Norman Chappell wrote: > What many of you seem to be forgetting in the latest edition of this thread > is that A-DEP mode is basically provided for use with zoom lenses, on which > it is virtually impossible to incorporate DoF scales.
It's apparently not easy to incorporate a usable DoF scale on most AF primes, either. > Also it is clear that others don't really understand why or how A-DEP does > what it does. The DoF at a given aperture changes with focal length, so it > needs to be recalculated for each zoom setting. That's what the camera's > processor does in A-DEP mode. Correct me if I'm wrong, but I think the thread began with DEP rather A-DEP (which the EOS-1/1n/1v don't have and with which I'll admit I'm not really familiar). The complaint was that the high-end EOS-1/1n/1v lacked a very simple capability that the EOS-5/A2/A2E had included. > The reason Canon don't provide a "shift" capability is that it would > basically defeat the entire purpose that the mode is meant to be used for. > There may sometimes be a need for more DoF (smaller CoC) but almost never > for less (larger CoC). Canon did provide such a "shift" on the EOS 5/A2/A2E and several others. The focus distance is independent of f-number (and focal length, for that matter), so selecting a smaller aperture defeated nothing. Again, doing so was akin to what users of manual-focus lenses have done for years. > I think the suggestion of a CF to select a preferred Circle of Confusion is > an excellent one as long as 0.035mm is used as the starting point and the > range were say 0.025mm & 0.017mm. That would probably keep everyone happy. > And the argument that it wouldn't get used enough doesn't hold water as you > can say that about most CFs. That's why they are programmable CFs and not > finger operated controls. I think the comment about minimal use pertained more to DEP mode, period, than to a specific CF. > I'd almost be willing to bet that this is how Canon will implement this > function in their bodies when there is sufficient consumer demand. As I've mentioned quite a few times, this would be a desirable feature, especially if combined with an improved algorithm that made use of the distance information provided by most E-mount lenses. Canon could even provide the option for different CoCs for the near and far limits of DoF for people who chose to use Harold Merklinger's "object field" method of determining DoF ... Jeff Conrad * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
