nelsonfotodotcom
31-Dec-2007, 12:05
Eddie's thread in the FS forum had me asking questions about the minimum focus distance of the Wolly he has for grabs. Some replies were made, but do not satisfy my curiosity, and as I do not wish to further interrupt his for-sale post, I'd like to continue the matter here.
When I write minimum focus distance, I do not mean the focal length. What I mean is the distance from lens to subject at the focal length extension for a specific LF lens.
I am new to LF, though I shoot an RB67, and therefore have some experience with increased magnification when bellows are extended beyond infinity.
It might be best if I describe this in terms of using standard lenses (no bellows/macro/tube modifiers), each lens having a minimum lens-to-subject distance, depending on the specifications of the lens. For example, the old Nikkor-NC Auto 35mm/1.4 that I owned until recently which would close-focus to inches on my Nikon F4s body.
Now it suddenly occurs to me that the Nikkor only focused to inches on the basis of the internal mechanism for, in essence, extending the distance from rear element to FP.
If this is correct, then the same could be accomplished if the lens elements within the Nikkor were removed from the housing, made fixed, and a bellows or assortment of tubes replacing the helical within the Nikkor, to obtain the same results. Thus, there is no minimum magnification value for LF lenses beyond the amount of bellows extension available? Would any given LF lense image-circle be exhausted beyond a certain bellows extension, or does the image circle remain constant regardless of extension, provided movements do not cause vignetting?
OK, so maybe I've no real question after all.
But, if I am missing some or all of the issue, any further clarification here would be most appreciated.
;)
C.
When I write minimum focus distance, I do not mean the focal length. What I mean is the distance from lens to subject at the focal length extension for a specific LF lens.
I am new to LF, though I shoot an RB67, and therefore have some experience with increased magnification when bellows are extended beyond infinity.
It might be best if I describe this in terms of using standard lenses (no bellows/macro/tube modifiers), each lens having a minimum lens-to-subject distance, depending on the specifications of the lens. For example, the old Nikkor-NC Auto 35mm/1.4 that I owned until recently which would close-focus to inches on my Nikon F4s body.
Now it suddenly occurs to me that the Nikkor only focused to inches on the basis of the internal mechanism for, in essence, extending the distance from rear element to FP.
If this is correct, then the same could be accomplished if the lens elements within the Nikkor were removed from the housing, made fixed, and a bellows or assortment of tubes replacing the helical within the Nikkor, to obtain the same results. Thus, there is no minimum magnification value for LF lenses beyond the amount of bellows extension available? Would any given LF lense image-circle be exhausted beyond a certain bellows extension, or does the image circle remain constant regardless of extension, provided movements do not cause vignetting?
OK, so maybe I've no real question after all.
But, if I am missing some or all of the issue, any further clarification here would be most appreciated.
;)
C.