Canon focus limiter setting effect on AI servo focus?

[FlyingSquirrel]

On some Canon lenses, you can set a "focus limiter" switch to a certain range, for example on my 500 f4 one of the options is 10m to infinity. Thus, it will only focus at about 32 feet or beyond, in this example. This, or any other setting, is useful to speed up AF, since the camera knows to only rack the lens elements within that distance range.

Now, you also have an AF setting called AI servo, which is a continuous focusing method that tracks moving subjects, keeping them in focus as they move.

Here's a possible scenario: I have my focus limiter switch set to 10m to infinity. I am tracking a subject in AI servo, in this example, a flying bird. While the AF AI servo is locked onto the bird, it approaches closer than 10m. Does the focus drop off, or does the camera know it is tracking the subject and override the focus limiter setting?

This is something I could test if I had a willing assistant, but since I do not, I thought it would be easier to see if anyone knows the answer or has experience with it.

[mrinmoyvk]

This is something I could test if I had a willing assistant, but since I do not, I thought it would be easier to see if anyone knows the answer or has experience with it.

Not sure about this setting but you are your willing assistant. Let the subject be stationary and you move towards the subject.

[Donald]

The focus will drop off because you have told the lens that the closest focusing point is 10m.

[FlyingSquirrel]

Thanks for the assistance. The truth hurts, but it is what it is.

[William W]

. . . set a "focus limiter" switch to a certain range, for example on my 500 f4 one of the options is 10m to infinity. . .

I have my focus limiter switch set to 10m to infinity . . . tracking a subject in AI servo . . . a flying bird. While the AF AI servo is locked onto the bird, it approaches closer than 10m . . .

If it did keep focus it would be a very VERY TIGHT SHOT of that bird.

At 32ft SD, you only have about 16" x 11" Framing, using your new 7DMkII.

If the bird flys to 20ft SD, that reduces to a Framing of about 10" x 7".

WW

[William W]

Thanks for the assistance. The truth hurts, but it is what it is.

Well, no, I don’t think so. I think that you are over-thinking this.

IF you were tracking a Bird in Flight you could choose NOT to have the FL set. Once the AI had locked, there would be NO loss in AF Speed.

Arguable there would be NO initial loss in AF Speed anyway when locking onto a Bird in flight.

Typical scenarios for employing ‘Focus Limit’ are for longer distance shooting when there is a BARRIER likely to be BETWEEN the SUBJECT and the CAMERA, which could cause the AF to hunt closer and waste time. One oft used example is: shooting sport BEHIND netting or a fence or similar barrier - a Bird in flight usually has no such barrier.

Then again (following on from my first comment) - realistically how often would Bird in Flight get to 32ft or closer SD? And then, if it did fly that close, the question is with such a TIGHT FRAMING, using a 500mm lens (especially on a 7D MkII) - would the shot be useful?

WW