scopes and point them exactly how you describe. Once the azimuth is found, you just rack the tube up and down to find the object. It takes me literally seconds to find the Sun or Moon like this, although with the Sun I use the Dob side support shadows to find azimuth.

I've put your Sky at Night Siril link in a new tab and will look at that shortly. Thank yo9u for that. It should help a lot.

I usually forget to put a card in the DSLR and spend ages wondering why it won't trip the shutter release with the remote, or I forget that I have it in muppet (MUP) mode and can't understand why it won't take a picture on the first press of the remote! Doh!

Thanks for these tips. I think it is what I need.

[Mandy D]

50 minutes ago, alacant said:

Hi

By far the easiest way to get started is by having someone with deep sky imaging experience by your side. Your local astronomy club will be sure to be able to supply you with such. Everything becomes less of a frustration that way and you'll be underway in minutes rather than hours. Or months!

Cheers, good luck and HTH.

Thanks. In an ideal world, that is exactly what I would like to do. However, I'm pretty much stuck at home for now. If the chance arises, I will do this.

[Elp]

Tbh, all the help I ever needed was found online including here on SGL.

[happy-kat]

Just to share I use a 10m usb extension cable with the ASI462MC usb3 lead connected to a pc inside and this works fine.

I had crudely rubber banded a red dot finder to the ASI to help with manual aiming but I'm more into sharpcap and plate solving now.

ASI studio wide field and the DSO imaging apps are next on my list to try from the pc.

The 50ED is great but I do use a home made simple dew shield it dews otherwise

If you want to use your DSLR with it then you might want to check starizona out for their field flattener

If using synscan then I use one star alignment as it's the one that will move the mount to where it thinks the star picked is, centre it and confirm, choose another one star and repeat, do this three times. I do this as it saves me fixing a red dot finder as other alignment options don't auto move to the first target star. Mount must be level and 50ED level and pointing north if starting with altaz imaging. You can pretend practice inside to get a feel for how the mount moves in different alignment options.

I use a filter holder that sits inside the ASI462MC camera well 1.25 filter will fit. I wonder if a 2 inch filter screws straight in the well, I don't know

Edited September 7, 2023 by happy-kat

[Mandy D]

@happy-kat Is that a plain 10 m cable or one with a box of electronics? Can I ask where you got it from?

The dew shield is something I hadn't given a thought to, so I will note that. Thank you.

Definitely a big no on using the DSLR with this telescope, I have longer lenses for that. Although I will be getting the dedicated 50ED flattener from Skywatcher.

Interesting note on the n star alignment. I always imagined the 3 star to be superior, but it loks like the one star actually uses three stars anyway, just in a different way. I'll remember that.

Having just checked, I can confirm that 2" filters do not fit the ASI camera body, at least, not the 178.

I'm going to hang fire on a red dot finder for now.

Thank you for a wealth of useful information.

[happy-kat]

The usb 10m usb2 extension lead does not have a visible booster box I'll see if I can dig up where I got it.

The starizona flattener gives more back focus allowing for a dslr (it works with the canon 1100d I have) there's only so much back focus with the skywatcher and it wasn't enough for the dslr I use.

The one star alignment can be repeated on a different star you choose as many times as you like, I use it as it's vital the mount slews to the first star chosen and I've found other alignment options don't .

Edited September 7, 2023 by happy-kat

[happy-kat]

Sorry I have reread my post again as the lead does not have a visible bump.

[Mandy D]

28 minutes ago, happy-kat said:

Sorry I have reread my post again as the lead does not have a visible bump.

I've found a USB3 A-B 5 metre cable for £5.70 at CPC. I'll order it in the morning.

That just leaves focusing and control of the mount to deal with. This is starting to look like remote operated telescope territory, now! I think I am going to have to start with the DSLR on the A105M until I can get a laptop outside or remote everything.

[happy-kat]

if outside could use mobile device and ASICAP to sit with telescope and fiddle manually to get focus, then disconnect and put camera usb in your extension cable and go inside and carry on with asistudio

[Mandy D]

16 minutes ago, happy-kat said:

if outside could use mobile device and ASICAP to sit with telescope and fiddle manually to get focus, then disconnect and put camera usb in your extension cable and go inside and carry on with asistudio

So, I connect the camera to the tablet with an OTG cable?

This sounds like it might be a solution.

[AstroMuni]

26 minutes ago, Mandy D said:

So, I connect the camera to the tablet with an OTG cable?

Here is an alternate solution which I use. I run teamviewer on the laptop and use my mobile to connect to it. This way I can stand next to the scope and twiddle focus while watching display on laptop.

EDIT: I also used a long FTDI cable to connect the mount to the laptop. So had 2 long cables running from inside the house to scope. Consider learning software such as NINA or Cartes du Ciel etc. as these will help you control mount, camera platesolve etc. Once you do platesolving then n-star alignment will be a thing of the past 🙂

And tip on imaging M42. Try using smaller exposures upto 30s to prevent over saturating the central part of the nebula.

Edited September 8, 2023 by AstroMuni