Focus Distance/Rangefinder app?

[gtuned]

I got a old rangefinder with a camera a while ago, but I think it's pretty much off. Stuff that's maybe 20ft away is being told as 50ft, and I'd really like to use some of my viewfinder cameras more. So does anyone know of a good app for an iPhone or something?

 

[F1GTR]

Make one of these: http://tomchuk.com/misc/rf/