Reflex finders are unit power (i.e., no magnification) devices that use a simple optical system to project the illuminated image of either a dot or a reticle of concentric circles onto the sky. The red dot finders tend to be more compact than the reticle type, and you may find that you can store it in the binocular case. Reticle finders are more bulky but are usually considered to be more useful, especially if the diameter of one of the circles is a close match to the field of view of your binoculars. Regardless of whether the circles match the binocular field, you can use the circles for precise star hopping.
Reflex finders usually include some form of aiming adjustment. In the red dot finders, this is usually achieved by ridged screws that move the finder relative to its base. In reticle finders, it is usually the orientation of the reflecting surface that is varied to change the aim. Most include a dimmer switch to alter the brightness of the dot or reticle so that it can both be seen against a bright sky and not "drown out" faint objects in a dark sky. The base of the finder slips into a mounting bracket that is attached to the binocular. Once I have established the optimum position for the finder, I fix the mounting bracket to the binocular with double-sided adhesive foam pads. Some manufacturers provide these pads with the finder but, if this is not the case, you may obtain either pads or double-sided adhesive foam tape from a good stationery or hardware store. These finders may be provided with two mounting brackets so that they can easily be swapped between instruments; alternatively, spare mounting brackets can usually be obtained via the supplier. To avoid breathing on the eyepieces and fogging them when you use the finder, if you use your right hand eye with a finder, you should mount the finder on the left tube and vice versa.
It is a common misconception that reflex finders are used only with one eye looking through it. Although this mode of use is possible with bright objects, if
you are looking through the reflecting surface all objects appear dimmer and most stars disappear entirely. The correct mode of use, as with all straight-through finders, is to begin with both eyes open. The eye that is not looking through the finder gets an unattenuated view of the sky and your brain merges the images received by both eyes, exactly as it does in "normal" use of a pair of Mark I eyeballs!
My preferred reflex finder is the Rigel Quik-finder (Figure 7.1), which is relatively compact and whose aperture stands some 75 mm (3 inches) from the body of the binocular. This sighte also has the advantage of the ability to make the illumination blink on and off at an adjustable rate; this can be a great aid when targeting a faint object when its light is obliterated by the finder illumination.
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