• 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. tenex

    Telescope light transmission figures

    It's a good question. I think your intuition may be sound: transmission ends up lower for zoom eyepieces due to their complexity -- and I'd suggest also budget models like a CTC drawtube due to simpler coatings. Someone could measure it for top-quality scopes with prime eyepieces to confirm...