Depth of Field Quest. From Newbie, Please

Discussion in 'Digital Photography' started by Robert11, Aug 29, 2004.

1. Robert11Guest

Hello:

Newbie Photographer.

Have a question about depth of field.
Have been experimenting a bit, but haven't been able to reach any firm
conclusion on this.

Let's say I have a subject in the foreground, perhaps six feet or so away,
and also some
real pretty mountains at infinity that I would also like to be in focus, and
clear.

I would like the close in subject and also the mountains to both be in
focus.

For a sunny day, am I better off focusing on the subject, or setting my
distance to infinity ?
Why ?

Does the answer change if it is cloudy out, and i guess my aperture would be
much larger ?

Thanks,
Bob

Robert11, Aug 29, 2004

2. Roland KarlssonGuest

There is a setting called hyperfocal distance that you shall
use if you want both the background and the foreground to
be sharp. This setting is a compromise between infinity
and the nearest sharp object.

You can find a calculator for the hyper focal distance here
http://www.tangentsoft.net/fcalc/

You have to remember to use the actual focal length and the
actual sensor size.

And - yes - the focal depth is much larger in bright weather,
i.e. when you step the camera down.

/Roland

Roland Karlsson, Aug 29, 2004

3. Roland KarlssonGuest

Roland Karlsson, Aug 29, 2004

5. jpcGuest

Amusing.

But a little misleading in a digital group. With the toughly 5X
greater DOF that most of have over 35 mm film, manually focusing in
the aperture priority mode becomes a very useful technique. Got
shutter lag problems when the grandkids are dashing about in the back
yard. Disable autofocus and you'd be surprised how fast your camera
responds.

jpc

jpc, Aug 30, 2004
6. Mark MestmanGuest

Newbie,

Keep it simple.....

Depth of field depends only upon the size of the camera's aperature,
sunny day, cloudy day, indoors or underwater, no matter.

The smaller the aperature, the greater the depth of field. The larger
the aperature, the less depth of field. F22 is a small aperature, F4
is a large aperature.

This is because light is infinately in focus thru a pinhole. Make
your aperature like a pinhole in order to gain maximum depth of field.

Demonstrate the above principle to yourself.... poke a pinhole thru a
blackened piece of cardboard or piece of black paper and peek thru the
hole.....the mountains in the background, the car across the street
and the person standing right in front of you will all be in focus.

To capture the shot you describe with all in focus, set your aperature
as small (f22 or smaller) as good exposure will permit....you will
have to use a slow shutter speed to maintain good exposure with such a
small aperature.

Shoot for the smallest aperature you can, and you will be happy with
the depth of field.

Hope this helps!

Mark

Mark Mestman, Aug 30, 2004

8. NostrobinoGuest

Somewhere in between. If your camera doesn't allow manual focus this may be
difficult to do, but you may be able to find some object farther away than
your main subject that you can lock focus on and then recompose the shot as
you like. This will probably take some experimentation in order to give you
the best results.

What you are concerned with here is called "depth of field"--the range of
distances in front of the camera in which the subject appears to be sharply
focused. Depth of field (DoF) varies with focal length (the longer, the
shallower the DoF), aperture (the larger, the shallower the DoF), subject
distance (the closer, the shallower the DoF) and final image magnification
(the greater, the shallower the DoF).

The greatest range of sharpness for all subjects INCLUDING those at infinity
occurs when the camera is focused on the "hyperfocal distance"--the distance
at which everything from half that distance to infinity will appear to be
sharp. But this may be difficult for you to do in any case, and especially
with a digital camera.

That may or may not be true. Some digital cameras tend to keep the lens wide
open most of the time, regardless of whether it's sunny or cloudy. If your
camera "stops down" the lens in sunnier conditions, or allows you to choose
a smaller aperture, then yes, that will give you more DoF which is of course
what you want. Be aware that a smaller aperture will force the camera
(assuming full auto exposure) to go to a slower shutter speed and/or a
higher ISO speed, and either of these may (but will not necessarily) have an
unfavorable effect on the photo.

For what you want to do, make sure you're using the shortest focal length
(widest angle), assuming your camera has a zoom lens. If your subject is as
you say six feet or so away, try locking focus on some other object 10 or 12
feet away, then recompose and take the shot. If this leaves your subject
unsharp, either stop down to a smaller aperture (if your camera permits
this) or try locking focus on a closer distance. If that still doesn't give
you the results you want, you may have to back farther away from the
subject, or just settle for having the subject sharp and the background as
little unsharp as possible.

N.

Nostrobino, Aug 30, 2004
9. NostrobinoGuest

Well, that was pretty nasty.

Nothing in jpc's comment justifies that sort of hostility or insult, and
nothing in the OP's post suggested or implied that his camera had any "DOF
preview in the first place." The vast majority of digital cameras do not,
and since the OP is a self-described newbie it seems unlikely that he has a
digital camera with DoF preview.

N.

Nostrobino, Aug 30, 2004
10. jpcGuest

Ah--the famous kill file strategy. Never could see much point to that.
Since I'm in your killfile, you are never going to have a chance to
respond to all the nasty things I might decide say about you over the
next three years.

And of course you also cut out what I said. Snip, snip, snip and than
insult. Very .... infantile might be the right word.

Anyway, I'll quote both of us and let the rest of the group decide
who's the jerk and ass

Me---- Amusing.

Believe it that was intended as a compliment, something I doubt I'll
repeat.

You---If you only use a P&S you have no DOF preview in the first
place, jerk.

What ever gave you that idea? Read the rest of my message and you will
see I was talking about aperture priority which mean I have the full
boat of controls, shutter, aperture, manual exposure and focus, macro
etc. Hardly a lowly P&S. Unless, of course, your definition of a lowly
P&S is any camera you don't own. There's been some of that going
around recently

And in case you haven't noticed, digital camera don't have a DOF
preview button. That a 35 mm film thing.Me But a little misleading in a digital group.

Some facts

With my camera and its 5X crop factor, if I manually focus at 9 ft,
set the zoom to the equivalent of a 50 mm lens and set the aperture at
f5.6 I have a DOF of 4.5ft to 900ft. Very useful.

With a 35 mm camera the DOF of field is ony 7ft to 12 ft. Not all that
useful.

So confusing the OP with 35 mm info when he was asking about digital

You---If you can't say something intelligent -

To expand on my original post.

When I set up my camera this way and lock the exposure, either by
setting the shutter speed or by using the spot meter and exposure lock
button I have virtually no shutter lag. Moreover if I go into the
multiple image mode I can snap off up to 17 pic in about 8 sec before
the camera's buffer fills and it has to take a few seconds to write to
the memory card.

Is this the answer to all the problems in digital photography? Of
course not. But it is a reasonablely intelligent workaround for when
you have a fast moving subject that may do some unexpected and
photographically interesting things while he she or it is still
visible in the viewfinder,

jpc

jpc, Aug 30, 2004
11. jpcGuest

Thanks for jumping to my defense. You did it so nicely I almost wish
I'd been a trifle nicer when I defended myself--althought I must
confess the operative word is 'almost.'

Anyway, after thinking about it and doing a few experiments, it looks
like most of us have a DOF preview button and screen--the shutter
button and LCD on the back of the camera.

I put my camera in manual and macro mode, half pressed the shutter to
spot focused on a cactus six inches in front of me, and raised the
camera to see what was in focus. At f2.8 there wasn't much in focus
besides the cactus, at f11 the whole kitchen was closed to being in
focus.

A simple and graphic demostration of DOF--one I'll have to remember
the next time I'm trying to explain the concept.

Oh, what the hell--Thanks Tony for making me think a bit more about
DOF.

jpc

jpc, Aug 30, 2004

If you can't figure out how to find the dof using the screen on the back of
the camera than you are as brain dead as the other troll - aren't you.
Actually you are probably the same troll. I don't care if you actually are
someone different - you obviously have the same lack of brain.

--
http://www.chapelhillnoir.com
home of The Camera-ist's Manifesto
The Improved Links Pages are at
A sample chapter from my novel "Haight-Ashbury" is at
http://www.chapelhillnoir.com/writ/hait/hatitl.html

13. Alan BrowneGuest

Tony's mission is not to reveal the secrets of DOF as much as to
draw traffic to his websites and his amusing attempt at getting
his book recognized and published. (Note his tenacious
top-posting and somewhat tedious sig lines).

replied with a link to his own pages, saying there would be a
link to fcalc therin... I replied to Tony's post and to the OP
with the fcalc link directly (and chided Tony at the same time)
and this has pissed Tony off so much that I am (he claims) a
permanent resident of his killfile...

Tony has squandered a lot of previously earned goodwill over the
past year. I hope that his recently corrected cataracts will
allow him to photograph more, be an asshole less and deal with
adversity with more mature actions than declaring people members
of his killfile... although, therein it is nice and cuddly.

Cheers,
Alan

Alan Browne, Aug 30, 2004
14. Alan BrowneGuest

Oh, but he will... he'll reply to others replies where you appear
and attack you there. Have fun!
No need. It's clear. And Tony can only killfile a person once
which is probably REALLY frustrating to him, eh Tony?

Alan Browne, Aug 30, 2004
15. NostrobinoGuest

That doesn't work on many digital cameras. You need to get out more.

Not worth any extra effort, so I'll just paste in here the last part of my
The bottom line here is, obviously, that Tony's lavish admiration of his own
expertise is centered on what he understands of his own limited experience.

N.

Nostrobino, Aug 31, 2004
16. NostrobinoGuest

You're welcome.

Well, that depends. . . . Do you have a digital SLR? I don't.

Sure, but the question is whether that is something usable by the OP. He
describes himself as a newbie but doesn't mention the kind of camera he's
using. I am assuming it is probably a relatively simple camera,
auto-everything but not allowing much in the way of manual control.

For example, my Minolta Xt and Xg cameras don't have any means of manually
controlling the aperture. And these are extremely popular models.

My other digital cameras all do, but repeating the experiment you describe
doesn't show any difference in DoF on the LCD monitor at all on my 7i. I can
get to about six inches (from the front of the lens) to the calendar in
macro mode, which this camera allows only at 28mm and 200mm (equiv.)
settings. At 28mm I have f/2.8 wide open and f/8 stopped all the way down.
Half pressing the shutter to lock focus and then pointing at the other end
of the kitchen looks EXACTLY the same to me on the LCD monitor at either
aperture setting. At 200mm I have f/3.5 wide open and f/9.5 stopped down.
Doing the same thing produces the same result, no apparent difference at all
on the monitor. So evidently on this camera going into aperture priority and
changing the setting doesn't actually change the aperture until the moment
of exposure.

Even if there were a visible difference, I doubt very much it would be of
much use for gauging DoF because of the coarseness of the LCD screen. I
don't even think DoF preview buttons on 35mm SLRs are as useful for that as
other people seem to think. That is, what you see in the viewfinder stopped
down gives you some sense of DoF change as the aperture is changed all
right, but it doesn't really show you in any CRITICAL way what the range of
apparent sharpness will be on, say, an 8x10 or larger print. I think the DoF
preview is useful for getting some general sense of what relative sharpness
in different parts of the photo will be like, but nothing more than that.

I've just tried the same thing with my S414, same result. Locking focus on a
close object in macro mode (78mm equiv. f.l.) and then pointing at a distant
subject, looks exactly the same on the LCD at f/3.6 as it does at f/8 (the
only two apertures available in this mode). Also, going into manual focus on
S414, macro mode, setting at the closest focus, switching back and forth
between wide open and stopped down shows no difference at all with a distant
object on the monitor with the shutter release half pressed. Taking the shot
in each case does show an obvious difference in DoF, of course.

The bottom line here is, obviously, that Tony's lavish admiration of his own
expertise is centered on what he understands of his own limited experience.

N.

Nostrobino, Aug 31, 2004
17. NostrobinoGuest

----- Original Message -----
From: "Alan Browne" <>
Newsgroups: rec.photo.digital
Sent: Monday, August 30, 2004 6:13 PM
Subject: Re: Depth of Field Quest. From Newbie, Please

Ah. Until you mentioned it I hadn't noticed--I rarely bother reading those
lengthy kinds of sigs.

I have to wonder about people who claim to do that so much. I can understand
plonking (and have plonked) a very few people whose posts seemed only
intended to be aggravating or insulting and with no redeeming value. I just
have no further interest in anything they have to say.

You, on the other hand, I cannot imagine ever killfiling under any
circumstances. We have argued strenuously and even with mutual exasperation
over some issues as I recall, but such disputes have always been
thought-provoking, good gray-cell exercise and worthwhile.

Well, since he hasn't claimed to have killfiled me yet I suppose he will

N.

Nostrobino, Aug 31, 2004
18. jpcGuest

No I have a 3 year old Olympus 3020Z, Not the latest and greatest but
it does have all the controls.
On mine, the differences are strinking. Obviously-- and not
surprisingly--different manufactures do things in different ways.
Agreed. If you want to find out what is truly going on you have to set
up a test scene (the classic signs-every-few-feet, for instance) and
take pictures. But this is more important for film and large sensors.
One of the biggest advantages with small sensors is that they are so
forgiving to focus errors. The flip side is that it become almost
impossible to completely blur a background.

If the original poster hasn't been driven off by either the confusing
advice or the mini flame war, come back and tell us what camera you
have.

jpc

jpc, Aug 31, 2004
19. ArchibaldGuest

Not so -- he has kill-filed me many times. He even replied to one of
them where I said, "No you haven't!". What a moron!

Most folks that are bothered by a thread or author will quietly filter
those posts out... but not our little Tony. He has to make a fussy
show about it, as though to intimidate those of us who have not yet

And what punishment it is to be kill-filed by this little tyrant...
not. He doesn't seem to understand that kill-filing affects only him.

A.

Archibald, Aug 31, 2004
20. Alan BrowneGuest

Blush. Not sure they go that far, but it is better to argue
sanely than to ignore completely. In most NG arguments both
positions are often saying the same thing in a different way, but
neither understands the others frame of reference until long
after the insults begin. I have used filters from time to time
when warranted, but that's not aimed at people in the NG.

Cheers,
Alan

Alan Browne, Aug 31, 2004