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  1. #1
    Join Date
    Jun 2005
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    Teach me about aperture

    I would like to know more about aperture I dont really understand it

    i know at night when I dont want to overexpose stationary lights I should use a lower aperture

    I wanna know when i should use a higher aperture F2.7
    And when I should use a lower Aperture F8

    a graph would be nice

    I also know that Higher aperture and lower shutter speeds mix well
    And lower aperture and higher shutter speeds mix well
    Does anyone just find the S2's AF assist beam cool?

    I mean it shoots a friggin cube at your head

  2. #2
    Join Date
    Mar 2005
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    Quote Originally Posted by nitr0uzv
    I would like to know more about aperture I dont really understand it

    i know at night when I dont want to overexpose stationary lights I should use a lower aperture

    I wanna know when i should use a higher aperture F2.7
    And when I should use a lower Aperture F8

    a graph would be nice

    I also know that Higher aperture and lower shutter speeds mix well
    And lower aperture and higher shutter speeds mix well
    The aperture determines how much light enters the camera.
    A few practical applications to think about:
    Larger aperture=lower ISO
    Larger aperture plus faster shutter speed to freeze action
    Larger aperture at longer focal length=shallow depth of field/zone of focus
    Smaller aperture=greater depth of field/wider zone of focus
    Small aperture plus slower shutter speed to show motion

    Here is a link to as easy (yet in-depth) an explantion as you can get...
    http://www.photoxels.com/tutorial_aperture.html

  3. #3
    Join Date
    Jun 2005
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    83
    Alright alright so let me get this straight

    Larger aperture
    Blurs background
    can use faster shutter speed
    less DOF

    Small aperture
    doesnt blur background
    Slower shutter speed
    more DOF

    thanks! wasnt aware of the DOF thingy till now
    Does anyone just find the S2's AF assist beam cool?

    I mean it shoots a friggin cube at your head

  4. #4
    Join Date
    Dec 2004
    Location
    Charleston, SC
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    You can creatively use your aperture ranges to capture very different looking pictures.
    F/1.2 will provide a lot of background seperation and very smooth bokeh (background blur). F/2.8 is what most expensive zoom lenses max out at. This provides for great low light use and still excellent background blur. Longer lenses, like the 200mm f/2.8, the background blur is even greater though. The 135 f/2, although not as long, is at f/2, so it has very nice bokeh, some say one of canon's best bokeh lenses. The 85 f/1.8 and 200 f/1.8 are better though.

    F/8 provides a sharper picture, (most often), and includes a sharper, less diffused background.
    For portraits it is good to use larger apertures to isolate the subject. For landscapes I would recommend shooting at f/8 or smaller.

    With Digital SLRs, it is often necessary to use f/16-f/22 to get the widest depth of field. F/22 is similar to f/8 on most point and shoots.
    US Navy--Hooyah!

    Nikon D700/D300|17-35 f/2.8, 24-70 f/2.8, Sigmalux, 80-200 f/2.8, 16 f/2.8 fisheye,

    Lots of flashes and Honl gear.

  5. #5
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    Quote Originally Posted by nitr0uzv
    Alright alright so let me get this straight

    Larger aperture
    Blurs background
    can use faster shutter speed
    less DOF

    Small aperture
    doesnt blur background
    Slower shutter speed
    more DOF

    thanks! wasnt aware of the DOP thingy till now
    And don't forget, when shooting with a large aperture, the longer the focal length, the shallower the apparent DOF (perceived blurrier background) also.
    Last edited by JTL; 07-01-2005 at 02:50 PM.

  6. #6
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    Apr 2005
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    Near St. Louis
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    And for good measure, always remember that when shooting at the largest aperature you are not going to have the sharpest picture. so if the shot allows for it and you know you need a sharp picture, increase your aperature to 8, use a tripod if the shutter speed slows down to much and use the timer or a shutter release, and don't forget to breath, in through mouth out through nose, very very important.
    Nikon D90 | Sigma 10-20 HSM | DX 18-105 f3.5-5.6 VR | DX 55-200 VR | 35 f/2.0 D | 50 f/1.4 D | 85mm F/1.8 D | SB-800 x 3 | SU-800
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  7. #7
    Join Date
    Aug 2004
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    CA
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    Quote Originally Posted by TheObiJuan
    With Digital SLRs, it is often necessary to use f/16-f/22 to get the widest depth of field. F/22 is similar to f/8 on most point and shoots.
    Hey Obi -
    What's the difference on F stops vs DOF between P&S and Digital SLRs?

    If this were a multiple choice exam, I'd guess it has to do with film (OK, cyberfilm) plate size. But if I were pressed for an explanation, I just can't figure it.

    "F stop" is the focal length divided by apeture diameter. Its a ratio and not a hard measurment. Therefore, f8 on a 500mm is 10 times wider than f8 on a 50mm lense. And since longer lenses (given the same subject distance) give considerably less DOF, it follows that DOF is determined by the physical (hard measurement) of the apeture width.

    Probably some web site has a fancy diagram showing little lines with arrows bouncing off the lense mirrors like billiards.

    Since a Digital SLR uses the same lenses as a 35mm lense, the actual plate will be positioned exactly where the 35mm film would be, so DOF would be identical between DSLR and 35mm-Film-SLR. Correct so far?

    I get real fuzzy on this coffeeshop logic where different lense sizes, much smaller pixil-plate sizes, and therefore physically smaller lenses are used (as in P&S cameras). After all, we normally only hear about the efl (Equivilant Focal Length) of those cameras. Who knows what the actual focal length is in mm on a Canon Elf shooting at 38mm(efl 35)? Its surely tiny. Maybe 20mm?

    So, let me breath (properly, oh Obijuan), and rest those hampsters running around my brain, while you elaborate the ying and yang of DOF.
    Canon 20D
    Canon Lenses 135L f2.0, 50mm f1.8, 18-55mm kit
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  8. #8
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    Dec 2004
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    Quote Originally Posted by eastbluffs
    Hey Obi -
    What's the difference on F stops vs DOF between P&S and Digital SLRs?

    If this were a multiple choice exam, I'd guess it has to do with film (OK, cyberfilm) plate size. But if I were pressed for an explanation, I just can't figure it.
    You got it. Because the sensors are so darn small on point and shoots, they have huge depth of field. The actual lenses on these p&s cameras are actually only a few millimeters. Some as low as 4mm!

    Quote Originally Posted by eastbluffs
    "F stop" is the focal length divided by apeture diameter. Its a ratio and not a hard measurment. Therefore, f8 on a 500mm is 10 times wider than f8 on a 50mm lense. And since longer lenses (given the same subject distance) give considerably less DOF, it follows that DOF is determined by the physical (hard measurement) of the apeture width.

    Probably some web site has a fancy diagram showing little lines with arrows bouncing off the lense mirrors like billiards.

    Since a Digital SLR uses the same lenses as a 35mm lense, the actual plate will be positioned exactly where the 35mm film would be, so DOF would be identical between DSLR and 35mm-Film-SLR. Correct so far?
    Yep, right thus far. DOF is a product of aperture, focal length, and image size.
    Adjust any of these three and you get different directly proportional results.

    Quote Originally Posted by eastbluffs
    I get real fuzzy on this coffeeshop logic where different lense sizes, much smaller pixil-plate sizes, and therefore physically smaller lenses are used (as in P&S cameras). After all, we normally only hear about the efl (Equivilant Focal Length) of those cameras. Who knows what the actual focal length is in mm on a Canon Elf shooting at 38mm(efl 35)? Its surely tiny. Maybe 20mm?

    So, let me breath (properly, oh Obijuan), and rest those hampsters running around my brain, while you elaborate the ying and yang of DOF.

    Here is a great link for calculating the DOF of your camera, (our) and your lenses. Be sure to use the actual, not effective focal length, as your sensor is essentially cropping the center of the lens, so the physics stay the same.
    http://www.dofmaster.com/dofjs.html

    I could go on and on about DOF, and there is a lot to go on and on about. Especially formulas.. but Bob Atkins does it best here:
    http://www.photo.net/learn/optics/dofdigital/
    US Navy--Hooyah!

    Nikon D700/D300|17-35 f/2.8, 24-70 f/2.8, Sigmalux, 80-200 f/2.8, 16 f/2.8 fisheye,

    Lots of flashes and Honl gear.

  9. #9
    Join Date
    Dec 2004
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    Quote Originally Posted by eastbluffs
    snip

    With a small sensor, you get to use really small, true focal lenght lenses, like 5mm. At 5mm and f/2.8, the DOF will be many feet. If it were a big sensor, and a 5mm lens were used (I think impossible, 8 is bad enough), then their would also be greater dof at f/2.8 than a 50mm lens.


    Once again, the smaller the sensor, to smaller the lenses, the greater the dof.

    'Macro' shots, on any camera, will yield very little DOF. The closer you get, the more pronounced the small DOF becomes. With DSLR, f/16 is considered shallow for macro photography.
    Try f/2.8, at any focal length, for 1:2 or greater macro shots on a dslr, and you will see, it will be very frustrating. But with a small sensor/short focal length lens, on the point and shoot. f/2.8 works out beautifully!
    US Navy--Hooyah!

    Nikon D700/D300|17-35 f/2.8, 24-70 f/2.8, Sigmalux, 80-200 f/2.8, 16 f/2.8 fisheye,

    Lots of flashes and Honl gear.

  10. #10
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    Jun 2005
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    Sydney, Australia
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    Quote Originally Posted by JTL
    The aperture determines how much light enters the camera.

    Here is a link to as easy (yet in-depth) an explantion as you can get...
    http://www.photoxels.com/tutorial_aperture.html
    Sorry...I'm still confused. As Denzle Washington once said...."explain it to me like I'm a 6 year old".

    Referring to the link given, it explains "The aperture of a lens is the diameter of the lens opening..."
    From this, I can understand that the greater the opening, the more light is let in (so far, so good). In garden variety English, I would have thought if I have an opening of 10mm (therefore an Aperture of 10mm), and compared it to an opening of 5mm (therefore an Aperture of 5mm), then the 10mm would be the larger aperture of the two. Am I correct, or have I lost the plot already ?

    If I'm still on the right track how then, does this suddenly mean that an F2.8 setting results in a larger aperture than an F16 setting ?

    What is the relationship other than "remember, the smaller the F-stop, the larger the aperture". I want to know why !!!!!!!!!!!

    Is it the mechanics of the shutter, is it white man's magic....what is it ?

    Help please.

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