Sorry that this is being posted somewhat late after the original message about 600mm lenses--Aerosmith was in town and, well, first things first!.
I use Nikkor 200mm f/2 and 300mm f/2.8 lenses ( which are just super), and sometimes combine these with the Nikkor TC-200 and TC-300 tele-convertors to form 400mm f/4 and 600mm f/5.6 lenses for special occasions. There is less weight and less expense for the few times that I need to use such long lenses. When in the 600mm mode, I use either a brace on the lens barrel that is connected to the tripod leg or TWO light weight tripods to hold that monster tight. It depends on how much heavy equipment I want to lug around and other factors. I'd rather use the prime lens as a 300mm, and, if the image were too small, then crop the photo for use in some publication than to haul my big tripod everywhere I go--I have a herniated disk in my back and arthritis in my knees, so I am not much interested in carrying heavy stuff or walking very far. I have run into very few circumstances (e.g. photo for a magazine cover that cannot be cropped any more without losing too much quality) where I absolutely had to use the 600mm rig. Depth of field is nil, camera shake is magnified by a factor of 12X vs. the "normal" 50mm lens and by 2X for the 300mm lens, and heat from the railroad tracks precludes the use of such long lenses in the afternoon after the rails have heated up. Because of this 2X magnification from a 300mm lens, with a 600mm lens you would need twice as fast a shutter speed to freeze action as opposed to the 300mm. I have found that getting a little closer to the subject and using the 300mm oftentimes is better than using the same lens with the 2X tele-converter in order to produce the 600mm lens. In any event, buy the fastest, sharpest lens that you can afford. John B. Corns --LAA24732.883763216/tscrypt1.transcrypt.com-- --------- End forwarded message ---------- -> SPORRS: Serious Photographers of Railroad Related Subjects -> Web Site: http://www.anet-stl.com/acphotog/sporrs
