- Computes coordinates in less than a second
For comparison, the sky moves 15 arcseconds per second. So without a motorized mount to keep the telescope on target, the accuracy will be short-lived.
It would be easier if you could use an eyepiece adapter. I have no idea why the page claims "The field of view is typically too small for plate solving to work." for that approach - it works just fine with a FOV of at least 0.2 degrees or so, which is much smaller than what most beginner/intermediate scopes have.
And if you do have a scope with a smaller TFOV, I'd argue you're likely not the target audience for the app. (Yes, you can get there cheaply and as a first scope, but it's not the usual route)
Edit: I want to be clear it's not a diss on the app - it's great. Plate solving at that speed is pretty cool. I just wish it'd work at smaller TFOVs :)
As for why we don't support adding optics between the phone and the sky, there are a few reasons. The accuracy from phone's camera lens is good enough, and we don't want to introduce complexity. The plate solving algorithm also benefits heavily from knowing the field of view, which you get from phone's built in camera but need user input for custom optics. Finally, supporting smaller field of view means shipping a much larger star database which most users won't use, so it's just a waste of storage and bandwidth. Not to mention blind solving a small FoV would be very slow and not work interactively.
For alignment, we support two alignment methods. You can align it like a finderscope, i.e. aim your telescope at a distant treetop and drag the crosshair over it. Once you begin observing, you can also sync to the object, which should give you better accuracy.