"F. Craig Callahan" wrote: > > Thomas Bantel wrote: > > > You seem to think about DOF a little different than I do. > > Not necessarily. For my own work I think of it as a zone of apparent sharpness > extending in front of and behind the plane of true focus. The issue of what happens > to image sharpness when enlarged seems to me somewhat tangential, since then we're > talking about a lot of variables, including the resolution of the printing paper, > the sharpness (and focus) of the enlarger lens, viewing distance, etc. >
There have been some responses to your post which have covered most of my point of view, so I'll keep it short. IMHO, the issue of what happens to image sharpness when enlarged, is not at all tangential, it is most important. Most of the shots I would use DEP mode for require a certain area to be acceptable sharp *on the print* up to a certain print size. Canons CoC of 0.035mm would yield acceptable (in my book) prints up to print size of about 4x6 or maybe 5x7 inch. That's not big enough most of the time. I'd prefer this "maximum print size" to be 8x10(12) inch. I also mainly agree with those fellows who say: If it's sharp enough for an 8x10 print, it's sharp enough for any size. This is because starting at some print size (probably around 8x10), the viewer will usually look at bigger prints from a bigger distance. This doesn't work with 4x6, I'll look at the 8x10(12) print from the same distance. I certainly won't with a much bigger print (which will usually be framed and hang on a wall :-)) Well, if the desired zone is sharp on a 8x12, it will be sharp on a 4x6 as well. An even larger zone will be sharp, but that doesn't hurt most of the time. Although, there are rare occasions where in order to achieve "perfection" I'll need to know the final print size exactly, because too much apparent DOF might destroy it. But that's the exception and not the rule (for me). Simply stopping down a lot more to assure enough DOF often doesn't work, because you get too slow shutter speeds with a moving subject or simply for handholding. Argh, did I say "short"? Now it got long again :-( Thomas Bantel * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
