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metering and exposure problem
My A80 has metering mode to choose in full manual mode. My question is if you set the aperture, shutter speed and iso yourself, you pretty much determine the exposure already, so what's the point of having those metering thing? the metering is for determine the exposure like the iso, aperture and shutter speed, right?..

Comments (23)

New_type wrote:.

My A80 has metering mode to choose in full manual mode. My questionis if you set the aperture, shutter speed and iso yourself, youpretty much determine the exposure already, so what's the point ofhaving those metering thing? the metering is for determine theexposure like the iso, aperture and shutter speed, right?.

I don't exactly understand your question ???.

In full "manual" you set all parameters yourself ... you can determine those parameters by using an external (hand-held) meter ... or use the internal camera circuitry to determine what levels to set..

OR ... in manual you may want some very different specific setting for some unusual reason ... or for an event that has not happened yet..

Example, you may want to preset for an "explosion" that is going to be VERY bright ... any "meter" is useless cause it does not yet know how bright/dark the event may be ... so make your own determination and "preset" those values..

BUT ... the metering "modes" usually apply to "auto" modes. They may be "program" where both aperture and shutter speed is set for you by the cameras electronics..

Both Aperture and Shutter "priority" modes allow you to preset ONE of those factors, and the camera sets the other one to compensate. (In shutter priority, you preset the shutter speed, thus "prioritizing" it).

ISO is usually kept as LOW as possible for the lowest noise in your image .... however ... if there is low light ... (or you need a very high shutter speed, or small lens opening) ... you may want to set the ISO higher..

Something else you didn't mention was Exposure Compensation. To lighten or darken the image..

This can sometimes be most important. Your camera is designed to produce a GRAY image from a GRAY-card. (more specifically, Kodak called it an 18% gray-card)..

So IF you are photographing in the bright WHITE "SNOW" .... the image will be "gray". Conversly, if you have a "black-cat" in a black "coal-bin" .... the image will again be "grey" instead of black..

Using a +2 or +3 Exposure Compensation can lighten the snow back to a correct white ... (but be careful to not overdue or you will "saturate" at full-white)..

And a -1 or -2 can darken to get the desired shade of black on that black-cat..

Another use for Exposure Compensation can be an unevenly lit SUNSET .....

Or, if a person is in the shade, with bright sun behind them ... using +1, +2, or +3 can lighten the person face ... (but the background WILL be washed out - you can't save everything)..

Hope that helps .... any more specific questions ... ask.

Thanks for reading .... JoePhoto.

( Do You Ever STOP to THINK and FORGET to START Again ??? )..

Comment #1

There are plenty of situations when using manual metering (i.e. taking the camera's advice, but making your own decision) is a good idea. Here is one....

Http://forums.dpreview.com/...forums/read.asp?forum=1002&message=26533006.

Best wishesMike..

Comment #2

New_type wrote:.

My A80 has metering mode to choose in full manual mode. My questionis if you set the aperture, shutter speed and iso yourself, youpretty much determine the exposure already, so what's the point ofhaving those metering thing? the metering is for determine theexposure like the iso, aperture and shutter speed, right?.

No..

Metering establishes an exposure value. That's all..

Maybe an example would help..

Let's say you are shooting a piece of paper which has a black rectangle in the middle. The rectangle is about 1/5 of the surface of the paper. You want to take a picture of the paper, filling the LCD..

Now, by experimentation, you find out that at ISO 100, f4 and 1/100 the exposure is "right".Let's see the metering in action.You are in manual mode, ISO 100, f4 and 1/100..

Evaluative metering. Every manufacturer has it's own calculation formula, but since the black rectangle is about 1/5 of the image, evaluative will say the exposure is right, because the image has about 20% black. The camera meters for 18% gray..

Spot metering. Exactly the same settings and framing, the camera will complain of a severe underexposure, about 2 stops. Because it's seeing black, and expects 18% gray..

Center weighted, it will indicate SOME underexposure, but probably less than 2 stops...

Comment #3

The question is that you set all the parameters in manual mode, what's the point of having those metering method. say you set f4, half second, iso 50.the exposure is already set, what's the point of having those metering mode?..

Comment #4

You're not 'getting it'..

Just because you dial in some random combination of shutter/ap/iso, that doesn't mean you're going to get a usable high quality photograph on the other end..

You can 'set the exposure' all you want to anything you want but unless that exposure is correct for the subject/lighting/artistic intent, you're gonna get garbage..

The meter is there to tell you what the camera thinks should be the correct exposure which is very often correct. The camera & it's meter is not as smart as a good photographer who has knowledge and experience..

In full manual mode, the meter serves an informational/advisory function...

Comment #5

Say for certain aperture, shutter speed and iso, use spot or evaulative or weight weight metering make any different?..

Comment #6

As the other poster said, you don't get it..

New_type wrote:.

The question is that you set all the parameters in manual mode,what's the point of having those metering method. say you set f4,half second, iso 50..

And exactly how did you come with those numbers? Are you taking pictures with random values until you get a good one? Or just following the METER indication?.

The exposure is already set, what's the point of having thosemetering mode?.

Because, as I was trying to explain, the metering mode sets the suggested exposure..

The LCD and histogram are good tools, but a light meter can be a much more valuable tool... if you know how to use it...

Comment #7

Say you don't want to use the in camera's metering, and you set all the parameters yourself and you ignore the camera's suggestion...

Comment #8

Yes, the 3 different metering modes are not there just because the manufacturer thought it would be a good marketing tool..

The meter will indicate what it thinks you should set the speed/ap for. Your choice is to follow/interpret it's information or not..

Setting the meter to use the different modes *usually* will yield different readings esp. if the lighting is non-trivial. You wouldn't expect a metering mode that averaged the brightness for the entire scene (say, a picture of your kid at the beach) to yield the same results as a mode that only looked at a tiny bit of the scene, zero'd in on the kid's face..

New_type wrote:.

Say for certain aperture, shutter speed and iso, use spot orevaulative or weight weight metering make any different?..

Comment #9

How do you come with the exposure paramters?.

New_type wrote:.

Say you don't want to use the in camera's metering, and you set allthe parameters yourself and you ignore the camera's suggestion...

Comment #10

Then you get what you get. Most likely, it'll be poorly exposed photo..

Manual mode is exactly that. If you want to drive the camera w/o any real knowledge of how the variables interact, then you shouldn't be surprised when 95% of your photos are non-keepers. And the other 5% are just good luck..

Are you under the belief that you're just going to randomly twiddle some camera control knobs and magically get well exposed photos? If so, you are wrong..

New_type wrote:.

Say you don't want to use the in camera's metering, and you set allthe parameters yourself and you ignore the camera's suggestion...

Comment #11

I am sure there are people don't use the metering. sunny 16 rule or from their experience..

Comment #12

And you have such experience?.

Honestly, this is getting boring and redundant. Everyone is trying to help and you seem to not want to hear a single thing or are just trolling..

Good luck w/ your random photography..

Comment #13

New_type wrote:.

I am sure there are people don't use the metering. sunny 16 rule orfrom their experience.

You have the choice. You can use the cameras brains or your own. Now go and try it out and see how you do..

Chris Elliott.

*Nikon* D Eighty + Fifty - Other equipment in Profile.

Http://PlacidoD.Zenfolio.com/..

Comment #14

New_type wrote:.

The question is that you set all the parameters in manual mode,what's the point of having those metering method. say you set f4,half second, iso 50.the exposure is already set, what's the point of having thosemetering mode?.

It gives you a second opinion. You make the choice of settings, the camera indicates whether or not it agrees. You may find that helpful, or you can ignore it..

Alternatively, the camera metering may be used as the "first opinion". Say you want to shoot a panorama, and want to keep the exposure the same for every frame. You could use the camera metering to guide you to reasonable settings before starting to shoot the sequence.Regards,Peter..

Comment #15

I guess I can randomly twiddle the camera control knobs and if the photo turns out too overexpose or underexpose, I can adjust accordingly until I get the right one. isn't that newbies do?.

Howard Moftich wrote:.

Then you get what you get. Most likely, it'll be poorly exposed photo..

Manual mode is exactly that. If you want to drive the camera w/o anyreal knowledge of how the variables interact, then you shouldn't besurprised when 95% of your photos are non-keepers. And the other 5%are just good luck..

Are you under the belief that you're just going to randomly twiddlesome camera control knobs and magically get well exposed photos? Ifso, you are wrong..

New_type wrote:.

Say you don't want to use the in camera's metering, and you set allthe parameters yourself and you ignore the camera's suggestion...

Comment #16

New_type wrote:.

I guess I can randomly twiddle the camera control knobs and if thephoto turns out too overexpose or underexpose, I can adjustaccordingly until I get the right one. isn't that newbies do?.

Only newbies that aren't very intelligent.Chris R..

Comment #17

New_type wrote:.

I guess I can randomly twiddle the camera control knobs and if thephoto turns out too overexpose or underexpose, I can adjustaccordingly until I get the right one. isn't that newbies do?.

No. Newbies stick the camera on fully automatic mode and let the camera set the exposure, which on the whole it will do well..

You could spend a lot of time randomly twiddling. On my camera there are five ISO values to choose from, 11 apertures (in half-stop increments) between f/4 and f/22, and eighteen shutter speed values (assuming only whole stop increments) between 1/4000 sec and 30 sec. That makes 990 possible combinations, most of which will be badly wrong..

Good luck with your random guessing.Mike..

Comment #18

New_type wrote:.

The question is that you set all the parameters in manual mode,what's the point of having those metering method. say you set f4,half second, iso 50.the exposure is already set, what's the point of having thosemetering mode?.

People have answered your question, but perhaps not explicitly enough. So here's my attempt:.

The light meter does not have a direct impact on the photograph in full manual mode. In all other modes, the camera uses the light meter to set the aperture/shutter (and sometimes ISO). In manual mode you override the camera's "opinion" on proper exposure".

The light meter reading is there solely as a piece of information to help you get exposure right (based on the camera's interpretation). There are different metering methods the camera can use. You set the one you want for the sort of information you are interested in. If it's important that the scene be well exposed overall you choose evaluative. If you're only concerned about a particular subject, you can set it on spot metering..

In semi manual modes, like aperture priority, the meter reading has a direct input. Say you set it for f/8 and ISO 100. The camera will set the shutter speed to a value that will let in an appropriate amount of light, based on the reading from the meter. Again, the type of metering you use will have an affect...

Comment #19

Czeglin wrote:.

New_type wrote:.

The question is that you set all the parameters in manual mode,what's the point of having those metering method. say you set f4,half second, iso 50.the exposure is already set, what's the point of having thosemetering mode?.

People have answered your question, but perhaps not explicitlyenough. So here's my attempt:.

The light meter does not have a direct impact on the photograph infull manual mode. In all other modes, the camera uses the light meterto set the aperture/shutter (and sometimes ISO). In manual mode youoverride the camera's "opinion" on proper exposure".

The light meter reading is there solely as a piece of information tohelp you get exposure right (based on the camera's interpretation).There are different metering methods the camera can use. You set theone you want for the sort of information you are interested in. Ifit's important that the scene be well exposed overall you chooseevaluative. If you're only concerned about a particular subject, youcan set it on spot metering..

In semi manual modes, like aperture priority, the meter reading has adirect input. Say you set it for f/8 and ISO 100. The camera will setthe shutter speed to a value that will let in an appropriate amountof light, based on the reading from the meter. Again, the type ofmetering you use will have an affect...

Comment #20

They are not learning photography then.

Mike703 wrote:.

New_type wrote:.

I guess I can randomly twiddle the camera control knobs and if thephoto turns out too overexpose or underexpose, I can adjustaccordingly until I get the right one. isn't that newbies do?.

No. Newbies stick the camera on fully automatic mode and let thecamera set the exposure, which on the whole it will do well..

You could spend a lot of time randomly twiddling. On my camera thereare five ISO values to choose from, 11 apertures (in half-stopincrements) between f/4 and f/22, and eighteen shutter speed values(assuming only whole stop increments) between 1/4000 sec and 30 sec.That makes 990 possible combinations, most of which will be badlywrong..

Good luck with your random guessing.Mike..

Comment #21

Let me add a slightly different viewpoint..

Most of the posts have been talking about exposure and how you set the exposure in manual mode. However, once you have determined the exposure that you want to use, there are other decisions to be made before deciding on the combination of aperture/shutter speed/ISO to be used to arrive at this exposure. (Note that when using full flash there is a fourth variable to be considered, the length of time of the flash burst.).

Aperture controls depth of field. You need to decide what you want to be in focus in the image and what you want to be out of focus..

Shutter speed affects camera shake and motion blur. You need to decide what shutter speed you require to avoid camera shake and what shutter speed you require to freeze motion or deliberately blur motion..

ISO affects noise. You need to decide how much noise you are prepared to tolerate in the image..

In anything but very good light you are unlikely to be able to use the optimum setings for all three and still get the required exposure. Skilled judgement is then required to decide what compromises to accept, or whether to use other equipment, e.g. a flash or a tripod..

By using auto mode the beginner passes these decisions over to the camera.Chris R..

Comment #22

New_type wrote:.

I am sure there are people don't use the metering. sunny 16 rule orfrom their experience.

You are correct .... the Sunny/16 rule is an excellent example of when you can indeed use "manual" ... (and ignore the meter)..

But ... that only applies to a narrow period of time, on a bright "sunny" day .... with NO CLOUDS (and not in shadow). But no question that under the right circumstances, pre-setting manually by the Sunny/16 rule will actually provide more "consistent" results than "auto-metering" which can provide variable results depending on the subject brightness (reflectivity)..

Manual can (MUST) also be used for FIREWORKS, or for FULL MOON, (which is actually Sunny/16 rule)..

Manual must be used for FLASH photography..

So I use manual just as often as I use "auto" .... (or manually set according to my internal metering suggestions)..

BOTH are important .... BOTH are useful .... BOTH are essential for different situations; and it is important to know when to use either one ... and just as important to know which (auto) "mode" to use in which situation..

Thanks for reading .... JoePhoto.

( Do You Ever STOP to THINK and FORGET to START Again ??? )..

Comment #23

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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