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Home > Forums > ASTRONOMY EQUIPMENT > Reflectors > Message #832545

Re: 36-INCH TELESCOPE

Posted by Thomas Dey on 2/4/2017 4:53 PM in response to Re: 36-INCH TELESCOPE   (248 hits)
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Thanks, Rod. On the 29, the SM folding flat is 5-in. I used a very short focuser very far in; on the 36, I have a 6.25-in. and will use the same close-in configuration. I used Mel Bartels calculator for a sanity-check on sizing. http://www.bbastrodesigns.com/diagonal.htm Both give generous "full illumination" fields. He shows a slight illum drop across the entire field, because normalized to a completely unobstructed PM. He does NOT account for coating reflectivity losses, which generally overwhelm the diag shadow contributor. So I use enhanced Al on the PM (because it's durable) and (could/should) use enhance silver on the folding flat. Dielectric diagonals are wonderful, but can (generally DO) severely effect polarization, so anyone wanting to do polarimetry should be aware of that. I did interferometry on the flats, as-used configuration. Good and good. So many gremlins can thwart performance... trying to preclude most before 1st light. Tom


29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos

Thread:

Subject Posted By Date/Time Hits 
36-INCH TELESCOPE Thomas Dey 2/2/2017 4:43 AM 409
Re: 36-INCH TELESCOPE Thomas Dey 2/2/2017 4:44 AM 292
Re: 36-INCH TELESCOPE Thomas Dey 2/2/2017 4:45 AM 286
Re: 36-INCH TELESCOPE Thomas Dey 2/2/2017 4:46 AM 299
Re: 36-INCH TELESCOPE Greg Shaffer 2/2/2017 5:38 AM 280
Re: 36-INCH TELESCOPE Thomas Dey 2/2/2017 6:30 AM 216
Re: 36-INCH TELESCOPE Rod Kaufman 2/2/2017 6:09 PM 211
Re: 36-INCH TELESCOPE Thomas Dey 2/2/2017 9:11 PM 243
Re: 36-INCH TELESCOPE Walter Hamler 2/3/2017 9:30 AM 192
Re: 36-INCH TELESCOPE Thomas Dey 2/3/2017 10:31 AM 280
Re: 36-INCH TELESCOPE Thomas Dey 2/3/2017 10:32 AM 229
Re: 36-INCH TELESCOPE Thomas Dey 2/3/2017 10:32 AM 236
Re: 36-INCH TELESCOPE Rod Kaufman 2/4/2017 9:06 AM 225
Re: 36-INCH TELESCOPE Thomas Dey 2/4/2017 4:53 PM 248
Re: 36-INCH TELESCOPE Thomas Dey 2/6/2017 5:55 AM 319
Re: 36-INCH TELESCOPE Greg Kim 8/20/2017 11:01 PM 122
Re: 36-INCH TELESCOPE Thomas Dey 8/22/2017 11:12 PM 92
Re: 36-INCH TELESCOPE Greg Kim 8/25/2017 135
Re: 36-INCH TELESCOPE Thomas Dey 12/1/2017 5:14 PM 46
Re: 36-INCH TELESCOPE Thomas Dey 12/1/2017 5:15 PM 40
Re: 36-INCH TELESCOPE Thomas Dey 12/1/2017 5:18 PM 36
Re: 36-INCH TELESCOPE Thomas Dey 12/1/2017 5:19 PM 47

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