Price: $100 or best offer
This astrophotography accessory is designed for manual guiding using your guide scope. Manual guiding helps long exposure photography yield pinpoint stars, correcting for mount periodic error and other factors. You observe the motions of a guide star (or comet) and manually make small adjustments using your RA and DEC mount controls.
You insert your 1.25" eyepiece into the black port (shown at left). The port has a lock knob to hold the eyepiece securely. The silver barrel (shown at top) fits into the 1.25" focuser of your guide scope. The GA-2 illuminator (shown at right) projects a red reticle into the field of view. The helical diopter adjustment on the eyepiece port allows for perfect focus of both the reticle and the guide star. Even if you are nearsighted or farsighted, you can obtain crystal clear focus even without eyeglasses. The unit includes a built-in diagonal for comfortable positioning. The reticle has crosshairs and six concentric circles. The reticle photo below was taken using hand-held (shaky) 20mm eyepiece projection.
The reticle can be easily rotated to match your RA/DEC axes. The most advanced feature of the GA-2 is that it has two knobs that allow centering the reticle anywhere in the field of view. This allows selection of a guide star without moving the mount or guide scope.
The illuminated reticle is powered by a 3v button battery. I taped together two fresh RS76 1.5v batteries, which are included with this unit. The white recessed knob on the illuminator can adjust the reticle brightness from bright down to incredibly dim.
If desired, you can attach a barlow lens on the silver barrel of the GA-2.
This GA-2 does not include an eyepiece; is not intended for use with an autoguider; and does not have a flip mirror.
Note: Although I have used other OAGs, I have never use this one.
Condition excellent. Operates perfectly.