White Balancing Question


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qing02051981

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Dec 25, 2005
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Simei
hancheng-travel.blogspot.com
Hi,

I am using Nikon D70s. I took a picture of an object on a white paper. However, the photograph shows the paper as grey. Thus I did the following

Press the WB button and turn the thumb dial until "Pre" is shown on the top panel. Release all buttons. Then, press and hold the WB button for a few seconds. "Pre" will flash. I took a photo of the paper to measure the white balance.

However, the photograph still shows the paper as lighter grey. How do I solve this?
 

after shooting at the paper, did you see "good" on the LCD? if not, then the camera has not captured the correct WB.

Check your EV setting, making sure not EV compensation.

use AWB to take a shot of the same paper using flash, if the paper turn out grey, something is wrong.
 

there is nothing wrong, the camera meter does not know this is a piece of white paper, so it produce it as gray paper.

white paper is two stops lighter than mid tone grey, so you dial +2 when you use A or P mode, or open up two shops in M mode.

to check whether you do the correct custom WB setting, shoot this white paper and load the image in photoshop, use the eye droplet to check are the RGB value show all same or very close.

hope this help.
 

as mentioned by catchlights this is not a WB prob but a wrong exposure prob :)
 

camera meter reads all things in mid tone gray, if you shoot a piece of black paper with A, S or P mode, it will turn out grey also.

don't bother to change to matrix, center weighted or spot metering mode, the result will be the same.

you can find a piece of mid tone grey paper, take meter reading on this grey paper, than using the same reading to shoot a piece of white paper and a piece of black paper, both papers will turn out as it is.
 

can refer to this thread for why white paper appears grey.

http://www.clubsnap.com/forums/showthread.php?t=309544

I followed the article to set the exposure compensation after I measured the white balance. If I do an exposure compensation of +1.3, it causes the paper to be white but the subject becomes over exposed.

How can i ensure the paper to be white and the subject to be correctly exposed?
 

I followed the article to set the exposure compensation after I measured the white balance. If I do an exposure compensation of +1.3, it causes the paper to be white but the subject becomes over exposed.

How can i ensure the paper to be white and the subject to be correctly exposed?

Set up your lighting so that the paper is +1.3 while the subject is 0. Then shoot at 0.
 

its not a problem of white balance.
white balance isnt used to get white paper white and not grey.

its abt the colour temperature (yellow/blue cast)


ur problem is the way the camera meters, and u've gotta use exposure compensation to get it right like what others mentioned.

in layman terms, if u shoot a piece of white paper coving the whole frame, the camera "sees" it as too bright, and thus, u'll get a lower exposure so that highlights isnt blown. similarly, if u do so with a piece of balck paper, the camera finds it too dark, and thus increased the exposure (eg: longer shutter speed, larger aperture, etc) to capture enought light.

the camera's metering is fooled by the bright/dark paper. so u'll need to compensate the EV accordingly.
 

Does that mean a desktop light is not enough to brighten the paper to +1.3?

Open the shutter long enough sure can get to +1.3. So the light source is not so important, just have to ensure lighting ratio of 1.3:0.

We can help you better if you explain what you want to do, what you shooting, what eqpt you have etc.
 

Open the shutter long enough sure can get to +1.3. So the light source is not so important, just have to ensure lighting ratio of 1.3:0.

We can help you better if you explain what you want to do, what you shooting, what eqpt you have etc.


I want to learn product photography.
I am trying to photograph an object (paper clip, pencil, anything) with a white background like those you see in stock photos.

My Equipment
- Nikon D70s
- Kit lens (18-70mm)
- Tripod
- Self made light box
- Desktop lamp

Hope this helps! and many thanks for the patience with me :)
 

if you want your subject to be properly exposed while the paper appears white in colour, you should dial in a +2 stop, meter the paper, lock the exposure and shoot the subject. you should play with the lighting so that the brightness difference between the subject and paper is within the acceptable range. you can do it by either bringing down the brightness on your subject, or increased the brightness of the paper/background.
 

Let me try to explain that.

WB and exposure are two different things. When you set Custom WB to your paper, what the camera do is ensure the paper will not cast any color. That mean the paper will not become yellow, or blue, or green but a certain color from pure black, dark grey, light grey to pure white. So, the term "white" in "white balance" just mean "colorless" and refer to the whole range from black to white, not only pure white.

To get really white color on the paper, what you need more than WB is your material, lighting, exposure and PS. I suggest as following

For material, choose a really white paper for your background, do not choose a grey one.

For lighting, give proper lighting on your paper, not on your subject

For exposure, use spot metering on your paper, and set exposure to 2+ stop. Ensure that the subject is not overexposed. If cannot get that, use PS.

For PS, use color picker to measure the lightness of the paper and the subject. Normally, they are in two seperated region (that mean the paper is much brighter than the subject generally. So, use can choose the curve tool to boost lightness of the paper only while keep the lightness of the subject (almost) unchanged.
 

I want to learn product photography.
I am trying to photograph an object (paper clip, pencil, anything) with a white background like those you see in stock photos.

My Equipment
- Nikon D70s
- Kit lens (18-70mm)
- Tripod
- Self made light box
- Desktop lamp

Hope this helps! and many thanks for the patience with me :)

Ok. Some items easily obtainable to help you. Pieces of white and black cards for bounce. You can use mirrors as well to get a more shiny reflection but white bounce cards work well in most situations.

Depending on how reflective your subject is / how intense your light source is, have plenty of tracing paper or the thicker diamond paper (I got it at almost $1 per A1 from Art Friend) sheets on hand.

Getting a cheap external flash would be useful, or go look for some bright desk lamps. Play with your lighting. Tip: Not all lights have to be pointed straight at the subject to make a photograph.

It's going to be a bit hard for you to learn balancing lighting ratios shooting clips and pencils on a simple setup because there is no separation between subject and background. Try shooting something that can stand on it's own and is not too reflective like metal or glass. A block of wood if you must, just for experiment. Get 2 lights, one for subject and other for background. Place background paper beyond your shooting dof. It should not be in focus.

Eh, it can only get more complicated in shooting product but just shoot within your ability and if it's acceptable to you then that's reasonable enough till you want to go further.
 

I want to learn product photography.
I am trying to photograph an object (paper clip, pencil, anything) with a white background like those you see in stock photos.

My Equipment
- Nikon D70s
- Kit lens (18-70mm)
- Tripod
- Self made light box
- Desktop lamp

Hope this helps! and many thanks for the patience with me :)
basically you place an object on a white paper b/g, you light the object and b/g as it is, you will never get pure white b/g. cos the white paper is only two stops brighter than mid tone, consider "important highlight with details", you want it to be in pure white, most of the time you will over exposed your subject too. so what most people do is either PS it or use a light table as b/g to get pure white b/g.
 

the other way is u can expt using 2 flash, 1 behind the paper and the other on the camera. but the flash behind should not touching the paper though, adjust the distant such that it is enough to cover the paper.
 

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