BinoViewing Bliss: Baader MaxBright II Binocular Viewer

Credit: Baader

The Baader MaxBright II provides noticeable improvements in image quality and ease of use over low-cost binocular viewers at a price well below premium units. It is for experienced observers looking for a new viewing experience, but reluctant to spend over $1000 for a top-of-the-line binocular viewer.

Binocular viewers are a unique telescope accessory. I find using one provides a more pleasant experience because using two eyes is more natural and less fatiguing compared to single-eye viewing. I am able to linger much longer on each target.


A prime advantage of the MaxBright II over low-cost binocular viewers is that it has large 27mm prisms, like the more expensive binoviewers but at a lower price point, allowing use of 24mm 68° wide-field or 32mm 50° eyepieces. Both types yield the maximum True Field of View (TFOV) that a 1.25-inch eyepiece can provide, with little or no vignetting on the MaxBright II.


The MaxBright II comes standard with a Zeiss-standard micro bayonet adapter, and with a T-2 Cap Nut (M 42 x 0.75) adapter to connect to diagonals or focusers with those connection types.

For my refractors I already had a T2 capable diagonal so the MaxBright II would connect as is. This low-profile design reduces the amount of back focus required and allows the diagonal to be clamped directly to the MaxBright II so less backfocus is required and, depending on the telescope, can reach focus without a Glasspath Corrector (GPC) lens.  I also tested additional accessories so I could use it with my non-T2 capable diagonals (i.e., 1.25-inch nosepiece and GPCs).

Credit: Baader

If the user’s refractor and diagonal does not have sufficient back focus then they may need to buy at least one Glasspath Corrector (GPC) lens, which magnifies the image like a Barlow, with GPCs from 1.25x to 2.6x offered.

However, the GPC also corrects for spherical and chromatic aberration from the binoviewer prisms when used on f/7 or faster telescopes. A GPC also shifts the focus point outward (by 20mm to 80mm, depending on the GPC) to allow most telescopes to reach focus. Only if your telescope and diagonal can accommodate the 117mm of inward focus travel required by the MaxBright II can it be used without a GPC for the maximum field of view and lowest power. Both my refractors could accommodate the 117mm back focus, so could be used without a GPC, but not all models will.

The downloadable instruction manual explains the complex options and is required reading before purchasing.

Depending on the telescope and accessories a user already has, no additional items may be needed from what is supplied.  However, the most common that might be needed would be a 1.25″ nosepiece for use in non-T2 diagonals, and perhaps a GPC if the user’s refractor does not have sufficient backfocus. If the user has a Newtonian or SCT, then there are separate GPC accessories so these designs can reach focus. These accessories are all at additional cost.  My tests were all on refractors. I did not need GPCs or the 1.25″ nosepiece but acquired them to provide more informative testing.

At 21 ounces (595 grams) the MaxBright II is similar in weight and size to the low-cost William Optics binoviewer I’ve long used (it is no longer sold).

The MaxBright II’s eyepiece lock/release and diopter height adjustments have separate rotating collars that turn smoothly and effortlessly. With Baader’s ClickLock mechanism, you grab the metal posts and pull them away from each other to secure the eyepiece, or push them toward each other to unlock the eyepiece. Quick, yet it precisely aligns the eyepieces.

The diopter height adjustment (the lower collar on each eyepiece holder) has a small protrusion to make it easier to identify by feel and rotate. Turning that collar does not rotate the eyepiece, useful when using eyepieces with winged eye guards.

Baader MaxBright II within the case. Credit: Baader


To test the MaxBright II, I used Takahashi TSA-102 f/8 and Lunt Solar Systems-152 f/7.9 apochromatic refractors. The MaxBright II yielded crisp and sharply defined images with no perceivable differences between binocular views with the MaxBright II, and monocular views with just the prism diagonal alone.

I did not notice any difference in brightness from the left side vs. the right side. The MaxBright II maintains an equal 50-50 split of the beam, which lower cost binoviewers often do not.

Venus was a breathtaking sight. Its crescent was razor sharp, both limb and terminator, with small albedo differences visible in the Venusian clouds. Moving to the Moon, views were highly etched and richly contrasted.

In the past I’ve found binoviewing deep sky objects less than satisfying when using low-cost binoviewers. The MaxBright II has changed my opinion. Objects such as M1, the Crab Nebula, and M101, the Pinwheel Galaxy, appeared brighter and more detailed than when viewed with the entry-level William Optics binoviewer.

When viewing the Moon, Venus or bright stars like Sirius I did not see any stray light artifacts. The background sky appeared consistently rich with no more scatter around stars or planets than in single-eyepiece views.

When using an Orion 35mm Ultrascopic and University Optics 32mm König, eyepieces each with 29mm diameter field stops, some darkening of the edge of field was apparent. However, it was mild enough to allow the field stop to remain sharply visible.

By comparison, eyepieces with 27mm field stops, such as the Explore Scientific 24mm 68°, showed fully illuminated fields from center to edge, with no obvious darkening near the field stop. The William Optics binoviewer, with its smaller 20-22mm clear aperture, shows severe vignetting with these same eyepieces.


Using the MaxBright II binoviewer has been a transformative experience for me. I have been binoviewing with my telescopes for over a decade, but the experience has never been what I would call a pleasant one due to the quirks of lesser units.

However, the MaxBright II resolves all the issues I encountered. Its compact size, moderate weight, excellent mechanics and ergonomics and superb optical performance has made me a fan of binoviewing again! Very highly recommended.

Read the author’s comprehensive review of the MaxBright II binoviewer on CloudyNights here..

MSRP: $499



About William Paolini

William "Bill" Paolini has been actively involved in optics and amateur astronomy for 45 years, is author of the desk reference on astronomical eyepieces: Choosing and Using Astronomical Eyepieces which is part of the Patrick Moore Practical Astronomy Series published by Springer of New York, has published numerous product reviews on major online amateur astronomy boards, and volunteers with public tours at a famous vintage Clark refractor site.

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