Sorry for such a stupid question, I'm just the beginner... Will you please explain me how to use the "macro" button on these lens? Thanks in advance.
#1. "RE: AF35-70 Macro mode" | In response to Reply # 0f8bthere Basic MemberTue 28-Aug-01 11:07 AM
A short lesson in focusing closer:
Lenses can focus closer by several means. Traditionally, the main way was to increase the extension of the optics from the film plane, which then requires the camera to move in closer to the subject to be in focus. Most older lenses use extension, whether macro or not. Simply focus a lens from infinity to its closest distance, and you can see it get longer.
New methods of getting closer involve internal shifting of elements which reduces the amount of extension needed. If you want to see the difference, look at an old manual 55mm f/2.8 Micro and the new 60mm f/2.8 micro. The first lens uses a tremendous amount of extension only and only delivers a half life size image on film. The new 60mm lens uses a combination of extension and optical shifting, allowing full life size and less light loss due to extension. Many non-macro lenses today use "internal focusing" which does not require the lengthening of the lens when focusing closer.
Several zoom lenses that have a "macro" function use this button you mention to keep the normal range shorter, thus speeding up the use in most situations, because the travel of the focus rotation is reduced by not allowing very close focus. When you are finding that you need to move closer than the lens will allow in the normal range, simply press the chrome button, rotate the lens' macro function to add some extension. At this point, manual focus is needed to tweak the exact point of focus. What I do is to have the normal focusing ring set to the minimum distance and then to use the macro ring slowly to bring the image in focus. It can be used at any point, but many people rack it right to maximum rotation, and then move up and back until focus is achieved. Sometimes, only a rotation of a few degrees is all that is needed to achieve focus... use your viewfinder to know when to stop.
So in essence, it is simply a method of adding some extension into the lens to allow closer focusing. Always make sure that when not needed, that you reset the macro ring until the chrome button "clicks" back. If you don't do this, your lens will not focus to infinity.