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07-01-2008, 11:55 PM   #1
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dof

Hey i have a noob question regarding depth of field. I'm wondering how to take a picture with my k100d and have most of the viewable area in focus..is this possible? Say for instance i'm just taking a random picture..i want the whole picture to be as clear as possible. I'm thinking that choosing the smallest aperture possible would do this and zoom out to the widest position..but sometimes i still get blurry areas. i've tried manually focusing but it doesn't work. Should i change my autofocus settings? I'm using the kit lense by the way.

07-02-2008, 12:22 AM   #2
axl
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check out this web page: Online Depth of Field Calculator
there is an dof calculator, that lets you calculate hyperfocal distance, for each f stop on maybe any imaginable focal lenght, among the others.
Hyperfocal distance is distance of focusing point that maximisis (sorry for the spelling) dof. In other words, if you focus on this point, everything from certain point to infinity will be in focus...
good luck
07-02-2008, 12:24 AM   #3
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PS: it sharpness depends on the lens too!! and greatly. Some lenses have abbyssimal difference in centre and corner sharpness, so corner detail will appear softer...
07-02-2008, 12:52 AM   #4
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A kit lens is not exactly the best lens if you are looking for an overall sharp picture.

Most lenses function best when stopped down by 3-4 stops. The better quality the lens the better performance outside this range.

The very best lenses are sharp and nearly all apertures.

Try stopping your lens down to around f/8 or f/11 and see how that goes.

07-02-2008, 02:36 AM   #5
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You have had some good advice here.

I would only add that stopping down the lens to the smallest aperture f22 or f32 will give you the greatest DOF. However stopping down beyond f11-f16 will lead to something called diffraction which will cause your photos to become less sharp. So like most things in photography it is a trade off. I suggest you do some expiriments at home to see the results.

Using a smaller aperture will obviously necessitate using a slower shutter speed. This can lead to blur caused by camera shake. using a higher ISO will help keep the shutter speed up, but will also add noise (another trade off), so you may need to use a tripod to keep the camera still.

For general photography you will find that the DOF will be roughly 50% either side of the point of focus, so you should not use auto focus but focus manually on something in the middle of the scene you are capturing. This will give you the sharpness you want at the near and far parts of your photograph.
07-02-2008, 05:17 PM   #6
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I sometime tell noobs to remember that a high aperture number = high amount of things in focus (that is a large dof). After a while you remember it anyway, but that's a start.
07-02-2008, 08:16 PM   #7
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The "hyperfocal distance" is a myth, be careful with it. Most of the times you're better off focusing at infinity, you lose very little DOF in the front, but gain a lot in sharpness.

As said in this article by Harold Merklinger,
QuoteQuote:
The general rule for scenic photographs, where one wishes to maximize the depth of field, is as follows. Set the focus at the distance of the most distant object. Then set the lens opening to the size of the smallest object to be resolved in the foreground. No calculations needed!

DOF Revisited
07-04-2008, 02:26 PM   #8
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QuoteOriginally posted by ricardobeat Quote
The "hyperfocal distance" is a myth, be careful with it. Most of the times you're better off focusing at infinity, you lose very little DOF in the front, but gain a lot in sharpness.

As said in this article by Harold Merklinger,

ABSOLUTELY NOT!

Depth of Field is a very precise optical formula. Look it up.

07-04-2008, 03:39 PM   #9
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QuoteOriginally posted by ricardobeat Quote
The "hyperfocal distance" is a myth, be careful with it. Most of the times you're better off focusing at infinity, you lose very little DOF in the front, but gain a lot in sharpness.

As said in this article by Harold Merklinger,
If hyperfocal is a myth, then so is depth of field. (Hyperfocal is just application of depth of field to the subject at hand.) Probably best to just focus on your subject or if depth of field is limited, focus on the part of your subject that is most important to the viewer's perception.

Consider this image:



There was not a whole lot of light available and the shot was done wide open at f/2 (i.e. almost no depth of field). Most people I show this to are impressed with the sharpness and detail. In reality the only part of the picture that is truly in focus is the surface of the cat's eye. Since the cat's eye is relatively sharp and in focus, the viewer's brain interprets the remainder of the image to suit.

Steve
07-08-2008, 12:30 AM   #10
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Go here Download The INs and OUTs of FOCUS and download the book "The INs and OUTs of FOCUS". It's a very good book about focusing.
07-08-2008, 01:20 AM   #11
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what kind of photography are you doing? landscape/natureish? My style of photography is such that I like to limit my focus to my subject, and when you have EVERYTHING in the frame in focus, sometimes it's hard to understand what the mood and subject of the photograph are. A lot of times you can set a real low fstop, I usually shoot at the lowest one possible for the distance of my subject (usually setting my camera at aperture priority, auto shutter speed, auto focus), crank up the shutter speed, shoot at the lowest iso's to avoid noise/grain, and isolate that subject. More often then not the eyes float straight to the subject and don't even notice that the background is blurred out, it's only when everything is in focus that you look at backgrounds/foreground much, because the subject isn't clear. I like my subjects to pop, and part of the sacrifice (if you look at it that way, which i don't) is less sharp backgrounds. That being said, just because other stuff isn't in sharp focus doesn't mean that you don't get a definite gist of it and let it compliment the subject.
07-12-2008, 07:23 PM   #12
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QuoteOriginally posted by ully Quote
ABSOLUTELY NOT!

Depth of Field is a very precise optical formula. Look it up.
QuoteOriginally posted by stevebrot Quote
If hyperfocal is a myth, then so is depth of field. (Hyperfocal is just application of depth of field to the subject at hand.) Probably best to just focus on your subject or if depth of field is limited, focus on the part of your subject that is most important to the viewer's perception.

Consider this image:

There was not a whole lot of light available and the shot was done wide open at f/2 (i.e. almost no depth of field). Most people I show this to are impressed with the sharpness and detail. In reality the only part of the picture that is truly in focus is the surface of the cat's eye. Since the cat's eye is relatively sharp and in focus, the viewer's brain interprets the remainder of the image to suit.

Steve
Ully, I said that hyperfocal distance as a focusing technique is a myth, go look it up.

Let me rephrase it: the idea that focusing at hyperfocal distance when you want to have both a relatively close object (in the meters range) and the background in focus is a myth. In this situation focusing at infinity, not at hyperfocal distance, will give you an overall sharper image. You may lose a very little bit of sharpness on the foreground, but the background will make up for the difference.

The cat example simply does not apply, in this case you don't want the background in focus and the subject is too close, it's not a situation where you would want to focus at hyperfocal distance anyway, it has nothing to do with it.

BTW, hyperfocal distance is a fixed focus point for a given focal length and aperture, it's not a variable. It's a focus point where theoretically most of the scene from a few meters ahead to infinity will be "in focus", but usually the resulting sharpness is less than stellar. I think you had something else in mind.

Last edited by ricardobeat; 07-12-2008 at 07:28 PM.
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