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White Balance - Grey background

Discussion in 'Talking Pictures' started by superfly, Mar 3, 2013.

  1. superfly

    superfly New Member

    Hi all,

    please be gentle with me :)
    I've recently brought myself a new camera - olympus pen e-pl3 and looking to take close up shots for jewellery.
    I've been reading and watching youtube videos on how to take decent close up shots on a white background, when i started out everyihng was coming out grey and it was frustrating as hell to me why a camera was colour blind!
    Anyway I heard of this magical term "white balance" started playing around with settings, using a light tent kit, using a reflective white plate but to no avail still the background comes out greyish.

    I'm wondering if you guys could assist or point me into the right direction of some reading material, my head is thumping from trying to understand it.

    I've upload an image onto imageshack for you to review

    http://img542.imageshack.us/img542/5450/p3020668.jpg

    Thanks in advance
     
  2. Bob Maddison

    Bob Maddison Well-Known Member

    The big problem is NOT the White Balance, but the fact that your camera is being fooled by the white background into underexposing. Depending on the area of white background you need to increase exposure by at least 1EV. Better still try to use a "grey card" and set the exposure manually. A large buff makes a good substitute, but it is easy to experiment until you get a good white without overexposing the subject! It is also possible to correct in Photoshop etc, but it is always better to get it right in the camera and then use Photoshop to make only small final adjustments.

    I would also suggest that you experiment with a coloured background. For jewelry and the like, a mid green background seems to be effective. I use one of those inexpensive matt green plastic 'cutting boards' used by model makers: either the plain side or the side with a white 10mm grid, depending on the purpose of the photo. Even then I have found that I sometimes need to make some colour adjustment to get the best contrast between the jewelry and the background and this is where Photoshop comes in.

    Lighting is critical for photographing jewelry. Totally flat lighting is wrong such as from a ring flash or flat daylight "artists studio" light, and so is very directional lighting such as from a flash from a single unit near the camera. What you need is lighting that gives multiple "sparkles" from the jewelry. I have found that a couple of inexpensive 20w Halogen desk lamps work well although when set at about 45 degrees to the subject plane: you will have to experiment with their position for best effect. If you do use these, then set the White Balance to "tungsten".
     
  3. AlexMonro

    AlexMonro Old Grand Part Deux

    I think that your problem might not be white balance, which adjusts the colour (hue - e.g red-blue) of the picture so much as exposure compensation , which adjusts the brightness. Most camera auto exposure systems are set up on the assumption that the average picture will contain bright bits and dark bits, but when averaged out they balance out to a mid grey brightness level. If you take a picture of something a bit unusual - e.g. a black cat in a coal cellar, a snow scene, or as in your case, an object on a plain white background, the autoexposure system is going to try to adjust it to make it average out as grey, and get it wrong.

    So you need to tell the camera that this is an unusual scene, by using the exposure compensation control. I'm not familiar with the E-PL3, but most cameras have either a button marked with a "+/-" symbol, or a menu item similarly marked - check the camera manual under "exposure compensation". From the look of the image you posted, I would guess you need to set it to +1.5 to +2 stops - try a bit of experimentation. If your camera has a histogram facility, try adjusting the exposure compensation until the graph just touches the right hand edge.

    You might find these tutorials at Cambridge in Colour helpful:

    Camera Metering (click here)

    Histograms (click here)
     
  4. RogerMac

    RogerMac Well-Known Member

    I am a bit late but here is another vote for exposure compensation. Look for the +/- symbol on a button, hold this down and press the left and right arrow buttons. You should have a maximum of 3 stops in each direction which will be about twice what you need

    Roger
     
  5. Wheelu

    Wheelu Well-Known Member

    There is a problem with the white balance, the background has a pink cast on my screen. There is also a problem with exposure, but I think that has been caused by the highlights on the stones, the camera has attempted to prevent over-exposure. Further there is a problem with vignetting or dark edges.

    I don't know your camera but many models allow you to set a custom white balance by shooting a sheet of white or grey paper in place of the object to be photographed. Read your manual to see if it is possible. However, if you shoot raw images you can correct the white balance in raw conversion.

    Re exposure, it's always useful to check the histogram in circumstances such as these as it's very difficult for the automated meter to get it right. Take a few shots at differing exposures - it costs virtually nothing.

    WRT to the vignetting many cameras can now auto correct this, but raw conversion software or Photoshop can deal with it.

    If you are possessed of infinite patience, you could produce a cut-out, taking out the existing background and then dumping the subject onto a plain white or coloured background.
     
  6. Roy5051

    Roy5051 Well-Known Member

    Another vote here for exposure compensation. Those of us brought up on film photography, where we didn't have white balance, will know that any over-light background will under-expose because the meter is expecting the image to average out to 18% grey (or gray as the Yanks say). Thus, pictures of snow will be under-exposed. By the same token, pictures with a predominantly dark background will over-expose.

    So, try +1 or +2 exposure compensation on light backgrounds, and -1 or -2 on dark backgrounds.
     
  7. RogerMac

    RogerMac Well-Known Member

    Looking at it very carefully I am going to withdraw my previous post as there are highlights in the central stone that are brighter than the background and need to be shown. I downloaded the image (Hope that's OK - I have since deleted it) and played around with the exposure and if the background is brought up to pure white then all detail is lost in the central stone. There is also a pink case on one side and a blue one on the other caused by reflections off the various stones.


    If you want to get rid of the colour casts you could put it onto a dark background but it does look good on white. My only suggestion is to light the background and the jewel totally separately - a technique that is often used in portraits. There are two ways to achieve this either make some form of light box with translucent frosted glass for the background and separate lighting from the rear or make a stand to support the jewel a distance away from the background and light them both separately.

    Sorry if that seems a lot of trouble but it is a difficult subject to get right

    Roger
     
  8. Roy5051

    Roy5051 Well-Known Member

    I suppose another way round the problem would be to place the jewellery on a lightbox.
     
  9. Bob Maddison

    Bob Maddison Well-Known Member

    Two things to note:

    1 If a white background appears to be grey, then the picture is underexposed.
    2 If a white background has a colour cast, then the White Balance is wrong. This can usually be corrected easily by switch from Auto WB to a setting that matches to light source such as daylight or tungsten. Custom WB is another (and probably better) way to go but this does require just a little more work.

    If there is a dominant colour in the frame then AWB will attempt to make it look like white. Fortunately, there is a limit to what colour changes AWB can make and the result is usually that that colour looks a little washed out. For instance a red background looks like pastel pink. This is also white blue skies sometimes look too pale. This can be avoided by NOT using AWB but but setting either a custom WB or set it for the light source in use.

    Photography jewelry or indeed any highly reflective subject demands a lot of skill and experience. Take a very simple example: a piece of glassware such as a plain glass tumbler. Not only is it transparent, but it has a very reflective surface and this will pick up the surroundings including the photographer and his camera! Likewise a piece of silverware. What you see in the photo is not the silverware but a distorted reflection of the surroundings. This is why both of these subjects are best photographed in a muslin tent. Without a lot of careful preparation, neither of these subjects will look well in a photo.

    Jewelry takes this one stage further. It has multiple reflective surfaces but as this is a macro subject, any reflections are actually so well out of focus that a tent isn't necessary; the reflections are blurred out of all recognition. However, to get the best out of it, the ideal lighting is multiple small directional sources which are picked up by the many surfaces of the jewelry. One trick is to use only one or two lights but to surround the subject with roughly crinkled polished aluminium kitchen foil to create the effect of mutliple lights. However, for most jewelry shots, particularly record shots, you can't do better than to use natural daylight, preferably well diffused and not direct sunlight. Otherwise, carefully placed small spotlights (or flashes) can work well, but this needs some experimentation. There is no substitute for experience!
     

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