Olympus-OM
[Top] [All Lists]

[OM] hand-holding SLRs and RFs; 24mm shift

Subject: [OM] hand-holding SLRs and RFs; 24mm shift
From: William Sommerwerck <williams@xxxxxxxxxx>
Date: Tue, 09 Feb 1999 06:25:24 -0800
"The general "rule of thumb" to avoid camera shake is to use a shutter
speed of at least the inverse of the focal length in question... Is
there an advantage held by rangefinders due to their lack of mirror
bounce that is significant? If so what is that advantage in F stops --
1, 1/2 or less?"

To answer this question, you have to make a distinction between camera
shake at normal speeds and shake at slow speeds.

At normal speeds (1/60 or faster), you usually don't do anything special
to brace the camera. The "muscle shake" that occurs when you try to hold
still can cause visible blur, especially with longer lenses that are
hard to hold in the first place. At these speeds, the RF camera _does
not_ have an advantage (unless the SLR "slaps" especially hard).

At slow speeds, the photographer is consciously trying to hold the
camera still during a long exposure. Even if you lean against a wall or
on a table, you still have to avoid moving your hands. In this case, the
RF camera _does_ have an advantage, but not because of mirror slap.
Rather, being able to see the subject _continuously_ provides feedback
that makes it easier to hold the camera steady.

I use both RF cameras (35mm P&S and Polaroid pack cameras) and SLRs. I
can't give an exact figure, but you can assume at least a one-stop
improvement with an RF camera -- and I'd say it's _at least_ two stops.

I've read that _not_ drinking coffee helps, but since I don't drink
coffee, I can't comment. On the other hand, I find when shooting with
SLRs it helps to ignore the viewfinder and keep your left eye on the
subject during the exposure.


"If a 24mm lens has an 84 degree angle of view, and if you used maximum
shift of 10mm on the 24mm shift, what would be the equivalent
rectilinear wide angle to take in the same undistorted image? (This is
difficult to ask clearly). Would a 14mm or 15mm allow me to to use just
the top half of the photo to keep rectilinearity and would this allow me
to get in more of the building than the 24 shift? In other words, would
this be a good lens to take on a slot canyon trip?"

I think you're confusing the focal length of a lens with its coverage.
The two have nothing to do with each other.

A 24mm lens is a 24mm lens, regardless of its coverage. The 24mm shift
has significantly wider coverage than a regular 24mm lens, but it's
still a 24mm lens, and produces exactly the same image size as any other
24mm lens. Being able to shift it does not give you a wider field of
view than you would get with a regular 24mm lens. If a regular 24mm lens
won't give you the field of view you want, neither will a 24mm shift.

I _think_ what you're asking is this... The 24mm lens shows what you
want to show, but you have to TIP IT UP, and that produces unacceptable
convergence. (The lens and its image are still rectilinear, converging
lines or not.) You want to be able to photograph the canyon, etc,
without obvious convergence of vertical lines. My guess is that a 14mm
lens has a wider angle of view than a 24mm shift at full coverage, and
should therefore allow you to get in "everything" without having to tip
the camera.

< 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 >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz