henry link
Well-known member
The Zeiss Tripler has a long history. It's a tiny 3x12 monocular/loupe that appears in my 1984 Zeiss brochure and probably goes back much further. The one I just bought appears to be mechanically identical to the 1984 brochure photo and, except for phase correction, must be optically unchanged too (not even T* coated). It's an insanely expensive item now, around $400, but I ran into a demo for $99.99 which is the only reason I bought it. I can't believe Zeiss actually sells many of these.
I tested it just as if it were a real fully grown optical device. Boosted magnification resolution at a whopping 15x was OK, about 12 arcsec, more than good enough for a very sharp image at 3x. It also star tested pretty well. The only real defect was a visible line from the roof edge in the out of focus diffraction pattern, perhaps unavoidable in such a tiny prism. Eye relief is about 19mm from the eyelens glass, 15mm from the rim of the rolled down eyecup. Apparent field seems to be a little larger than spec, around 37-38 degrees, which for some reason doesn't feel all that narrow in a device like this.
Perhaps the most interesting thing I found is that the real magnification changes significantly with focusing distance. This is really to be expected in an optic that focuses by changing the distance between the objective and the eyepiece, but here the difference is huge because the close focus is extremely close. The magnification is about 3x for infinity focus but increases to almost 6x at the closest focus (about 8" for my eyes). This has implications for its use as a binocular magnification booster. By varying the focuser position of the Tripler it can be used to boost binocular magnification from as little as about 2.8x (farthest focus setting past infinity) up to about 3.8x (closest focus setting). The binocular focuser has no trouble compensating for the differences in the Tripler focuser setting.
In use the Tripler mostly gets out of the way optically and just allows you to see how good your binoculars are at higher magnification. This may not be a pleasant experience for the uninitiated. We're used to the forgiveness of low magnification and stopped down objectives in daylight. It can be a shock to see how crummy the image looks at full aperture and higher magnification. Still, I think this device will be $100 worth of fun, both as a focusing loupe and as a last resort for ID's that are impossible at binocular magnification.
I tested it just as if it were a real fully grown optical device. Boosted magnification resolution at a whopping 15x was OK, about 12 arcsec, more than good enough for a very sharp image at 3x. It also star tested pretty well. The only real defect was a visible line from the roof edge in the out of focus diffraction pattern, perhaps unavoidable in such a tiny prism. Eye relief is about 19mm from the eyelens glass, 15mm from the rim of the rolled down eyecup. Apparent field seems to be a little larger than spec, around 37-38 degrees, which for some reason doesn't feel all that narrow in a device like this.
Perhaps the most interesting thing I found is that the real magnification changes significantly with focusing distance. This is really to be expected in an optic that focuses by changing the distance between the objective and the eyepiece, but here the difference is huge because the close focus is extremely close. The magnification is about 3x for infinity focus but increases to almost 6x at the closest focus (about 8" for my eyes). This has implications for its use as a binocular magnification booster. By varying the focuser position of the Tripler it can be used to boost binocular magnification from as little as about 2.8x (farthest focus setting past infinity) up to about 3.8x (closest focus setting). The binocular focuser has no trouble compensating for the differences in the Tripler focuser setting.
In use the Tripler mostly gets out of the way optically and just allows you to see how good your binoculars are at higher magnification. This may not be a pleasant experience for the uninitiated. We're used to the forgiveness of low magnification and stopped down objectives in daylight. It can be a shock to see how crummy the image looks at full aperture and higher magnification. Still, I think this device will be $100 worth of fun, both as a focusing loupe and as a last resort for ID's that are impossible at binocular magnification.