One of the most competitive segments in the amateur telescope marketplace these days spans 3- to 5-inch apochromatic refractors. Once considered telescopes for the well-to-do, these instruments are now affordable to many backyard stargazers. And one of the newest companies to enter this market segment is Starfield Optics from Caledon, Ontario, a suburb of Toronto.
Since opening its doors in 2017, Starfield Optics has produced amateur equipment geared largely toward astroimaging. Notably, the Géar line of imaging apochromatic refractors, ranging from a 2.4-inch f/5 to the 4.5-inch f/7 model reviewed here, have attracted a lot of attention in North America.
Recently, I had an opportunity to put their flagship, the Starfield Géar 115 Triplet APO, through its paces.
First impressions
The telescope arrived safely directly from the manufacturer nestled in a foam-lined case inside a thick cardboard box. As soon as I unzipped the case and pulled out the optical tube assembly, I could tell that this was a well-built instrument.
The tube itself is made from high-quality aluminum, which delivers a solid feel while keeping the weight manageable. The tube measures approximately 28 inches (710 millimeters) long with the extendable dew shield stowed, and 35 inches (890 mm) when the shield is extended. The tube assembly weighs 15 pounds (6.8 kilograms), light enough to carry to remote locations.
The heart of the Géar 115mm is its triplet apochromatic objective lens, which significantly reduces chromatic aberration (the color fringing around bright objects). The result is sharp images with excellent color fidelity. The lenses are fully multicoated, which enhances light transmission and minimizes internal reflections. Staring through the objective and into the aluminum tube shows the interior is fully blackened. Four internal baffles minimize stray light from intruding into the optical path.
Putting it to the test
Each Géar 115mm comes with a comprehensive optical test report to objectively demonstrate the quality of its objective lens. The scope’s test report for this review showed that the objective had a low peak-to-valley wavefront error of 0.143 wave. In the world of telescope optics, 0.25 wave is considered “diffraction-limited” performance (when a telescope has reached the theoretical maximum sharpness and clarity that is possible for its aperture).
Another measure for optical excellence is the Strehl ratio. A Strehl ratio of 1.0 is considered optical perfection. Our test Géar 115mm came in with an impressive Strehl ratio of 0.972.
Although I couldn’t validate the report’s values, I can confirm that the optics were excellent. When I performed a test by viewing stars at high magnification, the stars showed textbook diffraction patterns. Further, when I shifted the view slightly to either side of focus, I couldn’t detect any sign of astigmatism or chromatic aberration.
Besides exceptional optics, this refractor also includes mechanical features valued by visual observers and imagers. The dual-speed 2.5-inch rack-and-pinion focuser, with its included adapters, accepts both 1¼” and 2″ eyepieces and star diagonals. The focuser’s movement was smooth and responsive with no backlash. Its 10:1 reduction gearing makes it easy to achieve focus. The focuser is also fully rotatable and can be outfitted with optional motor control.
The Géar 115mm includes nicely machined CNC heavy-duty tube rings and a Vixen-style dovetail bar for easy mounting on a wide range of equatorial and alt-azimuth mounts. A second beam across the top of the rings serves as a carrying handle. It also has five tapped holes. The center hole has a ¼”-20 thread, while the others are M6 metric threaded. Additionally, the telescope’s focuser incorporates a standard Synta-style finder scope mounting shoe.
I set up the Géar 115mm on my German equatorial mount and attached my own finder scope. All tests were done from my suburban backyard.
Time to play
The first object I looked at was the gibbous Moon. Our satellite’s limb is a telling sight through refractors. When using lesser-quality instruments, the lunar edge is rimmed with yellow and purple chromatic aberration, whereas a true apochromatic instrument keeps it gray. And that’s exactly what I saw through the Géar 115mm, even with magnifications above 200x.
The two stars of Albireo (Beta [β] Cygni), my favorite double star, displayed a striking golden and azure vibrance. The Géar 115mm also beautifully displayed the quadruple Trapezium system in the Orion Nebula (M42). The view took my breath away as I stared at the four blue-white stellar sapphires twinkling amidst the surrounding wisps of nebulosity. The belts of Jupiter’s atmosphere also showed themselves nicely, as did the Great Red Spot. Even Saturn’s clouds, which are far more subtle, hinted at delicate variations in color.
The 805-millimeter focal length of the Géar 115mm also makes this a great telescope for guided imaging. With that in mind, the company included a Camera Angle Adjuster. It lets the user rotate their camera while not affecting focus, useful when you want to frame your image a certain way.
For those striving for image perfection, a flattener is a must. For this, Starfield Optics sells an optional 0.8x adjustable reducer and 1.0x flattener separately. The former flattens the field to produce pinpoint star images to the edge, while also reducing the focal ratio to f/5.6. The flattener also creates pinpoint stars, but maintains the original focal length and focal ratio. With or without the 1.0x flattener, the scopes’s actual field of view at prime focus measures 2.6° x 1.7° on a full-frame camera sensor. Adding the 0.8x adjustable reducer expands the field to 3.2° x 2.2°.
A scope you’ll be proud of
The Starfield Optics Géar 115mm triplet APO refractor offers an impressive combination of optical performance, build quality, and value. Though a quality mount and other accessories are required, its value remains outstanding.
This telescope suits both experienced astronomers and those developing their skills. Use it for casual viewing, and then branch into photography if you wish. It delivers tack-sharp images of the rugged lunar surface, crisp views of the planets, and is great for deep-sky targets.
In every way, its performance is comparable to more expensive models. I highly recommend the Starfield Optics Géar 115mm triplet APO refractor to anyone in the market for a high-quality refractor that promises years of happy stargazing.
