First off, I'd like to thank Dazzzla, who send me all of the math that he used in his Windows Focal calculator.

I've set up a duplicate as a web page, which uses Javascript to do the same functions. This should make it cross-platform compatable, so that Mac or Linux users can have the same functionality. Of course, it works on Windows as well.

Click to view attachment

Unzip the archive into a directory. It should create the subdirectories "js" and "css" as well. Open the focalcalc.html file in your javascript enabled browser.

Select your optics style (split or unsplit), enter in your known parameters except those which you want the calculator to determine. All measurements can be entered or calculated in inches, feet, mm, cm, or m. Click the calculate button.

Known issues: As at current version, the calculator does not determine the triplet field angle. I'm new to Javascript programming, being more of a C / C++ person, and haven't got the appropriate trig functions working yet.

It doesn't look as slick as Dazzzla's yet, but it returns identical values, given the same input.

What ever happened to the PHP version I keep seeing referred to in google results?

http://www.lumenlab.com/forums/lofiversion....php/t7912.html

Also, I noticed another one online, but probably not as good as yours for projectors

http://www.giangrandi.ch/optics/lenses/focalcalc.html

I did supply a member with the math and background a couple of years back but unfortunately he never completed it.

DJ

I'm still working on a PHP version, as I'd preffer to just have a URL to point people to, rather than downloading an archive. (The current one could be hosted on the webserver here, I suppose.) I was working though on somehthing that could be as platform independant as possible for linux/mac users.

FWIW, Linux is the only OS I've ever used the executable version of Focalcalc with, I have never loaded it on a Windows machine at all. Yes, I do have the default Windows emulation turned on and installed, just so i can do things like that if needed.

I am also now running both a Windows2000 and a Windows XP virtual machine in Linux with VirtualBox, and so I could load it in it's native windows version, I just have never done it yet.

Here's a screenshot of my openSuse desktop with Win2k, WinXP VMs, and each of those 3 running their native calculator app, then Focalcalc running directly on the openSuse desktop.

http://i33.tinypic.com/28bw3ko.jpg

There's really no reason to need a different version anymore for Linux users - not that there are that many building projectors, but there is certainly nothing wrong with having a web-based one for exactly the reason you stated: not having to download an archive. It's a web-enabled world these days anyway.

True, the Windows binary is good enough for the vast majority of users, however, I've seen the odd request here and there from people who can't (for whatever reason) run it. They probably COULD with the right software, but I hacked this together mostly just as an excercise in Javascript, and partly just to make it available.

There are OSes out there other than Windows and Linux, and some of them really can't run Windows binaries. This one even works on my palmtop, for example. (Not that I'd seriously use my aging palmtop to do projector design with!)

Anyway, if this works for the minority that can't run Dazzzla's (Much nicer) version, then that's what it's here for.

The original simple version is back online:
Lumenlab Focal Calc

I also put SupraGuy's version online so it doesn't have to be downloaded:
SupraGuy's Focal Calc

Hey Supra/Dazzzla, one of you guys mind PMing me the math behind this?
Thanks!
-Luke

Just download this one, and it's all in the .js file.