They're confusing digital cameras with shorter than 35mm focal lengths
which is understandable since probably 99% of digis do have small
sensors and shorter lenses and the shorter focal lengths do produce
greater DOF than their 35mm equivalents.
The DOF calculator will be on its way soon. You don't need to know
anything to use it other than to understand that different resolution
values need to be applied for different formats. The default value is
30 lines/mm which is a typical value for 35mm in order to produce a
sharp 8x10 at a 10" viewing distance. That value is also reasonably
close to what most camera manufacturers use on their DOF scales. Since
an E-1 has a 2X "crop factor" over 35mm the equivalent resolution value
would be 60 lines/mm. For a Canyon 300D/350D/400D/10D/20D/30D it should
be 1.6X or 48 lines/mm. Nikon sensors are 1.5X crop factor or 45 lines/mm.
I use the DOF calculator as much for hyperfocal distance as anything. I
find it interesting that hyperfocal distance is something I've known
about for probably close to 40 years but is something I've really only
started to use in the last couple of years. Don't know why. Maybe too
many zooms without DOF scales. But the calculator can recitfy that if
you jot down a few key numbers for some of your lenses at commonly used
apertures.
Actually, I tend to use more what I'll call psuedo-hyperfocal distances
than true hypefocal distances. By pseudo-hyperfocal distance I mean
trying to set an aperture for DOF covering, say, out to about 50 or 60
feet instead of infinity. Just enough to cover a function hall rather
than a landscape. The Minolta A1 at 7mm (28mm equivalent) and 120 lines
resolution will cover from 2.6 - 51.5 feet when focused at 5 feet even
at f/3.5. Too dark to focus? Focus on a bright spot about 5 feet away
and don't bother focusing the rest of the night. DOF calculators are good.
Chuck Norcutt
Bill Pearce wrote:
>>I don't know how film is getting into the equation here and can't
>>understand your first paragraph.
>
>
> Chuck,
>
> I may have misunderstood the original post. I think I read someone stating
> (or inking to someone stating) that dof is different on a 4/3 digital than
> on the equivelent cropped area on film. I've heard a lot of people making
> statements that dof is enhanced/extended by digital cameras. If that isn't
> true, then I simply misunderstood. I'd like to see the calculator, but I AM
> math challenged.
>
> Bill Pearce
>
>
> ==============================================
> List usage info: http://www.zuikoholic.com
> List nannies: olympusadmin@xxxxxxxxxx
> ==============================================
>
>
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|