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Posts Made By: Ron Oehlert

December 20, 2002 09:55 PM Forum: Telescope Making

Personal history

Posted By Ron Oehlert

Hello. I've posted here recently and thought maybe you would like to know who I am (I've followed many of you over the years in S&T). I began my interest in astronomy in 1956 and knew all the constellations by 1957. I had a quality 2.4" refractor (no mm designations then) soon after and ground/polished my 1st 6" f/8 mirror in the early 1970's. A 2nd 6" and a 10" f/6 followed, but I've not pushed glass for some time. I guess I'm from the old school during Thomas Cave's reign. I participated in the ALPO's Luna Incognita mapping project of the 1970-80's but spend my observing time for fun now. John Westfall (acting director of the ALPO at the time) was impressed with the quality of my optics. I live in rural central US but not conveniently close to any organizations, and sometimes consider possibly re-figuring one of my mirrors to even better performance. I gave the 10" to a friend and still have the two 6". Happy holidays, Ron

January 1, 2003 07:10 PM Forum: Off Topic Discussions

Re: Caldwell's???

Posted By Ron Oehlert

What is so special with Moore is that he has been at this for a very long time (maybe even longer than you are old) and has thru his enthusiasm helped popularize an interest in astronomy. Ron

January 2, 2003 08:17 PM Forum: Equipment Talk

Celestron Erfles revisited

Posted By Ron Oehlert

per the discussion of 12-9-02, I have an eyepiece marked Celestron 20mm Erfle 1 1/4 Fully Coated. Circle V on barrel. Advertised 65* AFOV. This eyepiece appears to be in the same housing as the common 25mm ortho, and in fact the lens set also appears to be the same 25mm ortho with the addition of a plano-convex field lens. I found it had severe vigneting when used in f/8 telescopes (reflector and refractor). Both these scopes support a fully illuminated FOV with a 32mm type I UO Konig (much larger field stop). Knowing the same thing occurs when the field stop of common orthos is removed, I suspected that this basically ortho (ala Goerz) implementation could not support such a wide AFOV. I stopped mine down to ~17mm as is used in the common 25mm ortho and this resulted in a ~55* AFOV. True field now is the same as a 25mm ortho but with increased magnification and larger AFOV per the 20mm fl. The field remains sharp to the edge with a little edge distortion present (no distortion in the 25mm configuration with the extra field lens removed). It also Barlows well in this mode with no vigneting. Ron

February 8, 2003 04:42 PM Forum: Eyepieces

Re: High Quality Orthos and a Televue 102

Posted By Ron Oehlert

It means you will need an adapter bushing of 0.965" I.D. to 1.25" O'D. and preferably one for each eyepiece. Ron

April 6, 2003 09:54 AM Forum: Equipment Talk

Re: Anyone know what this 1.25 eyepiece is?

Posted By Ron Oehlert

Sometimes Suppliers took spotting scope eyepieces and added a 1.25" barrel adapter screwed on with a tiny set screw to lock. Their labeling was then painted on. Vernonscope did this with a 20mm modified Erfle and placed their Brandon label on it, but they didn't do it for long as the eyepiece was clearly stamped Japan inside and Vernonscope advertised their products as made in USA. Customer returns promted the deletion, but it was indeed an excellent eyepiece dispite the mis-representation. Ron

August 11, 2003 06:46 AM Forum: Telescope Making

Star Images in the Presence of Aberrations

Posted By Ron Oehlert

S&T Gleanings for ATM's article April, 1978 page 347 concluded that there was no evidence (from an optical point of view) that a schiefspiegler or refractor should outperform a newtonian with a small CO. All exibited similar degradation; for the tilted component telescopes it is coma, for the refractor it is defocusing and for the newt it is the CO, but the effects of each are comparable and not worse than the others. If one design gives less (or more) performance than the others suspect surface quality, alignment, or air currents as the reason. Thought this might be of interest in the wake of recent discussions. Ron

October 10, 2003 07:19 PM Forum: Equipment Talk

Re: Optics Questions

Posted By Ron Oehlert

You should ask in the Telescope Making section.

January 11, 2010 09:44 PM Forum: ASTRONOMY

Identifying Constellations & 1st Magnitude stars

Posted By Ron Oehlert

In these nights of GOTO 'scopes, I was wondering if anyone still could, from a glance at the sky & without the aid of a chart, identify the Constellations & 1st Magnitude stars visible tonight or on any given night. I learned them at age 11 in 1956 but observing methods have changed since then.

April 10, 2010 05:44 AM Forum: Beginning Astronomy?

Recreational Astronomy booklet

Posted By Ron Oehlert

See Astromart Classifieds catagory Software & Publications(ASTRO) currently per a new booklet for beginners. While I have not reviewed it, the included pics hit the mark on basic info I started with some half-century ago. Seems this may be worthwhile for club distribution, perhaps along with Astronomy Day events.

April 15, 2010 09:36 PM Forum: Reflectors

Re: Mirror help

Posted By Ron Oehlert

Probably minerals or additives in the *Spring* water. Waiting will just allow the mineral spots to themselves harden thus making their removal difficult or impossible. I've not heard of aluminum needing to harden, BUT the aluminum should have a protective clear coating of hard silicon or such; plain un-coated aluminum is not the norm for astronomical mirror coatings. So, PAY ATTENTION to what your coating actually IS and What you use to clean it with & HOW you clean it (because it seems you Do Not know how to do this properly). Clean ASAP accordingly per All of the following Guidelines. Line kitchen sink with towels to soften sink surface. Flush mirror with running tap water (no temperature extremes) then let mirror soak for 10 minutes immersed in lukewarm Tap water to soften those mineral spots (a little dishwashing detergent added is OK) & Do Not scrub them (No Rubbing, Ever!) but pull only a gentle (no pressure, weight of cotton only)) swipe with STERILE Genuine cotton roll-wadding (found in First-Aid section, Do Not use cotten balls from the Cosmetic aisle); only one pass each side of a torn-off piece of cotton & discard for another, you will likely use the entire box during one cleaning procedure. To Repeat: No Rubbing, Ever! RINSE with Distilled water & prop mirror on-edge to drain & air-dry. The occasional errant droplet can be wicked with a corner piece of paper towel. All of the materials neccessary for this should be accumulated & at hand Before beginning & turn your phone OFF. AND there is absolutely NO reason for a small child to be nearby whenever optics are out of the scope or exposed. You seem to have your prorities mixed-up; If You are the designated child-tender at the time, exhibit some adult patience per your optics & simply wait until later; Never multi-task where your optics are concerned (& absolute Silence while cleaning will permit Hearing if sleeking is occuring). BTW, persons of Any age with food & drink in hand should NEVER be allowed to view thru or be nearby your scope (consider what it took to make or buy it).