By Dave Fiala
This switch is encountered on Macro and some telephoto lenses.
These may have two or three distances that you can limit the focus to thereby providing a solution to the camera and lens searching for the focus. For example, when using a macro lens and we are photographing a bug at a close distance sometimes the lens will miss the focus. Without having the limit switch set to close range the lens will run all the way to infinity. Once it reaches the stop at infinity it will start on its way back to the closer distances to try and find the focus. If it misses again the lens will hit the close-range stop and start searching for focus again. If we have the limit switch set for the close distance it will not run all the way out to infinity because we have set the lens not to allow that long travel. The same is true if we are using a macro lens to shoot a head and shoulders portrait. If we are shooting someone at say, 12 feet away and the camera misses focus it might run the focus all the way back to the closest macro distance. Only when it hits the close distance stop of the lens will it start running back out to search for the focus. My Fujinon 80mm macro has a 3 position switch. The distance can be limited to, 0.24 to 0.5 meters or 0.5 meters to infinity, the 3rd setting is Full. Only if set to full will the lens run the full range of travel searching for focus. By setting the limit switch I can save time, battery power, and the aggravation of having the camera and lens searching for focus.
My Fujinon 100-400 telephoto lens also has a limit switch. On this lens, it is a two-position switch providing the option of setting the focus limit to 5 meters to infinity or full. If set to the 5 meters to infinity it will not attempt to focus any closer than 5 meters. So if I am out shooting birds I would probably not need the lens to ever run the focus down to its closest focus distance which is 1.75 meters.
The limit switch serves an important function by providing the benefit of controlling the amount of focus travel of your lens.Thus, affording you with a solution to the aggravation of your lens doing a lot of unnecessary focus searching. Try it out and become familiar with the way it works. One tip I might give it after you are done shooting reset your lens to the Full setting so that the next time you get it out it can run the whole focus range. Otherwise, you may be trying to shoot some macro photos and the lens will not go to close focus distance until you think. Oh yea, last time I used this lens I was shooting portraits and I set that switch! Well, easy fix.If you have any questions about the limit switch on your lens call or stop by one of our locations and one of our friendly staff will be happy to help you out.
