Posted by Kirk Greene on April 3, 2006 at 12:12 AM
I am looking to purchase a new 500mm lens that I will mount on a Canon 1D Mark II N which has a 1.3 conversion factor. I am trying to determine what my effective focal length would be with the 1.4x and 2x converters.
Do you calculate as:
500*1.3*1.4=910 and 500*1.3*2=1300
or
500*1.7=850 and 500*2.3=1150?
You multiply by each one (Lens FL * sensor size conversion * telconverter), so your first example is correct, 500mm = 910mm with the 1.4x and 1300 with 2x.
Posted by Kirk Greene on April 3, 2006 at 11:44 AM
Mike,
Thanks for the reply. That is the way I have always figured it also. I posted this question because I was recently corrected by a professional photographer when I stated the effective focal length calculated that way. I just wanted to be sure.
Discussion
2 repliesDo you calculate as:
500*1.3*1.4=910 and 500*1.3*2=1300
or
500*1.7=850 and 500*2.3=1150?
Thanks for the reply. That is the way I have always figured it also. I posted this question because I was recently corrected by a professional photographer when I stated the effective focal length calculated that way. I just wanted to be sure.