Photographing for Photogrammetry

Camera
Setup

• ISO should be set as close to 100 as possible. No higher than 800.

• The focal length of your lens will affect how many images you will need to gather, as well as the resolution of the final model. Certain lenses will also create unwanted affects, such as skewing. To avoid this, do not use a focal length lower than 20mm on full frame sensors, or 16mm on cropped sensors.

• The aperture should be set between f/8 to f/12. The ideal aperture will change based on the lens you are using.

• Autofocus modes are fine to use, but review your images often to ensure the camera is selecting the appropriate focus plane.

• Auto white balance should not be used, as the colors will shift as the camera detects changes in light qualities. You should make a concious decision as to which white balance mode to use (Daylight, Fluorecent, etc). 

• RAW files should be used as they are uncompressed and will retain the most amount of information. Only shoot JPG if you have complete control of the lighting conditions.

Camera Adjustments

There are five critical settings on an advanced camera you want to be aware of: Zoom, ISO, white balance, aperture (f/stop), and shutter speed. All cameras are different and the target numbers will depend on the environment in which you are shooting. All four of these settings are interrelated, though white balance does not affect exposure times. It is important to have a sense of how changing one setting will impact the others.

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1. ​Zoom:  Set your lens to properly frame the subject and use painter's tape to tape down the setting. (If you have a prime lens you can skip this step.) DO NOT ZOOM your lens while shooting the subject. Keeping the same zoom will ensure your photos are consistent. You may need to adjust the focus when you move your camera to different heights. Just make sure you don’t change any of the other settings!
    

2.  ISO: The ISO setting on your camera allows you to control its sensitivity to light. Typically, you set the ISO based on how bright your setting is-the brighter the environment, the lower the ISO. However, a higher ISO, i.e. more light-sensitive, the more noise you introduce into your photo. For photogrammetry we want to reduce noise by setting a low ISO. (Note that this will increase exposure time which is OK when the camera is on a tripod.)
    

3. White Balance:  This setting helps you balance the quality of light and color. Setting white balance helps whites actually render white in your photo. The light in your environment exists on a spectrum between warmer light (toward the red end of the spectrum) and cooler (towards the blue spectrum). There are different ways you can calibrate the color and white balance on your camera (we use the Color Checker in Lightroom to adjust the white balance in post production), however regardless of how this is completed, it is important that the white balance is set to a consistent measurement, and does not change as you move through a space.
    

4. Aperture:  Aperture, also called f/stop, controls the opening of the lens on your camera. The lower the aperture number, the wider the opening in the lens, which provides less depth-of-field i.e. a blurrier background. The higher the aperture number, the smaller the opening in the lens and therefore the greater the depth of field, and the sharper the background will be. We want to ensure that the entire object is fully within the depth of field. (Note there is an inverse relationship between shutter speed and aperture.)
    

5. Shutter Speed:  The shutter speed is the amount of time the shutter on your camera is open. Shutter speed is measured in fractions of seconds, so you’ll see on your camera screen a fraction 1/1000 to ⅛. When we use a tripod, we avoid some issues with stability and slow shutter speeds resulting in blurry photos. With the tripod we want to set the shutter speed very slow (higher number) to allow for the low amount of light coming in due to the smaller apertures (high fstop) and low ISO settings. Use a quick release while taking photos so as not to shake the camera during shutter release. If you are working in aperture priority (A or AV) mode, the camera will calculate the correct shutter speed for you!

General Workflow

 As challenges with light, weather, and time can change per shooting location, there is no set equation that will provide perfect pictures each time. However, there are some basic guidelines we can follow to help produce the best quality images possible

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1. When possible, use Aperture Priority (A). This allows you to select the ISO and aperture of your choosing, and then the camera will select the best shutter speed for a proper exposure. Because we will be on tripods, we do not need to be as concerned with the shutter speed. Manual settings (where you change ISO, aperture, and shutter speed) should be reserved for situations where exposure is not easily calculated (high contrast situations, very low light, etc).
    

2. Use the 2 second delay for the shutter release: this will allow the camera to stabilize itself after the shutter is clicked and help reduce camera shake. If you are shooting higher angles and the tripod is fully extended, you may need to wait 4-6 seconds before shooting to help avoid camera shake.
    

3. When possible, avoid high contrast situations where there are areas of extreme brightness and extreme darkness in your composition. This will require additional editing in post and affect your exposure metering negatively.
    

4.  There will be times where we will not be able to use a tripod (i.e. when you do not have explicit permission from locations to photograph). Without a tripod, exposure times must be decreased to avoid camera shake and blurry images. A general rule of thumb is that your shutter speed should be double the focal length- if you are using a 35mm focal length, you’ll want your shutter speed to be no lower than 1/70th of a second, if you are using a 20mm lens, you’d want your shutter speed to be 1/40th of a second or faster. In these situations, to ensure our shutter speed is fast enough, using a higher ISO is critical. In these situations, try not to raise the ISO past 800.