Mars Eye Red Dot Finder

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Brand and Model:Mars Eye Red Dot Finder
Price ($USD):15.95
Description:A small Unity Finder, with dovetail base, and switchable red or green dot.

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Mars Eye Red Dot Finder
I have long wanted a unity-finder for use with my Fuji 16x70 binoculars. When using binoculars in a dark sky, it can be difficult to figure out just what you are looking at - thousands of stars, all looking pretty much the same =:O

After reading Tom Trusock’s Cloudy Nights comparison review at

I decided on the Mars Eye Red Dot Finder.

I purchased mine from Apogee. Around $20 with shipping, a heck of a deal IMO.

In summary, it is a compact and competent finder (much smaller than a Telrad), with a large main lens which projects a red or green dot against the sky –a small slider switch on the right side changes the colour. My unit came with a detachable dovetail base included in the price, which can be slid onto the unit, and tightened in place with two thumb-wheels.

A thumb-wheel at the rear allows vertical alignment. Another thumb-wheel along the right-hand side allows horizontal alignment. (These adjustments are quite stiff, although I suspect this stiffness can be adjusted.)

There is a rotary brightness control knob under the front, with an inbuilt on-off switch. (Also stiff)


1 - The dovetail base is not especially suitable for attaching to binoculars. Some have suggested mounting these finders with Velcro, but in my opinion this is not solid enough, given the stiffness of the various adjustments. So I drilled a hole in the vertical surface at the front of the dovetail base, and screwed it permanently onto a strip of 1-inch wide by one-eighth inch thick by 3 inches long aluminium stock. The lower end of this stock has a quarter-inch hole – to mount the finder, I place the lower end of this stock between my parallelogram mount and the binocs, pass the parallelogram’s mounting bolt through the hole in the stock, then tighten the attachment bolt. Doing this in the dark should be an Olympic event, as you need at least 3 hands - difficult to do, but it makes for a very solid mount. Once aligned, the finder *stays* aligned.

2 - The brightness control had an intermittent open-circuit, so I rewired the unit, bypassing the brightness control and switch, and made the red-green slider switch into an on-off switch, and used only the red light. (In my teen years I worked as a radio-TV tech, and I have a deep hatred for rheostats with inbuilt on-off switches). Anyway, the rewired finder works great – a flick of the slider switch turns on the red dot, and another flick turns it off. I installed a 10-ohm resistor in series with the red LED to reduce the brightness a little.

3 - Fogging up. The finder’s main lens is exposed to the night sky, so I expect to get some fogging. I will work on a solution to this. Also, when looking through the finder, my nose is at the binocular eyepiece level, so DO NOT BREATHE OUT. This indiscretion can lead to a 15-minute wait while the condensation evaporates from the eye lenses.

4 - Brightness. In my opinion this unit is not well suited to daytime use, the dot is simply not bright enough. This is hardly a criticism, as one seldom needs a finder in daylight. Another thing, the finder’s main lens is slightly “smoked”, reducing the brightness of whatever target you are aiming at.
Bob Bennett, Maple Vly, WA

Overall Rating: 9
Performance:9 Value:10
Weight: 17 (Trustworthy Vote)
By: rjb
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