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Douglas729
super member

Reged: 12/25/10

Loc: Clarksville Mo.
Friday's Pop Quiz
#5682596 - 02/15/13 11:32 PM

The Aperture-holics Anonymous Pop Quiz

1. What is the 0.82x rule as pertains to binoviewer magnification by Sir Thomas of Denmark?
2. Describe the 0.88x plossl rule of forum mathematician EdZ.
3. What is the 1.25x rule regarding binoviewers and eyepieces?
4. Describe the relationship between an fstop and a binoviewer ca?
5. Have you ever had more fun in the dark with your clothes on?

DG
Damaged Goods

Edited by Douglas729 (02/16/13 12:15 AM)

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EdZ
Professor EdZ

Reged: 02/15/02

Loc: Cumberland, R I , USA42N71.4W
Re: Friday's Pop Quiz [Re: Douglas729]
#5682903 - 02/16/13 07:37 AM

Quote:

Describe the 0.88x plossl rule of forum mathematician EdZ.

Ummm, never heard of it
edz

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Douglas729
super member

Reged: 12/25/10

Loc: Clarksville Mo.
Re: Friday's Pop Quiz [Re: EdZ]
#5683379 - 02/16/13 12:14 PM

Excuse me EdZ, then from whom did I learn that a 30mm Plossl x's 0.88 will reveal a field stop of 26.4mm?

do you concur?

Edited by Douglas729 (02/16/13 12:18 PM)

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EdZ
Professor EdZ

Reged: 02/15/02

Loc: Cumberland, R I , USA42N71.4W
Re: Friday's Pop Quiz [Re: Douglas729]
#5683463 - 02/16/13 12:50 PM

Quote:

Excuse me EdZ, then from whom did I learn that a 30mm Plossl x's 0.88 will reveal a field stop of 26.4mm?

do you concur?

ahh, is that what you're referring to. Didn't recognize that as some factor. OK, I suppose that could be used as a rough number. That would give a 50° Afov.

But not all plossls have the same size field stop. Plossl eyepieces have field stops that range from 46° to 53°.

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GlennLeDrew
Postmaster

Reged: 06/18/08

Re: Friday's Pop Quiz [Re: EdZ]
#5683764 - 02/16/13 03:48 PM

I'll take a stab at #4. The clear aperture at the front end, in conjunction with the optical path length from there to the focus, determines the fastest f/ratio which can be accommodated before aperture reduction occurs.

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junomike
Pooh-Bah

Reged: 09/07/09

Loc: Ontario
Re: Friday's Pop Quiz [Re: GlennLeDrew]
#5684078 - 02/16/13 07:04 PM

#3 is easy. An eyepiece will appear to have a magnification factor of 1.25X It's given Focal Length when used in conjunction with a Binoviewer and SCT/MCT.

This is only approximate an varies depending on 1) the optical length of the Binoviewer, 2) the Telescope being used, and the optical length of attachments used to connect 1 and 2.

Mike

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Douglas729
super member

Reged: 12/25/10

Loc: Clarksville Mo.
Re: Friday's Pop Quiz [Re: GlennLeDrew]
#5684337 - 02/16/13 10:04 PM

Glenn and Mike-

Both answers are absolutely correct and very well defined in our native tongue, thank you.

My reason for creating this test is simply that I have learned to configure binoviewers with a pair of eyepieces properly can become a complicated process of trial and error. I refer to eddgie as a prime example.

Edited by Douglas729 (02/17/13 12:23 AM)

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