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Equipment Discussions >> Refractors

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Daniel Warner
journeyman
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Reged: 05/03/09

Celestron 80 mm F 7.5 ED Light baffles new
      #5874383 - 05/20/13 06:35 PM

Hi all,
I just took my Celestron 80 ed down to the shop to be powder
coated .while I was at the shop one of the baffles fell out of the optical tube. Its the one that has the largest diameter hole in it and im sure that would be the one that is the furthest away from the focuser does anyone know how far ( in inches ) that this baffle needs to be placed from
the objective lens ?
Thanks any help.
Dan


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Rich V.
Post Laureate
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Reged: 01/02/05

Loc: Lake Tahoe area, Nevada, USA
Re: Celestron 80 mm F 7.5 ED Light baffles new [Re: Daniel Warner]
      #5874418 - 05/20/13 06:47 PM

In some scopes the baffles are just pressed into position. Perhaps if you are lucky you will see some marks left in the tube's interior paint that indicate the original position of the baffle.

Good luck,

Rich


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Daniel Warner
journeyman
*****

Reged: 05/03/09

Re: Celestron 80 mm F 7.5 ED Light baffles new [Re: Rich V.]
      #5874835 - 05/20/13 10:17 PM

Hi Rich,
Thanks allot for your help, when I get the scope back ill check
Maybe ill get lucky and find those marks
Cheers,
Dan


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GlennLeDrew
Postmaster
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Celestron 80 mm F 7.5 ED Light baffles [Re: Daniel Warner]
      #5875014 - 05/21/13 12:04 AM

This is certainly the baffle closest to the objective; they always taper to smaller opening size the closer they get to the rear.

You can do as I did when making up a modified OTA. While looking into the focuser, with your eye near to the focal plane, place the baffle so that it meets, as closely as possible, these two conditions:

- It blocks any direct view of the tube's inner wall between baffle #2 and the objective cell, as viewed from the opposite side of the focuser opening.
- Its edge lines up with the following baffle edges, as viewed from near the same side of the focuser opening.

For the first condition, the objective cell *may* provide some degree of shadowing on the portion of the tube wall nearest to it, depending on cell size with respect to tube I.D. If this is the case, only the tube wall portion which can be illuminated by oblique light getting through the lens shade is of concern.

To understand which factors matter here, try to find a diagram which shows in cross section a schematic of a baffled tubes that includes the relevant shadow zones and sight lines.


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