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10 in. Refractor Collimation part 2

Started by David Simons, 10/03/2004 02:21PM
Posted 10/03/2004 02:21PM | Edited 10/03/2004 07:08PM Opening Post
I have finally gotten around to mounting an 11" triplet lens I have had for a couple of years that was used in a flight simulator system.

I thought about trying to adjust the 35lb 35" fl lens that I have held in place with two retaining rings, but everything is fairly close to square inside the tube and doing any kind of shimming and adjusting would be pretty scary as I would likely have to remove the lens a few times. The internal mounting rings clear aperture is 10", but this still gives an f3.5 light cone!

For collimation, I made the holes that mount the focuser end plate to the tube quite large, (they can be seen in the second picture) and tilted the end plate a little at a time until star images tightened up. This helped a lot, and now Vega focuses down to a small brilliant point. Outside of focus still shows a lot of color, but inside focus is pretty sharp now, although the Double Double smaller components were showing no sign of splitting at this low power. I have yet to do final critical alignment, as I needed just a little more adjustment range in one axis. I will try it again tonight.

For fun I pointed the scope at the rising moon, and was getting clean low power images, but things went muddy around 122X. I then stopped the lens down to 7", and everything was sharp again. This made an F5 7" refractor, and I was using a 7mm type 1 Nagler, which made a nice combination. I wanted to push this "Comet Finder" scope a little and tried an old 4mm Clave. I don't use this ep. much, but the image was still holding up sharp at 214X. Color was just starting to show. My Skywatcher 6"f5 refractor would be giving me a purple bath at this time. I think I was getting close to the limit of the lense and put in an 8mm Clave and a 2.5X Powermate for 267X, and either the seeing or the lense was setting the limit here, as I no longer would see the glimpses of greater detail, and hints of color error were starting to be more obvious.

Although I did not intend this to be a planetary scope, it's nice to know that with a little decrease in aperture, there is some capability. I have not made any baffles or flocking inside the tube yet, and I was getting a bright background, so this should make a big diffence. But I think with darker skies coming up, there should be some nice wide field viewing with this scope!

David Simons

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David Simons
Posted 10/05/2004 10:23AM | Edited 10/05/2004 10:24AM #1
Nice looking scope and mount, David. If you still have trouble with the final collimation, you might shoot Mark @ Clear Vue Optics (an Astromart Sponsor) an email and talk to him about his Antares Collimateable 2" Diagonal. I have one of his 2" Non Collimateable Diagonals I use on a SV78S, 80ED and 120 SVST and it is good, real good. Mark is an Optician by trade and knows quite a lot about refractors and optics. If you are already using a 2" Diagonal of your choice, you can always sell one of them on AM once you get everything fine tuned. Mark answers all of his emails and if you emailed him this afternoon you'd hear back from him tonight. Anyway, just a thought.

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