Using lenses what determines focal point?

[randomer3]

Ok, so in anticipation of my laser arriving i've been destroying binoculars and cameras and stuff to get the lenses.

So far i have made two lens caps both using plano convex lenses.

Using a cheap 1mw red laser i decided to test the focal points the first one has a focal point of about 1cm from the lense and the other one has a focal point of about 8cm from the lense.

What determines where the focal point is?
Is it to do with the curvature of the convex side of the lense or what?

Thanks
Rich

 

[paper183]

Is it to do with the curvature of the convex side of the lense or what?

Directly, the curve determines the way light takes, and where it makes the focal point, not a very scientific way of explaining it but i hope you understand

 

[randomer3]

I think i do, so the smaller/shallower the curve the further the focal point would be...?

 

[paper183]

I think i do, so the smaller/shallower the curve the further the focal point would be...?

I think so, not 100% sure, i know that is true for mirrors where it curves inside..

 

[BlueFusion]

paper183 is correct. The shallower the lens, the further the focal point. You can go into using multiple lenses and adjusting them (like the Aixiz modules) but I don't know so much on that.