Off axis experiment

I was setting up for the ISS transit of Jupiter tonight and decided to play around with the off axis mask I built for my solar filter for my 11" Starmaster. It's a 4.5" OA hole.

1. Without a doubt, I prefer the presentation without all that diffraction stuff going on. A much more engaging view.

2. Without a doubt, there was a great deal more detail visible on Jupiter without the mask than with it. Seeing was a 4 of 10. I have a 16% CO in this f/5.6 Starmaster. This was no contest.

So, I have a question: Anyone know where I can get an 11" APO?

I am definitely going to try out curved spider vanes. I want to get that unobstructed look. I know about the spread out diffraction and all that, but I am in this hobby for my own (and as many kid's as I can find) enjoyment, and I REALLY enjoyed that unobstructed, accurate color view. Anyone put curved spider vanes on an 11", f/5.6, 1.83" secondary Starmaster?

Tom

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and I REALLY enjoyed that unobstructed, accurate color view. Anyone put curved spider vanes on an 11", f/5.6, 1.83" secondary Starmaster?
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Hi Tom,

Here is my attempt at getting decent aperature, small obstruction (11%), and no spider diffraction! It's a 10" scope with a perforated flat mirror and a normal 10"f6 parabolic mirror. The light path sketch shows the external light entering from the side, reflecting toward the parabolic, then the focussed image exits the hole in the flat mirror.

With two big mirrors to cooldown I have had mixed results. I will be adding some fans to see if that helps.

David Simons

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So, I have a question: Anyone know where I can get an 11" APO?
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I was wondering what to do with this 11" triplet : )

(It's a relay lense, and only good for low powers)

David Simons

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