SharpCap Forums

Use case: I'm trying to align my main scope and guide/finder/second scope so that they are looking at the same thing. I have two cameras: one attached to each scope. This is to use the second scope as a digital finder scope when my main scope has a long focal length.

Why is this important: the second scope does not have adjustments for alt-az like the dual rings of a finderscope usually do. Even if it did, I find that this adjustment has to be done precisely and every time the rig is torn down. Platesolving is difficult with tiny FOVs, and trying to find small targets (eg. planets) is very difficult in these cases without a properly aligned finder scope.

The difficulty of this is compounded when one has a mount that cannot be manually slewed (e.g. most of the harmonic mounts). In this case, slewing the mount using a hand controller or arrow buttons so that the main scope is pointing at a star is very hit and miss. If the mount is an EQ mount, teeth-pulling would be preferred.

Does Sharpcap have any way to assist in this?

If Sharpcap has a way to tell me the RA/DEC location of the center of my finder scope, so that I can switch to the camera of the main scope and ask it to go to this location, would this work? Can I actually do this currently? But I'm thinking that this too would depend on how accurate the Goto is, which brings us right back to the need for an aligned finderscope.

How are your scopes mounted? If your finder is in rings, and they can be adjusted, I just use my main scope to center on a star (Vega for example) and then either use phd2 with the second camera and adjust the rings until the star is centered there too, or close the main camera in Sharpcap and open the second one and adjust the rings until the star is centered. You can also do this during the day (which you may find easier) if you have a distant object you can see and center in the cameras.

If you don't have adjustable rings, then it involves some shimming, and is generally more annoying, but you can do it.

Good luck,
Charles

My second scope is the askar fma 180, which I also often use by itself. My main scope, in the worst case is an sct with no reducer.

The fma 180 pro version, which I have, does not have the double rings. I cannot find any for it either. Shims are possible, but again we have the same problem. This must be done every time I set up, because I change scopes between sessions.

Hi,

well, without tube rings or similar, it's going to be hard to get the tubes aligned from a purely 'physical adjustment' point of view (and probably slow too), but assuming that you want to try, maybe this approach would work...

1) Pick a target and GOTO it on the shorter focal length telescope - let SharpCap use plate solving to center the target.

2) Switch to the camera on the SCT and use the 'Push To' assistant to move to the same target.

3) Adjust the mounting of the SCT while watching the push-to assistant readings, trying to adjust to get zero error in both directions. This will put the same target centered in view of the SCT.

Of course the assumption here is that (a) you can get plate solving to work with the long focal length of the SCT and (b) that you intend to physically adjust the SCT to line up with the Askar180.

I must admit that I would consider just adding a 50mm f/4 guide scope onto the SCT with a guide camera. That will have tube rings, allowing it to be easily aligned with the SCT. Obviously you have to then buy a new guide scope and guide camera, but perhaps you have a planetary camera that could be re-used - it should save time every time you set up...

cheers,

Robin