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Exposure Difference: Which is correct?

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DavidP #28649

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It appears that my refurb 1D and original 1D are exposing differently. The refurb underexposes by 2/3 relative to my new one.

In the following photographs, I exposed using Av with spot-metering on the gray card. I have put the R,G,B values of the gray card (along with the R,G,B values of a white sheet of Bright White Injket Paper by HP) on the images.

Which camera is exposing correctly? (Or are both incorrect?). Does anybody who has a known properly exposure meter on the 1D know the correct values for R,G,B of a gray card?





--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
 
David

nothing new

This is why in the old days where we used to use these odd plastic rolls that they called film we had to calibrate the cameras by changing the ISO setting (shoot ISO 100 film at a setting of ISO 50 for example)

With digital there is nothing like it available. Would be nice to be able to calibrate digitals and it would be so easy to as all you need would be an EV value for compensation of the meter so you could calibrate multiple bodies to work the same way.

--
Michael Salzlechner
StarZen Digital Imaging
http://www.starzen.com/imaging
 
DavidP said:
It appears that my refurb 1D and original 1D are exposing
differently. The refurb underexposes by 2/3 relative to my new
one.
Click to expand...
And what happens when you calibrate your light meter on each body.

Use your Expo/Disk, put it on the front of the lens attached to the camera body and when the Sun is at it's zenith, point the lens with E/D attached at the Sun.

As you know, you should get a f/16 @ 1/125th with your ISO set at 100.

Use the Expo/Disk Luke, use the Expo/Disk:-)
 
I'd just like to know which is correct.

I'm sure Canon can calibrate the two cameras to the same (presumably correct) value, and I can calibrate the Sekonic meter myself to match.
Mike Salzlechner said:
nothing new

This is why in the old days where we used to use these odd plastic
rolls that they called film we had to calibrate the cameras by
changing the ISO setting (shoot ISO 100 film at a setting of ISO 50
for example)

With digital there is nothing like it available. Would be nice to
be able to calibrate digitals and it would be so easy to as all you
need would be an EV value for compensation of the meter so you
could calibrate multiple bodies to work the same way.
Click to expand...
--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
 
Unfortunately, the "f/16 and sunny" rule is just an approximation, and probably doesn't work too well in the dead of winter. Even down in Houston.
Thomas Gardner said:
And what happens when you calibrate your light meter on each body.

Use your Expo/Disk, put it on the front of the lens attached to the
camera body and when the Sun is at it's zenith, point the lens with
E/D attached at the Sun.

As you know, you should get a f/16 @ 1/125th with your ISO set at 100.

Use the Expo/Disk Luke, use the Expo/Disk:-)
Click to expand...
--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
 
DavidP said:
Unfortunately, the "f/16 and sunny" rule is just an approximation,
and probably doesn't work too well in the dead of winter. Even
down in Houston.
Click to expand...
The further South you are, the higher the Sun. You're going to be close if you shoot at the zenith.

Give it a try, it only takes a few moments to try and you'll be a lot closer then two stops. At worse, on a clear blue sky day, with the Sun low as opposed to Spring high, you'd be within a half stop.

The point? This gives you a simple calibration tool in which to compare the two cameras; if that's what you want to do:-)
 
Your original is doing the best job. There is no exact values for a grey card exposure. There is a range which is governed by the 1/3 stop resolution of the camera's controls. When using a grey card, the old rule is to take a reading and open up 1/2 - 2/3 stop. That would mean your original shot would end up being in the 115 -120 area or so. And that should be a good place to be.
The new camera is being confused by something.

But if your hand-held is up to snuff, then why is it reading 1/25? It should agree with your original camera. (or the other way around) Seems like something is wacky.
DavidP said:
My Sekonic L-358 reads

ISO 800
f/2
1/25

Another 2/3 stop below the refurb 1D (which reads 2/3 stop below
the original 1D).

--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
Click to expand...
 
The Sekonic is known to come from the factory out of adjustment a lot of the time (or so I've read). Fortunately, it's easy to adjust that inside the meter.

PS - in Av or Tv, the meter actually reads (internally) to the nearest 1/8 stop. Not 1/3 or 1/2. It just displays in values of 1/3 or 1/2.
Al Pacheco said:
Your original is doing the best job. There is no exact values for
a grey card exposure. There is a range which is governed by the
1/3 stop resolution of the camera's controls. When using a grey
card, the old rule is to take a reading and open up 1/2 - 2/3 stop.
That would mean your original shot would end up being in the 115
-120 area or so. And that should be a good place to be.
The new camera is being confused by something.

But if your hand-held is up to snuff, then why is it reading 1/25?
It should agree with your original camera. (or the other way
around) Seems like something is wacky.
Click to expand...
--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
 
DavidP said:
It appears that my refurb 1D and original 1D are exposing
differently. The refurb underexposes by 2/3 relative to my new
one.

In the following photographs, I exposed using Av with spot-metering
on the gray card. I have put the R,G,B values of the gray card
(along with the R,G,B values of a white sheet of Bright White
Injket Paper by HP) on the images.

Which camera is exposing correctly? (Or are both incorrect?).
Does anybody who has a known properly exposure meter on the 1D know
the correct values for R,G,B of a gray card?





--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
Click to expand...
 
DavidP said:
The Sekonic is known to come from the factory out of adjustment a
lot of the time (or so I've read).
Click to expand...
That's not good...I'd expect better since meters are the only thing they make!
DavidP #28649 said:
PS - in Av or Tv, the meter actually reads (internally) to the
nearest 1/8 stop. Not 1/3 or 1/2. It just displays in values of
1/3 or 1/2.
Click to expand...
And that's what they call...snake oil! Doesn't matter if the meter can read down to a hundredth of a stop...if the hardware can only do thirds then that's what you have. I've tested a friend's 1V for him...(and I believe the 1V is the film world's 1D/1Ds) ...and 1/3 stop is all you get.
DavidP #28649 said:
Al Pacheco said:
Your original is doing the best job. There is no exact values for
a grey card exposure. There is a range which is governed by the
1/3 stop resolution of the camera's controls. When using a grey
card, the old rule is to take a reading and open up 1/2 - 2/3 stop.
That would mean your original shot would end up being in the 115
-120 area or so. And that should be a good place to be.
The new camera is being confused by something.

But if your hand-held is up to snuff, then why is it reading 1/25?
It should agree with your original camera. (or the other way
around) Seems like something is wacky.
Click to expand...
--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
Click to expand...
 
Sell the refurb to me, and let me worry about the metering problem! ;-)

JL

--
Jonathan Lefcourt
D60,24-70L, 70-200L 2.8 IS, 15-30 Sigma (wish it was 2.8!)
100 Macro, 50 1.4, 28-135 IS, Metz 54, 550EX, S40
and a lot of other stuff I drag around!
 
I don't know how you'd test that, unless you could adjust your light source in 1/8 stop increments.
Al Pacheco said:
DavidP said:
PS - in Av or Tv, the meter actually reads (internally) to the
nearest 1/8 stop. Not 1/3 or 1/2. It just displays in values of
1/3 or 1/2.
Click to expand...
And that's what they call...snake oil! Doesn't matter if the meter
can read down to a hundredth of a stop...if the hardware can only
do thirds then that's what you have. I've tested a friend's 1V
for him...(and I believe the 1V is the film world's 1D/1Ds) ...and
1/3 stop is all you get.
Click to expand...
--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
 
With all due respect to Chuck...he MAY be correct about the meter...but the hardware only does 1/3 stop jumps. And, you bet, I have the equipment to adjust a light source far beyond the 1/8 stop resolution. Color temperature control and all. That's what I do...photographic instrumentation. I have a grey wall in my lab that measures 8 feet square and all the little toys to play with.

But all that aside....I'm still surprised your fe-furb is off a bit. Could it be the previous owner requested Canon to adjust it?
DavidP said:
Al Pacheco said:
DavidP said:
PS - in Av or Tv, the meter actually reads (internally) to the
nearest 1/8 stop. Not 1/3 or 1/2. It just displays in values of
1/3 or 1/2.
Click to expand...
And that's what they call...snake oil! Doesn't matter if the meter
can read down to a hundredth of a stop...if the hardware can only
do thirds then that's what you have. I've tested a friend's 1V
for him...(and I believe the 1V is the film world's 1D/1Ds) ...and
1/3 stop is all you get.
Click to expand...
--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
Click to expand...
 
Maybe that's why the person returned it? Possibly somebody returned it for an exchanged unit? Who knows.
Al Pacheco said:
But all that aside....I'm still surprised your fe-furb is off a
bit. Could it be the previous owner requested Canon to adjust it?
Click to expand...
--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
 
not from one day to the other but over time they will.

Any electronic will change over time. This is why you need to recalibrate your monitor, our light meter and your camera.

this is only important if you shoot with two bodies. You would want them to act pretty much the same so you dont have to always think what camera you are using.

--
Michael Salzlechner
StarZen Digital Imaging
http://www.starzen.com/imaging
 
... they would change as they aged. The one that I have could be 'recalibrated' by drilling out pre-marked holes in the sensor cover! I doubt that the system in modern DSLRs would change enough to matter during its lifetime.

The D60 I just sold and the 1D that I have now metered about 2/3 of a stop apart! With just one DSLR, I don't worry about whether it's spot on ... but with two, it was annoying!
KP
DavidP said:
Mike Salzlechner said:
cameras change over time and need to be recalibrated. No point in
having to send them in all the time

a simple CF could do the trick
Click to expand...
--
The Unofficial Photographer of The Wilkinsons
http://thewilkinsons.crosswinds.net
Photography -- just another word for compromise
Click to expand...
--

A couple of Canon DSLRs, a nice off-white lens and some red-stripe lenses and one with a gold stripe, some misc. accessories including various photon ejectors and paper holders. A ton of film equipment from 35mm to 4 x 5. A minivan and a Fender Stratocaster. A three bedroom ranch on an acre. Also, absolutely no Canon 1200mm f/5.6.
 
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