| The Meade #644 flip-mirror system is the first reasonably-priced 1.25" enhanced aluminum multicoated flip-mirror system specifically designed for virtually any medium chip size CCD camera (SBIG ST-7 and smaller, for example). The #644 permits a dramatic reduction in camera setup time for astrophotography. The basic function of the flip-mirror system is to allow you to inspect, center, compose, and focus the telescope image with an eyepiece before the CCD or 35mm image is taken. This eliminates the normal (but tedious) CCD composing and focusing process that requires taking short exposures through the CCD camera after each small focus change and examining the result on the computer screen. It is essential to note that the flip-mirror system does not allow simultaneous guiding through the eyepiece port while imaging though the telescope, as is the case with an off-axis guider and illuminated reticle eyepiece or separate CCD autoguider. The #644 can be used for simultaneous imaging and guiding only with a self-guiding CCD camera such as the SBIG ST-7 that has an integral CCD guider built into the camera housing. 35mm and CCD cameras that use separate autoguiders or illuminated reticle eyepieces for guiding must use a separate photoguide telescope for guiding. They cannot use the #644. The flip-mirror system threads onto the rear cell of any Meade LX-Series catadioptric telescope, as well as onto the rear cell of Celestron Schmidt-Cassegrains. An optional #157 adapter allows the #644 to be used with 1.25" focuser refractors that have sufficient focuser in-travel to accommodate the long light path of the #644. To use the #644, once it is mounted on a scope, you flip the mirror down to center, compose, and focus the image while viewing with an eyepiece at 90 degrees to the light path, then flip the mirror up to pass the light on to the CCD chip or to the film plane of a 35mm camera. A fine helicoid focusing thread allows you to precisely match the focus of the eyepiece image in the down mode to that of the camera focus in the up mode. The normal (but tedious) manual CCD focusing procedure must be done to match the focus points before the #644 can be used on an every-night basis. However, a lock-ring on the eyepiece holder fixes this visual focus so the focus-matching procedure only has to be done once. The Meade 25mm Plössl illuminated reticle framing eyepiece in an excellent choice for a focusing eyepiece, as it is etched with rectangles that match the size of popular CCD chips. This allows the image to be easily centered and composed while you focus. The #644 flip-mirror uses a high-resolution, low-expansion Pyrex optical flat mirror. This minimizes focus changes as the air temperature changes. It also allows the #644 to be used for normal 1.25" eyepiece visual observing with the telescope, as well as for photography, without having to remove the flip-mirror from the telescope. The UHTC (Ultra High Transmission Coated) flip mirror is made of enhanced aluminum, multicoated with layers of titanium dioxide and silicon dioxide. These coatings increase the mirror reflectivity to 97%, compared with the 89% reflectivity of a standard aluminum mirror. The #644 includes 2-axis mirror adjustment screws and locks for precise image centering. Once set, the mirror alignment remains fixed for future applications. For CCD cameras that use standard 1.25" barrels, a barrel adapter is included for attaching the CCD camera to the flip-mirror housing. CCD cameras with T-thread interfaces (including all Meade Pictor CCD models) are attached using the longer of the two T-thread extension tubes included with the #644. 35mm cameras use the shorter extension tube and an optional T-ring to connect to the flip-mirror housing. The barrel adapter and both of the extension tubes attach to the flip-mirror housing by means of a bayonet fitting. This allows the barrel adapter or extension tube to be rotated for the best image composition on the CCD chip or 35mm frame. The #644 accepts any 1.25" eyepiece. The mirror has a clear aperture of 22mm. The #644 can be used with the Meade Pictor 208XT, 216XT, or 416XTE cameras; with the SBIG ST-5C through ST-7 or other similar-size CCD cameras; or for visual observing with 1.25" eyepieces. The #644 is not recommended for use with large-chip CCD imagers (for example the Meade Pictor 1616XTE or SBIG ST8 through ST-10), or for serious 35mm astrophotography, as the 1.25" system will vignette the image. The larger 2" #647 flip-mirror system is recommended for unvignetted use with 35mm cameras and large chip CCD cameras. The #644 cannot be used with a focal reducer, as its long light path may prevent your camera from reaching focus.
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