Meade RCX400TM instruction manual Photography, Few tips on photography with the RCX400 telescopes

PHOTOGRAPHY

The RCX400 optical design consists of a hyperbolic secondary and corrector lens/pri- mary combination that performs as one hyperbolic element. The corrector plate advan- tage, aside from the obvious optical correction that the lens produces, allow astropho- tographers to make images free of diffraction spikes, with diffraction spikes being the only real negative to a traditional Ritchey-Chrétien design.

You may perform through-the-telescope photography with any 35mm camera body with a removable lens. You may connect a camera to a #62 T-Adapter. Using this method, the telescope effectively becomes the lens of the camera.

The #62 T-Adapter connects to a T-Mount for the particular brand of 35mm camera being used, followed by the camera body.

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 dark- ening (vignetting) at the corners of the 35mm frame (Fig. 34).

Photography through a long lens such as the RCX400 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 RCX400 telescopes:

1.		Use the Field Tripod for the telescope. At an effective focal length of 2000mm or
		more, even small external vibrations can easily ruin an otherwise good photo.
		For best results in photographing celestial objects, a wedge and One-Star polar
		alignment is recommended. See APPENDIX A, page 57.
	2.	Use a cable-operated shutter release. Touching the camera body to initiate shut-
Fig. 34: Example of vignetting.		ter operation almost certainly introduces undesirable vibrations.
3.		Focus the image with extreme care. While observing the subject through the cam-
		era’s reflex viewfinder, focus the telescope. 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 con-
		nected to the telescope with the T-Mount. If used for terrestrial photogra-
		phy, 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 RCX400 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 RCX400 can be especially grat-
		ifying, but points 1 through 4 should be particularly noted in this case. If you wish
		to take photographs using polar alignment, see APPENDIX A, page 57.

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