As the "shake" of the camera increases directly with the focal length
of the lens (distance travelled at the "other" end is longer - here
"other" refers to what is being captured), I would say that the only
thing that matters should be the "effective" focal length of the lens
being used. So, with a 50mm lens on a 1.6x camera the "hand-holdable"
shutter speed would be 1/80. The nominal specs of the lens should not
matter.

-arifi

Since a 120 film photo is being enlarged less than a 35mm one, then to
get the same degree of camera shake the shutter speed of the roll film
camera can actually be slower for a given focal length. However, other
factors are important.

First, the type of camera matters; SLRs do tend to suffer internal
movements on taking a photo more than rangefinders; conversely a light
camera is more susceptible to moving than a heavy one (more inertia).
The best camera I use for shake is a Mamiya 6 (a heavy rangefinder)
which can with care give usable results at 1/30 with a 50mm lens.

Second, the use of the result matters. You can get away with a lot more
on a photo for printing at 4x6" or for web display than you can on one
for printing at 12x16". Since the main reason people use 120 film is to
get ultimate quality, they probably want less camera shake.

Third, the person's own skill at hand-holding varies a lot. I have known
people who would need to use 1/4f not 1/f seconds to get a sharp result.
Personally I try to use 1/2f where I can; though I get usable results at
1/f, those at 1/2f are sharper under critical examination.

Given the extra magnification required from an APS-C sized image to get
a given sized output, then the "35mm equivalent" would be closer to the
mark.

1/90.

Even for normal-to-wide, there is a cut-off point!

David

arifi wrote:

That would be my take, too -- the "effective" focal length of the lens.
Keep in mind that this old rule of thumb is for you to obtain
"hand-holdable" shots the "majority" of the time -- presuming you know
how to properly hold a camera ;-)  We SLR shooter usually do, but the
point-n-shoot people don't usually get the benefits of a "3-point
holding system" (your two hands - with your elbows braced against your
body, and with the camera's eye-piece and back braced against your
cheek, nose and forehead).

Have you noticed how most of the point-n-shoot people avoid their eye
level viewfinders like the plague, and instead use their LCD screen in
real-time video display to view and frame their images?  This comes
from imitating the way most have chosen to shoot their video-cams --
holding the camera out away from them at arms length as they view their
LCD displays!  In fact, many of the consumer "slimline" digital cameras
have NO eye-level viewfinders anymore.

STABILIZATION: Lenses with the stabilization feature will often enable
you to reduce your shutter speed by a factor of 2 (going from say,
1/125 to 1/30) and sometimes to a factor of 3 (down to 1/15); but
REMEMBER: stabilization has no effect on the subject's movement  ....a
little problem I sometimes keep forgetting when I'm photographing
active children!

Another method of personal "stabilization" is to use the same
techniques (in breathing, etc.) that firearm shooters use in
competition matches.  Older photographers could also shut off their
pace makers momentarily before each shot ;-)

Royce Bair
Stock Photographer and Writer/Consultant for InkjetART.com
Epson P-2000 Storage Viewer - How to Upgrade to P-4000 specs
http://www.inkjetart.com/p2000/

I think the correlation between the focal length of the lens and a shutter
speed to hand hold an exposure was merely co-incidental happenstance, a
clever someone noticed it seemed to be a good rule, but there's no factual
basis.   It is certainly a case of  YMMV.

There are couple variables, the mirror slap being one of them.  I don't
think I would want to hand hold an RB at any shutterspeed, yet it was a
common practice in early color photography at weddings to shoot at 1/15th at
wide open with candles for some arty orange blobs, (yeah sure, it would be
underexposed but you would get 'something' on the neg that was printable and
for the era that was cool.)

Mirror slap was usually less of a problem with a 35mm so an extra stop on
the shutter was theoretically possible.

OTOH, if you used a tripod more often you'd be surprised at how often your
images look crisper, sharper, clearer, snappier.

What if you said, don't hand hold slower than your flash sync.  If you had a
camera that synced at 1/60th the rule would make some sense more often than
those who camera's synced at 1/250th or 1/30th.

This reply is echoed to the z-prophoto mailing list at yahoogroups.com

You have been misinformed. An increase or decrease in focal length
will result in an increase or decrease in apparent hand shake
regardless of format. Try hand holding an 8X10 with normal lens at
speeds under 1/300th and the consequence will be a blured contact
print (zero enlargement print). A 50mm wide angle lens on a medium
format can be held at 1/50th while a 100mm lens on the same format
will requireat least  an 1/100th second shutter speed. I can easily
hand hold a 24mm lens on my 20d at 1/25th second just like I can the
same lens on my 35mm EOS RT.

No. Increasing focal length will magnify hand shake to the same extent
regardles of format.

The actual focal of the lens will require the same shutter speed to
off set hand unsteadiness regardless of how much the image plane is
cropped.

The rule of thumb would require at least 1/50th.

Shutter speed should equel or exceed the lens focal length in
millimeters reguardless of crop or format.

You should consider an IS type lens. Also keep in mind that the
minimum shutter speed rule of thumb is only an approximate. You should
make carefull tests under your normal shooting conditions. I  want to
take the hand shake factor out of my images so I increase shutter
speed at least one stop over what the rule of thumb dictates, when
ever possable.

Dave
East Englewood

The proof is in the print.