Using Aperture Priority Mode - Inconsistent Exposure

[mcflickr]

Hi Everyone,

I currently shoot with a Nikon D7000, and find that a tend to defer to AP mode most of the time. After I've selected the desired Aperture, I let the camera do the rest, and will only tinker with ISO if the resulting shutter speed is too slow. With that said, I find that when I import my photos to Lightroom, and use the "auto" feature to correct my photos, most are underexposed.

I guess my question is, why would my photos be underexposed if the camera meter reads in the middle (not over or under exposed)?

Would I be better to shoot in Manual Mode, selecting a desired aperture and shutter speed, and then choose Auto ISO to achieve correct exposure.

Loaded questions, but looking for any advice you may have to getting consistent "correct" exposures.

Thanks!

 

[Overread]

The meter aims to expose to around 50% grey whilst lightroom is (in my view) often trying to go closer toward the "expose to the right" theory when it comes to exposure. Furthermore the meter in the camera works off reflected light, different surfaces will reflect light differently which can cause complications.

For example if you meter snow, a bright highly reflective white, the camera will expose it grey - it will underexpose because its trying for that 50% grey value (that's not exact it varies from camera to camera so its more a term than an actual fixed value). As such part of learning photography is learning to judge the reflectiveness of your subject and adjust the result based upon experience and understanding.

For another example I'll often underexpose by 1/3rd to a full stop when shooting in bright weather because highlights are more likely to blow.

This is why you've got the exposure compensation feature on the camera to help you balance the cameras setting that its controlling.


Note that if you read the manual you can enable the histogram to show when you're shooting and then reviewing your photos on the back of the camera. It's an ideal way to check exposure and get a quick histogram reading to really show you how the exposure has measured up - if its over or under you can quickly adjust to compensate.

 

[sashbar]

Aperture mode, just like any auto or semi-auto mode of any camera will overexpose or underexpose depending on the scene. If there is a lot of light reflective surfaces like snow or white sand, it will trick the metering system into "thinking" that the scene is brighter than is really is an dit comes out as underexposed. So you need to stop it up by using the exposure compensation. Google it, there is a lot of info on the subject.

 

[EIngerson]

Aperature priority is going to meter the scene the way the camera sees it. therefore, every time you actuate the shutter, the camera will reevaluate what it sees. Usually a very bright scene will be underexposed because the camera will favor correcting the highlights of the scene. A couple things that will help; really understand the metering modes and exposure compensation.

I shoot in Aperture priority the majority of the time, but there are many, many times that Manual mode is a must.

 

[Overread]

Remember even if you go into full manual mode; so long as you are still using the built in meter you've still got to learn to compensate the exposure based upon the meter reading when needed.

 

[mcflickr]

Hi Everyone,

Appreciate the very quick responses. My mission over the next couple of days 1) Use the histogram display on my camera 2) Adjust on the fly using exposure compensation (still have to do a little reading on how this works, and how it impacts the shot in A mode). Have been told to use histogram in the past, but perhaps stupidly, relied on only the image as it displayed on my camera to determine if it was exposed (only to be disappointed afterwards).

 

[KmH]

What metering mode do you use?

Plus, being mass produced consumer electronics, each camera has a sort of 'personality' and your camera may consistently underexpose.
If so, dial in some +EV of exposure compenstion (EC)

EC does not reset when you turn the camera on/off, so it remains set to compensate for your camera.

 

[AlanKlein]

What metering mode are you using and why?

 

[mcflickr]

Right now I'm using Spot Metering, and Single-Point AF. My understanding is the meter reading is taken from the focus point (my intended subject). Could be off base here. Would I be better off using Centre-Weighted, or Evaluative Metering Modes?

 

[Overread]

Try centre weighted metering instead. Spot metering is a very specific form of metering where the camera is using only a very small area right under the middle AF point in the camera. That means that you can use the spot meter to read different light values in a scene (by moving the camera around to point at the different areas) but that its also reading your exposure for a whole photo upon a very tiny area. Centre weighted is more accurate much of the time because whilst its still looking mostly in the middle its looking at a larger area of the scene, so that its more likely to give an exposure balanced for more of the subject area, rather than one very specific spot (and that can throw the meter - if you metered right off a highlighted area you could end up with a very underexposed shot overall; similarly if you spot metered on a very shadowed area you'd get the rest of your shot way over exposed.

 

[KmH]

Using a Nikon DSLR and Spot metering mode the spot metered is concurrent with the selected AF point, and is not locked to the center AF point like on other makes of DSLR.

 

[dennybeall]

Exposure compensation says you know your camera so well that you know that the camera will over or under expose the scene you're getting ready to shoot and you don't want to manually compensate by setting a line or so off the center on the meter or you're shooting in AUTO.
If you set it and then forget that you did and change locations you can end up with really messed up shots until you notice that you're +3 or somesuch.

 

[bratkinson]

I guess I should say 'I go either way', depending on what camera I'm useing.

With my 'big gun' DLSR, I'm in the 'set it and forget it' mode with center weighted metering. Why? Nearly all my shots have the subject at or near the middle, and so if I'm shooting a portrait on a beach for example, it'll likely end up just a tad underexposed for the persons' face but that can be corrected in post. (I don't shoot/haven't shot on beaches, by the way). The same is true for my indoor no flash work where the subject is reasonable well lit but the surroundings are not. The meter will over expose a tad to compensate for the darker surroundings. Again, it's easily corrected in post. But unless I'm in a 'fixed' lighting situation, I will chimp most of the shots I take looking at both the histogram and the photo itself on the LCD. If it's too dark, I'll adjust what's needed, even if that's the priority-mode I'm using. Fortunately, the 5Diii is surprisingly 'smart' at getting the metering and exposure right, in my opinion.

But then I bought a Canon G15 a couple of months ago as a pocketable point-and-shoot that has full manual and creative mode options available. A couple of months ago, I was on a moving train shooting out the window. Using Tv at 1/160 or 1/200 to stop camera shake/30-50 mph motion, I simply used the very convenient EC wheel to increase/decrease exposure as needed, after seeing the result on the LCD. I'll admit I haven't been motivated enough to slog through the menus for EC with the 5D3, so I've completely ignored that capability. Maybe someday.

 

[Big Mike]

Hi Everyone,

Appreciate the very quick responses. My mission over the next couple of days 1) Use the histogram display on my camera 2) Adjust on the fly using exposure compensation (still have to do a little reading on how this works, and how it impacts the shot in A mode). Have been told to use histogram in the past, but perhaps stupidly, relied on only the image as it displayed on my camera to determine if it was exposed (only to be disappointed afterwards).

Welcome aboard.

I teach a photography class that covers this type of stuff. One of the very first things I tell the students, is that they shouldn't trust how the image looks on their camera's LCD...at least not in terms of how bright it is (exposure). I later teach them how to read and use the histogram. So that is certainly something I would encourage you to look into.

I also go on to teach them that simply 'getting to zero' on the camera's meter (whether in auto or manual) isn't a sure bet for proper exposure. As mentioned above, a camera's meter is calibrated to a mid level value, so when shooting (metering on) things that are brighter or darker than this mid tone, the camera will give you an incorrect (over or under) exposure. As a photographer, you need to regognize what you're metering on and compensate for it.....or find some other method of determining exposure. For example How to use a Grey Card ~ Mike Hodson Photography

 

[mcflickr]

Okay - Home from work yesterday, and decided to give things a go
1) First adjusted my display to include the histogram - Much easier to tell where the exposure was falling
2) Adjusted metering to Centre-Weighted, being mindful to keep my subject relatively in the middle
Side note for this - Centre-Weighted seems to fly in the face of compositional guidelines (rule of thirds, etc). Thoughts on this?
3) Still working on exposure compensation - I definitely have a tendency to adjust settings and forget (particularly with ISO, and sometimes adjusting to M mode without flipping back to A).

Overall exposure has improved, but still coming out a fair number of underexposed photos. My home does not have a lot of light at the best of times, so I am finding it tricky to get a nice "natural" looking exposure (I guess this speaks to my inexperience using flash, but that's a whole other issue). I seem most comfortable with the relationship of Aperture and Shutter Speed, but am not confident with ISO. My "noise cleanup" in post is somewhat lacking. I don't know the tools at my disposal for this in PS or LR.

Appreciate feedback and insight... Thanks Everyone!