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Simple Eyepiece Calculator

brympton

By brympton
in Primers and Tutorials

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brympton

brympton

Posted
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I couldn't find a simple eyepiece calculator on here so I knocked up one in Excel for my own use and have attached it to save anyone else the bother. I'm sure there are "better" calculators available and not everyone will agree with the output but maybe someone will find it useful. All you have to do is input the data into the clear cells. The file is tiny, does not contain any macro's and is protected without a password so feel free to change it. Criticism (constructive) welcome as always :D

EP_Calc.xls

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Andrew*

Andrew*

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That's just fantastic!! :D

This will sound weird, but for some reason I got the giggles when using that - it knows EVERYthing!

You're the man - if you don't mind, I'm going to use more than my fair share of that nifty little tool.

One criticism: points instead of commas for decimal points... possible?

One question: why wouldn't everyone agree on the output?

Thanks! 8)

Andrew

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blackgerby

blackgerby

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Very good, and your timing is impeccable! I'm just putting FOV indicators into KStars for my eyepieces and I didn't think the TFOV number that it was giving me was right. Turns out I'm wrong. :D (Explains why I'm having trouble finding anything up there in the occasional clear 5 minutes since I got my telescope.)

Thanks!

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John

John

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In with the hard numbers there are opinions, some people may disagree... :D

It's a useful tool but I think the the stuff on exit pupil size, max magnification etc should be regarded as guidedlines, not rules. I've had a lot of fun breaking all of them ..... :(

John

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brympton

brympton

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AstroPhethean, You should be seeing decimal points, can you check your settings: Control Panel > Regional & Language Options > Customize (Decimal Symbols). Anyone else have this problem? I wasn't sure everyone would agree with the comments but these where for me! Anyway I messed up with the TFOV results comment so have corrected and attached version 1.1 - already :oops: Regards Mark

EP_Calc_v1.1.xls

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FLO

FLO

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That is a really is useful, thanks for sharing it :thumbright:

... why wouldn't everyone agree on the output?

The opinions/guidelines are subjecive. For example, it states the exit-pupil is too large when it exceeds 7mm. I guess that is based on the assumption that an exit-pupil greater than our dilated eye-pupil will waste light. There is some truth in that but maximum eye-pupil varies according to age. Also, whether the light is wasted (or resolution is effected) depends to some degree on the telescope type.

Anyhow, I mention it only to answer Andrew's question, not to criticise what is clearly a neat and effective utility :D

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GazOC

GazOC

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And even if you are wasting the light you are still getting the FOV which may be your primary concern. You will still be seeing the object as bright as the scope can show it, just not as large (resolution).

I've made a couple of similar sheets and that ones a LOT neater and uncluttered than mine!

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Andrew*

Andrew*

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Okay, I get the idea - I thought you meant in the figures.

I think it's okay to leave the "results" as is, but include a disclaimer that they're only guidelines. I think the advice is pretty sound anyway.

Mark - thanks! I'll change the settings. My German partner's probably been using Excel and that's why I'm getting commas (what are they like? :D ).

Can we make this a sticky in a new topic, please?

Cheers

Andrew

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brympton

brympton

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Taking on board everyone's comments the "Results" have now been renamed "Guidelines". Also, instead of "ERROR" you now get "WARNING" and a toned down message. Andrew, if you are asking me I have no objections in making this a sticky but suggest we use this latest version. Can someone delete the earlier versions please?

Regards

Mark

EP_Calc_v1.2.xls

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Chatham

Chatham

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Many thanks for all the replies :thumbright: The final version has now been tested and made into a sticky here:

http://stargazerslounge.com/index.php/topic,31411.0.html

Most if not all comments have been considered and included in this version. A big thank you must also go to AstroPhethean for his suggestions and testing.

Regards

Mark

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