• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Search results

  1. elkcub

    blackouts at AFOV of greater than 60 degrees- why

    Pat, Please read the section entitled "Spherical Aberration of the Exit Pupil" at the end of this article. "Spherical aberration of the exit pupil almost exclusively afflicts eyepiece designs with fields larger than 60° — wide angle or super wide angle eyepieces. Given the limitations of the...