looking for 55mm close up filters for my Leica 50mm f/2, can do 2:1 or 1:1 macro shot. looked at B&H, they have several 55mm Close-up filters available.
what confused me is the how to determine I need +1, +2, +3 or any combination of them.
B&H's description didn't help me, see below:
• The maximum magnification achieved with these attachments will depend on the focal length of your lens as well as the actual close focusing capability of that particular lens
• A +1 close-up lens will allow you to focus your lens somewhat closer than it already does; A +2 close-up lens will allow you to focus closer than the +1; A +3 lens will allow you to focus even closer than a +2
• A +1 combined with a +2 will equal a +3, while a +2 combined with a +3 will equal a +5, and so on
anybody can give me a clear idea how to calculate what combination I need based on lens focal length? is there any formula available? i.e. 50mm lens need +3 can do 1:1, 35mm lens need +4 can do 2:1, etc?