(original e-mail:)
Date: 15 Jan 96 22:40:54 EST
X-PH: V4.1@cornell.edu (Cornell Modified)
From: Vinh <72774.3546@compuserve.com>
To:
Subject: Re: Weak flash battery
YOU WROTE:
> Too bad I don't have
that flash meter - this would have ended long ago - maybe I will borrow
one.<
If you had had your flash meter, then we wouldn't have
gotten into our argument and life wouldn't have been as much
fun, now would it?
YOU WROTE:
> but if the capacitor has a full charge at, say,
300 volts, and you then connect up a 400 volt supply (as long as the cap
voltage rating is not exceeded!), and further the charge, you get
more stored energy, right? (With your pail, I added two more inches of
water level to the 6 inches of water that were already there: more
energy.) <
You've made the assumption that the battery (or power source)
continues to charge the capacitor as the flash is firing. I doubt
that this is true.
ANYWAYS, you sound like somebody who's more willing to believe
in measured facts than in just conjecture, SO-O-O...
I found my office flash meter and ran some tests. You can read
the measured results for yourself...
Set "A": New Alkalines (Duracells), fresh out of package
Average Voltage of set: 1.55 Volts
Voltage of each individual battery: 1.554, 1.550, 1.553, 1.543
Set "B": Old Alkalines (Duracells), used for past three months
Average Voltage of set: 1.490 Volts
Voltage of each individual battery: 1.500, 1.488, 1.488, 1.487
Set "C": New Lithium (Energizer, touted as "ideal" for cameras, etc.), fresh
Average Voltage of set: 1.768 Volts
Voltage of each individual battery: 1.764, 1.768, 1.770, 1.770
Set "D": Old Lithium (Same Energizer type), used about 4 months
Average Voltage of set: 0.971
Voltage of each individual battery: 1.543, 0.980, 0.659, 0.700
(UNLOADED voltage of each battery was measured with a digital volt meter.)
Camera: Canon F1
Camera settings: ASA 100 (doesn't matter since camera's on manual),
Shutter = 1/60 seconds, Aperature = F/11 (This is the F-stop
recommended by the dial on the flash when the subject is 10 feet away.)
Flash: Canon Speedlight 199A (dedicated flash)
Flash Settings: ASA 100, set on Manual ("M") mode
Flash meter: Metz flash meter.
Subject (the Flash meter) was set at distance of 10 Feet away on a tripod;
flash meter's sensor was pointed directly at the flash/camera 10 feet away.
Flash was set on camera (mounted on camera's hot shoe); camera/flash combo was
mounted on tripod exactly 10 feet away from flash meter. All lights in room
were dimmed to minimum and kept at the same (unchanged) level for all test
cases. Distance between flash and flash meter was kept constant for all test
cases. Orientation of all equipment were kept constant for all test cases
(that is, the directions that the meter, flash, camera were pointing were
kept contant for all test cases).
TEST ONE: Flash, mounted on camera with above settings, was allowed to
charge up to "maximum" with each set of batteries (A, B, C, D). The flash
has a "ready" LED that indicates several conditions: when the LED is lit but
NOT blinking, there is enough energy stored in the capacitor to fire the
flash, but the energy stored in the capacitor is NOT at full level. When the
LED is blinking, then the flash is ready with a FULL charge. For TEST ONE,
the LED was allowed to come to its blinking state (as noted below, the time
required to reach this state varied with different sets of batteries). The
exposure was then taken, causing the flash to fire, and the output level
was read from the flash meter.
The flash meter's gives readings in "recommended F-stops". So a reading of
5.6 indicates a flash output level that is a full stop HIGHER than
a reading on the meter of "4". The meter was set for "ASA 100 at F/11".
TEST TWO: Test two is a repeat of TEST ONE. TEST TWO AND TEST THREE are used
to avoid any single, eroneous result. (i.e., If I made a minor screw up in
TEST ONE, hopefully, it would be revealed in at least one of the two following
tests.)
TEST THREE: Same as TEST ONE and TWO.
TEST FOUR: For TEST FOUR -ONLY-, the flash was allowed to reach its "Ready but
-NOT- Fully Charged" state. That is, the LED on the flash was allowed to come
on before firing the flash, but the exposure was taken (flash fired and
measurement taken) BEFORE the flash was allowed to reach its fully-charged (i.e.,
LED blinking) state.
RESULTS FOLLOW:
--------TEST ONE (FULL CHARGE------------------------------------------------
BATTERY TIME TO REACH TIME TO REACH READING OF FLASH OUTPUT
SET "LED ON BUT BLINKING LED AS READ FROM FLASH METER
NOT BLINKING" (FULLY CHARGED) (IN "RECOMMENDED" F-STOP)
"A" 11 seconds 21 seconds 5.6 and 1/3
"B" 12 seconds 20 seconds 5.6 and 1/3
"C" 8 seconds 12 seconds 5.6 and 1/3
"D" 90 seconds NEVER REACHED* NEVER REACHED FULL CHARGE
--------TEST TWO (FULL CHARGE-----------------------------------------------
BATTERY TIME TO REACH TIME TO REACH READING OF FLASH OUTPUT
SET "LED ON BUT BLINKING LED AS READ FROM FLASH METER
NOT BLINKING" (FULLY CHARGED) (IN "RECOMMENDED" F-STOP)
"A" 12 seconds 21 seconds 5.6 and 1/3
"B" 13 seconds 19 seconds 5.6 and 1/3
"C" 7 seconds 13 seconds 5.6 and 1/3
"D" 45 seconds NEVER REACHED* NEVER REACHED FULL CHARGE
--------TEST THREE (FULL CHARGE)--------------------------------------------
BATTERY TIME TO REACH TIME TO REACH READING OF FLASH OUTPUT
SET "LED ON BUT BLINKING LED AS READ FROM FLASH METER
NOT BLINKING" (FULLY CHARGED) (IN "RECOMMENDED" F-STOP)
"A" 11 seconds 21 seconds 5.6 and 1/3
"B" 12 seconds 20 seconds 5.6 and 1/3
"C" 8 seconds 12 seconds 5.6 and 1/3
"D" 60 seconds NEVER REACHED* NEVER REACHED FULL CHARGE
--------TEST FOUR (PARTIAL CHARGE)--------------------------------------------
BATTERY TIME TO REACH TIME TO REACH READING OF FLASH OUTPUT
SET "LED ON BUT BLINKING LED AS READ FROM FLASH METER
NOT BLINKING" (FULLY CHARGED) (IN "RECOMMENDED" F-STOP)
"A" 11 seconds NOT ALLOWED 4 AND 2/3
"B" 12 seconds NOT ALLOWED 4 AND 2/3
"C" 8 seconds NOT ALLOWED 4 AND 2/3
"D" 55 seconds NOT ALLOWED 4 AND 2/3*
* NOTE THAT WITH SET "D" (THE OLD, NEARLY DEPLEATED LITHIUM BATTERIES), the
flash was NEVER able to reach its full charge. I waited for 5 minutes and more
during the first two tests, but finally gave up and just measured the flash
output levels for the set with the LED "ON" but NOT blinking (indicating
that the flash will flash, but it's not fully charged). For each of these
times, the output level for set "D" was always (a consistent) 4 and 2/3 (F 4 and
2/3 recommended by meter).
One thing I learned from the above: THOSE DAMN LITHIUMS ARE REALLY
NOT WORTH THE MONEY UNLESS YOU WERE IN A SITUATION WHERE
YOU HAD TO HAVE THE FLASH RECHARGE TIME REDUCED SIGNIFICANTLY. The
"used" set that I had were not used that much: maybe for
about five or six rolls of film, if I can remember correctly. (The
"used" alkalines--set "B"--were used for over ten rolls of the
same type of ASA100 film, yet they had more "energy" left in them.)
The prices of the batteries? About 3 bucks for a four-pack
of the alkalines (3 or 4 dollars); about 6 or 7 BUCKS for a
TWO-PACK of the lithiums!!! Lithiums are definitely not the
most economical...
Tha's all for now...
Date: 15 Jan 96 22:40:54 EST
X-PH: V4.1@cornell.edu (Cornell Modified)
From: Vinh <72774.3546@compuserve.com>
To:
Subject: Re: Weak flash battery
YOU WROTE:
> Too bad I don't have
that flash meter - this would have ended long ago - maybe I will borrow
one.<
If you had had your flash meter, then we wouldn't have
gotten into our argument and life wouldn't have been as much
fun, now would it?
YOU WROTE:
> but if the capacitor has a full charge at, say,
300 volts, and you then connect up a 400 volt supply (as long as the cap
voltage rating is not exceeded!), and further the charge, you get
more stored energy, right? (With your pail, I added two more inches of
water level to the 6 inches of water that were already there: more
energy.) <
You've made the assumption that the battery (or power source)
continues to charge the capacitor as the flash is firing. I doubt
that this is true.
ANYWAYS, you sound like somebody who's more willing to believe
in measured facts than in just conjecture, SO-O-O...
I found my office flash meter and ran some tests. You can read
the measured results for yourself...
Set "A": New Alkalines (Duracells), fresh out of package
Average Voltage of set: 1.55 Volts
Voltage of each individual battery: 1.554, 1.550, 1.553, 1.543
Set "B": Old Alkalines (Duracells), used for past three months
Average Voltage of set: 1.490 Volts
Voltage of each individual battery: 1.500, 1.488, 1.488, 1.487
Set "C": New Lithium (Energizer, touted as "ideal" for cameras, etc.), fresh
Average Voltage of set: 1.768 Volts
Voltage of each individual battery: 1.764, 1.768, 1.770, 1.770
Set "D": Old Lithium (Same Energizer type), used about 4 months
Average Voltage of set: 0.971
Voltage of each individual battery: 1.543, 0.980, 0.659, 0.700
(UNLOADED voltage of each battery was measured with a digital volt meter.)
Camera: Canon F1
Camera settings: ASA 100 (doesn't matter since camera's on manual),
Shutter = 1/60 seconds, Aperature = F/11 (This is the F-stop
recommended by the dial on the flash when the subject is 10 feet away.)
Flash: Canon Speedlight 199A (dedicated flash)
Flash Settings: ASA 100, set on Manual ("M") mode
Flash meter: Metz flash meter.
Subject (the Flash meter) was set at distance of 10 Feet away on a tripod;
flash meter's sensor was pointed directly at the flash/camera 10 feet away.
Flash was set on camera (mounted on camera's hot shoe); camera/flash combo was
mounted on tripod exactly 10 feet away from flash meter. All lights in room
were dimmed to minimum and kept at the same (unchanged) level for all test
cases. Distance between flash and flash meter was kept constant for all test
cases. Orientation of all equipment were kept constant for all test cases
(that is, the directions that the meter, flash, camera were pointing were
kept contant for all test cases).
TEST ONE: Flash, mounted on camera with above settings, was allowed to
charge up to "maximum" with each set of batteries (A, B, C, D). The flash
has a "ready" LED that indicates several conditions: when the LED is lit but
NOT blinking, there is enough energy stored in the capacitor to fire the
flash, but the energy stored in the capacitor is NOT at full level. When the
LED is blinking, then the flash is ready with a FULL charge. For TEST ONE,
the LED was allowed to come to its blinking state (as noted below, the time
required to reach this state varied with different sets of batteries). The
exposure was then taken, causing the flash to fire, and the output level
was read from the flash meter.
The flash meter's gives readings in "recommended F-stops". So a reading of
5.6 indicates a flash output level that is a full stop HIGHER than
a reading on the meter of "4". The meter was set for "ASA 100 at F/11".
TEST TWO: Test two is a repeat of TEST ONE. TEST TWO AND TEST THREE are used
to avoid any single, eroneous result. (i.e., If I made a minor screw up in
TEST ONE, hopefully, it would be revealed in at least one of the two following
tests.)
TEST THREE: Same as TEST ONE and TWO.
TEST FOUR: For TEST FOUR -ONLY-, the flash was allowed to reach its "Ready but
-NOT- Fully Charged" state. That is, the LED on the flash was allowed to come
on before firing the flash, but the exposure was taken (flash fired and
measurement taken) BEFORE the flash was allowed to reach its fully-charged (i.e.,
LED blinking) state.
RESULTS FOLLOW:
--------TEST ONE (FULL CHARGE------------------------------------------------
BATTERY TIME TO REACH TIME TO REACH READING OF FLASH OUTPUT
SET "LED ON BUT BLINKING LED AS READ FROM FLASH METER
NOT BLINKING" (FULLY CHARGED) (IN "RECOMMENDED" F-STOP)
"A" 11 seconds 21 seconds 5.6 and 1/3
"B" 12 seconds 20 seconds 5.6 and 1/3
"C" 8 seconds 12 seconds 5.6 and 1/3
"D" 90 seconds NEVER REACHED* NEVER REACHED FULL CHARGE
--------TEST TWO (FULL CHARGE-----------------------------------------------
BATTERY TIME TO REACH TIME TO REACH READING OF FLASH OUTPUT
SET "LED ON BUT BLINKING LED AS READ FROM FLASH METER
NOT BLINKING" (FULLY CHARGED) (IN "RECOMMENDED" F-STOP)
"A" 12 seconds 21 seconds 5.6 and 1/3
"B" 13 seconds 19 seconds 5.6 and 1/3
"C" 7 seconds 13 seconds 5.6 and 1/3
"D" 45 seconds NEVER REACHED* NEVER REACHED FULL CHARGE
--------TEST THREE (FULL CHARGE)--------------------------------------------
BATTERY TIME TO REACH TIME TO REACH READING OF FLASH OUTPUT
SET "LED ON BUT BLINKING LED AS READ FROM FLASH METER
NOT BLINKING" (FULLY CHARGED) (IN "RECOMMENDED" F-STOP)
"A" 11 seconds 21 seconds 5.6 and 1/3
"B" 12 seconds 20 seconds 5.6 and 1/3
"C" 8 seconds 12 seconds 5.6 and 1/3
"D" 60 seconds NEVER REACHED* NEVER REACHED FULL CHARGE
--------TEST FOUR (PARTIAL CHARGE)--------------------------------------------
BATTERY TIME TO REACH TIME TO REACH READING OF FLASH OUTPUT
SET "LED ON BUT BLINKING LED AS READ FROM FLASH METER
NOT BLINKING" (FULLY CHARGED) (IN "RECOMMENDED" F-STOP)
"A" 11 seconds NOT ALLOWED 4 AND 2/3
"B" 12 seconds NOT ALLOWED 4 AND 2/3
"C" 8 seconds NOT ALLOWED 4 AND 2/3
"D" 55 seconds NOT ALLOWED 4 AND 2/3*
* NOTE THAT WITH SET "D" (THE OLD, NEARLY DEPLEATED LITHIUM BATTERIES), the
flash was NEVER able to reach its full charge. I waited for 5 minutes and more
during the first two tests, but finally gave up and just measured the flash
output levels for the set with the LED "ON" but NOT blinking (indicating
that the flash will flash, but it's not fully charged). For each of these
times, the output level for set "D" was always (a consistent) 4 and 2/3 (F 4 and
2/3 recommended by meter).
One thing I learned from the above: THOSE DAMN LITHIUMS ARE REALLY
NOT WORTH THE MONEY UNLESS YOU WERE IN A SITUATION WHERE
YOU HAD TO HAVE THE FLASH RECHARGE TIME REDUCED SIGNIFICANTLY. The
"used" set that I had were not used that much: maybe for
about five or six rolls of film, if I can remember correctly. (The
"used" alkalines--set "B"--were used for over ten rolls of the
same type of ASA100 film, yet they had more "energy" left in them.)
The prices of the batteries? About 3 bucks for a four-pack
of the alkalines (3 or 4 dollars); about 6 or 7 BUCKS for a
TWO-PACK of the lithiums!!! Lithiums are definitely not the
most economical...
Tha's all for now...
Vinh <72774.3546@compuserve.com> (my answer:)
Hi--
>If you had had your flash meter, then we wouldn't have
>gotten into our argument and life wouldn't have been as much
>fun, now would it?
Nope!
>I WROTE:
>> but if the capacitor has a full charge at, say,
>300 volts, and you then connect up a 400 volt supply (as long as the cap
>voltage rating is not exceeded!), and further the charge, you get
>more stored energy, right? (With your pail, I added two more inches of
>water level to the 6 inches of water that were already there: more
>energy.) <
>You've made the assumption that the battery (or power source)
>continues to charge the capacitor as the flash is firing. I doubt
>that this is true.
Don't see how that follows - I was saying that there is the possibility
that an initially higher voltage (batteries) may translate into a
higher voltage on the capacitors when fully charged. I am not sure
about that, but so far, no one has said yes or no.
>ANYWAYS, you sound like somebody who's more willing to believe
>in measured facts than in just conjecture, SO-O-O...
>I found my office flash meter and ran some tests. You can read
>the measured results for yourself...
Excellent methodology!
>Set "A": New Alkalines (Duracells), fresh out of package
> Average Voltage of set: 1.55 Volts
> Voltage of each individual battery: 1.554, 1.550, 1.553, 1.543
>
>Set "B": Old Alkalines (Duracells), used for past three months
> Average Voltage of set: 1.490 Volts
> Voltage of each individual battery: 1.500, 1.488, 1.488, 1.487
>
>Set "C": New Lithium (Energizer, touted as "ideal" for cameras, etc.), fresh
> Average Voltage of set: 1.768 Volts
> Voltage of each individual battery: 1.764, 1.768, 1.770, 1.770
>
>Set "D": Old Lithium (Same Energizer type), used about 4 months
> Average Voltage of set: 0.971
> Voltage of each individual battery: 1.543, 0.980, 0.659, 0.700
>
>(UNLOADED voltage of each battery was measured with a digital volt meter.)
Ah, there's the rub, alas, because it is a good test, otherwise. The first
two sets are too close in voltage to prove much. The lithiums droop
considerably under load, so, for all we know, the working voltage may have
been the same as the other two. The fourth set was too far gone to present
much of a test, and firing the flash just as the first light comes on
(fourth test) is basically firing the flash when it has reached the same
charge voltage for each set: no test.
Here is what I would suggest: When you have a set of alkalines
that can just cause the first light to come on, compare it with a really
fresh set of alkalines. I will believe that test. (If you have access
to a fully charged gel-cell, it would be interesting to add that, too -
and a set of NiCads, which are about 1.2 volts) I guess measuring the
voltage across the flash terminals of a HV switching type flash at full
charge with different conditions of batteries would also tell me something,
but your test is potentially more interesting because it is actually
measuring output (in fully manual flash mode - no auto or TTL) of the flash.
>However! Hold the presses, and things like that!
I just reread the test results, and there may be no need to go
further. The test is between batteries of different voltages to see if
the output power of the flash will vary accordingly. Your tests indicate
that it does! If you take sets 1 through 3, all are capable of lighting
the blinking light (a charged voltage measure, almost certainly), and may
all be close enough in working (loaded) voltage to not offer much to the
test but a reference output of f5.6 1/3. The fourth set was able to light
the first light, but not the second (lower charged voltage), and maxes out
at f4 2/3. As they say in math, Q. E. D. (You have demonstrated my point!)
Thanks for the effort! And thanks for the info on lithiums - I guess
I will stick with NiCads, even if they do lower the flash maximum
output ;-)
David Ruether