Aperture priority mode and exposure compensation

[rehanb]

I shoot in aperture priority mode 95% of the time, use manual only when I am working with off-camera flashes using remote triggers. For the longest time, in aperture priority mode, I was shooting without dialing in exposure compensation either plus or minus and relying 100% on in-camera metering values. In doing so the exposure of my pictures were all over the place.

In the past couple of weeks I realized the value of exposure compensation and it was a moment of eureka for me. For example in the picture below

It was a bit dark room with dark wood all around. In aperture priority mode, looking at all the darks around, in-camera meter gave me a very slow shutter speed to compensate for all the darks in the room. It was difficult for me to take a sharp picture hand held with the given shutter speed and the subject was also a bit over exposing. I dialed down the exposure compensation and was able to get this picture with a shutter speed that allows me to easily take this picture without blurring it and with the correct exposure on the subject.

The same is applicable to the situation where your subject is in a very lit situation lots of lights around and camera calculates the over all exposure and give a faster shutter speed, this might end up underexposing your subject since camera is exposing for the entire scene in matrix mode. In this scenario you might have to take your exposure compensation on the positive side to correctly expose your subject.

So in short, camera is not smarter than you when it comes to exposure, so for the two lighting situations (dark or lit) and if you are in aperture priority mode with matrix metering,

-the exposure compensation should be adjusted to dial in negative (-) in a low light situation to get the good exposure on your subject

- the exposure compensation should be adjusted to dial in positive (+) in a well lit situation to get the good exposure on your subject

I am sure lots of people must already be familiar with this basic concept but I still thought to share it as it helped me a lot to manage my exposure and to get better pictures.

Thanks,
http://www.rehanbashir.com

[LeeR]

Yep, I do about 90% of my shooting with just the system you describe. By choosing AP I control DOF and with exposure compensation I can place the values. It's quick and easy and gets the job done. Plus, with a little work, you should be able to fit your flash system into this plan. Are you using a dedicated flash that reads TTL? That would make a difference.

[rehanb]

I am a flash user, I use it off-camera in manual mode.



This picture was taken with Nikon SB 800 in softbox, the flash was triggered with cybersync

[Skoropada]

I'll take advantage of this thread and ask you about a doubt I had recently.

I tried to use the Aperture Priority mode in my camera some days ago and, as always, I have have it set for spot metering. So, when dialing an aperture, and pointing the center of the viewfinder to the subject I got a shutter speed from the camera, but when I recomposed the center of the viefinder coincided with a darker background, thus changing the shutter speed for a longer one.

The question is, is it advisable to use matrix metering when on Aperture Priority mode? Or am I doing something wrong with the spot metering?

Thanks in advance for your comments!

[rehanb]

Originally Posted by Skoropada

I'll take advantage of this thread and ask you about a doubt I had recently.

I tried to use the Aperture Priority mode in my camera some days ago and, as always, I have have it set for spot metering. So, when dialing an aperture, and pointing the center of the viewfinder to the subject I got a shutter speed from the camera, but when I recomposed the center of the viefinder coincided with a darker background, thus changing the shutter speed for a longer one.

The question is, is it advisable to use matrix metering when on Aperture Priority mode? Or am I doing something wrong with the spot metering?

Thanks in advance for your comments!

Although the metering modes does have impact on the overall exposure measurement done by camera, which ever metering mode you are might be using in the Aperture priority mode, when you recompose the light changes from one spot to another, I am not a Sony camera user, but I would suggest you to look at the exposure lock function, it is usually a dedicated button on the body or once your meter and recompose do not release the shutter button that you press initially to achieve the focus and the exposure lock at the same time. So if you recompose while compressing the shutter button half way, you will keep the focus as well as the exposure.

[LeeR]

I agree with rehanb that you need to find out how to use the exposure lock system. That will allow you to meter for the area you want and place that area in the zone you wish. Look at the two images above with the man wearing the white coat. You could meter off the coat and add two stops placing it is Zone VII (did I mention it helps to know a little about the Zone System?) Just remember to lock the exposure value before recomposing the shot.

Note: Several months ago one of our members wrote a brief but very helpful explanation of metering and the zone system. I would highly recommend you read it carefully. It should help you immensely.

[Skoropada]

Thanks for your advise!

After some testing, I realised that my camera (Sony A200) continues metering and changing the values while you press half way the shutter release.

But there is that Exposure Lock button that I have hardly ever used because I was trying to shoot manual all the time.

[zpierce]

I find spot metering be a bit impractical for full time use. I only use spot metering when I have a really challenging scene to meter. I use the center weighted metering and use exposure compensation. Also, I use the center area autofocus and recompose method typically, and if I were to spot meter, often times that wouldn't be the same spot I want to focus on.

[C-mama]

I'm going to try this next time... Thanks

[RecurrentNerve]

I may be being dense here but is it not simpler to use spot metering? In the first example if matrix metering is deciding the room is too dark, why not simply use spot metering (or centre-weighted) to meter the subject and ignore the room instead?