Shooting Modes 

The camera's shooting mode is one of the most important camera settings.  Available shooting modes range from Manual mode to fully Automatic mode with a few "semi-automatic" shooting modes in between. In this post we'll look at the most common shooting modes for forensic and investigative work and how you might use them in different situations.

How you set the shooting mode varies from camera to camera but most use a mode dial located on the top of the camera. 

Automatic and Program Modes 

Automatic mode is just what it sounds like. With the camera set in this mode, the camera will choose the ISO, the aperture, shutter speed, and even the focus point without any input from the photographer. Just point and shoot and the camera will produce a well exposed photo almost every time. While this makes for easy snapshots, the photographer has no control over important aspects of the image. This lack of control may lead to less than optimal results. Let's say for instance, you're shooting a child's birthday party. The birthday girl is getting ready to blow out the candles. You get out your camera, put it in auto mode, and... click. The picture turns out great! The camera's algorithm chose all the settings and produced a well exposed photo of a stationary subject. But now the party games start. Kids, hyped up on cake and ice cream are bouncing off the walls! You want to capture all the joy and mayhem around you. But your camera doesn't know that you're no longer photographing a mild-mannered, well-behaved child in a chair. It doesn't know that these children are now chasing the family dog, leaping over furniture, and spinning in circles until they are dizzy. Auto mode doesn't know that you now need a faster shutter speed. As a result, all of the children in your photos are blurry from all the motion.

Let's consider an example more appropriate to forensic photography. In this scenario, you arrive at the scene of a working fire at night. The large fire has drawn a crowd of people from the neighborhood. You decide to take crowd pictures in order to document who was at the scene and to identify potential witnesses for future interviews. The camera, set in automatic mode, reacts to the low light situation by opening the aperture all the way, resulting in a shallow depth of field. Due to the shallow D.O.F. people in the foreground and in the background of the image are blurry and out of focus. Worse yet, the camera also chose a slow shutter speed so that anyone moving when the picture was taken is also blurry due to motion blur. The crowd pictures are a bust. Later on you move into the interior of the scene. Here, motion blur is less of a problem but the camera keeps the aperture large and depth of field shallow.  To make matters worse, the autofocus keeps locking onto objects in the near foreground, reducing D.O.F. even more. Even though we have a powerful external flash on our camera, Auto mode prefers to crank up the ISO to its maximum setting before increasing the flash output. The interior pictures, while marginally better than the crowd pictures, are still mostly out of fucus and noisy. 

Program mode (designated by a letter P on the mode dial) is very similar to Automatic mode in that it will choose all the settings for you. But unlike Automatic mode, in Program mode the photographer can make changes to the exposure if they want to. Program mode works differently in different cameras, however, most DSLR and mirrorless camera systems allow the user to choose a different combination of exposure settings by turning a command dial while in Program mode. Below, in the image of the failed incendiary device, Program mode chose the following settings: f/2, 1/250 sec. shutter speed, ISO 200. By rotating the command dial on the back of the camera, I was able to change to a reciprocal exposure with an aperture of f/11. This will result in a larger D.O.F. and increased sharpness.  The change in settings is temporary though. The camera will choose a new set of values for shutter speed and aperture each time the shutter is released.  

In many cameras, Program mode allows the photographer to control the autofocus and ISO settings, a major improvement over the Auto setting.  Program mode gives the photographer some control over the exposure. How much control depends on the camera and the shooting conditions. Some cameras allow you to choose from several different combinations of settings. Others, may only give you two or three options, especially in low-light. Some cameras will not allow you to change the exposure settings while shooting with a flash. Others do.  Like Auto mode, Program mode is great for quick snap shots. Like Auto mode, Program mode is not the best setting for forensic work.

Aperture Priority and Shutter Priority

For most of my shooting, I use priority shooting modes. The priority shooting modes allow the shooter to choose a value, either aperture or shutter speed, and the camera will automatically set the other value to achieve proper exposure. Of the two options, I use Aperture Priority the most. The Aperture Priority setting is typically designated on the mode dial by an "A" or "Av" (Aperture Value). When shooting in this mode, I can set the aperture I want and it will stay locked in unless I change it. It won't change with each shot like it would in Auto or Program mode. This is a great help when shooting fire scenes where I need to ensure that I'm capturing the scene with adequate depth of field. By dialing in a small aperture in Aperture Priority mode,  I can take advantage of the camera's automated features and still end up with a good quality shot with a large depth of field. 

In Aperture Priority mode, the shooter can either choose a particular ISO setting or enable auto-ISO. There are pros and cons to both approaches. If the ISO is set by the user, the camera's automated system will choose the shutter speed and the flash output level to achieve proper exposure. In dark fire scenes, the shutter speed will usually stay at the slowest available sync speed (shutter speed that will synchronize with the flash), so that in practice, the only thing that is changing between shots is the power output of the flash. This usually results in consistently exposed photos. 

The downside to this set-up is that if the scene is too dark or the flash too weak for the chosen aperture and ISO setting, the images can come out underexposed. If I see this happening, I'll just bump up the ISO one or two stops. The other option is to enable auto-ISO. Enabling auto-ISO will automatically compensate for dark scenes but, as we discussed in the last post, auto-ISO can result in unnecessarily high ISO settings when taking flash photos. The choice is up to you.

Manual Mode

Aperture Priority allows you to control depth of field. Shutter Priority allows you to control motion. But, what if you need to control both? That's where Manual shooting mode comes in. In Manual mode (M on the mode dial), the photographer chooses the aperture, the shutter speed, and the ISO that will give them the exposure that they want. In this mode the photographer has complete control over the image. The downside is that it requires a bit more fiddling to arrive at a correct exposure. In manual mode, correct exposure is accomplished with the help of the camera's built-in light meter. 

On this Nikon DSLR, the camera's light meter is located in the lower right corner of the LCD screen. The meter in the first image is indicating that it is underexposed by two stops. The last image is overexposed by one stop. The meter in the center photo is indicating proper exposure.

While shooting in manual mode might seem a bit archaic (and a lot of work), it can be very useful in certain situations. It's actually pretty easy too, once you have a bit of practice. Manual mode is the best choice when you need consistency across a series of images. For example, if you are shooting a series of images that you plan to stitch together into a panorama, differences in brightness, noise, and depth of field can be glaring in the final image. Anytime I shoot a series of photos for focus stacking, 360 imaging, panoramas, or for photogrammetry models, I shoot in Manual mode. When the same camera settings are used in every shot, the images go together seamlessly.

It's possible to use Manual mode as a kind of "semi-automatic" shooting mode. One way to do this is to enable auto-ISO while in manual shooting mode. With the camera set up this way, the photog can set the aperture and shutter speed where they need them and the camera balances the exposure by adjusting the ISO. This is my preferred setting for shooting wildlife. It's also a good option for surveillance subjects or crowd photos. When shooting like this, I'll set the aperture for the desired depth of field. Then I'll set the shutter speed to prevent subject motion blur and camera shake. Auto-ISO handles the rest. This is usually easier than trying to reset the minimum shutter speed in Aperture Priority mode.

Sometimes I'll shoot interior scenes in Manual mode with TTL (Through The Lens) flash. The key to proper exposure in this case is the flash's TTL system. TTL mode is kind of like Auto mode for your flash. When in this mode, the flash will send out an initial, low power, pre-flash. This small burst of light will bounce off the scene and back at the camera sensor. The sensor measures the amount of light reflecting off of the subject and the camera calculates the amount of light needed to properly light the scene. The camera adjusts the flash output according to the calculation and then fires. With this setup, the camera exposure settings remain the same for each shot. When shooting like this, I'll usually set the shutter speed to 1/60, the aperture somewhere around f/16, the ISO to 1600, and leave it that way. The TTL system automatically adjusts the amount of light for proper exposure.

Scene Modes

Aperture Priority, Shutter Priority, and Manual, are the best modes to stick to for forensic and investigative work. On the occasions when you just need a quick snapshot or if you have to hand off your camera to someone who is unfamiliar with how it operates, then Program mode is a good option. 

On consumer and enthusiast level cameras, the mode dial may contain several Scene or Art/Special Effect modes as well. These are not of much use to a forensic photographer. These modes, which usually include a portrait mode, landscape mode, sports mode, etc., will use camera settings and in-camera image processing that will result in pleasing effects for that style of photograph. For instance, in portrait mode, the camera will default to a large aperture and shallow depth of field to make the subject stand out against a blurred background. The jpg image will be processed so that skin tones appear soft and natural looking. Landscape mode will use a large depth of field and increase color saturation to produce more vivid colors. Sports mode defaults to a fast shutter speed to freeze the action. With a little bit of camera and image processing knowledge, you can do all of these things without changing to a special Scene mode.

One specialty mode that can be useful on the fire scene is the macro (close focus) shooting mode found on some point and shoot cameras. The Olympus/OM Systems Tough T-G series and the Ricoh/Pentax WG series cameras both have excellent macro settings. This setting allow the photographer to take extremely close-up images of tiny pieces of evidence. Some of these cameras also have built-in focus bracketing/focus stacking that will produce macro shots with a very large depth of field straight out of the camera.

Custom Shooting Modes

The last mode dial settings that we'll talk about are the Custom or User settings. These dial settings are typically indicated by a C or a U, followed by a number (C1, C2, C3, etc.). These dial settings provide a place for the photog to save the camera settings that they use most often. There are a lot of ways that you can use the Custom settings. For example, if like me, you like to use different settings for exterior shooting and interior shooting, you could save each of these settings to a position on the mode dial, i.e. C1 for exterior, C2 for interior. If you use your camera for shooting things other than fire scenes, you may also find the custom settings useful. For instance, you may want to save U1 to Aperture Priority, F/16, ISO 1600 for shooting interior fire scenes and set U2 at Shutter Priority, 1/1000 sec., and Auto ISO for shooting your kid's soccer games.

Conclusion

The shooting mode that you choose can have a big impact on how your images turn out. Using modes like Aperture and Shutter Priority, you can take advantage of your camera's sophisticated automated settings while still maintaining control over the critical aspects of your photographs. In Manual mode, you can have complete control over your images. If you've been shooting in Auto or Program mode, venture out. Give Manual shooting and the Priority modes a try!