Why small aperture?


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Jul 12, 2004
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#5
I use apertures smaller than 11 for macro shots, up to 56 (at least that is what is stated on the camera's status LCD display); more usually 18 to 20. This is for greater depth of field for close ups.
 

fWord

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Jun 23, 2005
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#6
For macro shots or closeups where the distance from the subject to the lens is very short, or under conditions when the focal length is long, the depth of field becomes very narrow. At these times, using a smaller aperture for a premium in depth of field is desired.

In landscape photos, there's also a trick I read in a book that describes how to achieve maximum depth of field. It states that the aperture should be closed down as far as possible (usually as much as f/22 or f/36), and then focusing on an object that is one-third the distance between the nearest and farthest object in the frame. Great impact is achieved when all objects, near and far, are in sharp focus in a landscape photo.

But for general shooting, I almost never close down further than f/8, and I am only just starting to experiment with f/11 because I am aware of an inherent flaw in my kit lens. When very small apertures are used, a phenomenon (diffraction?) actually causes images to be less sharp than when shot at larger apertures.

Personally, I've always thought that the sweet spot of my Canon EF-S 18-55mm is f/8. Of course, that would differ with other lenses.
 

JediForce4ever

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Aug 16, 2005
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#7
fWord said:
For macro shots or closeups where the distance from the subject to the lens is very short, or under conditions when the focal length is long, the depth of field becomes very narrow. At these times, using a smaller aperture for a premium in depth of field is desired.

In landscape photos, there's also a trick I read in a book that describes how to achieve maximum depth of field. It states that the aperture should be closed down as far as possible (usually as much as f/22 or f/36), and then focusing on an object that is one-third the distance between the nearest and farthest object in the frame. Great impact is achieved when all objects, near and far, are in sharp focus in a landscape photo.

But for general shooting, I almost never close down further than f/8, and I am only just starting to experiment with f/11 because I am aware of an inherent flaw in my kit lens. When very small apertures are used, a phenomenon (diffraction?) actually causes images to be less sharp than when shot at larger apertures.

Personally, I've always thought that the sweet spot of my Canon EF-S 18-55mm is f/8. Of course, that would differ with other lenses.
at 18mm sharpest f stop is f8, at 55mm, go for f11:)
 

ortega

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Nov 2, 2004
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#8
fWord said:
In landscape photos, there's also a trick I read in a book that describes how to achieve maximum depth of field. It states that the aperture should be closed down as far as possible (usually as much as f/22 or f/36), and then focusing on an object that is one-third the distance between the nearest and farthest object in the frame. Great impact is achieved when all objects, near and far, are in sharp focus in a landscape photo.
this "trick" is called the hyperfocal distance

for more information on this, do a google
there are many sites that explain this much better that i can with text
 

boreboor

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Nov 28, 2005
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#9
Regarding aperture and depth of field, does it only apply to digital cameras? I mean, using normal SLR cameras (even dSLR) does closing the aperture lead to more depth of field? Because in SLR cameras you won't see the effect of closing the aperture, i.e. what you see through the lens won't become darker. You have to use the meter to gauge whether the appropriate amount of light enters the camera. So doesn't the depth of field in that case rely purely on the focal length?
 

Madmax

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Nov 22, 2003
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#10
boreboor said:
Regarding aperture and depth of field, does it only apply to digital cameras? I mean, using normal SLR cameras (even dSLR) does closing the aperture lead to more depth of field? Because in SLR cameras you won't see the effect of closing the aperture, i.e. what you see through the lens won't become darker. You have to use the meter to gauge whether the appropriate amount of light enters the camera. So doesn't the depth of field in that case rely purely on the focal length?
Aperture and depth of field applies to all cams.
 

boreboor

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Nov 28, 2005
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#11
But in SLR cameras, will one be able to see the change in depth of field thru the lens? say one is shooting at f22 and shutter speed 1/60 vs shooting at f3.5 and shutter speed 1/300. (ok the figures may not be exactly right), both are allowing the same amount of light in. so does one have more depth of field than the other. Looking through an SLR camera, there won't be a difference right?
 

ortega

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Nov 2, 2004
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#12
if your camera has a DOF preview button then you can preview the difference
this applies to both digital and film cameras.

when you look into your camera's viewfinder (without dof preview) what you see is at the max aperture of the lens mounted. sothe view with a fast lens is brighter than one with a slower lens.
 

#14
boreboor said:
But in SLR cameras, will one be able to see the change in depth of field thru the lens? say one is shooting at f22 and shutter speed 1/60 vs shooting at f3.5 and shutter speed 1/300. (ok the figures may not be exactly right), both are allowing the same amount of light in. so does one have more depth of field than the other. Looking through an SLR camera, there won't be a difference right?
Unless your eyes aren't sharp enough, you can't notice the difference. The difference on an SLR is very obvious.
 

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