Review of spot meter and centre weighted picture

[Goldcoin79]

Hi, I took this picture and took a shot using spot metering on the subject (the boat) and a shot using centre weighted metering to see what looks best. Im not realy sure what one I like best but my wife thinks the one used on spot metering is best, however i'm not sure if maybe some might think the sky and water on the beach is a little over exposed on the spot metered one. Would appreciated any thought and opinions.

The one on the left is centre weighted and the one on the right is spot metered.


James

 

[ceejtank]

Subscirbing to this because I'm interested in the mechanics of peopels answers to it.. I personally like the detail of the spot metered boat colors... but the sky does seem blown out. Could always combine aspects of the two

 

[zcar21]

Neither one is going to give you the correct exposure every time. The first one is underexposed and the second one is slightly overexposed. The only different in those two shots was that the aperture changed from f7.1 to f5, that's 1 stop differnce and part of the sky is blown out. Using spot metering you'll find that your exposures are going to vary a lot depending on where your pointing the camera.

Another thing that I noticed is that the second picture looks sharper, probably because at 7.1 diffraction starts to blur the image. I'll just leave it at the default metering setting at pay more attention to aperture, iso and shutter speed.

 

[Graystar]

Exposure is based on the light source. That's why incident light meters work. With an incident meter you can meter the light directly, set your camera to the settings indicated by the meter, and you'll get an image with correct exposure. The incident meter works by using a small dome. The dome allows about 12.7% of the light falling on it to get through. Based on a presumption of 12.7% light, the meter will calculate exposure values.

Our cameras use reflective meters. These meters measure the light reflected from the scene. Now...a white object can reflect 90% of the light that falls upon it, and a black object can reflect 5% or less of the light that falls on it. How does the meter know how much is being reflected? The answer is that it doesn't...it simply presumes that the scene is reflecting 12.7% of the light that's falling on it.

For typical scenes of everyday life, this presumption isn't far off. But when bright areas or dark areas dominate a scene, the exposure that the camera calculates is usually off. This is what happens with snowy landscapes and close-ups of black dogs. Both turn out gray, because the camera presumed they were gray to begin with. So the exposure accuracy of a reflective meter is entirely dependent on the amount of light that the scene is reflecting.

Center-Weighted metering is an old metering mode developed to address metering inaccuracies. The idea was to concentrate the reading on the subject, and to minimize the influence of the surroundings, which might be bright sky, or darkness at night. CW allowed a subject to have a greater influence on the metering calculation, but if your subject is a snowman, it makes little difference...the same presumption of 12.7% gray exists, and the snowman will be rendered as gray.

If the camera is presuming that the world is gray, then the easiest way to get correct exposure is to give the camera what it wants...give it something gray to meter. This is the idea behind the gray card. When you put a gray card in front of a camera, you get the same effect as the dome on an incident light meter. A known amount of light is reflected, and that allows the meter to set aperture and shutter correctly. (That said, most gray cards are 18% gray and the camera is looking for 12.7% gray...but let's talk about that some other time.)

Spot metering is the mode that is used by people who understand all of the above. It is used with an expectation that the camera will be wrong. Spot metering allows a person to isolate a small area of the scene so that it can be metered without the influence of its surroundings. Then, based on the photographer's own personal evaluation of the tone that is being metered, the photographer applies a correction to the meter reading in order to achieve correct exposure. That's what the Exposure Compensation control is for. With Spot metering, EC, and a sense of how tones will be rendered (or a gray card in hand) you can precisely control how a scene will be rendered.

Which brings us to your images. It's impossible for us to make any sort of evaluation on the metering. If you were striving for accurate metering and an accurate rendition, then one, or even both, of the images is wrong. We can't say which one, because we don't have an independent incident meter reading of the scene. If you were striving to manipulate the mood of the scene using luminance, then the correct one is the one that conveys your message. That's simply artist's choice, and all we can do is like it or not like it.

What you definitely should not be doing, however, is trying to draw any conclusions on the effectiveness or suitability of various metering modes based on how a few images are rendered. That literally tells you nothing. Both metering modes can be accurate and both can be inaccurate. But If you understand how the meter works and how to control it, then you'll get the metering result you want.

 

[amolitor]

Is there a question in there, somewhere? I don't quite understand what you want from the forum, here.

 

[Goldcoin79]

I've not been doing photography for long so reviews and opinions on what I've asked above is what I was after so I can learn off people who are more experienced than me.

Thank you to comments received so far.

 

[amolitor]

Are you trying to understand the technical reasons that the two photographs look different? I think Graystar has that covered, did that make sense to you?

If you want to know which on eis "better" in some sense, that's going to be a bit subjective. They both look fine to me, but different, and different things are emphasized in them. One might almost say that the first one is "about" the sky and the beach, while the second one is "about" the pier and the boats, the objects between the sky and the beach. Both are perfectly good images, both are perfectly reasonable choices for the exposure, but each expresses something a bit different.

 

[Goldcoin79]

I understand the technical elements of the metering and why each one looks like it does. I guess I am looking at what people find is the most acceptable picture or the one that looks best, I guess what you are saying is that they are both ok and it is purely preference of the each person. I am mainly asking as there is people on this forum more experienced than me so that's why I'm interested in there opinion.

I was mainly trying to capture the the boats on the beach why the tide was out so I guess the lower picture which is spot metered shows this better.

James

 

[Tbini87]

I personally like the second photo more. I like the brighter colors and being able to see more about the boats. The colors pop a little more, the first one feels a little too dark and dull to me.