Archived posting to the Leica Users Group, 2000/05/18

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Subject: Re: [Leica] "Quick" DOF calculation
From: Johnny Deadman <deadman@jukebox.demon.co.uk>
Date: Thu, 18 May 2000 15:50:30 +0100

on 18/5/00 2:22 pm, Bmceowen@aol.com at Bmceowen@aol.com wrote:

> Hmm, figuring depth of field for "street shooting" with a 35mm lens wide
> open? Guesstimating focus? Hmm? I'm sorry I don't get it? Are you shooting
> secret photos at night on the street?

Bob, check out my HUMAN TRAFFIC site and you'll see I'm sometimes doing just
that. Or shooting at 1/1000 and f/1.4 to do grab shots with limited depth of
field... very neat when it works, and looks nothing like the standard f/11
street stuff you're used to seeing.

> Is it dark? Is that why you're shooting
> wide open? No? You want limited depth of field and that's why you're shooting
> wide open? Why not just focus then rather than guesstimate?

Most times I do, but sometimes it's just impossible... things happening too
fast, or for example you're in a dark restaurant and you want to shoot the
lovers at the next table... you can focus on something that looks the same
distance but you need to know how much chance there is of pulling it off.

> And this 
> spreadsheet, what's up with that? Do you take your laptop along and calculate
> your depth of field so you can guestimate?

No, when I feel curious I just type in the figures and remember them. I now
know that I have about seven inches of DOF wide open at my standard shooting
distance on the 35... about four or five on the 50, and so on.

It's also useful for knowing how far you need to stop down to get both eyes
sharp in a three-quarter portrait wide open and the minimum focus.

> Wouldn't it be simplier (and less
> noticeable) to just focus?

Hmmm... why didn't I think of that?

- --
Johnny Deadman

photos:      http://www.pinkheadedbug.com
music:       http://www.jukebox.demon.co.uk