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Saturday, October 1, 2005

Scoping The World

Use a spotting scope and a digital camera for wildlife photography

What Kind Of Camera?
When it comes to choosing a camera, there are several different items to consider for digiscoping: resolution, optical zoom, an LCD screen and whether or not it has a filter thread.

Resolution. A digital camera with a resolution between 3 and 8 megapixels will fit the bill for digiscoping. If you make enlargements no bigger than 8x10 inches, a 3-megapixel camera will provide sufficient image resolution. Using a higher-resolution camera, however, will offer you more than just a bigger print.

Even with the high magnification provided by a spotting scope, your subject still may not fill up the frame. In such a case, you may need to crop into the photograph when opened in an image-editing application like Photoshop. By using a digital camera that offers 4-, 6- or 8-megapixel resolution, you can crop out a good percentage of the image, but still have sufficient data left to create a quality enlargement.

Optical Zoom. The optical zoom of a digital camera is extremely important for successful digiscoping in that it helps to control a problem called vignetting, or the appearance of shadows in the corners of the frame.

This problem occurs when the front element of the camera lens is bigger than the circle of light emitted by the spotting scope's eyepiece. The image circle from the eyepiece, when smaller than the front of the camera lens, can't provide complete illumination to the camera lens, which results in shadows appearing in the corners. The remedy is to zoom in the lens until that vignetting is eliminated. Avoid using the digital zoom feature in your camera, as this will only decrease image quality.

LCD. Because a compact camera's optical viewfinder doesn't provide through-the-lens viewing, you'll depend on the camera's LCD to compose images. Therefore, it's good to have a camera that features as large a screen as possible. It's helpful to have an articulated screen that can be swiveled up or down, which allows you to easily view the screen regardless of how high or low the spotting scope is positioned. It's also beneficial when working with a spotting scope with an angled eyepiece.

Filter Thread. Having a convenient way of attaching the camera to the spotting scope is crucial. That's why many digiscopers prefer having a camera that features a threaded front element. Such threads make it easy for adapters to be securely fitted to the camera and spotting scope. They're not absolutely necessary, though, as there are various adapters available for cameras without a filter thread. Some adapters use the camera's tripod socket rather than the lens barrel itself for mounting, reducing stress on the lens assembly.

Digital SLRs. For digital SLR users, there are several adapters available that allow direct mounting to a spotting scope. While they provide higher functionality, they lack a live LCD, requiring images to be composed through the optical or EVF viewfinder.

Choosing A Spotting Scope
There are several considerations when evaluating a spotting scope. The first is the size of the front element. Often ranging between 60mm and 80mm, the size of the front element impacts the scope's light-gathering capability. The larger the front element, the more light it brings into the scope, resulting in a brighter image, especially under low-light conditions.

The eyepiece determines the level of magnification. Most spotting scopes feature a user-replaceable eyepiece. You can either choose a fixed-powered eyepiece from 20x to 60x or a zoom eyepiece such as the 20-60x. Although the zoom eyepiece gives the obvious advantage of adjusting the magnification at the turn of a ring, a fixed eyepiece features a wider angle of view. A wide field of view is beneficial when searching for a subject through the eyepiece. Too narrow a depth of field can make finding a subject incredibly difficult and frustrating.

A fixed 30x eyepiece is recommended for digiscoping with a compact digital camera. Although higher-magnification eyepieces increase the size of the subject in the frame, they also make the image more susceptible to softness due to vibration and camera movement. A solid and steady tripod is a must.

Scopes are available with either a standard or angled eyepiece. They don't make a difference in respect to image quality, but they do offer convenience. If you're using a camera with a fixed-position LCD, you may prefer a spotting scope with an angled eyepiece that allows you to simply look down onto the screen when composing your images. If your camera has an LCD screen that features articulation, either style spotting scope is acceptable.


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