ExpoDisc Filters

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KBCamera - Your #1 USA Authorized ExpoDisc Dealer

How does the ExpoDisc work?     

Under “pure daylight”, such as shooting the sun on a clear, unpolluted, day when it is above you, the ExpoDisc image would be R128, G128, B128, and look like a neutral gray card. Setting this as your custom WB, you are telling the camera, and conversion software, that gray looks gray.

The camera and software now know by measuring the RGB values in the image just how the values deviate from R128, G128, B128. At this point the camera and/or software add the opposite colors in the right amount to make the gray look gray again.

Why is the ExpoDisc better than a Gray/White Card?

When mounted on the camera lens (instantly available when used like a lens cap) it always provides a convenient and fast full frame image of a perfect neutral gray frame. Each ExpoDisc is individually analyzed and corrected to be accurate to within 1/12 f/stop for exposures, and 1/6 f/stop (+/- 3%) for near-perfect color balance-it comes with a card recording it’s exact density and color balance as noted on the color analyzer. There is no other product available which can even approach this level of accuracy. Different brands of gray cards are different colors of gray-there is no consistency. The ExpoDisc is far more neutral and accurate than commercial gray cards that have poor quality control and can be well off the beam.

The ExpoDisc will never be plagued by the many variables that diminish the accuracy of gray/white cards: glare and lens flare, reflections and angles and shadows. The performance of the ExpoDisc will never be affected by getting dirty or wet-it is weatherproof, it will never fade. The ExpoDisc makes it possible to give the same identical WB reference to an entire body of work over a period of years, dramatically reducing workload and reproduction expenses while enhancing creative control of the reproduction process.

There are also huge advantages gained by being able to set WB from the shooting position-no more trying to fill the frame with a shot of a card which is too small to fit the frame from a reasonable distance, and is too large to comfortably haul around (ExpoDiscs can fit easily in your pocket&ldots;). The ExpoDisc provides the only way to set white balance in mixed light, and the easiest way to set WB when the subject matter lacks a white (or true neutral) reference, or when there is one dominant color in the image. The ExpoDisc procedure for setting WB takes only 60 seconds-and you get perfect WB on the first proof! Compare that to . . .how long?. .. in Photoshop for each event. . .

When you use the ExpoDisc to meter Incident Light you can select the fastest exposure possible by determining the largest aperture you can use (for depth-of-field control-see Wallace Aperture Guide), and then just center the needle in the camera to set the shutter speed and shoot a gray frame to set WB while metering through the ExpoDisc. (Or you can use the ExpoDisc with Reflective Light to set WB only.) No dials or gadgets or transposed settings from a separate meter to the camera while you try to compensate for variables-the ExpoDisc automatically compensates for all of these with no chance of error.

You can sandwich the ExpoDisc with your preferred filtration (81A, 82A, 82B for portraits) to create your own personal custom white balance. In Photoshop, just put the eyedropper anywhere on the Expo/Disc grayframe to tell the software that is your neutral reference, and the software will produce images with perfect WB - cool white light without filtration, or slightly warm with 81A, 82A, 82B filters. This method was suggested in the March 2003 Bulletin of the American Society of Media Photographers, page 19.www.asmp.org

Will the ExpoDisc work on My Camera & Model ?

Yes. Here are basic instructions for the use of the ExpoDisc:

  • Determine exposure

  • Select Manual Focus on the lens and Manual Mode on the camera

  • Set White Balance to Auto

  • Compose your picture

  • Attach the ExpoDisc to the front of the lens and aim towards the subject from the shooting position

  • Make a single exposure facing towards the subject from the same position (it will record a gray frame)

  • Remove the ExpoDisc

  • Go to the menu and select Custom WB

  • Select the gray frame exposure, which was just made in step 6

  • The camera WB must also be changed from Auto to Custom

  • Use this setting for all images shot in the same light and with the same lens; if the lighting changes, or if you change lenses, repeat steps 1-10

  • Or simply following the instructions in your camera’s manual as to how to use a gray card, and substitute the ExpoDisc instead.

What size ExpoDisc do I need?

Same size as your camera lenses filter size is perfect.  Larger Expodisk's can also be use with smaller size lenses by holding the filter in front of the camera lens.  Works with Digital Point & Shoot cameras in this fashion (camera lenses without filter threads)

Does the ExpoDisc work with all lenses and filters?

Digital cameras are programmed to analyze all colors based on an accurate white balance reading. Different lenses have unique color characteristics, and vary even within the same product line. Filters and lens shades skew the readings even further. When the ExpoDisc is used in conjunction with the through-the-lens camera meter, it instantly and automatically compensates for all components of the optical system, which affect the light entering the lens assembly. It provides direct TTL diffused light metering (with incident), after the light has arrived at the film plane, and the elimination of all margins of error in metering, along with accurate WB reference. You can also use it for precise testing of cameras, data cards, monitors, and computer processing-to eliminate virtually all margins of error in the image-making process.

I have a lens size larger than 72mm. Can I still use the ExpoDisc?

Your camera meters only through the middle of the lens, making it possible to use a size ExpoDisc that is smaller than your camera’s lens size. You may even purchase a step-down adapter appropriate for your camera to fasten the ExpoDisc to your lens, however it is very convenient to simply hold the ExpoDisc in front of your lens to record your test shot and set WB.

How do I install my ExpoDisc?

ExpoDiscs are designed without thread in order to eliminate the possibility of crossing threads while mounting the ExpoDisc in front of your camera lens. To install one, just push it into the threaded recesses in front of your camera lens, rotating slightly as you go. To remove it, just pull it out while reversing the rotation.

Because there are variations in the inside thread diameters of lenses and filter rings of the same nominal size, occasionally the fit may be a little too tight. If this happens, take a fingernail file or fine emery board and gently file a few thousands of an inch off of the cylindrical skirt. Or return the ExpoDisc with your comments, and we will replace it with a better-fitting ring.

In very cold outdoor weather the fit between your ExpoDisc and camera lens may be a little loose. In this case, carry it in an inside pocket rather than in front of the camera lens when it is not in use. Put it back in front of the lens before going indoors to prevent moisture condensing on the cold lens.

How do I use the ExpoDisc to calibrate my camera’s meter?

Start by putting your setting back into AV where you set the aperture and the camera sets the shutter speed. Once this is done, make sure your camera meter is calibrated properly. You should be able to use the 1/ISO speed rule where you set the setting on ISO 100. Place the aperture setting, manually, at f/16 and the meter, while the lens is pointed at the Sun and the ExpoDisk is covering the front of the lens, should read 1/125th of a second.

If it doesn't use the exposure compensation thumb wheel to get the exposure to line up, and you will see your meter's error factor.

Now that you've calibrated your meter you're ready for the ExpoDisk shot.

How does the ExpoDisc read reflective light?

The prismatic front of the ExpoDisc collects light from 180 degrees - it is not looking only at what is directly in front of the camera. In fact, to get a reading influenced by a dominant color central subject, you would have to be very close in order to reduce the impact of skylight and other ambient light spilling in from the sides to contribute to the WB reading. When you step away from the central subject, the influence of skylight and ambient light will become more apparent.

The many faceted planes in the front lens provide the most efficient means (better than a dome) of collecting multiple samples of all light sources. The prismatic pattern of the lenticular front element transmits an increasingly larger percentage of ambient light as the source swings more off axis, yielding an accurate average of all illumination for perfect WB.

The near-perfect neutral balance (+/- 3%) of the ExpoDisc provides digital programs the best means for determining the amount of correction required in any lighting. You will download near-perfect WB.

For professional photographers, ExpoDiscs are white balance tools that quickly pay for themselves by speeding workflow and volume of production - by as much as 50% !!!

 

ExpoDiscs also make a huge difference in image quality by preserving subtle color contrasts attainable only at capture, by enabling saturated colors free of colorcast – at capture, and by increasing contrast and reducing noise. And don’t forget the increased enjoyment that comes from making it all easy.

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