Archived posting to the Leica Users Group, 2000/11/15

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Subject: Re: [Leica] composition, exposure & dof
From: "Rodgers, David" <david.rodgers@xo.com>
Date: Wed, 15 Nov 2000 12:41:17 -0600

Martin

You digitally scribed the following:

>>They are invaluable for zone-focussing.  I often set my lens (35mm or
50mm)
at 3m with an aperture of f/5.6 or f/8.  The DOF markings remind me of what
will be sharp in the final picture and then I can use my feet to get the
subject within that zone.<<

I agree that the dof markings on Leica lenses are  very valuable. And not
just for zone focusing. Sometimes I'll use the rangefinder to pinpoint an an
object that I want to be the near or far in focus point. Then I'll move that
point to the near or far dof marking for the aperture I'm using. It's much
easier to do that on the M system than any SLR system I've used.  IMHO, I
think that's one of the real strengths of the M. 

I guess every company has a different circle of confusion that they deem "in
focus". Based on the dof markings I've found Leica to be very conservative
in that respect. 

One thing I could never get accustomed to with AF lenses was the lack of
dof markings. It's like dof was no longer an important consideration in
photography! 

IMO the concept of dof is often misunderstood. It's not like there are two
walls and everything between is in sharp focus and everything outside is a
blur. (Unless you're using one of the Nikon DC lenses). Lots of factors
exists, and they may or may not come into play in a given photograph. 

Degree of enlargement a significant role. For instance, the dof markings on
a Leica lens may appear to be extremely conservative if the final image will
only be 5X7. But the markings ring true final image will be enlarged to
16X24. (Assuming, of course, that both images are viewed at the same
distance). 

I'll give a more practical example. I shot a portrait with a number of
candles in the photograph. It was in low light. I used my 35/1.4 ASPH. I
wanted the candles immediately behind and in front of the subject in focus.
I focused on the two candles and found that f2.8 was the appropriate
aperture to use. Then I put the near candle focus point at the near f2.8
marking. I made some 5X7 work prints. All the candles appeared to be in
focus. But when I enlarged to 11X14 the two candles I wanted in focus --
plus the subject -- were all in sharp focus, but those candles closer and
further were obviously out of focus. It added depth to the image. 

When I cropped down a frame (still an 11X14 print, but the degree of
enlargement was more like 20X30) dof was even more apparent. So here's the
same photograph, but based on the degree of enlargement dof markings on the
lens went from meaningless to very important. DOF isn't always critical, but
it's always a consideration. I appreciate the fact that dof markings are
there on Leica lenses when I need them.  

BTW, on the subject of image size, I can honestly say that I  didn't fully
appreciate Leica lenses -- and that includes the little things like accurate
dof markings -- until I began to make bigger enlargements (on a well aligned
enlarger with good lenses I might add). Yesterday evening I was at Mark
Rabiner's studio. He pulled our some really large prints (some 30X40) from
his archives. They were very impressive, especially when you consider that
the margin for error anywhere in the process is nil when making an
enlargement of that size from 35mm.   

Leica! There is no substitute! 

Dave