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custom white balance/exposure questions ?

 
 
picture taker
Guest
Posts: n/a
 
      07-09-2006
hi,
i understand exposure shutter speed,f-stop ,iso etc , shoot with a
canon 20d ,capture raw files all the time, convert with cs2 and adjust
the wb if i feel it needs it .
i have never fully understood whte balance / custom white balance etc

when people refer to a custom white balance are they trying to make
everything equal ,meaning the reference of 18% that is often mentioned
about custom white balance ?.

say there is a shinny red dress or a white one for that matter and
they look a lot brighter than the other colors, by doing the custom
white balance does the camera then read the dresses as the same and
won't blow out the details ? .

what is the difference between using a reference card ( gray card ,
expo disc etc ) to set the custom white balance but ive also heard it
referd to as usnig it to set the exposure not the white balance ?

say you are in a gymnasium shooting basketball with an expodisc for you
to use as reference on the end of the lens pointed at the lights to set
your custom wb in camera and you crank up the iso does it matter if you
set the custom wb at a differnt iso than what you will be shooting ?.
same situation in the same gym ,now your shooting with a flash
should you just leave the custom set or reshoot the custom wb with the
expodisc attached while using the flash ?.

thank you

 
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Cooter
Guest
Posts: n/a
 
      07-09-2006
Unless I totally misunderstand your question(s), I think you are confusing
exposure metering with white balance. ISO should not have any reasonable
effect on white balance and vice versa. White balance is simply a means of
setting the camera's response to the prevailing lighting conditions;
therefore, custom white balance normally refers to setting the camera's
color response to an existing condition that is different than one of the
listed white balance settings - Daylight, Incandescent, Flash, etc. Say you
are shooting in an area illuminated by a mixture of daylight, incandescent
and fluorescent lighting. Unless you want a particular effect, you would set
your camera's white balance via the custom (some cameras refer to it as
'Preset') white balance function.


 
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Ben Brugman
Guest
Posts: n/a
 
      07-09-2006
Lets start at an example where the white balance does matter.
Suppose you do a wedding. The bride clothing is mainly white.

Lot's of people (especialy the mothers) will complain if the
dress is not white in the pictures. So if you have a series of
pictures where the dress is a littlebit green, blue, pink or any
other shade you have a problem.

The problem is that in real live the dress takes on the color
of the lightning which is supplied. For example under cover
of trees in the grass the dress will turn up a littlebit green.

In artificial lightning the dress will turn up a bit red.
(In lightbulbs).

In the shade on a very clear day the dress will turn up a
little bit blue.

With a white dress from the bride this is not acceptable.

So to prevent the white dress having different colors, you
have to calibrate calibrate the camera everytime the
light changes from color. To do that you need a constant
reference, a white card will work, but a gray card will work
as well. Working with Raw you can take a picture of the
gray card and adjust the picture in postprocessing so it
comes out gray. Working with jpg you can use the graycard
to set the WB in the camera so the graycard appears gray
in the jpg file.

So doing the things correctly the wedding dress appears
so shade of gray in every picture. Depending on the light
situation this might be more or less bright, but somewhere
between white and black and never with a colorcast.
The exposure offcourse should be correct, but should not
influence the WB. The mothers will notice a very slight
color cast on the weddingdress, but wil be less critical
for the exposure.

The amount off lightning should not matter to the WB. But
large changes in the amount of lightning can also mean
large or small changes in the color of the lightning.
ISO settings should not influence the WB.

There are some situations where you can not set the
WB such that it works for everything in the picture.
If there are more lightsources, for example incandecent
and natural light in one scene you can not set the WB
to both.

Fluorrecent lightning is a problem as well because
it isn't a continues spectrum some colors look different
under this type of light.

Using a flash requires some thought. Normaly the flash
will produce light of about 5600 K, this is called the
color temperature. But if this is combined with available light
of another color temperature, you have to choose for what
to go.

Example of a difficult situation: A bride on the grass (green
casting) in the sunset (low colortemperature of about 3800 K)
and using a little flashlight to give some highlights (5600 K).
Now the underside of the dress will have more green colorcast,
The main lightning is provided by the sun of 3800 K rather reddisch,
and the flash which light mainly the front gives you 5600 K. So
the dress will turn up multicolored which you can not correct with
WB allone.

Sory to be this 'long' but I hope this gives you the information
to work with.

Ben


"picture taker" <(E-Mail Removed)> schreef in bericht
news:(E-Mail Removed) oups.com...
> hi,
> i understand exposure shutter speed,f-stop ,iso etc , shoot with a
> canon 20d ,capture raw files all the time, convert with cs2 and adjust
> the wb if i feel it needs it .
> i have never fully understood whte balance / custom white balance etc
>
> when people refer to a custom white balance are they trying to make
> everything equal ,meaning the reference of 18% that is often mentioned
> about custom white balance ?.
>
> say there is a shinny red dress or a white one for that matter and
> they look a lot brighter than the other colors, by doing the custom
> white balance does the camera then read the dresses as the same and
> won't blow out the details ? .
>
> what is the difference between using a reference card ( gray card ,
> expo disc etc ) to set the custom white balance but ive also heard it
> referd to as usnig it to set the exposure not the white balance ?
>
> say you are in a gymnasium shooting basketball with an expodisc for you
> to use as reference on the end of the lens pointed at the lights to set
> your custom wb in camera and you crank up the iso does it matter if you
> set the custom wb at a differnt iso than what you will be shooting ?.
> same situation in the same gym ,now your shooting with a flash
> should you just leave the custom set or reshoot the custom wb with the
> expodisc attached while using the flash ?.
>
> thank you
>



 
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Gene Palmiter
Guest
Posts: n/a
 
      07-09-2006
You seem to be mixed up on the difference between metering for the amount of
light and metering for the color temperature of the light. If you are just
moving over from film this is natural...you didn't have to worry about it in
most cases. Your film was rated for daylight and the printer adjusted it
from there. If you shot under certain kinds of artificial light such as
tungsten or florescent you got bad pictures and might not have known why.
Professionals had special films and filters to adjust for this.

With digital you don't get other kinds of film so you adjust for the color
temperature by setting the white balance. You can leave it on automatic and
let the camera do the best it can. In most cases it will do fine. You have
to learn of where it goes wrong so you can compensate and set the camera for
the color temp of the light where you are shooting. Rather than remembering
the temp of all the types of light you can also set a custom WB by
registering on a neutral "thing". This thing can be white, gray, maybe even
black (I have never tried that...but it might work). An 18% card would
work....and the back of the card is white...an even better choice.

If you are shooting JPGs you make this choice before you shoot...if you
shoot RAW you can wait until you get to the computer. Best of all worlds is
if for each shot you made custom WB and then shoot RAW...but that is too
much work! As the light temp usually changes slowly you only have to set the
WB when you suspect the light source changed.

There is an interesting product that I helped a bit with development that
overrides the WB. You can see it at www.warmcards.com . These were first
invented for video where you cannot easily change the color balance after
you shoot. Using warmcards you can trick your camera into thinking the light
is too cool (blue) so it makes the shot warmer and gives you nicer skin
tones and enriches the other colors.

--
Thanks,
Gene Palmiter
(visit my photo gallery at http://palmiter.dotphoto.com)
freebridge design group

"picture taker" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> hi,
> i understand exposure shutter speed,f-stop ,iso etc , shoot with a
> canon 20d ,capture raw files all the time, convert with cs2 and adjust
> the wb if i feel it needs it .
> i have never fully understood whte balance / custom white balance etc
>
> when people refer to a custom white balance are they trying to make
> everything equal ,meaning the reference of 18% that is often mentioned
> about custom white balance ?.
>
> say there is a shinny red dress or a white one for that matter and
> they look a lot brighter than the other colors, by doing the custom
> white balance does the camera then read the dresses as the same and
> won't blow out the details ? .
>
> what is the difference between using a reference card ( gray card ,
> expo disc etc ) to set the custom white balance but ive also heard it
> referd to as usnig it to set the exposure not the white balance ?
>
> say you are in a gymnasium shooting basketball with an expodisc for you
> to use as reference on the end of the lens pointed at the lights to set
> your custom wb in camera and you crank up the iso does it matter if you
> set the custom wb at a differnt iso than what you will be shooting ?.
> same situation in the same gym ,now your shooting with a flash
> should you just leave the custom set or reshoot the custom wb with the
> expodisc attached while using the flash ?.
>
> thank you
>



 
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Matt Ion
Guest
Posts: n/a
 
      07-09-2006
picture taker wrote:
> hi,
> i understand exposure shutter speed,f-stop ,iso etc , shoot with a
> canon 20d ,capture raw files all the time, convert with cs2 and adjust
> the wb if i feel it needs it .
> i have never fully understood whte balance / custom white balance etc


When you go to the supermarket, you'll notice that they never use
flourescent lighting over the meat section - this is because flourescent
typically has a yellowish quality to it, and you don't want your meat
looking yellow. Instead, they'll use incandescent lights, which have a
more reddish color, so the meat will look fresh and healthy. Similarly,
you'll see more flourescent lighting used in the vegetable section,
especially over green leafy veggies, because it brings out the green more.

Cameras respond the same way - if you shoot under indoor, incandescent
lighting, pictures will tend to have a reddish hue; shooting under
bright sunlight will usually give you the "whitest" light, but shooting
in the shade will give a "blue" tinge to things... and so on.

Setting a custom white balance involves giving the camera something
that's white or light grey to "look" at, something that will reflect all
colors equally... then "telling" the camera, "Okay, this is what WHITE
looks like in this lighting".

White balance is only REALLY applicable when you're shooting JPG and the
camera is doing internal processing of the picture. When you shoot RAW,
the camera just stores the data straight from the sensor without
altering anything. It will include information on the white balance
setting, that the RAW conversion software can read - this is handy if
you're using auto white balance or custom white balance, because it
tells the software what the WB readings were - but the WB setting
doesn't actually alter the image that comes out of the camera. That
allows you to correct the WB in software before converting the picture
to TIF or JPG or whatever format you're going to use.
 
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Gary Eickmeier
Guest
Posts: n/a
 
      07-09-2006


picture taker wrote:

> hi,
> i understand exposure shutter speed,f-stop ,iso etc , shoot with a
> canon 20d ,capture raw files all the time, convert with cs2 and adjust
> the wb if i feel it needs it .
> i have never fully understood whte balance / custom white balance etc
>
> when people refer to a custom white balance are they trying to make
> everything equal ,meaning the reference of 18% that is often mentioned
> about custom white balance ?.
>
> say there is a shinny red dress or a white one for that matter and
> they look a lot brighter than the other colors, by doing the custom
> white balance does the camera then read the dresses as the same and
> won't blow out the details ? .
>
> what is the difference between using a reference card ( gray card ,
> expo disc etc ) to set the custom white balance but ive also heard it
> referd to as usnig it to set the exposure not the white balance ?
>
> say you are in a gymnasium shooting basketball with an expodisc for you
> to use as reference on the end of the lens pointed at the lights to set
> your custom wb in camera and you crank up the iso does it matter if you
> set the custom wb at a differnt iso than what you will be shooting ?.
> same situation in the same gym ,now your shooting with a flash
> should you just leave the custom set or reshoot the custom wb with the
> expodisc attached while using the flash ?.



Expodisc is OK for setting the white balance, but I would rely on the
camera's reflected meter for exposure. Yes, white balance should be set
for flash if you change to flash. I don't believe that chaning ISO
affects the WB setting.

Not sure how to set WB with flash using Expodisc. Maybe just put the
disc on, flash an exposure with a typical subject distance, and use
that. Would be best if you could have a mostly white area to do it with,
but experiment.

Gary Eickmeier
 
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picture taker
Guest
Posts: n/a
 
      07-10-2006
ben, thank you for taking the time to reply ,

Example of a difficult situation: A bride on the grass (green
> casting) in the sunset (low colortemperature of about 3800 K)
> and using a little flashlight to give some highlights (5600 K).
> Now the underside of the dress will have more green colorcast,
> The main lightning is provided by the sun of 3800 K rather reddisch,
> and the flash which light mainly the front gives you 5600 K. So
> the dress will turn up multicolored which you can not correct with
> WB allone.
>

good example , what would the best way to handle this situation ?


So to prevent the white dress having different colors, you
> have to calibrate calibrate the camera everytime the
> light changes from color. To do that you need a constant
> reference, a white card will work, but a gray card will work
> as well. Working with Raw you can take a picture of the
> gray card and adjust the picture in postprocessing so it
> comes out gray. Working with jpg you can use the graycard
> to set the WB in the camera so the graycard appears gray
> in the jpg file.


ok everytime the light changes ,time for a new custom wb got it .
take the 1st picture with a gary card or expodisc click on it on acr
and save it as you your custom white balance apply it to every image
shoot under them same lighting conditions , sound right or leave
camera on awb and use the gray card in acr ?.

i usually shoot raw with small jpeg ,im thinking it would be better
to shoot large jpeg along with raw, as it has been said get it right
when you shoot it , i mostly shoot raw as it seems easier to adjust in
acr then just crop and sharpen in ps ..
if the image needs some major adjustments more room to work with a raw
file than jpeg
but there is a major difference the way a raw file looks compared to a
jpeg (when comparing images shot under strobe lights anyhow ,i will
try large jpeg ,raw later and see )so the custom wb dosen't really
matter that matter that much

thank you

Ben Brugman wrote:
> Lets start at an example where the white balance does matter.
> Suppose you do a wedding. The bride clothing is mainly white.
>
> Lot's of people (especialy the mothers) will complain if the
> dress is not white in the pictures. So if you have a series of
> pictures where the dress is a littlebit green, blue, pink or any
> other shade you have a problem.
>
> The problem is that in real live the dress takes on the color
> of the lightning which is supplied. For example under cover
> of trees in the grass the dress will turn up a littlebit green.
>
> In artificial lightning the dress will turn up a bit red.
> (In lightbulbs).
>
> In the shade on a very clear day the dress will turn up a
> little bit blue.
>
> With a white dress from the bride this is not acceptable.
>
> So to prevent the white dress having different colors, you
> have to calibrate calibrate the camera everytime the
> light changes from color. To do that you need a constant
> reference, a white card will work, but a gray card will work
> as well. Working with Raw you can take a picture of the
> gray card and adjust the picture in postprocessing so it
> comes out gray. Working with jpg you can use the graycard
> to set the WB in the camera so the graycard appears gray
> in the jpg file.
>
> So doing the things correctly the wedding dress appears
> so shade of gray in every picture. Depending on the light
> situation this might be more or less bright, but somewhere
> between white and black and never with a colorcast.
> The exposure offcourse should be correct, but should not
> influence the WB. The mothers will notice a very slight
> color cast on the weddingdress, but wil be less critical
> for the exposure.
>
> The amount off lightning should not matter to the WB. But
> large changes in the amount of lightning can also mean
> large or small changes in the color of the lightning.
> ISO settings should not influence the WB.
>
> There are some situations where you can not set the
> WB such that it works for everything in the picture.
> If there are more lightsources, for example incandecent
> and natural light in one scene you can not set the WB
> to both.
>
> Fluorrecent lightning is a problem as well because
> it isn't a continues spectrum some colors look different
> under this type of light.
>
> Using a flash requires some thought. Normaly the flash
> will produce light of about 5600 K, this is called the
> color temperature. But if this is combined with available light
> of another color temperature, you have to choose for what
> to go.
>
> Example of a difficult situation: A bride on the grass (green
> casting) in the sunset (low colortemperature of about 3800 K)
> and using a little flashlight to give some highlights (5600 K).
> Now the underside of the dress will have more green colorcast,
> The main lightning is provided by the sun of 3800 K rather reddisch,
> and the flash which light mainly the front gives you 5600 K. So
> the dress will turn up multicolored which you can not correct with
> WB allone.
>
> Sory to be this 'long' but I hope this gives you the information
> to work with.
>
> Ben
>
>


 
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picture taker
Guest
Posts: n/a
 
      07-10-2006
gene, thank you for the reply.


say for example you are shooting a bride /groom and there party under
the same lighting condition you did a CUSTOM WB for ,say out side in
the shade and you are using your flash for fill .wouldn't it be easier
to just shoot raw if they happended to want a larger print and if by
chance there was something you hadn't noticed and had to do some
seriuos corrections to ,working with a raw file would be alot easier
right ?
or to really do it right you would need to do a custom wb for every
shot amd lords knows on a wedding day you don't have the timne for that


thank you


Gene Palmiter wrote:


> If you are shooting JPGs you make this choice before you shoot...if you
> shoot RAW you can wait until you get to the computer. Best of all worlds is
> if for each shot you made custom WB and then shoot RAW...but that is too
> much work! As the light temp usually changes slowly you only have to set the
> WB when you suspect the light source changed.
>
> There is an interesting product that I helped a bit with development that
> overrides the WB. You can see it at www.warmcards.com . These were first
> invented for video where you cannot easily change the color balance after
> you shoot. Using warmcards you can trick your camera into thinking the light
> is too cool (blue) so it makes the shot warmer and gives you nicer skin
> tones and enriches the other colors.
>
> --
> Thanks,
> Gene Palmiter
> (visit my photo gallery at http://palmiter.dotphoto.com)
> freebridge design group
>
> "picture taker" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) oups.com...
> > hi,
> > i understand exposure shutter speed,f-stop ,iso etc , shoot with a
> > canon 20d ,capture raw files all the time, convert with cs2 and adjust
> > the wb if i feel it needs it .
> > i have never fully understood whte balance / custom white balance etc
> >
> > when people refer to a custom white balance are they trying to make
> > everything equal ,meaning the reference of 18% that is often mentioned
> > about custom white balance ?.
> >
> > say there is a shinny red dress or a white one for that matter and
> > they look a lot brighter than the other colors, by doing the custom
> > white balance does the camera then read the dresses as the same and
> > won't blow out the details ? .
> >
> > what is the difference between using a reference card ( gray card ,
> > expo disc etc ) to set the custom white balance but ive also heard it
> > referd to as usnig it to set the exposure not the white balance ?
> >
> > say you are in a gymnasium shooting basketball with an expodisc for you
> > to use as reference on the end of the lens pointed at the lights to set
> > your custom wb in camera and you crank up the iso does it matter if you
> > set the custom wb at a differnt iso than what you will be shooting ?.
> > same situation in the same gym ,now your shooting with a flash
> > should you just leave the custom set or reshoot the custom wb with the
> > expodisc attached while using the flash ?.
> >
> > thank you
> >


 
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picture taker
Guest
Posts: n/a
 
      07-10-2006
couter thanks for the reply .

i understand exposure but had seen pepole refer to using a gary card
instead of a CUSTOM TOOL for white balance i using it for exposure
setting ..

thanks


Cooter wrote:
> Unless I totally misunderstand your question(s), I think you are confusing
> exposure metering with white balance. ISO should not have any reasonable
> effect on white balance and vice versa. White balance is simply a means of
> setting the camera's response to the prevailing lighting conditions;
> therefore, custom white balance normally refers to setting the camera's
> color response to an existing condition that is different than one of the
> listed white balance settings - Daylight, Incandescent, Flash, etc. Say you
> are shooting in an area illuminated by a mixture of daylight, incandescent
> and fluorescent lighting. Unless you want a particular effect, you would set
> your camera's white balance via the custom (some cameras refer to it as
> 'Preset') white balance function.


 
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picture taker
Guest
Posts: n/a
 
      07-10-2006
matt, thank you for the reply,
ill be looking at the lights in the supermarket next time im there lol
, makes alot of sense
so you don't think it really matters if shooting raw to do a custom WB
or not if shooting raw ?
the hardest challenge for me is to be able to capture a black tux and
white gown with out blowing the highlights or underexposing the black.
thanks.

Matt Ion wrote:
> When you go to the supermarket, you'll notice that they never use
> flourescent lighting over the meat section - this is because flourescent
> typically has a yellowish quality to it, and you don't want your meat
> looking yellow. Instead, they'll use incandescent lights, which have a
> more reddish color, so the meat will look fresh and healthy. Similarly,
> you'll see more flourescent lighting used in the vegetable section,
> especially over green leafy veggies, because it brings out the green more.
>
> Cameras respond the same way - if you shoot under indoor, incandescent
> lighting, pictures will tend to have a reddish hue; shooting under
> bright sunlight will usually give you the "whitest" light, but shooting
> in the shade will give a "blue" tinge to things... and so on.
>
> Setting a custom white balance involves giving the camera something
> that's white or light grey to "look" at, something that will reflect all
> colors equally... then "telling" the camera, "Okay, this is what WHITE
> looks like in this lighting".
>
> White balance is only REALLY applicable when you're shooting JPG and the
> camera is doing internal processing of the picture. When you shoot RAW,
> the camera just stores the data straight from the sensor without
> altering anything. It will include information on the white balance
> setting, that the RAW conversion software can read - this is handy if
> you're using auto white balance or custom white balance, because it
> tells the software what the WB readings were - but the WB setting
> doesn't actually alter the image that comes out of the camera. That
> allows you to correct the WB in software before converting the picture
> to TIF or JPG or whatever format you're going to use.


 
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