and what about a 40 inch with a 5 inch secondary.
Or how about a 70 inch f4 with a 10 inch secondary. Please share the math, my telescope building texts are buried away. The motors will be a good addition. I don't understand your "true aperture" claim. It makes no sense.
The aperture is 70 inches with the resolution of a 70 inch scope.
The clear surface area of the 70 inch with a 29-inch secondary is 3,188 square inches. The clear surface area of a 40 inch with a 10-inch secondary is 1,178 square inches.
Yes, it does have a very small true field even at a 7mm exit pupil. Mike knows this, knew it well ahead of time.
He plans to add motor drives for tracking.
The usable magnification range is a low of about 280X up to whatever the seeing will allow, but probably less than 400X.
Again, Mike knew this in advance.
On Tue, Oct 29, 2013 at 1:29 PM, Erik Hansen <erikhansen@thebluezone.net>wrote:
I was not suggesting a smaller secondary, I was suggesting a smaller primary with a more efficient design.> The true aperture is 41 inches, so you are getting the resolution of a 41 inch scope, my point is a 45 inch primary with a more conventional secondary would give same light gathering with probably same ladder height as a 70 inch with a 29 inch secondary. I doubt it puts the Grim to shame, it would be interesting to compare the 2 at SPOC, and hear what the comments are.
The other issue, is what is the largest field of view with the scope? With some eyepieces any object centered will not be there long. The time it takes someone to climb down the ladder and another one up, the object will be out of the field of view....will they have more than a minute or less than a minute.
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