hyperfocal distance

karate-ka

karate-ka

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does anyone now where i can download a hyperfocal distance calculator.
 
Eighth Avenue said:
Hi guys, pardon my ignorance but what IS this? :S
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The hyperfocal distance is the point you focus on for absolute maximum depth of field. As such, to get maximum distance it always has infinity as the furthest point.

You use it when shooting something like a landscape with mountains behind and also some important foregound interest that needs to be sharp.

There is a different hyperfocal distance for every focal length and f/number. It's handy to note that the hyperfocal distance is always exactly double the nearest point in the hyperfocal range.

Edit: for example, with a 24mm lens on your full frame 5D2 (DoF varies with format) say you want something in sharp focus just 4ft away, and also right on the horizon. Checking a Hyperfocal distance table, you need to set a focusing distance of 8ft and aperture to f/8.

A couple other comments, in my view the agreed international standards for DoF have not caught up with the kind of quality you can get with digital, especially something like your 5D2. I think they need tightening up a bit for critical levels of sharpness so I would set f/11 in the example above, not f/8.

The other thing to note is that diffraction is real problem, especially with crop format DSLRs. It kills sharpness at high f/numbers - it's an optical problem, not a specific lens fault. On crop format, f/22 is pretty horrible and f/16 isn't too great either, but f/11 is fine IMHO. On full frame, you can get away with about one stop more before diffraction hits hard, so I would say f/16 max there.
 
:)
 
DoF is based loosely on whether the human eye can differentiate the out-of-focus on a 10*8 inch print held at arm's length. This is deemed to be about 0.01" cricle of confusion below which everything is deemed to be in focus.

If you blow the image up to a larger size without moving furtheraway, you'll have less DoF. Similarly, if you use the same lens on a smaller sensor (which will require less enlargement) you'll have more DoF.

As the human eye has not changed, then the charts do not need to change.

If you pixel peep, then the DoF charts are useless.
 
grahamsewelluk said:
DoF is based loosely on whether the human eye can differentiate the out-of-focus on a 10*8 inch print held at arm's length. This is deemed to be about 0.01" cricle of confusion below which everything is deemed to be in focus.

If you blow the image up to a larger size without moving furtheraway, you'll have less DoF. Similarly, if you use the same lens on a smaller sensor (which will require less enlargement) you'll have more DoF.

As the human eye has not changed, then the charts do not need to change.

If you pixel peep, then the DoF charts are useless.
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I know what you mean about the circle of confusion principle, and that nothing has changed there in terms of viewing distance etc.

However, if you look more closely than the standard viewing distance, there is clearly more detail to be seen from a hi-res sensor. My reasoning is that this used to be pretty much a waste of time with 35mm film - you could look as closely as you liked, but all you'd see was bigger grain.

But now, if I produce a nice big print - at least A4 (you won't see much on anything smaller) or 15in wide, or A3 size - if you look more closely than the DoF specification says you should, then there is a lot more sharpness to be seen.

I wouldn't call that pixel peeping, just looking more closely, everybody does it - because you can. And because, if you tighten up the DoF a bit by using an f/number slightly higher than the charts suggest, it's usually worth it :)
 
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