Setting Up My Imaging Rig.

[Proximo]

Hey guys, really could use your guidance on this project.

Let me first make a list of my equipment.

1. Canon Rebel T3i (unmodified)
2. Orion 8" Newtonian (1000mm focal length) F5
3. Altair 50mm Starwave & GPCAM guidecam combo
4. Regular Orion Skyview Pro mount (no goto)
5. Orion Polar Alignment Scope
6. EQStarEQ5 GoTo drive upgrade kit
7. Omegon 90/500 refractor.

This is my first imaging rig I'm  attempting to setup. At my first attempt i couldn't get the dslr to focus. So i did some research on this forum and saw a suggestion by one of u experts to move the primary mirror forward. So my plan is to cut my telescope from the back and reposition the primary mirror. This should also make the telescope a fraction lighter seeing that i cant afford to buy a heavy duty mount the shipping and handling alone would send me to an early grave. So I'm stuck with the mount my 8" Newtonian came with. The mount is rated at 20lbs and the telescope itself is 20lbs!So Ive made the decision to turn my Orion 8 inch newt into an astrograph. The refractor suffers from chromatic aberration  like there's no tomorrow so its not an option. The only other option i could think of is to purchase a used RedCat if i could find one. Ive already started modifying the Orion. Ive attached 3 cooling fans at the back and Ive purchased a cutoff saw and drill to cut the telescope and reposition the mirror. I would also like to add baffles inside the telescope but have no idea where i could purchase these or how to make them. Ill upload some images of the equipment.

So the question is, am i missing anything? Forgetting anything? Full steam ahead? Or Abandon ship?

Any and all suggestions/recommendations & help are welcomed.

Cheers!

 

Edited September 2, 2020 by Proximo

[DaveS]

OK

Well, imaging rigs are really built from the ground up, so the mount is the most important part. That being said, from your post it looks like it's what you're stuck with.

Don't do anything more or more drastic to your newt, as it really isn't suitable as an astrograph on that mount. For non-premium mounts (ie anything below 10 Micron / Mesu / ASA) the payload limit for imaging is reckoned to be 2/3 the limit given for visual. For that mount I'd say 1/2 the visual limit short short 'frac like you hav will be about the limit, but as you say, it has horrendous CA, and short triplet apos are expensive!

OK

You already have a camera, and a guide 'scope / camera, so what I'd do is get a side-by-side dovetail, so you can mount your camera and guider together and start imaging using whatever camera lenses you have to hand. This will at least give you a chance to learn the basics of image acquisition / guiding and processing while saving up for a Redcat or similar.

Keep your Newt for visual, as that's what it's designed for and it would be a shame to butcher it for a dubious imaging rig.

[Proximo]

Thanks for the quick response. Anybody in here have a redcat and or a side by side dovetail for sale?😁

But i love the idea of the DIY project and im curious as to what the results would look like if i got the math correct.

[AdeyBuzz]

Don't cut anything..... you just need to move your secondary mirror... but the primary mirror is set to the length it was made for. It will be out of focus if you get anything wrong and the seconday screw holes need to me 0.0000001 correct just like anything astronomy. it's not worth it, get a low profile focuser. It will work just fine, i'm not sure about filter wheels alltho I have seen pictured of people using live view cameras not DSLRS.

Starlight instruments or moonlite low profile will work. but news get flex ... thin you do get a focuser clamp for both sides which helps, but you will never get a perfect balance unless you use liveview, and even then you will need to plan your viewing sessions for best angles to what your gear is setup. MISSIONS. stay refractor and look for a second hand EQ5 your mount is equiv to a celestron AVX not much good past 200-300mm focal length... With what you have here from a year ago try to stay native focal length, less errors and stay bloating due to magnification.

[skybadger]

14 hours ago, AdeyBuzz said:

Don't cut anything..... you just need to move your secondary mirror... but the primary mirror is set to the length it was made for. It will be out of focus if you get anything wrong and the seconday screw holes need to me 0.0000001 correct just like anything astronomy. it's not worth it, get a low profile focuser. It will work just fine, i'm not sure about filter wheels alltho I have seen pictured of people using live view cameras not DSLRS.

Starlight instruments or moonlite low profile will work. but news get flex ... thin you do get a focuser clamp for both sides which helps, but you will never get a perfect balance unless you use liveview, and even then you will need to plan your viewing sessions for best angles to what your gear is setup. MISSIONS. stay refractor and look for a second hand EQ5 your mount is equiv to a celestron AVX not much good past 200-300mm focal length... With what you have here from a year ago try to stay native focal length, less errors and stay bloating due to magnification.

Drill either a new set of holes for the primary and move it up the tube or do the same for the secondary but move it down, it's trivial and takes basic measurement and drilling skills. I have done this several times on a home build and commercial scopes. 

 

[Gfamily]

Bear in mind that moving the secondary will imply moving the focuser as well - which needn't be a problem, but will be more things to move and line up again. 

 

You might also consider getting a filterwheel and some filters for the refractor - as that should eliminate a lot of the Chromatic Aberration - Yes, you may need to set the focus each time, but it should be do-able

 

Caveat - not done this myself - so it may be rubbish advice  

[alacant]

On 02/09/2020 at 06:06, Proximo said:

couldn't get the dslr to focus

Hi

It looks like you have an extension tube between the focuser and the camera. Without it, you should easily be able to reach focus.

Could you post a close shot of the focuser with and without camera?

Cheers

[scotty38]

I'm guessing half the OTA is on the workshop floor by now 🙂

[rickwayne]

If you are just starting, I would heartily recommend that you accept the aberrations and start with the refractor. Or even pick up an old 200 f/4 Pentax telephoto and a Canon adapter.

No, really! Learning astrophotography is different from doing productive astrophotography, and if you already have challenges from your mount, you'll learn faster and swear less at 500mm than at 1000, and 200mm would be better still.

You will need to learn to polar align your mount to within arcminutes. You will need to learn how to focus more accurately than you ever have before, without autofocus. You will need to figure out how to get the danged target in your field of view (don't laugh, I have wasted significant fractions of a night struggling with merely that). You will need to learn how to run your acquisition program to guide and shoot. You will need to learn a processing workflow.

Just about every one of these will introduce problems with your images till you get it right, and diagnosing where the problems are coming from is its own skill set. If you modify the Newt, you have introduced a whole new category of possible error sources. Are the stars bloated due to focus problems? Tracking problems? Improper processing? Introduced misalignment of the mirrors? Every added millimeter of focal length just exacerbates all those errors. Short refractors are recommended to beginners because they're the simplest things that can possibly work. 

If you want to cannonball into the deep end and enjoy yourself, please don't let me stop you. People do succeed with crazy-hard setups. But there are a lot of people who've said "Geez, I wish I'd started with something shorter".

[Notices date on original post] Oh, dear. I guess my advice is either moot or they've learned the lessons anyway by now...