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Spot metering off blue sky or green grass/tree for better exposure

Discussion in 'Digital Photography' started by YS2003, Aug 6, 2006.

  1. macrumors 68020


    For less than ideal "metering" condition, I heard taking a meter reading off the blue sky or green grass/tree would give you a quick and easy exposure setting.

    I have Canon D30. Do you know how I can do this? If I press the shutter a half way down and move the camera to aim the target, I can lock in the aperture/exposure setting. There is also an exposure lock button as well. But, does it cause some problem for focusing, as you need to move the camera after catching the meter reading off blue sky or green grass?
  2. macrumors 6502

    Use manual mode and you won't have to worry about pressing any more buttons or doodads. I know the AE lock button on Nikons can be configured to lock exposure only, focus only, or both.
  3. macrumors 6502


    The exposure lock button will hold the exposure until you take the picture unless you set the CF to autofocus. Use the button then compose your picture, zoom or what ever, it will focus then take the picture at that exposure.

    Or as beavo451 noted, record the exposure and set it manually. That is probably better in a studio setting, outside I would use the exposure button.
  4. macrumors 68020


    Thanks for the info. That is what I was looking for. It is good to know AE lock out feature (by pressing AE lock out button) allows the focusing while maintaining the exposure setting.

    Regarding writing down the exposure setting, what else do I need to remember other than the shutter speed and f-stop?
  5. macrumors 6502


    To take it off manual when you are done. : )
  6. macrumors newbie

  7. macrumors 601


    If you're setting exposure outside based on this, it's basically the same as using an incident meter- unless you're at the end of the day where the light's changing quickly putting it in manual isn't that bad, and it means you can take multiple exposures without having to worry about changing the settings or holding down the button for 15 or 20m. I also find that if I'm chimping the histogram and setting exposure compensation I'm happier in manual mode and drifting the compensation as the light changes.
  8. macrumors 6502a

    I'm confused. I know that pressing the shutter half way not only focuses but also sets the aperture/shutter speed (when not in manual, depending on mode). However, if you keep holding the shutter half way, I think that is focus lock, is it not? Your metering will change as you move the camera while your initial focused subject will remain so. That is what the AE lock is for. But, I could be very wrong too!

    I still am not comfortable with using AE lock, or more like when to use it.
  9. macrumors Penryn


    I can't remember, but for most basic DSLRs, the shutter button locks both the exposure and focus unless you tell it NOT to lock the exposure. If you (are given the menu option to) set your camera up so that your shutter button only locks the focus, and the AE/AF button only locks exposure (i.e., AE lock only), then you've taken care of your problem. I think spot metering off the grass is a good idea. Do that, press the AE/AF button to lock exposure, then move the camera and either take the photo, or lock the focus on your subject (by pressing the shutter down half-way) and recompose and take the photo.

    The exposure should automatically unlock after you take the photo. You don't need to press the AE/AF button again to unlock the exposure.
  10. macrumors G4

    Use manual setting. It really is faster. Because you only have to change the exposure when the light changes. So after you meter off the grass. You can leave the exposure set for an hour of so, or until a cloud moves in front of the sun.

    When you meter off grass you are measuring the level of the ambient lighting. It is the same as if you were to use a white dome hand meter. Both measure incident light. So you only have to re-meter if the light changes. That is why manual is faster. You do it just once. If you use the exposure lock then you have to re-do it every time you take your finger off the lock button. The manual setting stay set until you change them.

    With digital you can back this up. After metering the grass take a test exposure and then look at the camera's histogram display and you can fine tune the exposure. Once set you are good for the next 100 frames.

    People today forget that exposure is not rocket science. 60 years ago my grandmother could work a camera that did not even have a place to put a battery and she likely did fine just by reading the little sheet included with the roll of film that said "for bright sunlight use f/16, for open shade f/8. They always used to have those kinds of "cheat sheets" in the film box.

    If you are outdoors, on a clear day with the sun well above the horizon just set the camera to f/16 with the shutter speed equal to the ISO. You can trade some of the aperture for shutter speed as long as the overall exposure remains unchanged. This will get you very close and is as good as most automatic meters. You don't even have to meter the grass because we know how bright the sun is. It never changes.

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