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upping the f/ to 16...what to expect?

Started by pkelly, 06/02/2005 05:20PM
Posted 06/02/2005 05:20PM Opening Post
With any luck in a couple weeks I'll be moving from D&G 5" f/12 to D&G 6" f/15 of previously photoned refractor. A bridge 5" f/15 scope didn't turn up and the 6" opportunity was made, and close by, and I feel I'd be kicking myself not to snatch it up assuming everything goes smoothly.

The scope'll be on D&G 1.5" shaft GEM (I really DO miss the slo motions of my previous mounts and wish I could retro fit this old thing somehow) for visual use on the high pier plus have motofocus so a few refractorisms are covered. Since this is getting into classic scopes with both feet, are there any other tidbits of info anyone can toss my way on what to expect working this beast. My location is coastal, seeing pretty crappy most times, but not windy; hope to have a rolloff/pushoff down the road.

Thanks for any insights.BTW, for now I'll be saving the 5"er .

Pat in Maryland

8" f/12 D&G classic refractor
Astro-Physics 1200 DA equatorial mount
BlueStar Observatory (roll off) by Backyard Observatories of Lodi, Ohio
Previous telescopes A-Z...Astro-Physics to Zeiss
Posted 06/08/2005 07:28AM #1

Congratulations on the new scope. I have the 5" f15 version. This is a nice scope visually, so I would expect you to really enjoy the 6". In the 5", some chromatic abberation shows up on very bright stars, but is generally not a problem on planets. I have not looked through an f12 version, but you should have less CA with the new scope.

I've used mine primarily for double stars, and have been very pleased. In good seeing, you should be able to split stars less than 1" separation, and elongate or notch some down to the 0.7" or 0.6" range. If this is not an area of the hobby that you pursue, you should give it a try with the new scope.

The main drawback that I have with the scope is the mounting, as you have already touched on. I use a CI-700, which is rated for a good bit more weight than the scope, but the torque of the long tube makes balancing difficult. Even changing eyepieces can sometimes throw off the balance. This is as large a mount as I can handle, so if you could work out something with wheels (or some permanent set-up) you would be well served. Let us know how it goes when the scope arrives. I would love to hear a report.

Gary DuBose