Metering question (Split from A Photography FAQ

[togu]

Hrm, can I ask what's metering? Spare me if this had being answered million times :embrass:

Another noob question:

When I try to take a close up shot of a Garfield figure using auto-focus, I can see from the LCD that the camera is adjusting the focusing, it became sharp for a while, but back to blurrish after that. I did a manual focus then, but no matter how I change it, it seems like I can't get back that sharp focusing, any clues? Or am I way out? :bheart:

 

[ziploc]

Originally posted by togu
Hrm, can I ask what's metering? Spare me if this had being answered million times :embrass:

Another noob question:

When I try to take a close up shot of a Garfield figure using auto-focus, I can see from the LCD that the camera is adjusting the focusing, it became sharp for a while, but back to blurrish after that. I did a manual focus then, but no matter how I change it, it seems like I can't get back that sharp focusing, any clues? Or am I way out? :bheart:

Hi togu,

There is no noob questions here. All newbies questions are welcome, and we are here in the club to learn from each other.

Metering is the process of using your camera's inbuilt light meter to measure the correct exposure of a scene. For example, if you set your camera to "program" mode, the camera will decide the shutter speed and aperture to be used based on the current lighting condition (eg. evening time, since it is darker, the camera will need to let more light in to strike the film to get a correct exposure, so a larger aperture or slower shutter speed is needed). Similarly for aperture priority or shutter prioty mode, you set either the aperture or the shutter speed and the camera will set the other based on the iso of you film and the lighting condition. In manual mode, you get to set both shutter and aperture, but you can still rely on the camera's exposure meter to "meter" the scene and assist you in deciding the correct shutter speed and aperture setting.

As for your focusing problem, all autofocusing (AF) systems need contrast at the focusing zone (the area marked out in the view finder for AF) to do proper focusing.

Hope this helps.

 

[togu]

:what: That's a ...WOW!


Hi Ziploc, thanks for the tips!!

Hrm, for the manual settings, I found the settings on light sensor, and er... exposure control button, with a -2 to +2.0 EV values. And a button for Iris setting, with a F2.8 to F11 settings. The camera manual mention it's about the depth of field and the shutter speed. So am I right to say that, if any 1 of my pictures taken in auto appears to be too dark, I should adjust the exposure control to make it brighter?

Heh, this is getting interesting, guess I'll keep taking some pictures of the same thing but with different settings to try it out.

Sweet! Er... apologise if the pictures are too big, wanted to keep it original.

Oh, for the close up shot problem, I mangage to figure it out. I didn't press the macro button. :embrass:

 

[ziploc]

Originally posted by togu
:what: That's a ...WOW!

Hi Ziploc, thanks for the tips!!

Hrm, for the manual settings, I found the settings on light sensor, and er... exposure control button, with a -2 to +2.0 EV values. And a button for Iris setting, with a F2.8 to F11 settings. The camera manual mention it's about the depth of field and the shutter speed. So am I right to say that, if any 1 of my pictures taken in auto appears to be too dark, I should adjust the exposure control to make it brighter?

Heh, this is getting interesting, guess I'll keep taking some pictures of the same thing but with different settings to try it out.

Sweet! Er... apologise if the pictures are too big, wanted to keep it original.

Oh, for the close up shot problem, I mangage to figure it out. I didn't press the macro button. :embrass:

You are welcome.

There are 3 things that affect exposure: Iso value (sensitivity of the film/sensor to light), aperture value, and shutter speed. Generally you control the depth of field with the aperture: larger aperture (lower f-stop value, eg. f/2.8) gives shallower DOF. Shutter speed is for capturing motion: slow shutter speed (longer exposure time) creates motion blur while fast shutter speed freezes the motion.

The -2 to +2 EV you mentioned is exposure compensation: this is used in "Program" (P), "Aperture Priority" (A) and "Shutter Priority" (S) mode to tell the camera you want to override (compensate) the exposure metered by the camera. For example, if your camera was in (A) mode and you set aperture to f/5.6, and the camera metered the scene and determined the shutter speed to be 1/250s, setting +1EV compensation will tell the camera to set the shutter speed at 1/125s (1 stop more of exposure).

In general, you can rely on the camera to do the exposure setting for you based on the metering. However, there are times when the meter will be fooled (eg. the camera will tend to overexpose with a large part of your shot in dark color), and in these cases the exposure compensation can be used.

As for your 2 pics: yes they are too big! There is no need to show big pictures to show the exposure. The 1st shot's exposure looks ok if your main subject is the building. The 2nd shot is overexposed (and blur too, either due to camera shake or not focusing properly).

Nikon has some tutorials that I think will be beneficial for you:

http://www.nikon.co.jp/main/eng/photo_world/kumon/index.htm

Happy reading.

 

[togu]

Thanks for the prompt reply.

Oh, and the tutorials too, will need to digest it ;p