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Expodisc FAQ

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If you do not find answers to your questions below, then please
contact us directly for additional product support.

What is the difference between the ExpoDisc
v3 and older ExpoDisc models?

We have continued to improve our design, manufacturing and calibration processes over time,

and we designed ExpoDisc v3 with a better form factor, attachment design, and diffusion materials.

The new ExpoDisc represents the highest quality white balance tool that ExpoImaging has ever offered.

 

The new ExpoDisc v3 is thinner, lighter, and better at setting white balance and exposure than earlier models.

Thinner:  ExpoDisc v3 is about 1/2 the thickness as the ExpoDisc 2.0.  This makes it easier to hold, and more comfortable to slip into your pocket.

Bayonet Mount:  The new ExpoDisc v3 bayonet mount design allowed us to make the ExpoDisc thinner and lighter by moving the part of the design required for attachment to a separate step ring which is included in the box.  

Wide Spectrum Calibration:  We developed a new combination of diffusion materials and are now able to test the ExpoDisc v3 from 300nm-2200nm.  The new ExpoDisc v3 exhibits even better light transmission with optimum performance from 380-1600nm.  In the visible spectrum of 380-700nm the delta is just .9%, and from 380-1600nm it is just 1.8%, which means the ExpoDisc v3 can now be used for IR photography.

Total Transmission:  We are calibrating the light transmission of the new ExpoDisc to be inline with digital light meters, which means the new ExpoDisc v3 will transmit about 14%.  This will result in an improvement of about 1/3-1/2 f/stop when using the ExpoDisc to meter for exposure on digital cameras.

 

Does the ExpoDisc work with digital video cameras?

Yes. The ExpoDisc can be used to set white balance with any digital video camera that has the capability to set a custom white balance. This includes digital SLR's, point and shoot, and prosumer fixed lens cameras.

 

Can I use the ExpoDisc to set a custom white balance if the camera manufacturer recommends use of a gray card or white card?

Yes.  The ExpoDisc can be used to set an in-camera white balance, or it can be used to capture a reference image for post production color adjustments.

Most photographers discover that white balance targets like gray cards and white cards are inconvenient and awkward to use because they must be positioned precisely while avoiding shadows and reflections.

Small white balance targets are portable, but their small size also makes them difficult to use for in-camera white balance.  This often restricts their use to more time consuming post production color correction.

Large white balance targets are simply too big to carry with you all the time.

Keep in mind that printed gray cards and white cards must be replaced often because the inks and dyes used in their production change color when exposed to air and light. 

What makes the ExpoDisc the best white balance tool?
  • You can set an accurate white balance in just 10-15 seconds with the ExpoDisc.

  • Small and lightweight so it's easy to take with you. This means you will have it when you need it.

  • The ExpoDisc v3 is calibrated for color neutrality in the visible spectrum (380nm - 700nm) on a transmission spectrophotometer.

  • You can set your white balance in camera, which means that you do not need to spend hours wrangling your images in post processing with complicated software.

  • Each ExpoDisc is assembled and calibrated by hand in our California facility.

  • You can also use the ExpoDisc to capture a gray frame reference image for batch processing your RAW images in post production.

  • The ExpoDisc can also be used to meter for exposure.  ExpoDisc v3 has been updated with a 14% light transmission to be consistent with ANSI standards for photographic exposure meters.

  • The ExpoDisc can also be used to check for dust on your camera sensor, and to create a dust map for use in your image editing software.

 

How does the ExpoDisc work as a white balance filter?

When placed on your camera lens the ExpoDisc works like an incident light meter.  It diffuses light and produces a featureless image, or 'gray frame' that represents the average color temperature of light at the moment of capture.  When you set a custom white balance you are telling your camera to use the gray frame as a reference point for adjusting the color in your images.  

What size ExpoDisc v3 should I buy? 

The ExpoDisc v3 has a diameter of 86mm and can simply be held over lenses that take 82mm or smaller size filters.  For example, it is very easy to hold the ExpoDisc v3 over lenses that use 72mm or 67mm size filters.

However, the ExpoDisc v3 also incorporates a new bayonet mount design for those who prefer to briefly attach it to their lens while setting a white balance.  For this reason we package the ExpoDisc v3 for lenses that require 77mm and 82mm size filters.

If you don't know what filter size your lens requires, then check your lens or lens cap.  The filter size can typically be found on your lens barrel or inside your lens cap written in the following way:  ø77mm, ø58mm, etc… 

 

I have a 95mm lens?

The ExpoDisc v3 features a new mount design that incorporates a bayonet mount feature that quickly attaches to a step ring that you thread onto your lens.  

If you have a 95mm lens, then we recommend pairing the ExpoDisc v3 82mm with a 95 to 82mm step down ring. The ExpoDisc v3 82mm Step Ring will attach to the 95/82mm step down ring attached to your lens.

I have a 72mm lens or smaller?

We currently offer the ExpoDisc v3 step ring in a 77mm and 82mm size.  If you have a 72mm lens or smaller, then we recommend pairing the ExpoDisc v3 77mm with a step down ring.  For instance, if you have a 67mm lens, then the ExpoDisc v3 77mm step ring will attach to a 77/67mm step down ring attached to your lens.

Inexpensive step down rings can be found at your local camera dealer or online.

You can also skip using a step down ring all together and hold the ExpoDisc over your smaller lens.  The ExpoDisc v3 has a diameter of 86mm and can simply be held over lenses that take 82mm or smaller size filters.

 

Can the ExpoDisc be used with other filters?

Yes.  The ExpoDisc can be used in conjunction with most other photographic filters such as polarizing, skylight, UV ultraviolet filters, or even colored filters.  

However, care should be taken when changing lenses and filters.  A color cast can be introduced if a lens filter is attached, or removed from the lens after the white balance has been set.

When using a polarizing filter, you can simply leave it on your lens when setting a custom white balance with the ExpoDisc.

If you’re using a colored filter, like the yellow #8, then you would want to remove the colored filter when setting the custom white balance to achieve a neutral white balance and then add the yellow #8 back to your lens to create the color effect you are looking to achieve.  

Do I leave the ExpoDisc on the lens when taking a photograph?

No.  You must remove the ExpoDisc from your lens after setting the white balance.  The ExpoDisc is only designed to cover the lens while setting the custom white balance.  

Do I need to set a new white balance after switching lenses?

No.  Most modern lenses are optically clear and will not add any color cast that would affect the white balance.  However care should be taken if there are any filters on the lenses you are using because some filters will introduce a color cast to your images.

Will the ExpoDisc work with my digital camera?

The ExpoDisc works with all major camera brands, including:  Canon, Nikon, Sony, Panasonic, Pentax, Olympus, Samsung, Lumix, and Leica.  It can be used with any digital camera equipped with a custom white balance capability, including all digital SLRs and most point & shoot cameras.  

What is the ExpoDisc warranty?

All ExpoImaging products come with a limited warranty to be free of defects in workmanship and materials for a period one (1) year from the date of original retail purchase.  If the product proves defective within the warranty period, then it be will replaced.

What camera white balance setting do I use when setting a custom white balance?

Nikon cameras instruct the user to place the camera in the PRE white balance setting prior to capturing an in-camera custom white balance "reading".

If your camera's custom white balance procedure requires capturing and selecting a reference image, e.g. Canon, then we recommend using the designated custom WB setting.  

My Nikon camera displays the "no good" error message 
when setting my white balance.

Nikon cameras may produce a "no good" error message during the Preset white balance procedure if the exposure is incorrect (over or under exposed), or if the color temperature of light is out of range of the camera's ability to correct, e.g. campfire light is too warm (yellow).  

Generally, most Nikon "no good" white balance errors can be fixed by correcting the over/under exposure settings used to set the white balance.

If you're shooting in ambient light, then simply set the camera to Aperture Priority and set another Preset white balance. 

Do I need to set a new custom white balance when I change my exposure?

No, if you are photographing in unchanging (constant) ambient light, then you do not need to reset your white balance when you change your exposure.  

Yes, if you are using flash, then we recommend resetting the white balance when you change your exposure. 

Shutter Speed when Using Flash.  Changes in shutter speed will change the ratio of ambient light to flash.  For best results photograph your subject with the same exposure (shutter speed) used to set your white balance.

Should I save the "gray frame" custom white balance reference image?

If your camera requires selecting a captured image to set an in-camera custom white balance, e.g. Canon, then you only need to select the ExpoDisc reference image in the custom white balance procedure to import the relevant data into your camera's memory.  Your camera will save this information until you replace it with a new custom white balance reference.

Once the white balance procedure has been completed, you may change memory cards, or delete the reference photo without losing your custom white balance settings. 

If you wish to color balance your images later in photo editing software, then you should save the custom white balance reference image.  These reference images may also be useful as markers to indicate changes in lighting if you are post processing your images.  

How do I use the ExpoDisc with flash?

Off-Camera Flash. When shooting 1/125 or faster, stand at subject’s position and point camera towards the main light.  When using slower shutter speeds stand at subject’s position and point the camera towards your shooting position.

On-Camera (Bounce Flash).  A ceiling or wall may change the color of your bounced flash.  Aim your camera and flash towards the bounce surface (ceiling, wall) when setting your WB.

On-Camera (Direct Flash).  We do not recommend setting a custom WB with the ExpoDisc when using on-camera direct flash.  The ExpoDisc is an incident metering tool and cannot be used to meter on-camera direct flash.

My pictures have a colorcast after setting a custom white balance.

Pictures with a warm colorcast usually result from improperly aiming the camera towards a cooler light source.  Examples of cool lights include flash, blue sky, north facing windows, and shade.

If your images have a bluish cast after using the ExpoDisc, then it is likely the result of aiming the ExpoDisc towards a warmer light source.  Examples of warm lights include halogen, fluorescent, tungsten, warm LED, sunrise or sunset, etc.

Use the ExpoDisc like an incident light meter to ensure that you meter for the correct color of light that illuminates your subject.  To do this go to your subjects position and aim the ExpoDisc back towards your shooting position.

 
How do I set a white balance in mixed lighting?

Digital cameras can only balance to one color temperature of light at a time.  In a mixed color temperature shooting environment, we recommend identifying and white balancing your camera towards the predominant light source illuminating your subject.  

  • If the different sources of illumination on your subject are relatively equal in color and intensity, then stand near the subject and white balance your camera while aiming the camera back towards where you will be positioned when taking the picture.  

  • In a mixed light environment with warm and cool lights, overall warmer (yellow) image tones will result when the camera is white balanced while aiming towards cooler (white or blue) sources of illumination, e.g. electronic flash, north facing window, blue sky, etc.

  • In a mixed light environment with warm and cool lights, overall cooler (blue) image tones will result when the camera is white balanced while aiming towards warmer (yellow) sources of illumination, e.g. tungsten, halogen, late afternoon sun, etc.

  • We recommend white balancing towards the cooler illumination in a mixed light environment.  For example, photographing under a combination of tungsten and daylight illumination looks best when the camera is white balanced towards the cooler daylight.  This is because the correction necessary to color balance the bluish daylight results in warm image tones in those areas illuminated by the already warm tungsten light.

 
Can I use the ExpoDisc to white balance stadium and gym lights?

Yes, the ExpoDisc can be reliably used to white balance metal halide lamps, like those commonly used in professional sports stadiums and gyms.  Team photographers for professional football, hockey, baseball and basketball have used the ExpoDisc to white balance their cameras for many years.

However, white balancing your camera in the presence of Sodium or Mercury vapor lights is unpredictable because these lights have a discontinuous color spectrum (i.e. they do not contain all the red, green and blue primary colors).  Your camera may not be able to compensate for all of the missing color in your source light.  Furthermore, the continuous on and off cycling of these lights creates additional challenges because their color temperature fluctuates as they cycle.

Why do I need to use manual focus?

When attached to your camera lens the ExpoDisc presents a featureless, out-of-focus image to the camera (most cameras prevent the shutter from being tripped in auto-focus mode when the camera cannot focus on a subject).

If you cannot trigger the shutter with ExpoDisc covering the lens, then briefly set the lens to manual focus.  Return the lens to auto-focus mode after setting the white balance.

Or use the camera’s “back button AF” function to bypass autofocus while capturing the WB reference image. 

Note, Nikon camera users do not need to switch their lens focus to manual if they are using the in-camera Preset white balance procedure because the camera's auto focus function is disabled when PRE is blinking in the LCD panel.

How do I set the white balance when photographing a landscape?

In general, when using the ExpoDisc to set your white balance you want the same color of light illuminating your subject to pass through the ExpoDisc.  This means you need to point the ExpoDisc towards the primary light source.

In landscape photography, the best white balance results are obtained by aiming the ExpoDisc towards the sky when photographing under cloudy skies, open shade, or sunlight. 

Note, direct sunlight poses no risk to the camera's electronics because the ExpoDisc diffuses the light.

How do I set the white balance when the subject has his/her
back to the sun or is backlit?

Use the ExpoDisc like an incident light meter.  The best results are obtained by standing near your subject and pointing the camera, with the ExpoDisc on the lens, back to where the camera will be positioned when you take a picture.  By utilizing this method you will balance your camera to the color of light that is illuminating the front of the subject, not the backlight.  This method also works well when the subject is in shade or near a brightly colored, reflective surface.

Can the ExpoDisc be used for underwater photography?

Use of the ExpoDisc underwater is not recommended.  The properties of light underwater are significantly different than light in the Earth's atmosphere.  Major factors influencing light underwater are:  the attenuation of light as depth increases; the scattering of light from suspended particles; and, most importantly, reduced color saturation.  At a depth of just 20 feet (6 meters) almost all red light has been filtered out by the water.  Without special lights, underwater photography using natural light is only possible in very clear water at shallow depths of just a few feet.  The ExpoDisc was not designed to address these issues.

CAUTION:  The dyes in the special filters used to manufacture the ExpoDisc could be affected by immersion in water or other liquids.  Salt water, in particular, is very caustic and could severely damage the ExpoDisc.  The ExpoDisc Limited Warranty is void if the filter has been immersed in liquids.

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