David Lehlbach wrote: > I recently upgraded my non-d Nikon 80-200 F2.8 AF-ED to the new version > with the tripod collar. I did the same thing last November.
> That said, I see one optical difference between the old and the new - > the new one is alot more touchy in focusing than the old one. Actually there is no optical difference in these two lenses, what you are seeing is the effects of a shorter focus throw. > The reason for this design modification was to speed up its autofocusing > abilities Secondarily. The design modification was required because the room occupied by the tripod collar necessitated a two ring zoom design this time in order to keep the lens about the same size and weight as the old one. > (I shoot with manual focus so this doesn't matter to me > anyway), Me too (for the most part)... > but it seems that in the process the lens puts the background > out of focus faster with this version than the old. Am I nuts??? No. This is because this lens requires much less focus throw to achieve the same focus changes. Turn your focus ring very slowly and you will see this. Keep in mind that this pro lens was designed with auto focus primarily in mind, and even though it is 'touchier' that the previous version manually, a photographer proficient in manual focusing skills usually prefers a shorter focus throw. (This information is based on the feedback that Nikon receives from its NPS members, not the general camera buying public). > Nikon claims there is no optical difference between the old versions and the > current one. Nikon is correct. Only the focus method has changed. > - when I focus on an object that is closer than infinity (often times > the lead unit of the train falls into this criteria), the background > goes out of focus faster as I focus closer Correct, this is due to less focus throw necessary for this new lens to refocus on any given point. > - as though the focus is more "touchy" in this version, Exactly. > and this touchiness has affected the infinity > range of this lens. No, this is incorrect. That is a perception amplified by the faster focusing response. There are three things that will effect the way the depth of field will look through any given lens when it is wide open. The first two we can't control much because they are inherent to the lens design. One is the amount of coma correction designed into the lens formula (this is how Nikon's De-Focus portrait lenses work, by adjusting this) and the second is the maximum aperture of the lens, which is effectively what you are looking through when the auto diaphragm is held open to its widest aperture (smallest F number) by the camera and you are looking through it. When you look through a 2.8 lens, less seems sharp than when you look through a 4.0 lens of the same focal length. This is because you are seeing an image through a smaller aperture with the slower lens which appears as more depth of field on your focusing screen and this also means that the 2.8 lens will 'isolate' the area that you focus on better, so it is easier to focus with that lens. To compare a 2.8 80-200 with a 4.0 80-200, you would have to stop the 2.8 lens down one stop to 4.0 to have a fair comparison. This is why my 35mm 1.4 lens is easier to focus than my 35mm 2.0 lens was. You can literally see the area that you are focusing on better (more isolated and also brighter). This is true of all faster lenses. If you want to check depth of field during (a pro trick) or after you focus, use the depth of field stop down button to view your image at the actual intended shooting aperture while things are moving. You will be sure to contain the desired action in your depth of field this way. Knowledge of the 1/3 - 2/3 depth of field limitations at your particular lens's different apertures (and yes, autofocus!) will help you (and you better know this with new auto everything cameras because they don't let you do some of these things anymore!). Things will look darker (and harder to see) when stopped down, but this does not effect the exposure, (assuming you are correctly exposing in the first place), and you are not on auto exposure where DOF preview is not possible on some cameras now (and this is why!). That third thing is the degree of focus ring throw required to move the lens elements into focus between any two given points. Nikon didn't change the optical formula on this particular lens, but they did change the method of control that you have over focusing with this new model. Ten months later, I like to manually focus with this new version better despite the slight focus ring play. Zooming was easier with the old model though when shooting hand held. But that's what the tripod collar is for on this new one. The old one was more suited for hand held photojournalism, while the new one is better suited for autofocus operation. And it has a tripod collar for us railfans. :) > Depth of field on an image drives me nuts - I want EVERYTHING in > focus!!! Not always easy with slow film and low light! Don't forget DOF is a control tool that we can use at our disposal to emphasize an area as well as assure tack sharp landscapes! We need as much control as we can get sometimes. Dave Cohen Photographer [EMAIL PROTECTED] --> SPORRS: Serious Photographers of Railroad Related Subjects
