Re: 3D Caves

[P3D John W Roberts <roberts@xxxxxxxxxxxxxxxxx>]

>Date: Fri, 6 Dec 1996 15:39:41 -0600
>From: "P3D Gregory J. Wageman" <gjw@xxxxxxxxxx>
>Subject: Re: 3D Caves

>...
>A 'potato masher' is a one of those strobe units with a long vertical
>handle (which often contains the battery pack) beneath a tilt/swivel
>head, that mounts to the camera with a bracket.  The name comes from
>its resemblance to a now-antiquated piece of kitchen equipment once
>used to mash potatoes.  (Does anyone NOT use a mixer to do this, these
>days?)

I second Bob H's view that the name probably came from the hand grenade
(which in turn came from the actual potato masher. :-)

Speaking of which, something I've been wondering about:
There was recently a discussion by people who had been zapped (painful
shocks, burns, etc.) by their cheap camera flashes which developed electrical
problems. I've heard of this before, and get the impression that it's not
necessarily a rare occurrence - perhaps as many as one out of every several
hundred longtime users of cheap flashes has been zapped at least once.
But none of the posters claim to have been actually killed by this, and I'm
not too worried about the low-power flashes.

However - if one of the really big powerful flashes goes wrong, is it like
the scene at the end of "Raiders of the Lost Ark" (photographer's head
explodes, bolts of lighting shoot through bystanders)? Are the big flash
units designed with safety more in mind than the cheap devices that seem to
zap people every now and then?

>I've had excellent results using a Metz CL45-1 with the Revere 33
>in "auto" mode.  In "auto", the dial on the strobe head sets the maximum
>working distance (power), and indicates the aperture to use for proper
>exposure, once you've dialed in the ASA of the film.  The shutter speed
>is set to the X sync speed (or below, if you want the ambient light to
>have more effect on the result).

>The CL45 has a guide number of 45 meters (148 feet).  It uses a AA
>5-cell battery pack which fits into the bottom of the handle.  It can
>be gotten with or without a NiCad version of the battery pack and a
>small plug-in charger.

>They also make a CL60, which has a guide number of 60 meters (197 feet).
>The CL60 requires an external battery pack, however.

>These units are NOT cheap, but they are way more powerful than your
>typical camera-mounted strobe, which may have a guide number of 20-30
>feet or less.

Are there any really powerful flash units that can conveniently be triggered
by an external electrical signal? I'd like to get one someday, but one thing
I'd like to use it for is to freeze very rapid motion, i.e. to recreate some
of the works of Harold Edgerton, but in stereo. It would be convenient to be
able to generate an external signal and run it through a variable time delay
to trigger the flash.

(There are electronic kit companies that sometimes sell flash kits - I may
try to experiment with those sometime.)

......

A few notes for cave photographers:

 - The big flash devices are good, but if you can't afford those the smaller
     ones often work surprisingly well. I got some very good fairly distant
     shots in Carlsbad Caverns with a very ordinary flash unit. I expect the
     big ones are worth the money - just don't give up hope if you don't have
     one. (However, camera flashes are *not* useful for lighting up fireworks
     displays, as many people discover to their astonishment every July 4. ;-)

 - If you use a stereo camera, it's useful to not have the flash directly
     over either lens - it helps to have side shadows in both views.
     (Some units mount this way - for others side brackets are fairly widely
     available, but it may be hard to find a flash cable.)

 - If you use a 2D camera for 3D photography, then it's highly desirable to
     keep the flash unit in the same place for the two shots (which implies
     that it shouldn't be fixed to the camera).

 - Some tourist caves don't allow the use of tripods.

 - Try a few pseudoscopic mounts - sometimes they can be very surrealistic!

John R


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End of PHOTO-3D Digest 1740
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