Archived posting to the Leica Users Group, 1997/09/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> I have just been chatting with an ex aerial photographer >who has informed me that normally there is a 40-50% >overlap beteen frames and that only the Center 25% of >the image is used to in making a mosiac for a map. > This means that a lens for aerial work must be very >sharp in the center & the rest is expendable since it isn't >used. This might or might not account for the alleged >use of the un-holy Canon lens by our un-holy agency. > How about it Irwin & Mark and any ex aerial photogs >on the LUG; Do you get flare from the infra red band? > >Marvin Just jumping in here. If you are using standard photographic lenses, flare is a huge issue in IR, as the coatings are not functional in any region except the visible. The lens could conceivably be recoated for a specific portion of the IR spectrum, making it a lot less useful for visible light photography. Also, the interior of the lens barrel may cause a lot more flare in the IR than in the visible region, as the paints may not be as absorptive. With Kodak HIE, all the above doesn't usually degrade the image as much as expected, since the lack of anti-halation backing on the film causes more image degradation than the flare. I used a Canon 0.95 once in the 60's, and in my recollection it wasn't sharp in the center, either. * Henning J. Wulff /|\ Wulff Photography & Design /###\ henningw@archiphoto.com |[ ]| http://www.archiphoto.com