Eyepiece projection calculator

[legion48]

Anyone who has done or is planning on attempting eyepiece projection imaging may be aware of various websites with javascript calculators that give the focal lengths and focal ratios you can achieve using different lenses and varying the distance from eyepiece to CCD. Very usefull while internet access is possible and sorely missed when it is not.

For this reason I have written non web based version of an eyepiece projection calculator. It was written in VB5, as so will need the VB runtimes files installed on you PC before it will work (it is very likely that you have them already).

The eyepiece projection calculator can be downloaded from here, along with the VB runtime files if required.

http://homepage.ntlworld.com/tg.pirie/astro/downloadep.html

I hope this is of some use.

[geppetto]

Cheers matey, nice one.

Got it running, will input some sensible data later on.

For your info, it runs on Vista Home Premium but needed

the runtime files

[legion48]

Thanks for the info Phil. I had no way of checking it on Vista. I'll add that to the download page.

[daz]

L48

Question - the Telescope Focal Ratio (mm) box... What goes in here? The Aperture size?

[legion48]

Your F number - focal length/apperture. On your 10'' newt it would be 4.8.

[geppetto]

What goes in here? The Aperture size

Caught me for a second or two did that...

Might be worth removing the "mm" in that box?

[daz]

S'why I asked - confoosed me! But that doesn't take a lot really!!!

[GazOC]

'New focal ratio' doesn't seem to work....

[legion48]

What goes in here? The Aperture size

Caught me for a second or two did that...

Might be worth removing the "mm" in that box?

Tis done.

[legion48]

'New focal ratio' doesn't seem to work....

What numbers are you entering Gaz?

[GazOC]

For my 2700mm Mak, I tried a few different EPs but the new F# was always zero.

[legion48]

When you enter your scope's focal ratio, you are just entering the number? Not the "f" as well?

[GazOC]

Wheres the 'embarrased' smilie.....?

Cheers Legion!!

[legion48]

[GazOC]

Thanks mate! Whats the maths behind it all? 50mm doesn't change the focal length at all...

[legion48]

It's pretty straight forward:

magnification = (distance / focallength) - 1

newlength = oldlength * magnification

newratio = oldratio * magnification