Question on Nikkor 300 mm lens feature 3 meters to infinity

[Brownbear]

I'm trying to learn about all the technical/mechanical features my lens with the thought process being if I understand the technicalities of my equipment, this will help me with my photography.

My AFS Nikkor 300 mm 1:4D has a slider button on its side which allows me to choose

1.

Full - for focusing on close subjects

2.

Infinity 3 meters - my understanding is that choosing this setting allows for faster autofocus when photographing wildlife at distances greater than 3 meters... So I often use this setting when photographing birds in flight.

I'm wondering if how this setting works in relation to a landscape image? Say for a mountain for which faster focusing is irrelevant. Is it simply to ensure that my camera can focus efficiently when I'm focusing ~ 1/3 of the way into the scene and capture everything in focus to infinity?

And if yes... My Nikkor 105 mm lens has a full and limit slider... Is the Limit slider the equivalent to the infinity to 3 meter slider? And if yes, how would it apply to bugs, as one is always super close to bugs when photographing them.

But! Neither my 18-200 mm Nikkor lens or 10-24 mm lens have this slider button on the lens to choose focus distances?

Thank you.

[Shadowman]

Christina,

Try the feature out on your 105mm lens. At Full setting you should be able to auto focus on an object very close. Then try the same shot, same distance with the lens set at infinity. When set at infinity, you should have to move farther away from the subject before the lens will auto focus. With your 300mm lens, you shouldn't have to use in the same manner, but you may have to move your focus indicator, so you are probably correct that you may need to set at infinity to focus 1/3 into your image area.

[Brownbear]

Thanks John..

Yes, with the 105 lens I think I figured that out instinctively, but I'm not sure I understand it fully. And in the case of the 300 mm, the same reasoning.

And I wonder if their is an alternative setting on my other lens that don't have this slider on the lens? Or perhaps it is not important to these lens?

PS if the Limit set on the macro lens is the same as the infinity to 3 meter slider, it should allow faster focusing, and as bugs are always moving it would make sense to me to use this setting even if close (as long as I can grab focus)... And I wonder if these sliders also work in manual focus?

[Shadowman]

Thanks John..

Yes, with the 105 lens I think I figured that out instinctively, but I'm not sure I understand it fully. And in the case of the 300 mm, the same reasoning.

And I wonder if their is an alternative setting on my other lens that don't have this slider on the lens? Or perhaps it is not important to these lens?

PS if the Limit set on the macro lens is the same as the infinity to 3 meter slider, it should allow faster focusing, and as bugs are always moving it would make sense to me to use this setting even if close (as long as I can grab focus)... And I wonder if these sliders also work in manual focus?

Yes, focusing will be faster when used as a macro lens. I've found that on lenses without the slider, you get the same effect if you use the macro preset on your camera. With manual focus you should be able to focus more closely but lose the speed that autofocusing affords you.

[Saorsa]

It is less important on lenses with less of a focus range. It is an extra cost to create and control so you will find it on more expensive lenses than your kit lens.

It is not so much efficiency as speed (which is a form of efficiency). With the focus limiter on your AF system stops trying before it tries to focus from infinity to 1:1 and the 300mm stops when it is out of the longer range.

[Brownbear]

Thank you Brian!

Also thank you to John, truly appreciated.

[PhotomanJohn]

Focus speed is not really the issue since the AF system normally knows which direction to go so it takes so long to get to that focus position no matter where the selector is set. The issue is with some lens and camera combinations the AF can get confused and stuck at the close focus limit if allowed to go that far with a distant subject.

John

[Brownbear]

Thank you John... The manual for the lens speaks of the faster focus speed for the infinity setting but that is about all it says, other than how close or far the subject is.

Focus speed is not really the issue since the AF system normally knows which direction to go so it takes so long to get to that focus position no matter where the selector is set. The issue is with some lens and camera combinations the AF can get confused and stuck at the close focus limit if allowed to go that far with a distant subject.

John

[PhotomanJohn]

Thank you John... The manual for the lens speaks of the faster focus speed for the infinity setting but that is about all it says, other than how close or far the subject is.

I guess I should clarify my statement a little. That is true because the lens elements have to travel farther. In a practical application one is not generally focusing a very close then the next shot far away, then close, then far....... where limiting the focus travel would make a difference. I have had situations where the lens got stuck and I had to release the AF button then push it again to properly focus when the full range of focus was enabled by the selector. I believe that I have read this in one of the manuals but can't remember for sure where (getting old). My guess it is an issue with the spacing of the images on the AF sensor exceeding the limits of the sensor.

John

[NorthernFocus]

Christina, you are way overcomplicating this.

The way a lens focuses is by moving elements forward and back. At one end of the travel range is infinity focus. At the other end is close focus. The motor in the lens must move the lens elements until focus is achieved. If not to far out of focus, the camera's focus module can immediately determine which direction and how much to move the lens elements to achieve focus and it does so very quickly. However, sometimes if you are way out of focus when you start, the camera has no idea which direction to move the lens elements. So it travels from one stop all the way to the other until it can make sense of what it "sees". This is commonly known as "hunting".

The speed with which the lens elements are moved by the motor does not change based on the setting you choose. What changes is where the limit of travel is for "close focus". So the only time focus speed is actually improved is when the lens needs to "hunt" to find focus because it has less distance to travel between stops.

The only time the 3m to infinity setting is likely to help is when shooting birds in flight. That is the most likely time to cause lens hunting by moving completely off the bird thus causing the lens to hunt as it tries to focus on a featureless sky.

[Brownbear]

Thank you for a wonderful, easy to understand explanation!

Overcomplicated, simply because I don't always understand what I am trying to ask, only what I would like to know as it is applicable to using in the field. The lens manual doesn't explain the feature well, and I couldn't find any articles or anything on the subject.


Thank you.

Christina, you are way overcomplicating this.

The way a lens focuses is by moving elements forward and back. At one end of the travel range is infinity focus. At the other end is close focus. The motor in the lens must move the lens elements until focus is achieved. If not to far out of focus, the camera's focus module can immediately determine which direction and how much to move the lens elements to achieve focus and it does so very quickly. However, sometimes if you are way out of focus when you start, the camera has no idea which direction to move the lens elements. So it travels from one stop all the way to the other until it can make sense of what it "sees". This is commonly known as "hunting".

The speed with which the lens elements are moved by the motor does not change based on the setting you choose. What changes is where the limit of travel is for "close focus". So the only time focus speed is actually improved is when the lens needs to "hunt" to find focus because it has less distance to travel between stops.

The only time the 3m to infinity setting is likely to help is when shooting birds in flight. That is the most likely time to cause lens hunting by moving completely off the bird thus causing the lens to hunt as it tries to focus on a featureless sky.

[Colin Southern]

I'm not sure if this has really come out in any of the above replies, but think of the 80/20 rule; the distance the lens elements have to move (and thus the time it takes) isn't a linear thing; if you're shooting objects near the shortest distance that the lens can focus to then the movement will be considerable, but once you get into further distances then movement is quite small (thus fast). So if you don't have a need to focus at less than 3m (the "80% bit") then the lens can achieve focus far more quickly because it's only moving "20%" of the maximum distance.

Definitely use that setting for birding; not only does it speed things up to achieve focus, it also limits the "damage" (in a time sense) done hunting in the wrong direction (you don't go so far down the wrong path before you have to turn around).

[NorthernFocus]

...only what I would like to know as it is applicable to using in the field...

It is an advantage any time you won't be needing to focus within the 3m limit. Really good for birds in flight.

[Brownbear]

Thank you Colin,

For adding another great explanation that is also very helpful to my understanding.

Perhaps one day another photographer in the area will ask me about that button on their lens.. No doubt, when I explain it to them they will think I'm a genius!

I'm not sure if this has really come out in any of the above replies, but think of the 80/20 rule; the distance the lens elements have to move (and thus the time it takes) isn't a linear thing; if you're shooting objects near the shortest distance that the lens can focus to then the movement will be considerable, but once you get into further distances then movement is quite small (thus fast). So if you don't have a need to focus at less than 3m (the "80% bit") then the lens can achieve focus far more quickly because it's only moving "20%" of the maximum distance.

Definitely use that setting for birding; not only does it speed things up to achieve focus, it also limits the "damage" (in a time sense) done hunting in the wrong direction (you don't go so far down the wrong path before you have to turn around).