Hi, I'd have thought a lens hood could be arbitrarily long regardless of shape as long as it's based on a cone whose angle is not less than the angle-of-view of the lens. Imagine one of those diagrams that shows you angle-of-view. If you make a cone that matches that then it could be 200 metres long if you wanted it to be. You can make it rectangular if you want, because of course the image area of the film is rectangular, and that would 'cut off' the unused parts of the image circle, provided that the diagonal of the rectangle is equal to the diameter of the cone at the same length. The depth of a lens hood is generally restricted by the hood being a tube rather than a cone.
Does this make sense? It's the sort of thing that needs diagrams. --- Bob mailto:[EMAIL PROTECTED] Friday, March 15, 2002, 10:44:23 PM, you wrote: > The rectangular ones are the most effective, as they allow the greatest depth > without vignetting. > Paul > CBWaters wrote: >> So I've seen a few different types of lens shades (round, tulip, rectangle) >> but I've really no idea what the difference is. I see the pro-video guys >> use mostly round ones while the guys from NFL films use rectangles and I see >> lots of tulips on the pro PJs on the football sidelines. What gives? >> >> Cory Waters >> - >> This message is from the Pentax-Discuss Mail List. To unsubscribe, >> go to http://www.pdml.net and follow the directions. Don't forget to >> visit the Pentax Users' Gallery at http://pug.komkon.org . > - > This message is from the Pentax-Discuss Mail List. To unsubscribe, > go to http://www.pdml.net and follow the directions. Don't forget to > visit the Pentax Users' Gallery at http://pug.komkon.org . - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
