What should I know before imaging with a non-eq?

[Jojo204]

Hi all!

I have just ordered my first telescope, a Celestron Nexstar 6SE! Now admittedly all of you imaging folks are facepalming and shaking your head at my choice of scope! Please note this is my first ever scope and I’m just getting it to get the hang of basic imaging and in the future use it as a ‘grab n go’ scope and am thinking of my main setup being an Explore Scientific ED80 with an EQ6 mount. Still thinking though! Anyway, as I wait patiently these 5 days, what do you think I should know about non-eq imaging before starting?

(also no answers talking about the book ‘making every photon count’ I’ve been told about it hundreds of times without being given a chance to get it! ?)

[parallaxerr]

I'd start here....

Several users, myself included, have had some good results with the Nexstar SE mount (although using refractors as opposed to SCT).

It's a monster thread but it's full of useful information, including how to process the many short subs required with Alt/Az imaging.

[Mr niall]

Nothing really pal - the fundamentals are the same. You’ll get field rotation but DSS will fix that. I find the images aren’t quite as sharp looking - and you need to crop at least 10% off the edges but with some practice and dedication you’ll get cracking results.

honestly, I’ve said it before but “astrophotography on the go” is an absolute belter book  and would suit your needs perfectly.

[SteveNickolls]

10 hours ago, Jojo204 said:

(also no answers talking about the book ‘making every photon count’ I’ve been told about it hundreds of times without being given a chance to get it! ?)

Hi and thanks for posting. Rather than getting a copy of the United Federation of Planets Gunnery book as I refer to it I'd advise along with Mr naill to order a copy of this book instead-https://www.firstlightoptics.com/books/astrophotography-on-the-go-book.html it is available from our sponsors and deals much much more with 'things Alt-Az' and which will therefore be of immediate use to you.

Beware, you can image with an alt-Az mount and the link to the No EQ Challenge amplifies that point despite what tradition says.

Do enjoy imaging and don't forget to post!

Cheers,
Steve

 

[happy-kat]

All of the above and don't feel wedded to the SCT as that long focal length adds it's own demands. I'd look to use your camera and camera lens to start with get your toes wet and progress from there.

[ollypenrice]

Making Every Photon Count is available here: https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

Given that you're not using a mount optimized for imaging you'll need to experiment to find the longest possible exposure time you can manage without too much trailing. Theory can provide guidelines but I'd start at 15 seconds on a bright target and work up from there. You won't be guiding so there isn't much to control on the mount side of things.

Most of your preparation will centre on the camera side of things. You could familiarize yourself with DSS, the stacking programme, in advance. You could also take a set of bias frames and stack them into a master bias. You may well find that this will work better than a master dark. Have you thought about how you intend to capture? Are you using a DSLR? If so you could experiment with a camera control package designed to run the camera for astronomy. Such packages have useful features. You'll also need to think about how you aim to focus. You'll probably find that a Bahtinov Mask is best but some of the astro control packages offer Full WIdth Half Max focusing. (Basically these measure the star's width and brightness. Smallest width-highest brightness = best focus. Alternatively you'll need to zoom in to pixel scale on a star and eyeball it to the smallest size possible or you can look at the tiniest stars which will only appear at ctirical focus. Outside focus they'll be blurred out. (I can't recommend a DSLR package because I only use CCD cameras. Someone will help if you specify your camera.)

How are you going to process your images? (Don't forget to capture in RAW with a DSLR.) They will be delivered in linear form and will need 'stretching,' a process in which the lowest brightnesses are raised by more than the highest brightnesses so as to lift the faint parts into view. The big players are Photoshop and Pixinsight with Astro Pixel Processor making many friends. Or there's Star Tools or GIMP. If you'd like to practise stretching some linear data just PM me your email address and I'll send you a Dropbox link.

Have fun, but remember that even if a thing can't go wrong it will!

Olly

[happy-kat]

You can get red dot finder shoes that mount in a DSLR flash hot shoe, even 3 d print a base for  a RDF. This means you can then align a mount without the weigh of the OTA..

[Jojo204]

15 hours ago, parallaxerr said:

I'd start here....

Several users, myself included, have had some good results with the Nexstar SE mount (although using refractors as opposed to SCT).

It's a monster thread but it's full of useful information, including how to process the many short subs required with Alt/Az imaging.

I've read that previously and it greatly helped me choosing my scope! I don't want results better than any of these with this scope so I'm hopeful!

[Jojo204]

15 hours ago, Mr niall said:

Nothing really pal - the fundamentals are the same. You’ll get field rotation but DSS will fix that. I find the images aren’t quite as sharp looking - and you need to crop at least 10% off the edges but with some practice and dedication you’ll get cracking results.

honestly, I’ve said it before but “astrophotography on the go” is an absolute belter book  and would suit your needs perfectly.

Seems interesting, I'll add that to my checkout!

[Jojo204]

*ignore*

[Jojo204]

4 hours ago, ollypenrice said:

Making Every Photon Count is available here: https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

Given that you're not using a mount optimized for imaging you'll need to experiment to find the longest possible exposure time you can manage without too much trailing. Theory can provide guidelines but I'd start at 15 seconds on a bright target and work up from there. You won't be guiding so there isn't much to control on the mount side of things.

Most of your preparation will centre on the camera side of things. You could familiarize yourself with DSS, the stacking programme, in advance. You could also take a set of bias frames and stack them into a master bias. You may well find that this will work better than a master dark. Have you thought about how you intend to capture? Are you using a DSLR? If so you could experiment with a camera control package designed to run the camera for astronomy. Such packages have useful features. You'll also need to think about how you aim to focus. You'll probably find that a Bahtinov Mask is best but some of the astro control packages offer Full WIdth Half Max focusing. (Basically these measure the star's width and brightness. Smallest width-highest brightness = best focus. Alternatively you'll need to zoom in to pixel scale on a star and eyeball it to the smallest size possible or you can look at the tiniest stars which will only appear at ctirical focus. Outside focus they'll be blurred out. (I can't recommend a DSLR package because I only use CCD cameras. Someone will help if you specify your camera.)

How are you going to process your images? (Don't forget to capture in RAW with a DSLR.) They will be delivered in linear form and will need 'stretching,' a process in which the lowest brightnesses are raised by more than the highest brightnesses so as to lift the faint parts into view. The big players are Photoshop and Pixinsight with Astro Pixel Processor making many friends. Or there's Star Tools or GIMP. If you'd like to practise stretching some linear data just PM me your email address and I'll send you a Dropbox link.

Have fun, but remember that even if a thing can't go wrong it will!

Olly

Ok, my camera usually gets up to 27 seconds without field rotation but that's using an 18mm lens so I'll be sure to check that.

 

I have! I used DSS to stack my photo of M42 (in my prof pic) and a few others. Yes I'm using a DSLR and have it connected to an automatic shutter on my laptop. 

Of course RAW! It's amazing what you can do to a RAW image!

I have Photoshop and Lightroom and found them both useful in my M42 and M31 pics. 

Thanks!

[Jojo204]

3 hours ago, happy-kat said:

You can get red dot finder shoes that mount in a DSLR flash hot shoe, even 3 d print a base for  a RDF. This means you can then align a mount without the weigh of the OTA..

Never thought of that! I'll remember it!

[ollypenrice]

1 hour ago, Jojo204 said:

Ok, my camera usually gets up to 27 seconds without field rotation but that's using an 18mm lens so I'll be sure to check that.

 

I have! I used DSS to stack my photo of M42 (in my prof pic) and a few others. Yes I'm using a DSLR and have it connected to an automatic shutter on my laptop. 

Of course RAW! It's amazing what you can do to a RAW image!

I have Photoshop and Lightroom and found them both useful in my M42 and M31 pics. 

Thanks!

Sorry, I missed the connection to your earlier images.

Olly

[SamAndrew]

5 hours ago, Jojo204 said:

Ok, my camera usually gets up to 27 seconds without field rotation but that's using an 18mm lens so I'll be sure to check that.

That's trailing due to not tracking the stars, rotation happens when you're tracking the stars with an alt-az mount.

[Jojo204]

5 minutes ago, SamAndrew said:

That's trailing due to not tracking the stars, rotation happens when you're tracking the stars with an alt-az mount.

Ah yes oops ?