Focus

I may be way off the mark here, but I think what you are after is information about 'Hyperfocal distance'. Try googling it and see what it comes up with.:)
 
Aye that's it.
 
Yup, hyperfocal focusing is what you need to know about. Just find a printable table or online calculator with a guide and you'll be sorted ;)
 
I have always wondered why, given all the necessary details are sent from the lens to the body, manufacturers have not added a hyperfocal button to focus at the appropriate distance. Even despite the effort required working out the appropriate distance, modern lenses and their displays are too small to be able to use it other than as a rough approximation.

Michael.
 
mij said:
I have always wondered why, given all the necessary details are sent from the lens to the body, manufacturers have not added a hyperfocal button to focus at the appropriate distance. Even despite the effort required working out the appropriate distance, modern lenses and their displays are too small to be able to use it other than as a rough approximation.

Michael.
Click to expand...


Am I talking rubbish or do I just not understand , but is that not what the A-DEP mode is on a Canon
 
whiteflyer said:
Am I talking rubbish or do I just not understand , but is that not what the A-DEP mode is on a Canon
Click to expand...

A-Dep mode 'looks' at a scene, guesses how much depth of field you want, selects the best aperture for that, then sets the shutter speed for the correct exposure. You still need to either half press the shutter or * to focus, depending on how you have set things up, so the focal distance will be based on what it thinks you want to shoot.

With the hyperfocal distance there is a single focal distance for a given focal length and aperture. A camera would not even need to use AF, you could just press a button and rather than it looking at the scene and focusing (as A-Dep does) it just jumps to whatever the relevant distance is for the currently select aperture. I suppose you would not even need a button as it could change as you adjust the aperture.

The hyperfocal distance though gives you the maximum depth of field possible, while A-Dep could give you a shallow one if it thinks that is more appropriate for the shot. I would not trust it to get it right. Also A-Dep only allows you to adjust the shutter speed via EV compensation so you can only go two stops either way of the AE chosen speed.

But for all that at least it is not as useless as P mode!

Michael.
 
true_one_picture said:
So is the hyperfocal length is the same as depth of field????
Click to expand...

No. The hyperfocal distance is the point at which everything from X to infinity is in focus; at other focusing distances, the depth of field is finite—that is, there are out-of-focus areas both closer and further away than the depth of field.

Edit: here I made a crappy diagram that will serve only to further confuse people

hyperfocal.png
 
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