A/M focus question?

Hi,

I posted this in the begginers section but was advised that I might get a better answer over here.....

I have been shooting for a while with my D80 and 18-135 lens. I have recently been experimenting a little with manual and auto focus and wondered while there is a A/M switch on the lens and a AF/M switch on the body.

I do understand that if both the switches are set to M then I will have to be responsible to focusing the shot. Likewise if both switches are set to auto the it will focus automatically...

My question is why there is 2 switches? wouldnt 1 switch suffice? What would happen if I shot with 1 setting to Auto and the other set to Manual?

There is a switch on the camera if the camera has an AF motor. Your camera has one. There is a switch on the lens if the lens has an AF motor (an AF-S lens). Your lens has one. That is why there are two buttons.

Turning off either will disable autofocus.

There are two kinds of AF-S lenses. Lenses marked M/A + M can be manually focused regardless of how the camere or lens is switched. Lenses marked A + M can only be manually focused if autofocus is turned off.

mucksyabc123 said:

My question is why there is 2 switches? wouldnt 1 switch suffice? What would happen if I shot with 1 setting to Auto and the other set to Manual?

Click to expand...

Because some lenses don't have a M/A switch.

I think, if im not mistaking, if either one is on just M, there is no autofocus. They both have to be A or A/M.

The point of 2 switches is because the body has in camera AF motor. meaning if you have a lens without a focus motor inside the lens the body has its motor and thus you have to have a switch on the body to go from A/M to M. A camera that lacks an in camera focus motor has to use an AF-S lens therefore the lens will have the A to M or A/M to M switch

Eric