Eyepiece Magnification Calculator

[ukskies]

Hi everyone, I've made a simple excel spreadsheet calculator for eyepiece Mag and exit pupil size it also allows Barlow magnification to be calculated. 

I just thought some newer members might also get some benefit from it. You won't need to have excel on your device to be able to use it as it will work in your Google Chrome browser window.

You simply type in your objective  or mirror diameter in mm and the focal length of your scope in mm and the focal length of the eyepiece that you are looking at or considering and the sheet will calculate your magnification and exit pupil size. If you are using a barlow type the mag of the barlow (eg for a 2x barlow type 2 in the box under Barlow mag X) and the sheet will calculate the revised magnification and the size of the exit pupil too.

Depending on your device it may be necessary to download it to your device then click it to open it.

If you would like to give it a go you can download it here:  

 

 

 

 

Eyepiece calculator.xlsx

Edited December 20, 2022 by ukskies
Improved for calculating the barlow

[AstroMuni]

Useful for calculating exit pupil. You might want to default the Barlow mag value to 1 so that you dont get DIV/0 errors.

BTW, have you seen the calculators that FLO have created at https://astronomy.tools/calculators/magnification ? I am not sure they have a calculator for exit pupil but there is mention of exist pupil on this page

EDIT: The exit pupil calculation is on this page https://astronomy.tools/calculators/field_of_view/

Edited December 20, 2022 by AstroMuni

[Mr Spock]

Sounds like a good idea but excel files are one of the things I never download from anywhere, even a trusted source 

[ukskies]

10 hours ago, AstroMuni said:

Useful for calculating exit pupil. You might want to default the Barlow mag value to 1 so that you dont get DIV/0 errors.

BTW, have you seen the calculators that FLO have created at https://astronomy.tools/calculators/magnification ? I am not sure they have a calculator for exit pupil but there is mention of exist pupil on this page

EDIT: The exit pupil calculation is on this page https://astronomy.tools/calculators/field_of_view/

No, I hadn't seen any calculators for exit pupil so decided to make my own. Just thought Iwhilst I was doing it that I'd share it with anyone who may want to use it.

Edit: apologies I misunderstood your meaning about div/0 errors.

I posted this purely out of my desire to help others where I can and because I hadn't seen any readily available to newcomers.

Edited December 20, 2022 by ukskies
incorrect information in post

[ukskies]

8 hours ago, Mr Spock said:

Sounds like a good idea but excel files are one of the things I never download from anywhere, even a trusted source 

Hi Michael, no worries, it's not for everyone.

[AstroMuni]

13 hours ago, ukskies said:

Edit: apologies I misunderstood your meaning about div/0 errors.

All I was trying to say is that when Barlow mag is blank or zero Excel shows a division by zero error, so if you fill 1 in the Barlow mag column that will resolve it. 🙂

[F15Rules]

I understand some hesitation ref downloading online files, sadly it's a fact of today's life..

..but let's give credit and thanks to ukskies for their efforts and good intentions👍😉

Dave

[ukskies]

9 hours ago, AstroMuni said:

All I was trying to say is that when Barlow mag is blank or zero Excel shows a division by zero error, so if you fill 1 in the Barlow mag column that will resolve it. 🙂

Yes, I did get that but not on the first read thro unfortunately. My apologies.

[ukskies]

9 hours ago, F15Rules said:

I understand some hesitation ref downloading online files, sadly it's a fact of today's life..

..but let's give credit and thanks to ukskies for their efforts and good intentions👍😉

Dave

Hi, many thanks and I really appreciate your kind comments but Ill just be happy if a few newcomers find it a useful when they're considering buying eyepieces as that's the reason I made it for myself.

I could do the math on the phone but as I'm considering several eyepieces in the future it's nice to be able to see at a glance up to 10 possibilities at the same time and compare them. No point in having focal lengths to close together is there?

[jjohnson3803]

Not terribly sophisticated, but If you prefer not to download anything:

https://skyandtelescope.org/observing/telescope-calculator/

 

Edited December 25, 2022 by jjohnson3803

[Franklin]

I just use the SGL Resources page up at the top, Astronomy Tools, Fov calculator.

[Wyvern]

Hi,

Simple but effective. Does what it says on the tin. 

Many thanks,

Les