Meade LNT Instruction Manual download pdf (Page 39)

Photog

raphy through the LX90 requires the addition of the optional #62 T–Adapter. See

“OPTIONAL ACCESSORIES,” page 39. 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 (1, Fig. 14) threads on to the photo port, followed by a T-Mount (2, Fig. 14)

for the particular brand of 35mm camera being used, followed by the camera body (3, Fig. 14).

To orient an object in the viewfinder of the 35mm camera body, use a small jeweler’s

scre

wdriver 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 scre

ws.

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 lens-

es 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 (

8, Fig. 1) to achieve the sharpest possi-

ble 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 pro-

vide 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 46.

Photography with a Digital Camera

Although digital cameras still cannot match the quality of images provided by

traditional 35mm cameras, they provide some significant advantages to the casual

astrophotog

rapher: You do not have to develop the images (instant images), lower costs,

computer and inter

net readiness

And because unw

anted photos are easily discarded, the

pro

vide the freedom to e

xper

iment.

Digital cameras present some problems for the astrophotographer: Many models have lenses

that cannot be remo

ed, difficulties in attaching to a telescope

, possib

le vignetting, lac

man

ual f

ocusing and shorter exposure times.

Fig. 14: LX90 with #62

T-Adapter.

Fig. 15: Example of

vignetting.

PHOTOGRAPHY WITH THE LX90

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Meade LNT Instruction Manual Page 39

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