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Posts Made By: John Holt

November 18, 2007 05:31 PM Forum: Telescope Making

Very small Dob mount?

Posted By John Holt
Here are a couple of pictures of "pipe mounts".

http://www.astromart.com/forums/viewpost.asp?forum_post_id=452610&poll_id=&news_id=&page=

http://www.rtmcastronomyexpo.org/archives/photos/2004%20RTMC%20AE%20016.jpg


I have mounted a 6" f/5 similarly with great results.

November 22, 2007 06:51 PM Forum: Beginning Astronomy?

Parking lot astronomy

Posted By John Holt
One of the best things one can do with a scope sir. I salute you!

December 20, 2007 05:58 PM Forum: Reflectors

8" f/4.5

Posted By John Holt
Joe Herzing said:

Are there any current manufacturers making an 8" f4.5 that anyone knows of.
Thanks
Joe


Here's an ATM that came up when I looked:
http://www.mdpub.com/scopeworks/cookie.html

Though it looks like Murnaghan Instruments is no longer making 8" f/4.5 mirrors.

Royce Optics web site still offers this size mirror.

GSO's web site offers an 8" f/4 scope:
http://www.gs-telescope.com/content.asp?id=79

Parks offers f/4 ota and scope. Then there's Meades f/4 SN in 8".

But f4.5 may have dissappeared... unless one makes their own.

December 20, 2007 06:52 PM Forum: Reflectors

4 vane spider alignment

Posted By John Holt
Active cooling, across the face of the primary if possible, can also help.

December 23, 2007 08:06 PM Forum: Equipment Talk

Fifty Years of Progress

Posted By John Holt
Also the very affordable deeper field charting available now, in pixel or paper.

December 30, 2007 06:26 AM Forum: Ask rating questions here

Is anything short of a 5 star rating acceptable?

Posted By John Holt
It's a hobby. Those we deal with in the classifieds are peers, not customers or vendors. Attention to detail is important in most of life. But the definition of what's important and what's a detail is hugely variable.

The incredibley finely minced rating system on that big auction website looks like just the thing... for the giant free-for-all going on there. But I have no interest in participating in that kind of thing, and it's adversarial tit for tat. I've watched friends and family play there, and I'll pass.

It would be nice if everybody we did transactions with would at least bother to rate us when we rate them. But I'm not gonna four star anybody because of it, even though this personally seems kinda brain dead on their part. I don't want drama in hobbies. If I want strife and drama, then I'll go back in to work.


December 31, 2007 02:35 AM Forum: Beginning Astronomy?

Filters

Posted By John Holt
Skip lunar filters.

Modest sets of planetary filters are common in most folks ep cases, but seldom used.

If going for planetary filters, then keep to the lighter colored ones recommended for the specific planet to be observed.

UHC is generally considered to be the best all around DSO filter for modest aperture: as in works well on the most number of objects.

I've no experience with the either Baader. Looking foward to that oppurtunity some day.

January 7, 2008 07:55 PM Forum: Birding Optics and Photos

Barred Owl

Posted By John Holt
What a hoot!
One of my favorite companions when out under dark sky. With a tremendous vocabularly.

Neat picture!

January 21, 2008 02:19 AM Forum: Telescope Making

Tinsley Cassegrain type

Posted By John Holt
Perhaps some one here knows:

http://www.frazmtn.com/~polaris/history.html


January 26, 2008 08:04 PM Forum: Telescope Making

Dob Tube restoration

Posted By John Holt
>>>Any other things that are a good ideas I may be missing?<<<



If you do not already have it, then active cooling.

This size scope can really really benefit from variable speed, vibration free, moving air. To cool the mirror, exchange the air in the tube, and clean the boundary layer thermal turbulances at the mirror surface.

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