Hi - I have just purchased a casket set of four lenses. Unfortunately the focal lengths are not marked.
Obviously I can find out the focal length by focussing on infinity.
However in my small garden I cannot focus on anything that is far enough to use for infinity.
If I focus on an object say 10 meters away (I will measure it) is there a formula that I can use to find out the focal length at infinity?
Thank you in advance.
John Wills
www.londontramways.net
www.southernrailway.net
Bookmarks