Focus scale

rantasam

rantasam

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Hi all,

I've just bought myself a Sigma 10-20 to go along with my kit lens. I'm having a lot of fun with it, i love the distortion it gives at close distance as well as the wiide angles.

I'm struggling to understand how to properly use the focus scale however. I'm working my way through Understanding Exposure, and the author mentions using the focus scale on the lens to pre-focus for big depth of field landscape shots. I just can't get my head around it though, I keep re-reading the paragraph but it's just not making sense!

Can anyone attempt to reveal to me the mystery of those little numbers please, and how to put them to good use.

Thanks.
 
Just a guess here since I don't have enough context to be sure....

Some, but not all, lens have a scale right on the barrel that will let you set the focus distance before you even put your eye to the viewfinder. This was a lot more useful before autofocus.

It is still useful when you want to select a focus distance to set up for a shot where there is action.

For example, you want to get some pics of a football goalie in action. You set the lens on maunal focus, pic your spot (the front of the goal) and then follow the action with your lens. When the ball gets in the area where you have already focused, you snap the picture (takes practice!)

Of course, I could be completely bonkers too.... :)
 
Have a search for "Hyperfocal distance" focusing...I think that is the method that Peterson refers to.

It is not a method I practice though. I just use my 10-20mm lens at f13 most of the time to give me a great depth of field.

http://www.cambridgeincolour.com/tutorials.htm - check out the tutorials esp the hyperfocal one.
 
Go into Google and search with 'Depth of Field Calculator'

Paul
 
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