Archived posting to the Leica Users Group, 2002/05/05
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]In a recent thread initiated by Javier Perez the pro and cons of certain binoculars were scratched. Needles to say that there exists a huge spectrum of binoculars with all kinds of features on the market, and it is easy to spend 1000 of $ and still get the wrong one. Allow me to share a few observations I have made with binoculars: First of all, aberrations are not as much a topic as they are for camera lenses. The image in a binocular will not be recorded and blown up to poster size - you see a life image, which may be shaking in your hands, so that parts of the microstructure are lost anyway. Distortion can be annoying, however. A good coating is mandatory, so that ghost images are quite common in some cheaper models, and you will prefer to have a wide angle of view and robust mechanics - these are important features of a binocular. If someone asks me which binocular to buy, I will first of all find out what it is going to be used for. This will set the range for the magnification. The general rule is: Do not go for higher magnification than neccessary. 10x is about the limit which can be hand-held, and a tripod would spoil the mobility of the device. Image stabilization is a possible solution, but expensive and it could make you depend on batteries (the Zeiss IS does not need batteries, however the price of the 20x60 may be around 4000$). For cruising around in the mountains, 6x is already fine, for observing birds 10x is useful, to enjoy craters of the moon and the rings of saturn, 20x is more adequate. If you need a high magnification, you will need IS or a tripod. But you may then also consider to get a telescope instead. Next question is: Is it to be used during bright daytime or also in twilight (e.g. for hunting)? The diameter of the objective lens will determine the amount of light entering the device, and also its weight, of course. The exit pupil (ep) diameter can be evaluated using ep = (Objective diameter)/magnification For twilight use, it should have at least 5 mm, but once it is larger than the pupil of the human eye, light is wasted, which leads to a limit of 6-7mm depending on the individual who is using this binocular (elder people usually have a smaller pupil size). Is the binocular to be used in tough conditions? In this case, military devices are adequate because they are obviously quite rugged (beware of those faked 'military look' binoculars). I do not quite agree with Marc James Small that one has to spend two or three times of 500 $ for a decent binocular. I am using a DF 7x40 of the East German NVA which was produced by Carl Zeiss Jena and is available on e-bay for 150$ (good condition). This one is lying in my hands as if it were glued to, giving a bright and steady wide field image. Its mechanics appears undestroyable. If you spend 1000$ or more, you will surely get quality, but it is possible to get it for less. Here, someone has tested many binoculars for astronomical applications: http://www.weatherman.com/BINOCS.HTM These kind of tests are quite selective, because astronomical objects are often pointlike and bright so that aberrations and reflexions become easily visible. Alltogether I think Leica has no outstanding position on the binocular market. Others are similarly good and usually cheaper. First of all, however, find out what you really need it for and then spend as much money as necessary to satisfy your needs. Holger Merlitz, Karlsruhe - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html