What is: Aperture?

Discussion in 'Digital Photography' started by MACDRIVE, Dec 24, 2006.

  1. MACDRIVE macrumors 68000

    MACDRIVE

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    #1
    Ok I realize that in about 5 seconds someone is going to come on here and accuse me of being lazy for not using Google.

    I would much rather here from you; my fellow MR buddy. It makes me feel special and important. :)
     
  2. iMeowbot macrumors G3

    iMeowbot

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    #2
    It's iPhoto with mag wheels, a hood scoop and fuzzy dice.
     
  3. MACDRIVE thread starter macrumors 68000

    MACDRIVE

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    #3
    ^
    That's what I get for taking a shortcut by starting a thread. :eek:
     
  4. iMeowbot macrumors G3

    iMeowbot

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    #4
    They have a free trial now, you can download and play with it for a month. But really, Aperture is pretty much what I wrote before, a very fancy take on iPhoto.
     
  5. PodHead macrumors member

    PodHead

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    #5
    :p Haha...I like that.
     
  6. MACDRIVE thread starter macrumors 68000

    MACDRIVE

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    #6
    Umm... aperture is a setting on a camera isn't it? I get it... you guys had to start the hard way by learning photography, and now it's my turn. I get it... :eek:
     
  7. puckhead193 macrumors G3

    puckhead193

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    #7
    :confused: - i think they thought you meant the software made by apple.
    Aperture (the setting on the camera) is like the f. stop on "old" 35MM cameras. It allows you to control the amount of light that enters the camera and hits the film or the CCD.
     
  8. iMeowbot macrumors G3

    iMeowbot

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    #8
    Ohhhh, that aperture! It's the camera's version of your eye's pupil, it's just the hole where the light passes between the lenses and the film or sensor. And just like an eye, a camera (well, except for a cheap one) has an adjustable iris that controls the size of the aperture.

    If the iris is wide open, you can grab a picture in less time, because more light comes in. In exchange, focusing is more touchy. If you close up the iris, much less light comes in, the time it takes to get a good exposure increases (and so movement becomes an issue), but it increases the range of things that will be in focus (kind of like squinting).

    Squeezing the hole down smaller also lets you get a longer exposure (if you want that) so that you don't end up with a washed-out picture.
     
  9. MACDRIVE thread starter macrumors 68000

    MACDRIVE

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    #9
    Yeah that's the info I was looking for. I'm trying to figure out what the different camera settings mean. The camera guide tells me WHERE the adjustments are, but not WHAT they mean. :eek:

    Ok, thank you for the definition. :)

    This little camera is complicated; as I'm beginning to find out. :eek:
     
  10. sjl macrumors 6502

    sjl

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    #10
    Ok, here's Stuart's Patented Five Minute Guide to Photograph Exposures. :D

    There are four variables that affect exposure of a shot: ISO speed, aperture, shutter speed, and the actual amount of light. You have full control over three of those, and limited control over the fourth. Basically, if one of them changes, another one (or possibly all three) of the others have to change to compensate.

    ISO speed: measures the sensitivity of the sensor (or film for 35mm cameras) to light. Think of old black and white film, which used silver compounds to form the image. The larger the clumps of these silver compounds, the faster they'd react to light, and hence the more sensitive the film (and the higher the ISO speed). Against this, you'd lose detail: the smaller the clumps, the more detail the film could capture. This still holds true today: the higher the ISO speed you set the sensor to in a digital camera, the more noise the camera will put in the image.

    Aperture: the size of the hole letting in the light. It's expressed as a ratio: f/2 means the diameter of the aperture is the focal length (f) divided by two (/2). The wider the aperture (and hence the smaller the f stop), the more light you let in. There's a trade off, though: the depth of field (the thickness of the in-focus plane) decreases as the aperture gets wider. Handwave, handwave.

    Shutter speed: how long the camera exposes the sensor or film to light. Obviously, the longer it is, the more light gets in. If you want to freeze action in your shot, you need a fast shutter speed, which means the aperture needs to be wider, the ISO speed higher, and/or the ambient light brighter.

    Ambient light: you can affect this in two ways. A flash will give you more light for the exposure, but has limited range; there's not much use trying to use a flash on buildings a couple of kilometres away, for example. You can also cut down the light (useful if, for example, you want a shallow depth of field in bright sunlight) by using a neutral density filter - these absorb some fraction of the incoming light, but don't affect its colour. Circular polarisers are also very useful in many situations, especially outside in bright sunlight; they help to bring out the colour of the sky, for example - but they also reduce the amount of incoming light.

    Wiki has articles on the three main ones above (aperture, shutter speed, and ISO speed) - they make a good place to start for more info. Play around, and you'll start to get a feel for it. Note that sometimes, depth of field is more subtle than the camera might indicate - eg, this shot has a very shallow depth of field (it was taken at f/1.8 with a 50mm lens, fairly close), but more of the shot seemed to be in focus through the viewfinder than was actually the case. As I said: experimentation is the best way to understand all this.
     
  11. puckhead193 macrumors G3

    puckhead193

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    #11
    what camera did you get?
     
  12. MACDRIVE thread starter macrumors 68000

    MACDRIVE

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    #12
    Thanks Stuart, I'll read your post about 500 more times and hopefully it will sink in. :eek:

    And these numbers would mean: :confused:

    Auto
    64
    100
    200
    400

    F2.7
    F3.0
    F3.4
    F3.8
    F4.3
    F4.8
    F5.4
    F6.0
    F6.8
    F7.6

    -2.0
    -1.7
    -1.3
    -1.0
    -0.7
    -0.3
    0
    +0.3
    +0.7
    +1.0
    +1.3
    +1.7
    +2.0
     
  13. bartelby macrumors Core

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    #13
    Auto
    64
    100
    200
    400
    These could be the film speed setting (Basically how sensitive the film is)



    F2.7
    F3.0
    F3.4
    F3.8
    F4.3
    F4.8
    F5.4
    F6.0
    F6.8
    F7.6

    F if the aperture setting, but those numbers look a bit odd. (it's usually 2.8, 4, 5.6, 8, 11, 13, 16, 22)



    -2.0
    -1.7
    -1.3
    -1.0
    -0.7
    -0.3
    0
    +0.3
    +0.7
    +1.0
    +1.3
    +1.7
    +2.0

    These look like exposure compensation numbers.
     
  14. MACDRIVE thread starter macrumors 68000

    MACDRIVE

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    #14
    Nikon CoolPix P2

    The whole camera is odd.
     
  15. Abstract macrumors Penryn

    Abstract

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    #15
    Meh, it doesn't matter if the numbers follow the regular pattern or not. Maybe they were just trying to give you accurate numbers, like when Sony tries to sell an f/2.87 lens. Most f/2.8 lenses aren't really f/2.8. That's the number it's close to since f/2.8 is a number used by convention. As long as f/2.7 allows twice the amount of light as f/3.8, and f/3.8 lets in twice the amount of light as f/5.4, it's cool. It's basically the same thing as the conventional f2.8, f4, f5.6, etc... numbering anyway. This camera still increases the amount of light that reaches the sensor/film in 1/3EV steps.

    It is a bit weird, though....
     
  16. MACDRIVE thread starter macrumors 68000

    MACDRIVE

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    #16
    ^
    Well, I found out that an ISO setting of 400 gives a clearer picture than ISO 64; I don't know why though. :eek:

    The manual says to use ISO 400 when having the flash off. Of course I read that after the fact. :cool:
     
  17. srf4real macrumors 68030

    srf4real

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    #17
    I've been trying to learn this stuff too, MACDRIVE. Between the great resources here in MR and elsewhere online, with some experimentation (thank God I don't have to pay to get all these bad shots developed) it is very rewarding to have even a basic understanding of how the camera works! I'm glad you posted your question here because I've learned something new too.;)
     
  18. MACDRIVE thread starter macrumors 68000

    MACDRIVE

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    #18
    ^
    Thank you for the sympathy. :eek:

    For close up shots: Do you want a low f/number or high f/number? I mean real close; like less than 12.0 inches. :confused:

    And whenever your f/number goes down, (larger lens opening) your shutter speed needs to increase. Someone please correct me if I wrong. :confused:
     
  19. jamesW135 macrumors 6502a

    jamesW135

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    #19

    Apeture- The amount of light being let into the lens use a small apeture (Large F-Stop) to foucus the inage near to far. Use a large apeture (small F-Stop to make you focal point stand out from a blured backround.

    A little confusing but once you get the hang of it, It's very cool.
     
  20. adrianblaine macrumors 65816

    adrianblaine

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    #20
    ISO 64 is really slow film speed and depending on how light it is, you wouldn't be able to hand hold a shot at this speed unless it was fairly bright. This is when you need to buy a tripod :)

    My dad's rule of thumb when he taught me photography was to try not and hand hold a shot with a focal length larger than your shutter speed.

    For example, if you are shooting with a shutter speed of 1/30 of a second, try to have the zoom at 30mm.

    So the farther you zoom in, the faster the shutter speed needs to be. But if you have optical stabilization you can hand hold at slower shutter speeds.

    I looked up your camera and it basically has a zoom from 35mm to 125mm, so if I were you I would try to not shoot slower than 1/30 zoomed out, and when zoomed all the way in I wouldn't shoot slower than 1/125. Hope this helps!
     
  21. ChrisA macrumors G4

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    #21
    It's a trade off. ISO 400 makes the CCD more sensitive to light so you can use a shorter exposure. The short expose will "freeze" motion and reduce motion blur. But the Higher ISO setting increase noise. Noise appears as graininess in the image, the color is not as good or smooth looking.
     
  22. MACDRIVE thread starter macrumors 68000

    MACDRIVE

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    #22
    iMeowbot

    PodHead

    puckhead193

    sjl

    bartelby

    Abstract

    srf4real

    jamesW135

    adrianblaine

    ChrisA


    Thank You to everyone for your invaluable help. :)
     
  23. sjl macrumors 6502

    sjl

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    #23
    Last paragraph first: you're correct. Wider aperture means the shutter needs to be open for a shorter period of time, all else being equal.

    As for the close-up shots: depends. If you want the entire subject in focus, you want a high f number - f/22 is good. Otherwise, the depth of field will be razor thin; you'll get some of the subject in focus, but the rest will be blurred. Unfortunately, that then means you want a slow shutter speed, requiring a tripod to hold the camera steady (and a subject that doesn't move during the shot). Or you need to get extra lighting in - one or the other.

    There's a reason why Canon (for example - speaking as a Canon shooter, so their lineup is what I'm familiar with) sells macro ringlights ...
     
  24. Silentwave macrumors 68000

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    #24
    Nikon sells ring lights (complete and modular) too :)

    also, you might not want to stop down all the way for macro shots all the time when you want the entire subject in focus- there will be a point of diminishing returns, when diffraction from the high aperture will begin to destroy sharpness.
     

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