Infinity Focus Setting

[Los59]

How's it going people? I had a question regarding the Infinity focus setting within lenses. I'm shooting with a Canon 50mm 1.4 USM I mostly shoot with manual focus but can't really find an answer regarding this feature.

Another question is about the numbers indicated in the window when focusing, what is the distance for each number. i.e. 1.5 is how many meters/feet/yards away? How is it measured? Thanks in advance

[RichardTaylor]

Re the focussing marks.
In the old days we
(1) Estimated the distance
(2) or used an external range finder
(3) or used the range finder in the camera, if it had one, and then took note of the distance on the lens.
(4) Sometime some photographers would measure it with a tape measure
You need to know the shooting distance before the days of automated flash guns and sometimes for DOF tables if the lens markings were inadequate.

Re the infinity setting.
You usually just turned to the lens to that setting and that was it.
Sometimes you would line up the infinity setting with an aperture setting and the lens marking would then indicate the DOF.

Now days I almost never look at the distance settings on my lenses.

[Sterling]

Yes, in the old days I remember just racking out the focus ring and knowing I was set at infinity. These days I've read some references to lenses that focus past infinity when racked out. Not sure about that myself.

[Los59]

It definitely sounds like you guys have great experience within photography which is why I am here to get knowledge in the medium of photography. But it is still vague on the use of the "Infinity" setting. Sorry for sounding like such a noob..

[RichardTaylor]

It';s for when you want to focus on things relatively far away.
See this example.

How to focus to infinity digital camera technique


In practice what I do, and mostly when using a tripod, is to use manual focus, put the centre point over something with a bit of contrast, like a bridge light in the example below, and slowly rack the lens back and forward whist watching the focus indicator light in the viewfinder.
This will stoip me unfocussing past infinity.


Camera Canon EOS 5D
Exposure 3.2
Aperture f/8.0
Focal Length 45 mm
ISO Speed 200
Exposure Bias 0 EV

For subjects like this I will just autofocus (and recompose if necessary) on the mountains.

[OsmosisStudios]

Originally Posted by Sterling

Yes, in the old days I remember just racking out the focus ring and knowing I was set at infinity. These days I've read some references to lenses that focus past infinity when racked out. Not sure about that myself.

This is generally for IF (internal focus) and retrofocus lenses, as their "inifity" changes based on temperature.