Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

brympton

Simple Eyepiece Calculator

Recommended Posts

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

Share this post


Link to post
Share on other sites

Thanks, pal. Looks useful - I've downloaded a copy.

Cheers,

Brinders :cheers:

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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!

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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!

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

Thanks Mark

For taking the time to produce this useful calculator :D .

I've been playing with this for 5 minutes, its quick and easy to use.

Paul

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

This is really good - thanks so much for sharing with us!

I am sure that it'll come in handy

Share this post


Link to post
Share on other sites

Just downloaded your eyepiece calculator Mark.

It's very good indeed - and so simple to use.

Many thanks for your efforts there.

Regards,

philsail1

Share this post


Link to post
Share on other sites

Mark, just seen this and had a play, that's excellent. thanks for doing this

Share this post


Link to post
Share on other sites

This is very useful to get a grasp of EPs, FLs etc etc. :)

Thanks for the time took to make this! :(

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.