Posts Made By: Richard Keppler

May 6, 2008 11:38 PM Forum: Astro-Physics

Large mount - large scope

Posted By Richard Keppler

That 20" telescope just doesn't 'look' like it should weight 150 lbs. Deceptive viewing it on the 3600 and a good match for that mount. The 17" should ride nicely on a 1200 mount, or at least I hope it will.
Rick.

May 10, 2008 01:58 AM Forum: CCD Imaging and Processing/Deep Sky

dracos triplet

Posted By Richard Keppler

Lucien Kemble and others used to call this "The Sampler", for it is a sample of a face-on spiral, an elliptical, and an edge-on spiral, all in one eyepiece view. While visually trying to distinguish which one is the elliptical and which is the face-on in anything less than a 20 inch scope is pretty near impossible, with a 25 inch and likely even easier with a larger scope under excellent skies, I have heard that it can be done.

August 22, 2008 12:28 AM Forum: Astro-Physics

1200 mount in Antarctica

Posted By Richard Keppler

Just how do they manage to keep the corrector ice free in those conditions without it shattering?

This place is NOT on my vacation shortlist.

Rick.

December 1, 2008 02:58 PM Forum: Astro-Physics

AP160 to ST10 or STL11k connection

Posted By Richard Keppler

I would get Ashley with Precise Parts to make an adapter to go from the 2.7" thread of the AP extension tube to a T-thread for the camera end. It need not be more than about a half inch thick. It could be much thinner but leave something to be able to grasp it for removal from the camera. I'll leave it up to you to figure out the particulars of male or female threading and where. The rest can simply use off the shelf 2.7" threaded extension(s) available from Astro-Physics or possibly Anacortes to roughly adjust the spacing, and then the focuser to do the final fine focus work. Be aware you will likely see some slight optical imperfections in the corners of the ST11K without using a field flattener or telecompressor. The ST-10 sensor should be small enough not to require such.

January 15, 2009 03:37 PM Forum: Equipment Talk

Amici/correct image prisms

Posted By Richard Keppler

Ivan Ong said:

Hi, I am thinking about these for birdwatching. I have never used one or looked through one. Can someone with experience in choosing and using one kindly give me some hints?
-which brands are good
-any optical drawbacks?
-other thoughts?
-if I use this in a finder for astronomy, any issues?

Thanks very much,
Ivan

I have used the Baader 2" extensively. For magnifications used in birding it will work just fine and you will be able to track a subject as it moves. If you are planning on doing high magnification imaging then a high quality star diagonal might work better although I have never attempted daytime imaging with the Baader amici or a standard high quality star diagonal. For night-time use, I have found the amici prism to work just fine at low magnifications and has been mentioned, for low power star-hopping with a Dobsonian it is wonderful.


February 19, 2009 06:07 PM Forum: Takahashi

Sky 90 II dew shield dimension ?

Posted By Richard Keppler

A bit late but I'll add a few more notes to this. The dewshield is threaded on BOTH ends with the identical threading. It is fairly easy to remove from the OTA. On the objective end a stop ring is threaded in so that the dewshield cannot retract further than the front of the OTA. If you are considering getting an adapter for a Coronado or Lunt solar filter, there are several companies making adapters which thread in directly to this thread. Normally this works out wonderfully and the solar filter cannot slip off accidentally. In my case I purchased an adapter which was not for the Sky90 but it looked ok. When I threaded it in, it seized short of going on fully. I had a heck of a time removing it and managed to partially destroy those front threads doing so. It was NOT cross threaded, just incorrectly threaded, probably with a non-metric thread. When I finally did manage to get the proper adapter it, would not thread in reliably enough. I had severe concerns with the rigidity. One really doesn't want the filter falling off when observing the sun through a telescope. I ordered a replacement Sky90 dewshield from TNR but it is only threaded on one end and has no provision for installing the stop ring. It is an obsolete part probably for the original series of Sky90 telescopes. Once I saw this I inspected the original dewshield closer. I managed to remove the stop ring, measured the threads which turned out to be identical on both ends and reversed the dewshield on the telescope. The threading on the sliding ring on the OTA is longer and goes past the mangled portion of the dewshield threads and is rigidly held. The solar filter adapter threads in properly to what used to be the OTA threads and is also rigidly held. I even threaded in the stop ring. I am happy in that I can now use the Coronado 90 filter I purchased. I am not happy I wasted my money on a replacement dewshield that is not current and cannot be used.

March 23, 2009 09:02 PM Forum: Astro-Physics

155 EDT vs APQ 150

Posted By Richard Keppler

I have first hand reports of a visual test between a Zeiss APQ 150 and an AP155EDF f7. While incredibly close, the observer comments on the Zeiss having a slightly "whiter" white and a hair better contrast on extreme contrast areas such as brightly lit features at the terminator on the moon and those areas still in darkness. I haven't heard any direct comparisons of the EDT f9 version versus the Zeiss, but I would hazard that the differences would be exceedingly minor and may well be entirely beyond the ability to detect except via interferometric or measured light transmission as a function of wavelength testing.

April 3, 2009 07:43 PM Forum: CCD Imaging and Processing/Deep Sky

Virgo Galaxies

Posted By Richard Keppler

For a DSLR stack, it is very nice! I actually like the smaller image better as the field curvature is not as obvious. The colors are great, not extremely saturated. Good focus with nice subtle detail in the brighter galaxies. An incredible image considering the limitations imposed by the instruments used (DSLR capture, short focal length = high field curvature, etc). Very nice work processing and presenting the image Jim!

April 9, 2009 01:13 PM Forum: Astro-Physics

Amart auction AP Traveler

Posted By Richard Keppler

jim chung said:

I was just curious if anyone knew why this AP Traveler auction is doing so well, poised to break past 5k. Given the current economy I wouldn't have expected these prices.



1) It is an Astro-Physics Traveler.
2) Read the ad copy. It does not have the pebbly finish.

June 17, 2009 02:45 AM Forum: Equipment Talk

Looking to get a White Light Solar Filter

Posted By Richard Keppler

Brian Lee said:

I'm looking to get a White Light Solar filter for my meade ETX-70AT.
Does anyone have a suggestion?

Reg

Only 2 options I would recommend:

Inexpensive: Baader solar film.

More expensive: Baader Hershel wedge.