Re: [Leica] Digital Aesthetic

["Red Dawn" <reddawn@singnet.com.sg>]

- ----- Original Message -----
From: "Jim Laurel" <jplaurel@nwlink.com>
Subject: [Leica] Digital Aesthetic



> Correct me if I'm wrong, but I believe depth of field is related to focal
> length and aperture size alone.  The depth of field of a 25mm lens is the
> same regardless of the size of the film or digital sensor.  Consider the
> example above and let's assume that the film shooter is using a 50mm set
to
> f1.4.  To acheive the same FOV, the DSLR user will need a 31mm lens.  But
> lenses around this focal length with maximum apertures of f1.4 are few and
> far between, not to mention that a 31mm lens at f1.4 will still have more
> DOF than a 50mm at 1.4.  The DSLR shooter could use the same 50mm f1.4
lens,
> and back off from the subject, but then again, the increased distance to
> subject will result in increased DOF.

Hi Jim,

i do believe u're wrong.

Let's take the EOS 10D with a 50mm f1.4 lens (a combo which i happen to own
as well) and shoot a subject at f1.4. The equivalent focal length is 50 x
1.6 = 80mm.

Now let's then take a 80mm R Summilux and mount it on a EOS 1v film body
(again i also own this body), frame the SAME subject and keep the
composition and subject size EXACTLY THE SAME.

The 2 pictures will look identical because we have kept the subject size /
magnification and framing the SAME. If u compare the 2 shots, they will have
the SAME DOF. This is because the subject distance is constant, and so is
the aperture.

Remember, DOF is also affected by subject distance! Don't take my word for
it though - do your own visual tests and find out for yourself :)

The only thing u're right is the difficult of finding lenses to simulate
your favourite focal lengths. U're right in the sense if u want a TRUE 50mm
on a DSLR, and nothing but a 50mm, it is impossible to find a 31mm lens that
will fit the bill. However, you can use a 35mm lens on the 10D to simulate
56mm.

Can you really tell the difference between 56mm and 50mm in actual real life
shooting? I don't think so :)

Boon Hwee

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