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Brett

Thanks for your reply. Yes, by concentric I meant having the same view in the sky. Since I put a losmandy dovetail on the top and bottom of my c11 (it has hyperstar capability) and put an 80 mm refractor f5 on top of that it was apparetly their view in the sky was close but not totally concentric and the refractor doesn't have adjustable rings. So i was wondering do I shim the dovetail using a laser to get the two perfectly parallel or not. I understood in general their view of the sky would be nearly the same but would that matter and in what circumstances.? But I found they were slightly off of each other.? Since I don't do AP yet but have been playing with a camera and I am a complete babe in the woods with AP I was looking for input.?

Chuck
-----Original Message-----
From: E. Brett Waller <cedargreenobservatory@...>
To: Losmandy_users <[email protected]>
Sent: Tue, Aug 11, 2020 01:25 PM
Subject: Re: [Losmandy_users_io] Side by side saddle or piggy back scope alignment

Chuck,

If I am reading your post correctly, you are wondering whether the scopes?should be parallel?or should point to the same place in the sky (I assume that is what you mean by having the views concentric). If they are parallel, they will point to the same place in the sky, despite the fact they are separated by several inches. This would NOT be true for a terrestrial object where the distance between two parallel scopes would offset the field of view by the same spacing as between the two optical axes.? For an astronomical object such as the moon, your best case resolution is going to be on the order of a kilometer or so, and you would never notice such a small offset. In similar fashion, you would be hard pressed to see the difference in the fields of view on a terrestrial object at a distance?of several miles. In those cases, the lines of sight for the two telescopes?are effectively parallel. Thus, two telescopes which are parallel will point to the same location on?the sky.

I hope I haven't misread your original question, if so I apologize. At any rate, I hope you find my reply useful.

Best regards,

Brett

On Tue, Aug 11, 2020 at 12:02 AM crocco1250 via <crocco1250=[email protected]> wrote:

This may not be the right place for this question but a recent post talked about side by side saddles and it raised a question. If you had a side by side or piggy back, say a c11 and 80 mm refractor, do you want them perfectly parallel or have the views more or less concentric? What are the pros and cons? If someone has a site I would appreciate more info.

Thanks

Chuck