2/3 stop overexposure in 30D

[rob_hanssen]

<p>Over the past 2 months, I noticed that my otherwise perfectly performing 30D has slipped into overexposing. I

need to underexpose about 2/3 stops to get the right exposure. It happens across a range of lenses, including

70-200 f/4L and tokina 12-24 f/4</p>

 

<p>See <a href=" picture</a> for an example</p>

 

<p>Is this a common appearance in 30D's after about a year (certainly hope not)? Can the meter be recalibrated?</p>

 

<p>rgds,<br />

Rob</p>

[RobertChura]

The image looks exposed well to me

[bob_osullivan]

There is no such thing as "correct" exposure. Proper exposure is a decision made (hopefully) by the photographer. The meter is merely a guide.

 

I too would have chosen to bring down exposure on this shot a little to bring out the leave colors, or used a polarizer.

 

The in camera meter may well have provided a technically accurate exposure here. Is it possible that you've accidentally changed metering modes, or applied exposure comp?

 

A shift to spot mode might account for this.

[jonathan_b]

I have had a problem with my 40d inadvertently having some exposure compensation applied - I believe I am doing this by pressing an incorrect series of buttons (not a problem with the camera), but it's frustrating nonetheless. I would check to make sure exposure comp not set.

[rob_hanssen]

Some additional info: the exposure in this particular pictures was already dialed down by 2/3 stop. I also made the same picture w/o exposure correction, and most of the picture was just too light

[j_smith6]

My EOS 40D is underexposing pictures by 2/3 stop... Maybe staff at canon wanted to repair the problem too much :/

I don't know why it does it, I just set it to +2/3 stop and pictures look fine. I never had a problem like this with film

camera though.

[picturesque]

I'd re-read Bob's answer. There is no such thing as a correct exposure. Certainly no such thing as perfectly consistent correct exposures from frame to frame. If you are using an automated mode, or even manual mode, and the matrix or evaluative meter, what the camera 'thinks' is correct exposure is going to change every time the scene changes, even a little. One can make a generalization such as you did--'the camera under or over exposues, GENERALLY, 2/3 stop'... But 'perfectly performing' I don't believe.

 

I'd suspect a change in the metering mode. Check whether you've changed the metering mode from evaluative, averaging or partial/spot. That or you do have exposure comp set.

[alan_myers]

You can test the accuracy of any reflective meter (like the one in your camera) pretty easily with a gray card.

 

Just meter off the card in bright sunlight (read the instructions that come with the gray card). Set your camera

to f16 (using AV mode) and the ISO to 250. The camera should give you 1/250 shutter speed.

 

Sometimes it helps to switch to spot meter, or use a telephoto lens, so that the entire meter is on the gray

card. It doesn't matter if the card is in focus, only that it occupies as much of your viewfinder as possible (or

all of the spot metered area).

 

You actually can use any ISO. The shutter speed should always be the reciprocal. ISO 125 would give 1/25, ISO 500

would give 1/500, etc. (I'm using full shutter speed stops here, but 1/3 stops would work as well). This is

called the "Sunny 16 Rule".

 

Any variance would be of concern, but even then if it's only 1/3 or 2/3 stop, you can just remember to dial in

some compensation.

 

The only exceptions to the Sunny 16 Rule would be if you are making this test at a higher altitude or in a

particularly smoggy area. In those cases, you'll have to allow for atmospheric conditions with the reading.

 

It is possible for a camera's meter system to be off. Older systems needed fairly frequent calibration. Even when

set to 'factory specifications" in the good/bad old days we often had labels on our cameras to "tweak" the

ISO/ASA setting a little to correct for known meter variances, and ran careful test rolls of slide film every

three to six months to check for any changes.

 

It also has to do with the accuracy of the shutter speeds and the aperture controls. Today with electronic

cameras there is 10% or less tolerance. In older mechanical camera systems it was common for there to be 25%

tolerance (and if your meter was off 25%, your shutter was off 25% and your aperture controls were off 25%, that

could add up to nearly a full stop error!).

 

Today's cameras are pretty darned accurate. If you are judging by what you see on a computer monitor, I'd say

that's much more likely to where things are out of whack and a new monitor and/or monitor calibration are needed.

[jamie_robertson2]

Canon's dSLRs are notorious for overexposing in my opinion. My camera has been constantly set to -2/3 exposure since I got it. Thankfully I find it extremely consistent so once the exposure compensation is set I can forget about it so it doesn't bother me too much. I am puzzled as to why the OP's camera has just started doing it after a year though. Apart from a setting altered in error I can think of no reason why it should be doing this.

 

I know a well known UK wildlife photographer and his Canons were always set to -2/3rds just like mine. He was using the 1Ds2 bodies at the time. I don't know why Canon do it. The Nikons always seem to be better at getting the exposure bang on.

[chrisjb]

Do you see this in prints or just on a monitor? if monitor it may need calibrating. if in prints and consistant then permsnently adjust EC, or yes the meter can be recalibrated, but usually I believe there is a tolorance factor :)