I think no one can make sure the DOF (min. 30 lp/mm resolution in 35mm
camera) can cover the subject by looking at the viewfinder. For me,
the DOF button is for pre-view the result of the shoot, mainly for
checking the out-of-focus effect. Sometimes when you stop down too
much the out-fo background can be very distracting.
DOF should not related to the size of your output. Frieder explained
very well, you should keep a suitable viewing distance for the size of
prints.
The DOF scale marked on the lens works very well for me except macros
which I normally stop down to f16 for flash work or minimum
aperture/shutter combination which I can hand hold.
Talking about 90/2, which is a lens that can nicely balance between
distance object and 1:2 but it does not really perform very well at
macro mode, with my own experience and the result from Modern
photography, it is only a so so lens for macro works. For serious
macro, you should try 50/3.5 or 80/4.
C.H.Ling
Eric Pederson wrote:
>
> Greetings!
>
> I'm trying to reenter photography (well as much as the kids will allow)
> mostly using my OM equipment. And I realize that I don't know the answer
> to a question that had been nagging me decades ago!
>
> I find the d.o.f. preview button not very useful since my eye can't
> resolve near focus distances with sufficient precision in the viewfinder
> (I bet yours can't either). So using a non-visual calculation of d.o.f. is
> often useful to me. The markings on the lens are a good starting point for
> estimates, but I would love some rules of thumb to work from those.
>
> To wit, how are the depth of field indicators on Zuiko lenses calculated?
> Basically, they need to arbitrarily decide on a value for the Circle of
> Confusion. Is this 30 microns for all lenses (I read somewhere that this
> is fairly standard in the 35mm format, but I can't recall the reference
> or estimate its reliability)?
>
> Since the allowable value for the circle of confusion should vary with the
> anticipated enlargement (and to a lesser degree film speed/graininess), it
> would be useful to be able to reestimate d.o.f. for different values of
> the c.o.c. from the lenses as well. Is there a way to interpret e.g. the
> f8 mark as giving the f8 depth of field at 30 microns, but the f16
> indicating the same f8 depth but at ~100 microns?
>
> Similarly, any tricks for extended lenses (especially with the 14 and 25
> mm rings)? I find that my sense of d.o.f. is almost always off from the
> finished product with my very amateur macro work (mostly with the 90mm f2
> portrait lens which does a decent job pretending to be a macro lens)
>
> I'll happily summarize off-list replies, but this group seems to do
> everything on-list... :-)
>
> Thanks in advance!
> Eric
>
> =====
> Eric Pederson
> epederso@xxxxxxxxxxxxxxxxxxxx (no "n" in "epederso")
> Professional home page:
> http://logos.uoregon.edu/uoling/faculty/pederson/pederson.html
> Personal home page:
> http://darkwing.uoregon.edu/~epederso/
>
> < This message was delivered via the Olympus Mailing List >
> < For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
> < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|