[rollei_list] Re: Hearing Aid Batteries in Nikon F
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Wed, 3 Mar 2010 23:40:54 -0800
----- Original Message -----
From: "Marc James Small" <marcsmall@xxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, March 03, 2010 10:17 PM
Subject: [rollei_list] Re: Hearing Aid Batteries in Nikon F
At 12:50 AM 3/4/2010, Richard Knoppow wrote:
> Did you make any comparisons of readings with the
>alkaline cells vs mercury cells? I have not done that but
>have compared mercury with zinc-air and found no
difference
>but the voltages are closer. It may well be that plain old
>alkaline cells will work in most equipment.
Richard
The issue is two-fold. First, what is the
acceptance levels of film? For most purposes,
black and white films can produce decent images
about two stops down and three up, meaning that
an image which ought to be made at, say, 1/30" at
f/8 will produce a printable image at f/4 or
f/22. This might be extreme, but my own rather
extensive experience indicates that b&w films
certainly will permit a latitude of at least one
stop. Color reversal films certainly allow a
margin of at least 2/3 of a stop either way,
while chromes are more demanding, and 1/3 of a
stop is probably a matter of wisdom.
Second, most European cameras have "compensated
circuitry" with inbuilt voltage regulation, so
any power source will work, and work at the
prescribed voltage. The Japanese manufacturers
pushed for the mercury cell as its flat discharge
rate allowed them to eliminate this bridge circuit to lower
production costs.
But, in the end, the difference between 1.3 and
1.5 volts will not matter a damn for non-critical
photography. Use what you have, and take pictures!
Marc
I don't know what is included in "most" European
equipment. Certainly anything designed to work from alkaline
cells must have some sort of voltage regulator but one of
the advantages of mercury cells is that the output voltage
was stable enough not to need one. Regulators by nature must
dissipate some power so there is an advantage in battery
operated devices if you can eliminate the need for the
regulator.
B&W film, because of the way the speed standard is
written, has little underexposure latitude but lots for
overexposure. In general, color films are more critical but
modern ones have a very considerable latitude. I don't have
a copy of the standard for color negative materials so don't
know where the speed point is. Likely it is up the curve
further than the B&W one.
Reversal materials, either B&W or color, are very
critical of exposure because virtually all the halide in
them is used. Here I refer to reversal material designed for
direct viewing. There are reversal materials made with much
lower contrast, for instance, for direct duplication of
motion picture negatives. This material is designed to
duplicate the relatively low contrast of the original
negative material. Nonetheless, it is quite critical of
exposure. OTOH, its never used in cameras, only in the lab
under very well controlled conditions.
The difference between 1.5V and 1.3V is about 87%, or
about a 13% error. Not astronomical. However its effect
depends on the circuit its powering. If the circuit is
linear the difference is minimal but not all circuits are
linear.
Anyway, I've found a satisfactory and practical work
around for the absense of mercury cells.
BTW, I have been trying to find solid numbers on the
relative amounts of mercury in mercury cells an in compact
fluorescent lamps. There actually isn't much in either but I
am wondering if mercury cells got a bad rap. Much of the
mercury polluting the oceans comes from burning coal and
other industrial activity. Its bad stuff but sometimes
regulators get wierd.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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