Posts Made By: Bob Polcyn

Hi Fred -- Congrats on seeing the Rosette. I've never managed to see it, probably because my usual viewing site has too much light pollution.
What magnification did you use? -- had to be low power since it measures about a full degree in diameter.

Bob Polcyn

Hi Bill -- Sherline builds/sells very nice mini lathes and mills. So does Taig. I have a Taig mill which has served very well.

Bob Polcyn

I've done well by drilling with about three drill bits beginning with a small (3/32") and gradually increasing bit size. A 10% error with the small bit is a lot smaller than it would be with a much larger bit.
This process takes more time but the precision is good.

Bob Polcyn

Hi all -- I bought one of these a while back just for fun and did some research on possibilities. Their curve is spherical, not parabolic. Primaries like these have been used in scopes with Gregorian optics which if I'm remembering right mates the spherical primary with a spherical secondary mirror. The images produces are 'normal', not inverted or reversed. I was told that with a secondary of appropriate focal length the set up might make a decent low power scope for wide field scanning. I got as far as testing the 16" with cheap but handy parabolic secondary and with a struggle did get an upright image, barely visible for lack of any shielding. That was a year or more ago. I'll get back to it someday.

Bob Polcyn

It's a great image. Wide field views provide a sky context element which I find very beautiful. Thanks for sharing it.

Bob Polcyn

Hi Aris -- I have a pair of Nikon 20x120's -- bought them about a year ago. I haven't found a lot of user feedback on giant binoculars either -- some discusson on the Cloudy Nights website.

Giant binoculars are a mixed bag, like everything else in astronomy. Let me start with some negatives:

1. They're heavy and clumsy to move around. Mounting them is a major issue. Think in terms of a permanent mount. Parallelogram mounts can be used but they look huge and require heavy counterweights (Google image searches will turn up an example or two). I've built a one of a kind non-parallelogram mount that involves a counterweight and chair, all on wheels for use only on smooth surfaces like my driveway concrete.
2. In 'giant' size I'm aware of only Fujinon 150's with right angle eyepieces which cost much more than the straight thru version. Straight thru viewing requires special attention as regards body position/mount design. I don't think that its possible to view straight up or close to it for extended times if you're standing.
3. As with smaller sized binocs of higher quality the eyepieces are fixed (no interchangeable eyepieces) which of course means fixed magnification.
4. I haven't found a practical way to use OIII/UHC filters. Nor have I been satisfied with finder scope solutions (this may be a bigger problem with how the Nikons are designed).


The pluses:

1. The views are wonderful. My Nikons provide a 3° FOV which is ample enough to satisfy my sky sweeping style. And the light gathering power of 120mm objectives deliver many DSO's -- globular clusters are quite bright -- the detail visible in M42 is a delight -- open clusters are beautiful. Two eyed viewing with quality glass is great.
2. Though I'm still tweaking the design of my mount I'm able to view all parts of the sky comfortably enough.

So, mixed bag, yes. For me the Nikons are keepers.

Bob Polcyn

Hi Curt -- Thanks for the astro info your website provides. --- interesting and useful.

Bob Polcyn

Hi Michael -- Try a single strand of copper from a multistrand bunch in common electrical cord. Good luck with it.

Bob Polcyn

Hi Marcin -- It's a beautiful scope, nicely done. I'll bet you learned a lot in the process of building it. Thanks for sharing.

Bob Polcyn

Hi Floyd -- I should probably be able to recognize the galaxy but can't. It's identifier?
Thanks.

Bob Polcyn