Meade LX90-ACF Advanced Coma-Free, Инструкция по эксплуатации

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Photography through the LX90 requires the addition of the optional #62 T–Adapter. See
OPTIONAL ACCESSORIES,
page 42. With the #62 T-Adapter and a T-mount attached to the
telescope ( Fig. 14 ), through-the-telescope photography is possible with any 35mm camera body
with a removable lens. In this way, the telescope effectively becomes the lens of the camera.
The #62 T-Adapter ( Fig. 14, 1 ) threads on to the photo port, followed by a T-Mount ( Fig. 14, 2 )
for the particular brand of 35mm camera being used, followed by the camera body ( Fig.14, 3
).
To orient an object in the viewfinder of the 35mm camera body, use a small jeweler’s
screwdriver to slightly loosen three adjustment screws around the outer knurled ring of the
T-Mount. Rotate the camera body to achieve proper orientation of the object; then re-tighten the
adjustment screws.
The #62 T–Adapter permits close-coupling of a camera body to the telescope. In this format
vignetting occurs: the photographic image appears on film with a slight darkening (vignetting)
at the corners of the 35mm frame (
Fig. 15 ).
Photography through a long lens such as the LX90 requires special technique for good results,
and the photographer should probably expect to waste a roll or two of film in acquiring this
technique. Long-lens photography has its own rewards, however, rewards that short-focus
lenses cannot duplicate.
A few tips on photography with the LX90 :
1. Use the Field Tripod for the telescope. At an effective focal length of 2000mm, even small
external vibrations can easily ruin an otherwise good photo.
CAUTION: With the #62 T-Adapter and a camera body mounted to the LX90 photo
port, the telescope can only be rotated vertically about 45°. Moving past this point
may damage the telescope and camera.
2. Use a cable-operated shutter release. Touching the camera body to initiate shutter
operation almost certainly introduces undesirable vibrations.
3. Focus the image with extreme care. While observing the subject through the camera’s
reflex viewfinder, turn the telescope’s focus knob (
Pg. 7, Fig. 1, 8 ) to achieve the sharpest
possible focus. Note that some 35mm cameras may have an optional focusing screen
(available from the manufacturer) for use with a long telephoto lens. This screen provides
a brighter and clearer image to focus, and is highly recommended.
4. Correct shutter speeds vary widely, depending on lighting conditions and film used. Trial-
and-error is the best way to determine proper shutter speed in any given application.
NOTE: The camera used with your telescope may have an exposure meter that is
still active when the standard lens is removed and the body is connected to the
telescope with the T–Mount. If used for terrestrial photography, the camera meter
should be acceptable. If used for astrophotography, the meter probably will not
provide good results since camera meters are not made to compensate for a
dark sky.
5. Terrestrial photography through the LX90 is sensitive to heat waves rising from the Earth’s
surface. Long distance photography is best accomplished in the early morning hours
before the earth has had time to build up heat.
6. Photography of the Moon and planets through the LX90 can be especially gratifying, but
points 1 through 4 should be particularly noted in this case. Lunar or planetary
photography requires that the telescope be Polar aligned. See
APPENDIX A
, page 49.
Photography with a Digital Camera
Digital cameras provide some significant advantages to the casual astrophotographer: You do
not have to develop the images (instant images), lower costs, computer and internet readiness.
And because unwanted photos are easily discarded, they provide the freedom to experiment.
Digital cameras present some problems for the astrophotographer: Many models have lenses
that cannot be removed, difficulties in attaching to a telescope, possible vignetting, lack manual
focusing and shorter exposure times.
2
3
Fig. 14: LX90 with #62
T-Adapter.
Fig. 15: Example of
vignetting.
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PHOTOGRAPHY WITH THE LX90