problem

[dynablaster]

I have a biconvex lens of 80mm
as I can know the focal length of my lens?

I used an attached Excel sheet diy projector calculator for the optics and got some surprising values

LCD diagonal: 22.5cm
LCD to Lens distance:12 cm

Diagonal size of projected image: +- 4,5m this is pretty big.


Thanks for any help!

 

[ace3000_1]

re lens focal distance finding

Hi Dynablaster Trevor here in Madrid Spain not to far from you lol ok, what type of lens do u have? is it a single lens or is it 2? also if it is a single lens like a magnifying glass type just focus it on a page and messure the distance and that will be the focal length.

Regards Trev