What Is Active D-Lighting?

Active D-Lighting is the technology used by Nikon which is designed to control the exposure to recover the details in the highlights and shadow areas. It allows you to shoot in different lighting condition and give natural contrast to the photograph. It does so by adjusting the exposure value depending on the situation. Camera will set the exposure slightly underexposed when Active D-Lighting is set to ON. It will adjust aperture and shutter speed combination to give that underexposed result. According to Nikon, "Active D-Lighting optimizes high contrast images to restore the shadow and highlight details that are often lost when strong lighting increases the contrast between bright and dark areas of an image. It can be set to operate automatically or manually, and it's also possible to bracket pictures to get one with Active D-Lighting and one without." ADL can be selected from Auto, Extra high, High, Normal, Low, or Off in case of Nikon D90.

Where to set ADL option for NIKON D90?

1. Go to the Menu button.

2. Select Shooting Menu (camera icon) option.

3. Choose Active D-Lighting.

4. Set the option as you want.

NOTE: Using ADL at higher ISO (more than ISO 1600) will create more noise in the shadow areas. Sometimes it is a good idea to avoid ADL because of shadow areas noise issue in higher ISO sensitivities. The contrast can be managed using either Photoshop or Lightroom during the post production. To do this, you have to shoot in RAW format which produces less noise than shooting with ADL option ON.

Active D-Lighting decreases the contrast to add details in the areas of highlights and shadows only. It won't affect the whole image but only to specific areas that require detail recovering.

Understanding Metering And Metering Modes In Photography

In photography, Metering is the method to calculate the optimal exposure for the subject on the basis of information that the camera gets from the varieties of available light sources. Back in old days, photographers used to rely on an external light metering device because cameras were not equipped with the metering sensor that can measure the sensitivity of the light and give you the information about the exposure settings. But today, every modern DSLR camera comes with the sensor that meters the light entering the camera sensor through the lens and determines the correct exposure settings. Even though some DSLR brands use different naming convention for the metering mode, overall idea of the metering is the same. In this article, I will be taking a reference of Nikon D90 to explain different metering modes but the technique implies to all DSLR brands and models.

What is the Metering mode?

Metering mode is a different exposure mode available in modern DSLR cameras, which is responsible to deal with the light sources and calculate the optimal exposure for the subject and the overall image. When you frame the scene, the metering mode determines the intensity of the light coming from the scene into the sensor and gives that information to the metering system. If you are shooting in auto exposure mode or one of the semi-auto; A, S or P exposure mode, your camera will try to set the correct exposure automatically by calculating the correct combination of the ISO, shutter speed and the aperture value (F-stop). But, if you are shooting in manual (M) mode, you would take the reading from the camera metering system as a reference whether it is negative (underexposed) or positive (overexposed) and set the exposure values (Aperture, Shutter speed and ISO) manually. When you point the camera towards the scene and if the scene is too bright, the bar (shown inside the red box in the picture below) moves towards the positive side suggesting you to increase the shutter speed or reduce the aperture size by increasing the aperture value to properly expose the scene. And, if the bar moves towards the negative side, it means the image is underexposed and you would need to decrease the shutter speed or open up the aperture by reducing the aperture value.

Nikon viewfinder where the metering sensitivity is represented by the scale bar shown in the red rectangle box.

Most of the time camera metering system does a good job of sensing the light and calculate the correct exposure, but sometimes, it gets deceived by the light source when there is a mixture of dark and bright light sources. The common examples where the metering system might not give you the best exposure calculation might be a sunset with a darker sky and a bright horizon, or a subject under a very bright sunlight etc. Now, lets talk about the different types of the Metering modes available in modern DSLRs.

There are three common Metering Modes available in almost every modern DSLR and they are,

• Matrix Metering

• Center-Weighted Metering

• Spot Metering

1. Matrix Metering

Nikon DSLRs use different Matrix metering depending on the type of the lens you are using. Nikon D90 uses 3D color matrix metering II with the type G, or D lenses and color matrix metering II (which doesn’t include 3D distance information) with other types of CPU lenses, which is the default setting for the D90. When you look at the LCD screen on the top of the camera body (on the right side where the shutter release button is), the Matrix metering mode is indicated by the black rectangle shape with the dot in the middle.

While metering the scene using the Matrix metering mode, camera divides the entire frame into multiple zones and calculate the exposure based on the colors of the light, distance to the subject (if G, or D lenses were used), color tones etc. Camera collects the information from all the zones but gives the priority to that area where the focus point is on. Matrix metering mode does a pretty good job most of the time and should be used for a day to day photography.

2. Center-Weighted Metering

Center-Weighted metering mode is represented by the little circle with a central dot inside. Like in the Matrix metering mode, it also calculates the exposure from the entire frame but the center area is given more priority (weight) during the calculation. According to the Nikon, it gives 75% of the weight to the center circle whose diameter can be set to 6, 8, or 10-mm in Center-Weighted area from the Custom Settings Menu. As name suggests, Center-Weighted metering mode doesn't rely on your focused area but gives the priority to the center of the frame instead. It is not recommended setting for most of the time and also considered as a least accurate metering method to use because the subject might not be in the center of the frame all the time. It should only be used when you want to emphasize the center of the frame, in portrait shooting for example.

3. Spot Metering

Spot metering mode is indicated by the little circular dot. Unlike other two methods, while metering the light, spot metering only gives the priority to a small area where the current focus point is and ignores everything else inside the frame. According to the Nikon, it meters 3.5mm circle (about 2% of the frame) centered on the active focus area. It is widely used when you would want to give the proper exposure to the focused area no matter how the surrounding would be.

How to change the Metering mode?

It depends on the camera brand and the model, but in case of Nikon D90, there is a dedicated button left to the shutter release button. While the button is being pressed, if you rotate the rear command dial (also known as the main command dial), camera switches the metering mode from one to another. If your camera doesn’t have a dedicated button for the metering, you can go inside the Metering/Exposure menu and adjust the metering mode.

What Is An Exposure Compensation - Understanding Bracketing

What is an Exposure Compensation?

Exposure Compensation is one of the great features available in modern DSLR camera that allows you to adjust the exposure measured by its light meter. The range of adjustment depends upon the camera model. In case of Nikon D90, this range goes from -5 EV to +5 EV in increments of 1/3 or 1/2 EV where EV stands for Exposure Value.

This means that you can adjust the exposure measured by the light meter by telling the camera to allow more light in (positive exposure compensation, +EV) or to allow less light in (negative exposure compensation, -EV). Depending on how your digital camera deals with the exposure compensation and the shooting mode used, it may adjust the aperture while maintaining the shutter speed constant; it may adjust the shutter speed while maintaining the aperture constant; or, it may adjust both aperture and the shutter speed.

Let's look at these couple of photographs and see the effect of the positive exposure compensation.

At Normal condition (Without applying Exposure)

After applying Positive Exposure Value (+0.7 EV)

What is an Exposure Bracketing?

Exposure bracketing is a technique to make sure that the pictures are properly exposed under challenging lighting condition. Most of the times camera's sensor will automatically set the exposure setting by selecting an aperture and/or shutter speed combination to give the best result. But it doesn't work all the time. Sometime you may want to set the exposure manually overriding shutter speed or aperture settings depending on which shooting mode you are in.

Exposure bracketing technique allows you to take two (or more depending on camera model) pictures: one slightly under-exposed (e.g. -1/3 EV), and the second one slightly over-exposed (e.g. +1/3EV). This range of an adjustment vary with the camera's light meter. I believe it goes from -5 EV to +5 EV with 1/3, 1/2, 2/3, 1 or 2 EV range in case of Nikon D90.

When should we use Exposure Bracketing?

Whenever there is a complex situation of lighting, you should use this feature to get the proper result. Some photographers don't like to use this feature at all. They prefer to look at LCD and take another shot if they are not satisfied with their shot.

But the main reason we do this is to adjust the proper lighting condition over the main subject. Sometime camera's sensor gets confused by the light (too much or too little) to the main subject and hence the subject may be over-exposed or under-exposed. Taking three shots with the variation of exposure is good idea in this case. That is why we use bracketing.

As an example, you can see my above picture that I took under the normal condition. But it came out dark. Then I applied positive exposure compensation and got the balanced result.

Another example would be, lets say you are shooting portrait in snowy area. Your camera meter will adjust the exposure with the surrounding amount of light coming from the snow. In this case, camera senses more light and hence adjust an aperture (small aperture number) or the shutter speed (faster shutter speed) to compensate for the overall exposure. When you take the picture in this case, your main subject will be under-exposed. To fix this problem, you may want to set the exposure value to +EV to properly expose the subject and as a result, your background or surrounding might be over-exposed little bit. You have to calculate proper EV value to adjust this trade off between subject and background lighting in given situation.

Today's almost every DSLR camera allows you to shoot with different exposure value using automatic bracketing feature. If you are using Nikon D90, you can check my blog on Automatic Exposure Bracketing (AEB) where I explained how to setup the camera controls for Nikon D90.