I am participating in the "30 Days Wild" challenge just for the fun of it and because I am a big fan of nature.
You can find out more information about this challenge here
I spent 3 hours sat at my local nature reserve yesterday as part of my challenge and spent some time photographing wildfowl in their natural environment. The lighting conditions were changing frequently as the storm clouds finally moved off after a day of wind and rain and due to the layout of the hide and lake where I was camped out, I was shooting in full sun, shade and backlit conditions all within a few seconds of each shot.
I was using a Canon 7d2 with a long telephoto lens on the front to bring the birds as much into the frame as possible. I was shooting in AV as I didn't want to miss any of the antics of the local wildlife as I knew I would be shooting in very changeable lighting and I knew shooting in manual would be very challenging and too slow and I didn't want to miss any critical moments of behaviour.
Which lead me to ponder my cameras metering systems ability to read the light.
Spot metering = Takes a meter reading from the centre spot at ~3% of the frame (Note Nikons will meter the 3% from the active focus point not just the center point)
Evaluative Metering = Takes a reading from the whole frame and uses an algorithm to work out the correct lighting for the scene
Most cameras these days have the ability to use spot metering or evauative metering but most people use their camera in evaluative mode most of the time as it generally does a decent job under normal shooting conditions.
Cameras like grey
Most camera metering systems don't like white or black tones within a scene as the camera makes the assumption that these are mid tone areas that are being over or under exposed and therefore delivers an image that becomes "grey"
Here is an example of a white flower shot using evaluative metering:-
As you can see from the image on the left, the camera has decided that the white tone is too bright and lowered the exposure to what it thinks is correct. In this case spot metering wouldn't have helped us as the flower covers most of the frame and we don't have any mid tones to use to meter from.
White is not the only issue, black is also seen as a problem by the camera. Here is an example of a black camera shot using evaluative metering:-
As you can see from the image on the left, the camera has decided that the black tone is too dark and increased the exposure to what it thinks is correct. In this case spot metering wouldn't have helped us as the camera covers most of the frame and we don't have any mid tones to use to meter from on the main subject,
Can't I just edit it?
Whilst we could just edit both of these images in post production, we really should be aiming to get all of our exposures correct in the camera to ensure that we:-
Maintain shadow detail
Maintain highlight detail
Don't amplify noise when editing (brightening an image can amplify noise)
To ensure that the exposure is recorded correctly we need to take creative control of our camera. Using Exposure Compensation in AV/TV (A/S in Nikon land) or biasing our exposure in Manual mode to overide the cameras natural bias towards grey.
Exposure compensation allows you to dial in typically +/- 5 EV to your image
Here we return to our white flower and dial in +1 EV to our exposure to ensure that our white areas are properly exposed.
For our black camera we need to dial in -1 EV to ensure that the black areas are exposed correctly.
When to use compensation
I thought I should give you some other examples as it is not always easy to understand when to use Exposure Compensation and which way to correct your exposures
+ ev compensation
White/bright subject filling the frame (white flower)
Bird in flight against a bright sky
Dark object in a bright scene (bird on bright water)
Backlit subject (person in front of a window)
- ev compensation
Black / dark subject filling the frame (black dog)
Bright subject against a dark background (Swan on dark water)
Very bright subject (light bulb)
Taking control of your camera and making it do what you want is critical if you want to deliver well exposed creative images that reflect what you see rather than what the camera wants to deliver.
I hope you found this article helpful, please feel free to comment and keep following the blog as I will continue to post more tips in the future.