Posts Made By: Duane Jacobson

Just an FYI...

Jupiter and Neptune are near neighbors in the morning sky for the next month or so, with May 28/29 marking their closest approach to one another (about one-half degree of spearation, if I remember correctly). The Sky and Telescope website has nice charts.

Duane

Hi,

Can anyone tell me what hardware I can use to mount a TV85 on a GM-8? I was told that the DUP plate will work, but after receiving this plate, I don't see how it could work.

Thanks,

Duane

Just a short FYI for those who may be interested.
I noticed this announcement on his website.

Robert Royce will be offering Newtonian OTAs in 8" and 10" sizes:

http://www.rfroyce.com/ultimate%20newtonian%20portrait.htm

Regards,

Duane (I have no affiliation with R.F. Royce)

Hi,

I see that RF Royce is now offering 6" f/6 mirrors as a standard item. That made me think about building a 6" tube to sit on my GM-8. Do you think this would be a good match?

Any other suggestions? I've also wondered about a Mewlon 180.

Thanks for any ideas. I don't like to tax mounts too much, so would like to keep this to around 15 lbs or so.

Duane

Hi,

I'm purely a visual guy when it comes to astronomy, currently having a TV-85 for my grab-n-go scope. It also gets used as a daytime spotter, mostly for looking at owls in our neighborhood.

My wife has a Nikon DSLR, and it occurred to me that I could buy the field flattener for the TV85 so she could use it as a long telephoto (the flattener would make it a 480mm f/5.6). I've read good comments about that combo, but before I spend the money I wanted to get opinions here on other options to consider. I'm willing to swap for a different scope if it makes sense. Do the Petzval designs give a flat enough field to take photos without a flattener?

Thanks,

Duane

Just saw a talk given by Dr. Ed Lu. Here is his website if you're interested in efforts to discover near-earth asteroids...

http://sentinelmission.org/

I'm going to build a Newtonian tube for general visual use, either an 8" or 10" (have not decided yet).

I like the idea of the Royce conical mirrors... less weight and he claims the conical will cool faster.

I'm open with respect to most of the other components, so I'm looking for comments/suggestions for the focuser, mirror mount, spider, tube, etc. Cost is not a particularly big issue for the project. I'd like to do everything I can to improve thermal management, so I'll have a fan in the bottom of the tube. From what I've read, an unpainted aluminum tube has good thermal properties (low emissivity, I believe?).

Regards,

Duane

Thanks for all of the excellent advice. I honestly don't know if I'll be doing this alone or with help. I've always wanted to do this, but have been concerned about damaging my "good" equipment. I'll be moving to a new city soon, and I figure this will also be a good vehicle for getting to know teachers and principals.

Last year I went to a star party at our kids' school. They had two pretty nice scopes set up. They had an 8" SCT trained on Saturn, and a 3"-4" achromat on Venus. Both were on eq mounts, but the magnifications used were very low because the scopes weren't being driven. I'm sure it was a great experience for many people, but I think it could have been better with very little extra effort.

Duane

Bill and David...

Thanks much for the comments. I'll be down there in about a week with some of my "stuff", including a small scope. Looking forward to checking out the hill country.

Duane

Thanks for all of the comments. I'll look here for pics of the new 10" f/5.6.

Sofjan... I've thought about doing a split tube. However, having never seen one, or known anybody who uses one, I had always guessed there must be a reason for not doing this. Do you know anybody who has done this?

Truss scopes are certainly much more expensive. It's often difficult to do a real apples-apples comparison, but I looked at Discovery's prices, and see that their 12.5" truss scope is 60% more expensive than their 12.5" tube scope. Of course, that makes sense, as there are many more parts to buy or build, and assemble, when manufacturing a truss scope.

This folding tube scope really looks like a good design to me. It's very simple to assemble, and should be much cheaper to build than a truss scope.

Thanks again,

Duane Jacobson