Click here if you are having trouble logging into the forums Cloudy Nights - Official Forums of the 2009 International Year of Astronomy Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User   You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> Binoculars Previous   Index   Next   Flat   EdZ Professor EdZ Reged: 02/15/02 Posts: 12569 Loc: Cumberland, R I , USA42N71.4W Edge Performance - Sharpness of Field       02/06/04 11:48 AM Edit   Reply   Quote   Quick Reply:   In most binoculars, the image deteriorates the further out from the center of the field of view. Some binoculars have special lenses that help alleviate this problem, and some are just better than others. In general the wider the field of view, the more distortions present at the outer edges of the field of view. There are many threads where a brief comment is made about edge sharpness, but this one thread covers it in detail. Here is a good discussion related to edge performance. Edge Performance Also, you must recognize that edge performance, as noted in a concise statement made by Kenny in the thread above, "["Edge performance" is in itself a rather inadequate title to cover what I consider to be an attempt to categorise what could encompass a whole range of possibly quite different and unrelated properties of an optical system.]", can be caused by a number of issues. To understand better the causes, you should also read the Best Of thread titled Binocular ABERRATIONS AND DEFICIENCIES Another thread related to the same topic, once again initiated by Kenny J True ( SHARP ) field of view See also this table of measured Binocular Field Sharpness for approx 30 binoculars So often we hear brief reports about new binoculars to the effect, "this binocular is pinpoint sharp from edge to edge", or "I can only see distortion in the outer 5%-10% of the fov". How are we to believe subjective statements that are not supported by accurate measurments? Frankly, I have tested over 35 different binoculars and have found no fixed power binoculars that are sharp edge to edge and I have found only 2 or 3 that do not exhibit undesirable un-sharpness beyond 80-85% out. With well corrected eyepieces in variable power Binocular Telescopes, you can achieve edge to edge sharpness. This table shows results for a standardized means of measuring that sharpness across all brands of binoculars. It eliminates the subjectiveness. edz Edited by EdZ (08/24/06 04:06 PM) Post Extras       Entire thread Subject Posted by Posted on "BEST OF" the Binocular Forum - Start Here EdZ 01/24/04 07:51 AM GOOD STUFF FOR BEGINNERS EdZ   01/26/07 01:48 PM First Binocular Purchase? Questions? EdZ   01/26/07 01:47 PM Binoviewer - Scope - Binocular Equivalents EdZ   01/26/07 01:46 PM Surface Brightness of Extended Objects EdZ   03/17/06 04:00 PM Polish Binocular Tests and Reviews EdZ   03/07/06 09:52 AM Writing a Binocular Review EdZ   10/29/05 12:29 PM Limiting Magnitude and NELM EdZ   10/29/05 12:28 PM Resolution Testing and USAF Res Charts EdZ   10/29/05 12:27 PM Chromatic Aberration, Triplets, Semi-Apo, Apo EdZ   10/29/05 11:41 AM Dark Adaptation, Eye Pupils, Lights EdZ   08/25/05 10:50 AM BOOKS for Binocular Observers EdZ   06/02/05 07:46 PM Binocular Deep Magnitude Observing Charts EdZ   05/03/05 07:45 PM Binocular Photo Gallery EdZ   03/28/05 11:05 AM Binocular Vision Summation - Two Eyes vs One Eye EdZ   02/10/05 11:53 AM POLLS in Binocular Forum - take a poll EdZ   02/10/05 11:52 AM Testing Binoculars in the Store Before Buying EdZ   01/15/05 09:29 PM In Pursuit of Cheap Binoculars. What to Expect. EdZ   12/30/04 12:07 PM Handheld Binocular Observing EdZ   12/29/04 07:30 AM Fixed Focus Binoculars EdZ   12/16/04 12:08 PM BINOCULAR OBSERVING REPORTS AND TARGET LISTS EdZ   12/10/04 06:42 PM Depth of Field and 3D or not 3D! EdZ   12/10/04 06:36 PM What can be Seen in Various Sizes Binoculars EdZ   09/19/04 06:21 PM Philosophy and Binocular Ownership by Bill Cook EdZ   09/12/04 03:30 PM Affect of Eye Pupil on Binocular Aperture EdZ   07/22/04 11:38 AM Favorite Binoculars in Various Sizes EdZ   07/22/04 11:37 AM Best binocular overall or in a given price range EdZ   07/22/04 11:36 AM MEASURING / TESTING Optical Aspects of Binoculars EdZ   03/21/04 03:30 PM Contrast EdZ   03/20/04 08:48 PM Need Binocular Collimation or Repair? EdZ   03/17/04 12:08 PM Cleaning Lenses - Binoc Repair Eyeguards - Caps EdZ   03/15/04 09:36 AM If They Look the Same, What Could be Different? EdZ   03/15/04 07:06 AM Binocular Articles over on the Reviews side of CN EdZ   03/03/04 10:55 PM ABERRATIONS AND DEFICIENCIES EdZ   03/02/04 06:49 AM How to Focus Binoculars EdZ   02/07/04 10:18 AM Binocular Mounts - Tripods - Adapters - Motions - Homemade EdZ   02/07/04 10:17 AM PRISMS - BaK 4 vs BK 7 - Roof vs Porro EdZ   02/06/04 11:49 AM Edge Performance - Sharpness of Field EdZ   02/06/04 11:48 AM Terrestrial Viewing EdZ   02/05/04 06:23 AM Resolution and Visual Acuity EdZ   02/03/04 09:10 PM Aperture / Magnification relationship - Exit Pupil EdZ   02/03/04 09:04 PM Coatings EdZ   01/25/04 09:31 PM Zoom Binocular Cautions! EdZ   01/25/04 08:58 PM Exit Pupils 5mm vs 7mm EdZ   01/25/04 07:50 AM AFOV vs. TFOV and Separations for Measuring EdZ   01/24/04 01:48 PM Twilight Factor - Visibility - Binoc Index EdZ   01/24/04 01:43 PM Extra information 19 registered and 29 anonymous users are browsing this forum. 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