The TEC scopes are all oil spaced so we should learn from Rob not to mess around near the objective. The Takahashi are air spaced but I would strongly advice against disassembling one of their cells. The tolerances are tight and even the Texas Nautical techs have had problems with disassembly. It is easy to chip an element when trying to reassemble the lens cell. -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Friday, January 04, 2008 2:52 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] HELP!!! You dodged a bullet! It's actually rare to find cemented achromats in larger sizes, because differential expansion of the two glass types will generate stress and deform the glass- sometimes enough to pop them apart and damage them. Over about 70mm, most of the quality objectives are air-spaced. One other thing to note is that there should be registration marks on the edge of both elements, so you can re-align them in the correct radial orientation. It's sometimes just a pencil mark, so hopefully you didn't remove it with your cleaning. Not all makers use indelible ink for such registration marks. Often it's just a pencil line drawn simultaneously through the edge of both elements. Also not all makers even bother. Only the higher-quality achromats will have them. On Jan 4, 2008 1:27 PM, Rob Ratkowski Photography <ratkwski@hawaii.rr.com> wrote:
Follow up
the Burgess 127 doublet is air spaced. I was about to use mineral spirits to separate the elements when I noticed a space and then remembered the 3 clear tabs. It popped apart easily and w/ some fine surgical gauze and mineral spirits, clean up began.
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