The Herschell wedge is a useful item for solar observing and yes, it does require additional filtering. A good Herschell wedge will cut down the light to the eyepiece about 100 times so only 1% of the light gets to the eyepiece. This is still way to much for safe viewing so a solar filter is still required at the eyepiece. The majority of the heat from the solar image passes straight through the wedge so that you must be careful not to get anything where the image will be. The observers hand is the thing that usually gets burned. The Herschell wedge works very much like the dimming rear view mirror on most cars except that it is not silvered. Mylar filters are are just as good but not necessarily better than a wedge but are certainly easier to come by and can be used with larger objectives. Try using the wedge on Venus and the Moon. The reduction in brightness can be a big improvment.

• Safety is the question... - crockett - May 16, 2000 - 16:39 UTC
  • RE: Safety is the question... - Bill G - May 18, 2000 - 02:24 UTC