Locking lens at infinity focus

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Sunnytin

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Hello all,

Is there any way that I can focus a "focus by wire" Sony or Sigma or Tamron lens (having focus hold button) at infinity once and make sure that nothing moves the focus after that - neither the shutter release button, nor the AF back button nor the manual focus ring on the lens nor any combination of any actions even accidentally? Simply lock the focus at infinity for the whole of the photography session? If yes, how does one go about it?
 

Slug

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Greg Close
Not sure if there is a more technical way, but I would just select Manual focus, set it to infinity then apply a wide rubber band over the lens barrel part covering the manual focus ring to secure it. You can cut an old motor cycle tube or similar to make a rubber band.
 

Sunnytin

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Not sure if there is a more technical way, but I would just select Manual focus, set it to infinity then apply a wide rubber band over the lens barrel part covering the manual focus ring to secure it. You can cut an old motor cycle tube or similar to make a rubber band.
I am afraid the focus by wire lenses won't allow this, and I might damage the lens Motors.

I need to find some way to stop the lens in getting a signal from any camera control after infinity focus has been achieved.
 

jav_eee

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How would it damage the motors if the focus ring is what controls it? Restricting its movement with a band of some sort is the same thing as holding it with your hand which I'm sure you've done before. The band will not damage the lens (unless you do something wrong while putting it on).
 

Brownie

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I am afraid the focus by wire lenses won't allow this, and I might damage the lens Motors.

I need to find some way to stop the lens in getting a signal from any camera control after infinity focus has been achieved.

How would it damage the motors if the focus ring is what controls it? Restricting its movement with a band of some sort is the same thing as holding it with your hand which I'm sure you've done before. The band will not damage the lens (unless you do something wrong while putting it on).
Agree with this. If the focus is set to manual then the only way to control it is with the focus ring. Using the rubber band mentioned by @Slug seems to be a simple solution. Is there a chance AF could inadvertently be reactivated due to other hands?

If you don't mind my asking, what's the application? This seems like an odd need for most people.
 

Sunnytin

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How would it damage the motors if the focus ring is what controls it? Restricting its movement with a band of some sort is the same thing as holding it with your hand which I'm sure you've done before. The band will not damage the lens (unless you do something wrong while putting it on).
The manual focus is not through gearing but through the electric motors.

If you restrict the focus ring physically, and take any actions which act as a trigger for the lens to move to focus (like pressing the back button or even the focus hold button), the motor in the lens will try to move the glass elements which you have physically restricted. A lens with gearing can be out in manual focus mode and taped at infinity. I am not fully sure how this fly by wire system works. Hence the question to begin with.
 

Slug

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Doesn't the selection of Manual override any other inputs?
(I'm not familiar with this type of lens)
 

Sunnytin

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If in manual, it is possible to disturb the focus inadvertently. What I am hoping to do is to disable any controls or buttons which will disturb the infinity focus once it is achieved, if indeed such a thing is possible.
 
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