Tuesday, April 5, 2011

Zone focusing

David tried to teach me this technique in January. It's taken me this long for the concept to click into my brain. Ok can't help being stupid.
There are a few methods, one being mathematics... Hmmm I can't do the double wavy symbol but it looks sorta like this
H~ f2/Nc where N is the lens f stop, f is the focal length and c is the circle of confusion. Ok too hard already at we can use a search engine to look up the circle of confusion for each camera... But who wants to?

Next method is to use the numbers on your lens.
I have a Cmena 2 and so will use this old lady to try to show you. ( I was going to use a zorki-C but the numbers are so very tiny that you would never see them)

1.Look at your lens and set it to infinity focus. I had the Cmena set to f/11 so let's use that. At infinity focus, f/11 has a close to depth of field ( or near to) of 4.5m ( on this camera, your may be different. A 50mm may be closer to 6m)
This is handy, but my husband and child are sitting closer than 4.5m away .. What to do?

Infinity set to f/11

2. We must increase our close to DOF to do that, we move the infinity to the f/11 mark on the focus ring. So now the camera shows me that the focus is set to 4.8m this is the hyperfocal distance of this lens. Now, looking at the f/11 marking on either side of the lens, you see 2.2m and infinity.
This means that everything within 2.2m to infinity will be in acceptable focus.

f/11 hyperfocal distance

Nearest distance around 2.2m @ f/11

Of course something close to the boundary, at the 2.2m mark, will probably be out of focus to try to not have your focal point close to the end of the limits of the zone. Also with very old cameras the distances may not be accurate but this system works for all cameras with a scale.

Let's try f4.5 on this lens

1. Set to infinity and see that f/4.5 reads just over 10.2m
So is we left it here, everything over 10.2m will be in focus huh that's far away...

f/4.5 set-to infinity

2.now move the infinity to f/4.5 and read the hyperfocal distance which is almost exactly 10m wow! That's still far but the other end of the scale reads 5m that's better

F/4.5 hyperfocal distance 10m

So for the Cmena 2 at f/4.5 the zone of in focus is 5m to infinity with the sharpest focus being 10m

Close to DOF for f/4.5 5m

So once you set your aperture, and set your zone, don't touch it and shoot from the hip. You can now raise your camera and shoot without worrying about setting it up. Good for street photography.



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