Posts Made By: Lorne Johnson

Paul Neesam said:

I would love to get some feedback on mirror quality and any comparison you can provide on these two mirrors head to head. I'm at a point in my project where I need to purchase a mirror. I'm building an open truss GEM mounted f/5 Newtonian.

Thanks Paul

Hi Paul!

R F Royce is among the very elite mirror makers. His conical mirrors are supposed to cool quickly and only require a very simple mirror cell. I own a 12.5 f5 conical from Royce. Unfortunately the scope kit provider that I paid is 18 months behind on my delivery, so I can't tell you how wonderful it is at the eyepiece. But Royce is where I put my money, and I do not believe that you could go wrong with a Royce mirror.

That said, Discovery makes very good mirrors (full thickness), and there have been some posts suggesting that their figure is consistently good (some have been taken to experts to be refigured, and ended up only being polished to a finer level). You wouldn't really go wrong with a Discovery.

Carl Zambuto is the buzz-name in fine mirrors. I wouldn't suggest that anybody makes a finer mirror. But, I remain unconvinced that Zambuto mirrors are really visibly superior to the other elite mirror makers (Swayze, Spooner, Raycraft, Royce, and a number of others). Zambuto mirros are lightweight and require a sophisitcated cell for support. Obviously, you wouldn't go wrong with a Zambuto, unless you tried to put it in an inadequate cell (and that would not be Carl's fault).

The big issue will not be the actual views but your own worries about the views that "Could have been."

Lorne Johnson

George Kiger said:

There's an Abbe Ortho being auctioned. I know these are legendary, and have proven themselves in the field. My question is why are they so good?

I would think that modern makers could surpass the orthoscopic design, and that modern coatings would make things even better. Why is it (if that is true) that this old eyepiece is tops?

The information offered in response to your inquiry is certainly correct. However, I would add to it that Alan French's observation that differences between planetary eyepieces are "subtle."

Elmer Meiler said:

I'm an oldbie but really a newbie since it has been eons since I did anything with a scope. I'm getting back into it. Things have sure changed. I have coming a used 5" retractor with ring and dovetail. I am looking for advise/discussion on a mount/tripod. What was recommend was a CG-5 or equivalent. I am not really interested in the goto stuff yet. I'm looking for mostly used but would consider new (yes, I have been looking here too). I have seen some used ones listed like LXD-55, LXD-75 and some others. I have scanned the internet and found the usual; Celestron CG-5, Orion Skyview Pro and etc. I have even thought of a Vixen GP2 mount and I think that I can locate a surveyor's tripod. Any other suggestion or insight.

Thanks

Depending on the weight and length of your Tube a Vixen GP on a surveyor's tripod could be adequate for viual, but probably not comfy. The GPDX on a surveyors tripod would work for visual.

The Universal Astronomics Unistar on their surveyors tripod would probably be more than adequate, but it is an alt-az mount that doesn't track.

I would recommend going to a star party and getting a goood look at some set ups before springing for a GP (unless you get one on here for a price where you'll pretty much just lose shipping if you need to sell it.)

I would not call a night with moments of steady seeing at 100x "great seeing."

robert black said:

I recently purchased a 2" lumicon deep sky filter.
I then screwed into my celestron 6.3 reducer/flattener. Now, I can't get it off.
I have tried 2 pair of waterpump pliers to no avail. Thankfully, I haven't marked them. I am afraid to put too much pressure on them in case I break the glass.
I sent lumicon an email to see if they had run into this problem before and apparently they have. They suggested something that looks like a small oil filter remover but I have no idea where to get this.
Any suggestions would be appreciated. Not only how to get them apart, but how to prevent it from happening again. Many thanks, bob

The cause of your problem is likely a bur on the threads of either the filter or the reducer. You can figure out which if you have used the reducer threads before. I had this happen with a brand new astronomiks uhc filter. The pressure of the water pump pliers can deform the perimeter of the thread circle, making it harder not easier to turn the threads. I think that I finally got it off with a screw driver and an impact (ie small hammer) at a low angle. This certainly impacted the cosmetics of the filter, and could have broken it (so its defintely a last resort, and don't try it even then unless you really understand what I meant).

Gary Calobrisi said:

Does any body know how I can mount the head of an Orion EQ1 mount to a more stable tripod than the one supplied with it by Orion?

Thanks

Gary

I don't claim expertice with that mount, but assuming that it has a 1/4 thread (or something metric) you either tranfer it to a photo tripod of heavier duty or buy a bolt with the correct thread and use that to clamp it to something like a surveyor's tripod by putting a pice of plywood (5/8 or 3/4) under the hole in the tripod with the bolt (and fender washer) passing through the plywood washer and up to the mount.

If you want to upgrade to a half pier a PVC plumbing connector 2 or 3" can be fit as a pier (or sspacer) on top of the tripod with a suitably long bolt.

It's kind of hard to explain without an illustration, but it's actually very simple.

Hi Al,

I spent some time comparing an D&G 5" f12 (it's not the same scope of course) with my MN 56, which may be of some help to you. I did not have Steve's problems with thermal equilibrium (given a good 1/2 hour of cool down time), but his other points are well taken. I now have, but have not installed a feathertouch. The tube is also not round, which is frustrating on a GEM.

Now, we compared the D&G 5", the MN 56, and a Tak 130 f6 reflector, on a good night. The views on Saturn were about the best I have ever had. As best I can remember, resolving power and contrast were impressive in both scopes (THe tak lagged considerably on contrast until we improved a "dew" shield, at which point they were all very close). The MN 56 was not as bright as the other two scopes, just more surfaces. It certainly had the flat field and wide field of view. My general conclusion was that well executed examples of the three types of scopes produced very good results.

The D&G was just huge by comparison. The MN or the Tak work adequately on a Vixen GP (or SP) for visual. The D&G needed a lot more.

Al Ellefson said:

I am thinking of one or the other as a next purchase. The DGM OA 4" or the Intes MN56. Any and all of your thoughts , experience's and opinions would be greatly appreciated. Thank you for your time. Allen

Kevin VerMerris said:

Been long enough to qualify as a beginner, my equipment
1 - 8" Discovery reflector - purchased as eq mount - the not so great one that came with a lot of scopes. Focuser is suspect-probable upgrade
1 - Stellarvue 80/9D OTA w/rings - use the same mount
Telrad finder
Red Dot finder
Some EP

Hi Kevin,

I wouldn't swap out the Stellarvue unless you really want an APO. It's a good achromat. It's also hard to get much over $200 for the OTA. I bought one for my daughter here, and we really like it. (My personal 80 is an APM super apo, so it's not as if I don't have an idea what "the best" is.)

I'd love to get back into things but not sure I'm happy with what I have. My gut says sell everything and start over, but not sure thats necessary and was hoping to get some ideas as to what is useable or to go in a different direction. Thanks for thoughts

Bob Royce, rfroyce.com has some interesting and inexpensive suggestions for mounting dob mirrors using silicone. That's what I do, and it has been very successful for me.

Judson Mitchell said:

When I first received my 12" dob, the mirror was adhered to the cell by what seemed to be 2-sided tape. I reattached the mirror after cleaning in a similar manner. Now, my mirror will come back home after refiguring. Does anyone have other recommendations concerning how I may attach the mirror to the cell. It is a 9-point cell with floating 3-point triangles. One of the problems also is positioning the mirror while attaching the cell.

It appears that laying the mirror on its face is the most accurate method of positioning the cell points. Suggestions relating to this activity is also needed.

Jud

Paul Neesam said:

Looking for your help, why is it so hard to get a mirror supplier to return emails about their products, one site did not even have a way to contact them? Maybe its me, don't know, maybe business is soooo good they don't need any more business. It is driving me kind of nuts... I've sent emails out to maybe 10 suppliers looking for a good quality 16-inch f/4 prmary, received two responses from two excellent suppliers, thats only a 20% response. Not really a way to make money...thanks!

RE: "way to make money" generaly speaking, making mirrors for amateur astronomers is not a money making venture. Bob Royce is a true professional (and for my money, a great guy), but his primary business is not making astronomy mirrors. He loves astronomy and amateur astronomers. Because he runs a significant optical business he has the equipment, and he has the interest. In one way or another a lot of these people eat from a day job, or are semi-retired from a day job.

A version of this is true for a number lot of scope makers, who don't answer e-mails sometimes when its on the point of criminal negligence. You just couldn't run a business you were living off of that way for very long.