Robert Ellis
Larus marinus
If the depth of field is the same for a given configuration, and being a former photog I can believe that, there must be math to go with it? Is there a formula that one can use to determine the DOF at a given distance for a given aperture and magnification?
Further, if I do bite that DOF is related to configuration and nothing else, why is the 8x32 SE touted as having a huge DOF and the 8x32 LXL criticized for having a slightly narrow DOF? IS this perception that arises from the focus rate as resistence? I seem to remember a BVD article about the BL Elites, criticized for having a narrow DOF but in reality Mr. Ingraham found it was equal to the rest of the bunch and blamed the very rapid focus for the perception.
I also remember my camera lenses having markings for focus depth, which did get wider as one stopped down. There has to be a calculation somewhere for this optical phenomenon, but who is to say what is in focus and what is not?
Then again birders tend to proclaim larger apertures give a longer DOF which is opposite of a camera lense. Wha? IT seems we would have to know the f ratio of each binocular before we can make statements like that. Maybe the little LX is faster than the big LX, yielding a narrower DOF but not due to the size of the lense alone?
What we need more than the math would be a table of the focal lengths of all our binoculars, then we could quicly figure out which would have better DOF than others.
Further, if I do bite that DOF is related to configuration and nothing else, why is the 8x32 SE touted as having a huge DOF and the 8x32 LXL criticized for having a slightly narrow DOF? IS this perception that arises from the focus rate as resistence? I seem to remember a BVD article about the BL Elites, criticized for having a narrow DOF but in reality Mr. Ingraham found it was equal to the rest of the bunch and blamed the very rapid focus for the perception.
I also remember my camera lenses having markings for focus depth, which did get wider as one stopped down. There has to be a calculation somewhere for this optical phenomenon, but who is to say what is in focus and what is not?
Then again birders tend to proclaim larger apertures give a longer DOF which is opposite of a camera lense. Wha? IT seems we would have to know the f ratio of each binocular before we can make statements like that. Maybe the little LX is faster than the big LX, yielding a narrower DOF but not due to the size of the lense alone?
What we need more than the math would be a table of the focal lengths of all our binoculars, then we could quicly figure out which would have better DOF than others.
Last edited:
