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Posts Made By: Bob Polcyn

July 24, 2009 12:58 PM Forum: Equipment Talk

Meade 7" Mak-Cass question

Posted By Bob Polcyn

It may be hard to believe but I found and retrieved one of these at the local dump -- tube dinged a bit but star testing and visual views look great. Is there an adapter which would convert its 1.25" eyepiece end to a 2"? The eyepiece holder is threaded so I'm guessing that accessories were available. -- any help appreciated.

Bob Polcyn

February 2, 2010 01:01 PM Forum: Reflectors

Re: Maksutov Telescopes

Posted By Bob Polcyn

Hi Neil -- I have one of these too -- looked into possible uses a year or two ago and was advised by a maker of Newt mirrors (I don't remember who) that this kind of optic might make a decent low power Gregorian scope. It would take a spherical concave secondary (if I remember correctly) to do it properly.
I haven't had time to tinker with this possibility beyond a dining room table set up using an available 6" Newt mirror as the secondary -- no light shielding of any kind and difficult to evaluate but I did get glimpse of upright views of my neighbor's yard.
I'm going to look further into this one of these days/years. If anyone gets further into this than I got I'd be interested to know about results/design.

Bob Polcyn

May 4, 2010 12:01 PM Forum: Digital SLR AstroPhotography

Re: DSLR Mirror Lock

Posted By Bob Polcyn

Hi Paul -- Most cameras in this class have an exposure delay feature which eliminates shake artifacts related to mirror snap and such. I drive my Olympus 420 this way even though this camera has a mirror up option also.

Bob Polcyn

July 30, 2010 12:48 PM Forum: AstroMart FAQ

Prospect of the sale of Astromart

Posted By Bob Polcyn

I find Astromart to be an enormous resource even though I've sold very seldom (have bought more). It has been well run for a long time and I'd hate to see it sold. Is there an annual member fee that would keep it viable to Anacortes? WE NEED YOU!

Bob Polcyn

December 14, 2010 01:26 PM Forum: Meteorites & Meteors

Geminids!

Posted By Bob Polcyn

Clouds dominated in southwest South Dakota but last night at around 11pm mountain time there was a break in the clouds which exposed Orion. I saw three very nice meteor streaks during the 10 or so minutes I was able to view. With good skies it must have been a nice show.
Anyone else?

Bob Polcyn

August 23, 2011 10:08 PM Forum: Mounts

Alt/Az mounts for astrophotography?

Posted By Bob Polcyn

Hi all -- Are we anywhere near a time when alt/az mounts will have steppers fine enough for astrophotography? The big mountain top observatories have had them for years. IOptron sells units that GOTO and track but not well enough for astrophotography (I haven't had a chance to play with one myself).
I can guess at least part of the answer -- cost -- but are there other factors which make such a mount impractical?

Bob Polcyn

July 24, 2002 12:18 PM Forum: Equipment Talk

Filters

Posted By Bob Polcyn

Hi all --

A related question comes to mind -- 1.25" or 2" size for viewing of nebulae?
Do most nebulae benefit from wide field views or do shorter focal length eyepieces do the job just as well?

Bob Polcyn

July 27, 2002 12:45 PM Forum: Equipment Talk

Tracking with a Dob

Posted By Bob Polcyn

Thanks all for comments. I'm still not sure which way I'll go but at least I have a better feel for the options.
The link included with Alex's comment is worth a look.

Bob Polcyn

July 31, 2002 01:31 PM Forum: Telescope Making

Building my own refractor?

Posted By Bob Polcyn

Hi John --

I'm not aware of a book on the subject though there might well be one. I built a 6" with a 1200mm focal length and am enjoying it a lot.
The objective came from the Netherlands, the objective cell from Canada, aluminum tubing via an Astromart ad, the focusser from AstroPhysics.
There are a lot of decisions to be made, all of which seem to be compromises between scope size, image quality (color on bright objects, magnification limits), cost and available mterials.
It took months for me to arrive at a configuration which really satisfied me though there will always be things to tweek. I enjoyed the project and would be happy to share more details if you're interested.

Bob Polcyn (rural South Dakota)

August 21, 2002 12:32 PM Forum: Deep Sky Observing

Albireo with an UHC filter

Posted By Bob Polcyn

I've exchanged emails with Dale Mais who is seriously into spectroscopy. He thinks that the sharper looking yellow component is likely to be related to narrowing the view to more of the H-alpha region of its spectrum.
The change in blue would be related to good transmission at H-beta and O-II regions.
His thoughts match the published transmission characteristics of the UHC very well.
Fascinating stuff, this. I recommend that you look for yourselves when opportunity allows -- a big change and very pretty view.

Bob Polcyn