# Optical...... thing.

**URL:** <https://boards.straightdope.com/t/optical-thing/171444>\
**Category:** Factual Questions\
**Created:** [April 27, 2003, 4:27am UTC](https://boards.straightdope.com/t/optical-thing/171444 "2003-04-27T04:27:32Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\
**Post date:** [April 27, 2003, 4:27am UTC](https://boards.straightdope.com/t/optical-thing/171444/1 "2003-04-27T04:27:32Z")

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[What is it?](http://www.amazon.co.uk/exec/obidos/ASIN/B0000665VB/ref=ed_soc__1_2/202-4832738-5243841)

I know it’s optical, but what for?

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**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\
**Post date:** [April 27, 2003, 4:31am UTC](https://boards.straightdope.com/t/optical-thing/171444/2 "2003-04-27T04:31:02Z")

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Telescope eyepiece.

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**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\
**Post date:** [April 27, 2003, 4:33am UTC](https://boards.straightdope.com/t/optical-thing/171444/3 "2003-04-27T04:33:20Z")

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Made by [these guys.](http://www.celestron.com/access/eyep.htm)

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**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\
**Post date:** [April 27, 2003, 4:41am UTC](https://boards.straightdope.com/t/optical-thing/171444/4 "2003-04-27T04:41:48Z")

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Oh, thanks. I knew it might be something like that, but the amazon page wasn’t very helpful.

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**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\
**Post date:** [April 27, 2003, 4:43am UTC](https://boards.straightdope.com/t/optical-thing/171444/5 "2003-04-27T04:43:00Z")

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Yup, telescope eyepiece. The eyepiece is standardized so it works on any telescope. (Well, actually there is more than one standard, but not too many). Changing the eyepiece changes the magnification, and replacing an eyepiece with a better quality one can give you a sharper image, wider field of view and/or increased “eye relief” (how close your eye needs to be to get the full field of view). High end amateur telescopes don’t even come with eyepieces because most users already have a set of eyepieces they like. A high end eyepiece can cost over $600 and weigh over a pound.

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**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\
**Post date:** [April 27, 2003, 4:46am UTC](https://boards.straightdope.com/t/optical-thing/171444/6 "2003-04-27T04:46:03Z")

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> [@](#):
>
> \*Originally posted by Lobsang \*  
> \*\*the amazon page wasn’t very helpful. \*\*

What, you mean apart from providing a link to [this Celestron page](http://www.amazon.co.uk/exec/obidos/search-handle-url/size=20&store-name=electronics&index=electronics-uk&field-manufacturer=Celestron/026-9329564-3502863), and having the legend:

\*\*Photography \> Binoculars, Telescopes & Scopes \> Telescopes \> Accessories \*\*

at the bottom of the page?

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**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\
**Post date:** [April 27, 2003, 4:53am UTC](https://boards.straightdope.com/t/optical-thing/171444/7 "2003-04-27T04:53:42Z")

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Well I didn’t mean it was impossible to find out what it is. I just meant they didn’t make it obvious.

I made the thread to make a statement about ambiguity (and because I generally wondered what it was)

And I am stupid - I didn’t think to click on the link.

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**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\
**Post date:** [April 27, 2003, 4:55am UTC](https://boards.straightdope.com/t/optical-thing/171444/8 "2003-04-27T04:55:08Z")

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‘generally’? I meant to say ‘genuinely’.