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Posts Made By: Ron Oehlert

February 21, 2011 11:06 PM Forum: Meteorites & Meteors

I Screwed Up!

Posted By Ron Oehlert

What was Goodwills' response when you contacted them after realizing the mistake?

February 27, 2011 11:28 AM Forum: Beginning Astronomy?

query on Orion

Posted By Ron Oehlert

Hi Joe, the other responders are correct. And even the illustrative pic provided by Herbert displays much too much contrast & brightness for the location you had (it is also a lower-power & wider-field view than you had). Observing Tips: Dark-Adapting your eyes by not looking at any bright lights for 20-30 minutes & longer helps with seeing dim faint light thru the scope, as well as looking towards the side of or slightly beyond a faint object (known as Averting your vision) vs straight-on towards its' center. Draping a dark cloth over your head & the focuser helps keep stray city lights out of your view, too, as well as preserves dark-adapted night vision. (like the old-time photographers with their glass plates & tripods).

March 1, 2011 02:07 PM Forum: Beginning Astronomy?

Setting up a celestron CGE for 1st time use

Posted By Ron Oehlert

Enter celestron in-between the ubiquitous www dot dot com & select Support from top of page menu, then select Manuals/Downloads from the selected fall-down menu.

April 17, 2011 04:23 PM Forum: Equipment Talk

simple Vixen question

Posted By Ron Oehlert

How to DIY: Focus on the full or nearly-full Moon (any night this week) & remove eyepiece. Discover focal plane via a white card showing the Moon's projected image. Measure card position when the lunar image is sharp on the white card (adjust by moving the card, do not touch focuser knobs).

April 30, 2011 06:44 PM Forum: Beginning Astronomy?

what galaxy is good for beginners?

Posted By Ron Oehlert

Visually all you can see is a glow with unresolved edges. Long exposure (or combined multiple exposures) Photography is required to reveal spiral arms. Historically before photography, galaxies were catagorized along with gas clouds as Nebulae (nebulous-appearing or faint glows of ghostly light) because there was & is no visual difference. You can however detect subtle brightness levels between centers & edges or dust lanes as well as shape, just as with gas clouds (which also do not visually look like their photographs).

May 7, 2011 09:08 AM Forum: Telescope Making

Help needed with Cassegrain assembly

Posted By Ron Oehlert

Try it without the diagonal. And even without achieving focus, the varying size (as you manipiulate the focuser back & forth thru its' range) of an extrafocal star image should inform as to whether you need more or less back focus distance. It may be that mechanically you cannot use a diagonal with the present mountings. Or perhaps the mirror itself needs to be shifted for focus adjustment vs a separate focusser behind the mirror (& in that case there might be adequate back focus for a diagonal).

June 2, 2011 07:38 PM Forum: Eyepieces

Oldest ocular, why you've retained it?

Posted By Ron Oehlert

Not just one or two eyepieces, but I have full complete sets of early Vernonscope Brandons & Dakin 2X Barlow, Telescopics' Galaxy Optics eyepieces with Barlow, all of the Meade Research-Grade *Erfles*, all of the 1st-issue 1.25" barrel Meade SWA series, a full set of the common Orthos widely sold by Edmund, Parks, UO & others. Plus several more vintage eyepiece examples. My present scopes are a 6" f/8 equatorially-mounted self-made Newt, a 3.25" f/12 A.Jaegers doublet achromat on a user-intuitive Meade 390 Alt-Az mount & an Edmund 2.4" f/8 doublet achromat. All of the above eyepieces get regular use by myself or at neighborhood star partys. The newest mfg examples I have are some Televue Wide Fields & TV type 1 Naglers, but these are seldom used due to the superiority, at least in long-focus scopes, of the others mentioned above. My skies are dark rural Kansas with the Milky Way obvious & prominant, so deep sky as well as lunar & planetary viewing is normal backyard fare (the Veil nebula in Cygnus is easy to spot with the 2.4" refractor at 15X). I keep & use those vintage eyepieces simply because they can be counted on to readily reveal all the image detail available from the objective or mirror (& seeing such images is why I look in the 1st place).

September 24, 2011 09:23 PM Forum: Beginning Astronomy?

1.25" vs 2" eyepieces

Posted By Ron Oehlert

A 2" barrel allows a wider potential field of view with eyepiece focal lengths longer than about 30 or 32mmm; that is their only *advantage* vs 1.25" barrels. 32mm & shorter focal lengths have similar fields of view regardless of barrel diameter, because the useful fields of view for those focal lengths are fully accomodated by smaller barrels (so a larger barrel size in this case merely fits larger focussers without using an adaptor). Your scope must also be able to deliver a wider cone of light for such longer focal lengths with wider AFOV (which is why actual trial is preferable). In the shorter focal lengths, 1.25" eyepieces are usually less cost vs comparable 2" barrel sizes & there is greater variety of types, focal lengths, & brands to select from. Determine the magnification of any eyepiece/scope combo by dividing eyepiece focal length into scope focal length. Divide the resultant magnification into the scope's primary diameter to get the diameter of the exit pupil of light; more than 5 to 7mm exit pupil is wasted low power as your eyes' night-adapted iris cannot enlarge enough to see it all (this equates to using a smaller telescope as some of the primary aperture is wasted).

August 6, 2012 01:52 PM Forum: Telescope Making

question on adding turpentine to pitch

Posted By Ron Oehlert

The purpose of adding Turpintine or other such solvent is to soften the pitch so that it somewhat *flows* under the pressure of your working the mirror against it. Too soft a resultant pitch lap is also not good, just as a too-hard of a lap could be. So, those mentioned solvents available to you should readily suffice for the purpose (the pertroleum-based versions were invented to be less expensive than wood-based Turp). But before actually thinning the warmed pitch *just because* you heard you *should*, I suggest you read comprehensive instructions per mirror & pitch lap making so that you have a full understanding of what you are producing & wanting to accomplish. And mind the heat source when using volitle solvents (Turpentine was also known as lamp oil & used as a less-costly substitute for whale oil before the days of electric lighting; petroleum-based solvents are more volitile).

December 16, 2012 12:51 PM Forum: Telescope Making

Mirror clips

Posted By Ron Oehlert

With any such clips, ALL they do (or Should do) is to keep the mirror from falling out if the scope were positioned horizontal, or worse, at a greater angle(upside down). These clips should Never apply direct force to the mirror itself lest deformation of the mirror's figure occur with detrimental effects on the image; IOW always loose-fitting. So, you should be able to fabricate clips from sheet-metal, wood, or plastic using ordinary home tools & a hand drill for screw holes. Even simple blocks of wood attached to the inside of the tube or mirror box above the mirror will provide this fall-out prevention function; they needn't be attached to the mirror support itself. Alternatively, don't tip your scope to horizontal (and eliminate diffraction-creating clips in the optical path). Apply self-stick felt furnaure pads (a local Hardware store item) to the mirror-side of such clips to avoid scratching the mirror coating in the event the mirror does contact the clips. IOW you do not need mfg-specific clips for this purpose & making such clips for an already at hand mirror support is far simpler than making an entire support which also requires clip fabrication. For transport, a secured full mirror cover will protect against fall-out & protect the mirror surface as well = better than clips for this purpose.