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Capturing pictures of what you see in your telescope is one of the most rewarding and at the same time challenging tasks you can undertake in astronomy. In order to accomplish this you need a 35-mm SLR camera with a removable lens. A ring then is attached to the camera that will allow the camera to be mated to an adapter that directly threads onto the rear cell of the telescope in place of the visual back. The telescope then becomes the camera lens. This type of camera is the only type of camera that allows you to view directly through the light path rather than

Figure 2.6. 35-mm camera and lenses. Photograph by author.

Figure 2.6. 35-mm camera and lenses. Photograph by author.

through a parallel finder. This will allow you to directly sight and focus the target. Prior to reaching the film, the light is deflected by two 45-degree mirrors to the viewfinder. When the shutter is tripped, the first mirror is retracted out of the way either electrically or mechanically. This allows the light to reach the film when the shutter is opened. When the exposure is completed, the shutter closes and the mirror extends to its normal position.

Another important benefit of this type of camera is that it allows you to select various exposure time lengths. A typical setup will allow automatic exposure times from as fast as 1/500 of a second to one full second. Of even greater importance is the bulb (B) setting. This allows the shutter to be manually held open for as long as the user desires. This is critical since most deep sky photographs are taken at the full focal length of the telescope (in my case, that's f/10). Taking an exposure of a ninth-magnitude nebula might take as long as an hour.

When buying a camera for astrophotography, buy as much quality as you can afford. If you buy a good camera, you will only have to do it once. Manual cameras are relatively inexpensive and have the advantage of not needing batteries that can die on you in extreme cold. Electric cameras operate much more smoothly and precisely. The quality of the lens of your camera is important since you will not always use it to image through your telescope. You may wish to mount the camera on top of the telescope "piggyback" style. This allows a clock-driven telescope to serve as mount for beautiful wide-field panoramic shots. Also consider a camera that offers an array of telephoto lenses. This allows modest magnifications to be used while retaining a wide field view. The only other type of accessory that is an absolute must is a cable release for the shutter. This allows the shutter to be opened without you touching the camera and thus creating vibrations. This can either be a manual type of release with a spring or an air-loaded type. The air-release is smoother, but also more expensive. If you choose to settle for a spring cable release for your camera, make sure you use the camera's delay timer if you are not using the "B" setting. This will allow any vibrations created by the spring to damp out before the shutter trips. New cameras can cost $500 and up with just a single lens. When camera shopping, a trip to an Internet auction site is a great idea to get good-quality equipment at a cheap price. I recently bought a used Minolta and three lenses for under $100 in mint condition.

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Digital Camera and Digital Photography

Digital Camera and Digital Photography

Compared to film cameras, digital cameras are easy to use, fun and extremely versatile. Every day there’s more features being designed. Whether you have the cheapest model or a high end model, digital cameras can do an endless number of things. Let’s look at how to get the most out of your digital camera.

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