Optics Reports Publishing

The ease with which the product is actually used is critical to minimizing fatigue and maximizing the enjoyment of the product. Location of controls, weight, size, balance, etc., all play a role in the usability of the product. We usually involve at least two reviewers to get a balanced assessment of this subjective part of the product review.

Binoculars: Eyepiece design is a particularly tough challenge in the case of binoculars. Unlike other types of telescopic visual optics, it is difficult for the viewer to adjust for the moving eye pupil as the eye pans left and right. Optical designers must strike a balance between field of view, eye relief and comfort (size of the eyepiece). No two manufacturers strike the same balance, which gives rise to a lot of variation in this aspect of the optical performance. A poor design can result in eye strain, arm/shoulder fatigue, nonuniform illumination, degraded field of view, etc.

Rifle Scopes: The rifle scope eyepiece is unique because of the long eye relief required to prevent impact with the eyebrow due to rifle recoil, and the complexity of the riflescope design, which includes two afocal telescopes, one (the erector) inside the other. There are two closely related aspects to the rifle scope design that we assess:
   - Sight picture (view of the aiming reticle superimposed upon the target image)
   - Eyebox sensitivity (sensitivity of the sight picture to movement of the eye across the exit pupil)

If the sight picture degrades when the elevation/windage are adjusted close to the mechanical limit, the rifle scope utility can be compromised. Therefore we pay particular attention to function of the rifle scope at the extreme limits of turret elevation adjustment. The moving entrance aperture of the erector telescope can also effect the sight picture.

Entrance and exit optics are always cleaned before making optical measurements. Nothing degrades image contrast like dirty optics. We note whether or not the scope has hydrophobic lens coatings. These coatings are more durable, easier to clean and stay clean longer than conventional anti-reflection coatings. The ease of cleaning the optics is noted in the review because the easier they are to clean, the more likely they will stay clean in the field and the more durable they are.