Hello Mathew, you'll probably get the same answers here as on your previous post. Perhaps it is best not to make a new topic for the same question or subject and you could have asked this in that topic.
(+ you might want to look into how you make your posts with URL's in it. Unless it's just me?, I only see a whole bunch of text instead of links to the items. So it's very hard to figure out what you're saying)I don't see a huge point in trading in your 80ED for a 70ED with the hopes of using the star adventurer.
As the problem isn't just the weight of the scope, but also the focal length.
The star adventurer is made to be able to take scopes and lenses up to about 300mm, many people use shorter focal lengths on it. And either use camera lenses on it of 50-135-200mm. Or something like a William Optics RedCat 51 at 250mm.
Unless you plan on guiding, you will struggle with a star adventurer (or most mounts) at the 560mm or 420mm, regardless of weight. You would need good polar alignment to shoot unguided at a short focal lengths, but it needs to be perfect at 560mm or 420mm. Those aren't the best beginner focal lengths if you don't do guiding.. And guiding, isn't always beginner friendly.
The EQ-3M mount you mentioned would be able to deal with the weight better. But, again, you won't be able to do any guiding, so you might limit yourself a lot with your exposure lengths (maybe 30 seconds). The mount I suggested in your other topic was the "skywatcher EQM-35". Yes it is more expensive.. but you are "future proofing" yourself, and you could ad guiding to that in the future if you want.
As an example: I used to have a mount similar to the EQ-3M that you mentioned, with just a motorkit, and a 600mm scope. Within the 1st month I already upgraded the motorkit to a "Go-to" kit.
Because :
1: finding targets is hard enough already, especially at 500mm+ focal lengths.
2: I wasn't getting the greatest results, because I couldn't use a guide camera. and couldn't get nice long exposures.
- I made the mistake of not going for the more capable mount straight away, which made it difficult to get started in the hobby. And I had to upgrade it soon after anyway, at a higher cost of just buying it straight away.
- I made the mistake of getting "too big of a scope" too soon, which aren't always beginner friendly.
One suggestion I could make, you don't always need a scope to get good images.
If you're dead-set on the star adventurer. I'd return the 80ED scope. And get something like a Rokinon 135mm lens for your canon.
Or maybe you already have a 75-300mm lens and use that for a while. Saving you quite a bit of money.quick example of what is possible with just a camera+lens+star adventurer.
