It seems likely he the theoretical resolution will be unrealized. I have talked to people who have looked through it.

So, the Grim has the effective resolution of a 20" unobstructed scope and

the light gathering power of a a 28 inch unobstructed scope.  Mike's scope will have a 1.75 magnitude advantage over the Grim.  Another rule of thumb is that for every magnitue increase in light gathering power, there are about 10 times more stars visible.  That isn't quite that much for deep sky stuff, but closer to maybe 7 or 8.  Mike's scope should show about 50 times more stars and maybe a bit more than an order of magnitude more deep sky objects.  That is a pretty big difference!   The resolving power of Mike's scope will be more than twice as good as the Grim - assuming the seeing will support it.  Dawe's limit for Mike's effective 41 inches is about 0.11 arc seconds.  Seeing to support that is pretty hard to come by. Read almost never.   BTW, Dawe's limit is pretty close to the theoretical resolution as calculated in your physics book - at least for the apertures I've worked with.

From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, October 29, 2013 2:42 PM Subject: Re: [Utah-astronomy] Journey to the 1.8 meter

The Grim has a 10-inch secondary.

On Tue, Oct 29, 2013 at 2:39 PM, Brent Watson <brentjwatson@yahoo.com>wrote:

...

Just out of curiosity, what is the diameter of the secondary in the

Grim scope?

...

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