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a cable release. Releasing the shutter manually can cause vibration, something that can
produce unsharp photos. A cable release will keep your hands clear of the camera and
telescope, thus eliminating the possibility of introducing vibration. Mechanical shutter
releases can be used, though air type releases are best. In addition, remember the focusing
hints described earlier in this manual.
Your Firstscope 90 AZ is equipped with a built-on piggyback mount located on the top of
the mounting ring (figure 8). The adapter has a ¼"-20 photographic thread that attached to
the body of most 35mm cameras.
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With proper care your telescope should rarely need any maintenance work.
A. When not in use, always replace all lens covers to keep dust and contaminants off the optical surfaces.
B. A small amount of dust on any optical surface is ok. If the dust builds up then use a can of compressed air and then a
camel's hair brush to remove the dust.
C. If the lens need cleaning, it should be cleaned by a professional. Either have your instrument serviced by a telescope
repair facility or return it to the factory.
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NOTE: Specifications are subject to change without notice.
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Optical System:
Aperture:
Focal Length:
F/ratio:
Focuser
Standard Eyepieces
Resolution
Light gathering Power
Limiting Magnitude
Highest useful Power
#21084
Refractor
90mm (3.5")
1000mm
f/11
Rack and Pinion
20mm 1¼" (50x)
10mm 1¼" (100x)
1.3arc seconds
165x unaided eye
12.3
213x
11
Piggyback Camera
Mount
Figure 8
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