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Message: <blockquote data-quote="henry link" data-source="post: 1228728" data-attributes="member: 6806">I was able to spend more time with the 7x42 EDG prototype today. This time I concentrated  on comparing its off-axis behavior to several other binoculars (Zeiss 7x42 FL, Leica 8x42 Ultravid, Nikon 8x42 LX L, Swarovski 8.5x42 EL and Nikon 8x32 SE).  I also compared the glass reflection patterns and colors between the EDG and the LX L to try to see how things have changed in the new binocular.Beginning with the reflection patterns, I found that the optical formula for the EDG and LX L  eyepieces appears to be almost, but not quite, identical. The reflections at the objective end were also very similar. I don’t think any radical change has been made to the basic optics.  In fact, I found the pattern of off axis performance in the new binocular to be nearly identical to the old one as to astigmatism, field curvature and distortion.  The big improvements in the EDG are in the areas of light transmission, color accuracy and lateral color. The coatings colors are slightly different. Some reflections that are green in the LXL are an almost colorless dark gray in the EDG.To test off-axis astigmatism and field curvature I use a ruler with a grid pattern placed vertically through the middle of the field. I focus on the center, then examine the deterioration in the sharpness of the grid pattern as I move my eye to the bottom of the field. Binoculars with a large amount of astigmatism will not allow the vertical and horizontal lines of the grid to be focused simultaneously near the edge. The higher the astigmatism the more focus shift is required to change from sagittal focus on the horizontal lines to tangential focus on the vertical lines. Binoculars with mostly field curvature soften at the edge, but can be refocused for both vertical and horizontal lines simultaneously. I refocus the edge for “best” focus on both sets of lines, then compare that to center focus, using reading glasses of different strengths to measure field curvature. The off axis performance of the EDG and LX L were superior to any of the other binoculars in this test, even the excellent SE. The Zeiss FL has the most off axis astigmatism and the softest field edge, followed by the Leica and Swarovski. All three Nikons showed lower astigmatism and sharper field edges, but the SE has about 2.5-3 diopters of field curvature while the EDG and LXL have only about 1.5 diopters, so for my unaccommodating eye the EDG and LX L look sharper at the edge than the SE. Today’s tests reinforce my earlier impression that the EDG binoculars should be very strong competition. This prototype gives up just a little brightness to the AK prism of the Zeiss FL, but is easily superior to the Zeiss, Leica Ultravid and Swarovski EL off axis.</blockquote>

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