Hello
I do alot of spectroscopy so my primary OTA can't be used for plate solving as it has a spectroscope/grating installed. So I was planning on piggybacking a small guide scope for plate solving only. I can't think of any reason why this wouldn't to work.
I was planning on using 50mm f3.2 or a 30 mm f4 scope with the ASI 120 MM Mini (3.75 um 1280x960). Would this work or am I missing something.
Thanks
Dave
Dedicated guide scope for plate solving
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Re: Dedicated guide scope for plate solving
Hi,
It should work fine – these are both common configurations for people using the polar alignment feature and that is based on plate solving. Just make sure that work out your field-of-view and have the correct indices installed in your plate solving application. The shorter focal length will limit the accuracy slightly, but probably not to any significant degree. You can work out the pixel scale when you work out the field-of-view which will give you an idea of how accurate it might be.
Cheers, Robin
It should work fine – these are both common configurations for people using the polar alignment feature and that is based on plate solving. Just make sure that work out your field-of-view and have the correct indices installed in your plate solving application. The shorter focal length will limit the accuracy slightly, but probably not to any significant degree. You can work out the pixel scale when you work out the field-of-view which will give you an idea of how accurate it might be.
Cheers, Robin
Re: Dedicated guide scope for plate solving
Thanks for the reply, Yes I was thinking maybe a slightly longer focal length might be a little better.
Re: Dedicated guide scope for plate solving
So here is my dilema I can't guide thru the main scope not enough fov if I align the guide scope with the main scope using a reticle eyepiece and the crosshairs in sharpcap for the guide scope will it be close enough so that I can image across multiple nights? In other words will DSS be able to stack it?
Pardon my ignorance
ron
Pardon my ignorance
ron
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Re: Dedicated guide scope for plate solving
Hi Ron,
the accuracy of plate solving via a guide scope/guide camera should be fine - if you have a 200mm guide scope and typical (like ASI120 type) guide camera, the pixel size is about 4 arc seconds, so the plate solve should be accurate to close to that scale.
The bigger issue would be if you take your guide scope off between imaging sessions - if so, it will almost certainly end up in a slightly different position each time, much more variation there than in the pixel size limits of the guidng setup. Even if it is left attached, if it's not attached very firmly, there is a chance of it being knocked during put away/set up and ending up off target.
Even with the possibility of the guide scope moving, if you do your best to re-align it each time, I suspect you will get back to within about 1 arc minutes or better, and stacking in DSS should cope with that. Don't forget that you shouldn't move your main camera off of the scope between sessions, otherwise it could go back on with a different rotation, which would also cause issues!
cheers,
Robin
the accuracy of plate solving via a guide scope/guide camera should be fine - if you have a 200mm guide scope and typical (like ASI120 type) guide camera, the pixel size is about 4 arc seconds, so the plate solve should be accurate to close to that scale.
The bigger issue would be if you take your guide scope off between imaging sessions - if so, it will almost certainly end up in a slightly different position each time, much more variation there than in the pixel size limits of the guidng setup. Even if it is left attached, if it's not attached very firmly, there is a chance of it being knocked during put away/set up and ending up off target.
Even with the possibility of the guide scope moving, if you do your best to re-align it each time, I suspect you will get back to within about 1 arc minutes or better, and stacking in DSS should cope with that. Don't forget that you shouldn't move your main camera off of the scope between sessions, otherwise it could go back on with a different rotation, which would also cause issues!
cheers,
Robin