Getting Started • 13
When working with any optical instrument, there are a few things to remember to
ensure you get the best possible image.
• Never look through window glass. Glass found in household windows is
optically imperfect and, as a result, may vary in thickness from one part of a
window to the next. This inconsistency can and will affect the ability to focus
your spotting scope. In most cases you will not be able to achieve a truly sharp
image. In some cases, you may actually see a double image.
• Never look across or over objects that are producing heat waves. This
includes asphalt parking lots on hot summer days or building rooftops.
• Hazy skies, fog, and mist can also make it difficult to focus when viewing
terrestrially. The amount of detail seen under these conditions is greatly
reduced. Also, when photographing under these conditions, the processed
film may come out a little grainier than normal with lower contrast.
• When using your C5 as a telephoto lens, the split screen or microprism
focuser of the 35mm SLR camera may “black out.” This is common with all
long focal length lenses. If this happens, use the ground glass portion of
your focusing screen. To achieve a very sharp focus, consider using a
focusing magnifier. (These are readily available from your local camera
store.)
• If you wear corrective lenses (specifically glasses), you may want to remove
them when observing with an eyepiece attached to your C5. When using a
camera, however, you should always wear corrective lenses to ensure the
sharpest possible focus. If you have astigmatism, corrective lenses should
be worn at all times.
Your Celestron C5 can be used for both terrestrial and astronomical photography.
Your C5 has a fixed aperture and, as a result, a fixed f/ratio. To properly expose
your subjects photographically, you need to set your shutter speed accordingly.
Most 35mm single lens reflex (SLR) cameras offer through-the-lens metering that
lets you know if your picture is under or overexposed. This is important for terres-
trial photography where exposure times are measured in fractions of a second.
To reduce vibration when tripping the shutter, use a cable release. Releasing the
shutter manually can cause vibration, something that produces blurred photos. A
cable release allows you to keep your hands clear of the camera and spotting scope,
thus reducing the possibility of shaking the spotting scope. Mechanical shutter
releases can be used, though air-type releases are best.
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