Based on your comments I have filed the Merklinger paper for eventual
in-depth perusal which will include reading the last half of the paper
which I haven't done. However, I did view the sample photos of his
sister-in-law and concluded that he was trying to redefine the depth of
field problem in different terms... terms that I wasn't interested in.
Although he may be interested in knowing if June is recognizable as June
at 50 meters I'm not. I want to know if June is critically sharp at 50
meters for a 16x20 print and she's not. In trying to translate his
lesson into terms relevant to landscape photography, for example, I'm
led to wondering whether I might have concerns about where leaves are
recognizable as leaves or in a larger scale where bushes or trees are
recognizable as such. Although I accept that the main subject should
surely be in critical focus relevant to the print size I'm having
trouble viewing the world as a fractal where I have to be concerned
whether bits of it can be sufficiently enlarged to be recognizable as
what they are. I can't see planning my photographs to that degree.
And I don't agree DoF markings on lenses are hopeless. Although 1930's
definitions of film and lens resolution abilities may underlie the
assumption that you won't make an enlargement bigger than about 8X the
more fundamental assumption has to do with the resolution of the eye at
normal reading distance. That assumption is as valid today as it was in
1930. If your lens and film/sensor can resolve enough detail for a
crisp 16x20 rather than an 8x10 that's good. But it doesn't obviate the
accuracy of the DoF markings when used as intended... for an 8x10 max
print size. If you want to double the image size and make a 16x20 you
can use the scale for two stops smaller aperture. Eventually, of
course, you begin to run into diffraction limits or, more practically,
the limits imposed by numerous optical imperfections of your particular
lens and aperture combination. For that you need to discard the
calculator and do some empirical tests.
As I said, I will eventually read and probably re-read Merklinger's
paper in depth but I'm not in any hurry. But I'll be happy to listen to
anyone who points out why I should be.
Chuck Norcutt
Piers Hemy wrote:
> Most people I have introduced to Merklinger's work have the same reaction as
> Chuck and Iwert. BUT my experience is that the DoF markings on modern
> lenses are hopelessly optimistic - I suspect it is because modern lenses and
> film can vastly outperform those of the 1930s, when the definitions
> underlying DoF tables were "agreed".
>
> If you do make it through to his example images, you might be in for a
> surprise.
>
> I originally came to his DoF paper having found his work on focusing view
> cameras - and by extension, tilt lenses. For that application, I found that
> his explanations were absolutely spot-on.
>
> --
> Piers
>
>
> -----Original Message-----
> From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
> Of usher99@xxxxxxx
> Sent: 30 November 2007 00:37
> To: olympus@xxxxxxxxxx
> Subject: [OM] Is the emperor called hyperfocal distance that well dressed?
>
>
> Interesting argument that if one desires infinity to be in? sharp focus
> focus at infinity with little loss. Hyperfocal distance has its drawbacks.??
> Probably depends on what the emphasis of the image is.?
> Only read? the paper in a cursory fashion and we'll see what Dr. Focus et al
> have to say.
>
>
> Mike
>
>
> http://www.trenholm.org/hmmerk/TIAOOFe.pdf
>
>
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