Tuesday, December 8, 2009

REVIEW: ExpoDisc by ExpoImaging (Custom White Balance)

 

Update

As as I allude to below in my introduction, I’m not a white balancing expert. This original version of this review was done based on how I would use the product based on my understanding of how it should be used. However, I work with a bunch of fine engineers who are quick to point out that my usage was incorrect, and they were right. Please revisit the images in this article again and see text to see how the results changed.

Introduction

I’ll be the first to admit that before this review I didn’t give a rip about white balancing products, despite the fact that I always kept a gray card in my backpack. I thought the process was too much of a hassle, and I wasn’t sure that it helped all that much. More importantly, because I shoot in the RAW image format (CR2 for Canon, NEF for Nikon), I thought that I didn’t need to bother with doing a proper white balance because it is so easy to correct the problem in Adobe Lightroom, Photoshop or a host of other software products. Does this thinking sound familiar to you? Read on to discover how I learned more about why I should care and how this device made the process not only easier but also kinda fun!

What Is White Balancing?

At a super high level, White Balancing is the act of making an image represent the colors appear as they did to your eyes at the time they were captured so that your image is a faithful reproduction from the perspective of color from what you actually saw. Of course it is really a lot more complex than just that, so white balancing (a.k.a., color balancing) is best described on Wikipedia here (or for the super geeks, even better here on CambridgeInColour.com), but my crude definition will suffice for the beginner who isn’t ready to digest all of that information.

Why do you use a 18% Gray to White Balance? Shouldn’t it be called Gray Balancing?

If you didn’t read the detailed articles on white balancing, then I’ll break this one down in layman's terms as well. The idea here is that the color between pure white and pure black is a middle gray, which has been defined as 18% gray. Camera systems and software has been set up that if you can know the proper value of this color then all of the others from white to black can be calculated to produce a properly white/color balanced image. To do this on Canon systems, we take a picture of a 18% gray card and then tell our camera to use this value, and then set the white balance mode of the camera to Custom (white balance) to use this image. The reason we do this is so we can capture the tones in the environment which will contaminate the colors, so having that reference point that we know with 100% certainty is 18% gray, then the camera or software can adjust to accurately render the rest of the colors (or so the theory goes, other factors such as multiple light sources, exposure, etc… can come into play as well).

Why White Balance?
Auto White Balance ISO 6400 RAW Image Unprocessed Custom White Balance IS0 6400 RAW Image Unprocessed

The reason why we white balance is so our images out of the camera will faithfully represent the colors that were present at the time we captured our image. This is critical for in-camera JPEG images because the white balance can not be corrected completely via post processing (although some argue that you can do a “good enough” job). It is also very useful for videos (both camcorders and now the ever popular DSLR’s like the Canon 5D Mark II which shoot video). For those scenarios, not having a proper white balance can seriously compromise your final result. Taking the time to do this up front gives you an image with faithful colors that you can then choose to apply your artistic intent to. This usually results in making color adjustments to the image which results in an image that no longer represents a faithful reproduction, but you as the artist have chosen the final colors rather than being forced to live with compromised color due to a strong tone that couldn’t easily be removed from your image due to improper white balancing. Of course, RAW images can always be corrected after the fact, but a few seconds at the time of capture will result in exponential time savings for all of the images which no longer need white balance corrections.

A Word about Color

Whenever you deal with color accuracy issues on a computer, you can’t begin to have valid results until you have calibrated your computer monitor. If you haven’t already, I highly recommend you purchase a calibration device that will help make sure that the white you see on your display is the same shade of white as anyone else who is using a calibrated monitor will see. If not, then your whites may be a little more yellow, your blacks may be a little washed out or show no detail. You may also get comments from people that your photos look a little dark or the colors from your post-processing look a little overdone. This happens because the default settings of nearly every monitor on the planet suck and are not suitable for photo editing, and sadly most of us don’t realize this until we print our images and think that the poor results are the fault of the print service when in reality our improperly calibrated display has caused us to ruin our photos by adjusting them to something that isn’t the true color represented in the image file. Here’s a list of devices that you can’t go wrong with (multi-monitor users will need to be careful to choose suitable products, as will Windows 7 and Apple OS X users for compat purposes):

If you don’t own a display calibration device, then get one now as it should have been your first purchase after your camera. There is no software based solution that can reliably do accurate color management as they only allow you to calibrate color to your visual taste – not accurate reference values. A hardware based solution is essential gear for any serious image evaluation on a computer.

ExpoDisc – The Perfect White Balancing Solution

I’ll admit that when I first saw the ExpoDisc, I was a bit skeptical because I had used a gray card before and felt it was sufficient. I’m also pretty handy in Photoshop and Lightroom, so I thought I had both the before and after capture white balancing scenarios covered. I saw little that this device could offer me beyond existing very inexpensive solutions (heck, my lens cleaning cloth is 18% gray!), especially since the ExpoDisc was rather spendy. Photography is loaded with gadgets for suckers who are willing to buy anything to help make their photographs better, when simple, and inexpensive (or sometimes do-it-yourself) solutions already exist. This seemed like it might be one of those gadgets for suckers, so I went in to this review with a healthy dose of skepticism. I came away from it very surprised, and I now find myself bringing my ExpoDisc with me when the only other thing that is in my hand is the camera itself (you know, times when you are going downstairs to take a picture of your kid doing something cute where normally it’s just the camera and that’s it).

Video Demo

Visit here for video demonstrations of how to use the ExpoDisc.

What about Auto White Balance (AWB)?

Auto White Balance on my Canon camera is pretty good. In fact it was so good, that I saw little reason to use anything else most of the time. I like the results it produced right out of the camera, so I saw little point in using anything else. On Nikon systems, I found the Auto White Balancing to be a little too blue for my tastes, but Nikon guys usually say Canon’s are a little too warm for their tastes so to each his own.

Anyway, the one place where both fail miserably is indoors where tungsten lights cast a nasty orange tint over everything on your image. It’s easy to correct in Lightroom if you are shooting RAW images, but what if you didn’t need to do that extra step? Wouldn’t that save some time, especially when processing a large bunch of photos? What if you are shooting in JPEG where you can’t change the white balance, wouldn’t it have been great to have all those shots properly white balanced? What if you are shooting in video and your basic editing software doesn’t support white balance changes? Wouldn’t it suck to have those images of your child forever with that ugly orange tint on them? Auto White Balance is good, but it’s not foolproof.

ExpoDisc vs Gray Card vs AWB

UPDATE: My previous December 9th test results were invalid. This section has been updated to reflect the actual test results.

The following images were all taken with a Canon 5D Mark II using Auto White Balance (AWB) when capturing the white balance image, and the camera was set to Custom white balance mode using the white balance image when creating the respective photographs. The images you see are the original in-camera JPEG images with no additional processing. All shots were taken with the 77mm filter thread 24-105mm lens at f/4.0 and ISO 100 at 0.5 seconds on a tripod using mirror lockup a remote shutter release. All white balancing devices were held as far away as possible from the lens to fill the frame (the 82mm ExpoDisc must actually touch the end of the lens filter area).

For the white balance images in the left column, you can click the the hyperlinked text to see an image of how I captured the white balance image.

 
In Camera JPEG – Canon Auto White Balance (AWB)

 
In Camera JPEG – Canon Tungsten White Balance

 
ExpoDisc White Balance Image
 
ExpoDisc Photograph
 
18% Gray Card White Balance Image
 
18% Gray Card Photograph
 
Cleaning Cloth and Gray Card Combo White Balance Image
 
Cleaning Cloth and Gray Card Combo White Balance Image

Auto White Balance (AWB)  CR2 (RAW) Image 

Digital Calibration Target with a Photoshop CS4 Curves Adjustment

ACR / Lightroom 2.5’s Auto White Balance Setting

Lightroom 2.5’s Eye Dropper White Balance (clicked on gray)

Using the small images shown inline here, it is nearly impossible to tell the results. However, if your monitor is color calibrated and you click on the images to view the larger versions (which you can download) you can see the subtle differences between them. My observations are as follows:

  • ExpoDisc – Slightly warmer with a little color cast retained. Perhaps a little too much red (see the JIF cap) but overall a slightly more pleasing result thanks to the extra saturation, and warmth.
  • 4x5" Delta 18% Gray Card – Slightly more neutral than the ExpoDisc with probably a more accurate result, but a little too sterile looking. Red have less pop.
  • CleanStar Cleaning Cloth 18% Gray Card Microfiber  - A mild green color cast that feels cooler than the ExpoDisc but warmer than the Gray Card.
  • PhotoVision 6" One-Shot Digital Mini Calibration Target – With my CS4 Curves Adjustment Layer (and the eyedroppers default values set to 7,7,7; 133,133,133; and 245,245,245 using a 5x5 sample size with the eyedropper tool), I clicked the target white, gray and black points with the respective eyedropper to correct this image. The black was the hardest to hit as it was easy to get way too much back. The result is an image with a slightly brigher feel and what seems like a little too much brightness on the top of the paper towels.
  • Lightroom / ACR “Auto” white balance setting – Adobe Camera Raw and Lightroom have a more sophisticated Auto White Balance that nearly always beats the in-camera AWB for tungsten shots. The result here was a 2850 temp and +0 tint adjustment from the default CR2 RAW setting of 3150 temp and a + 5 tint.
  • Lightroom White Balance Eyedropper – I clicked on the gray portion of the Digital Calibration Target to get a 18% gray corrected value (which resulted in a 2500 temp and a +1 tint). This result was better than the CS4 Curves Adjustment (but its result will vary depending on exactly where you click) and Lightroom AWB setting, and it event performed better than the microfiber.

Which is best? That’s for you to decide. Click the images, download the originals and then use your favorite software to switch between the images and compare the differences. They are subtle, but they are there – and they’d remain there on your video or prints. For me, my favorite is the ExpoDisc because it left a little warmth in the image, and next would be the Ligthroom EyeDropper tool. My third choice (which is really almost a tie for 2nd) is the 18% Gray Card.

Here’s additional great before and after white balancing examples found on ExpoImaging’s web site. I encourage you to check them out.

RAW versus JPEG Test

I took an image with the white balance intentionally whacked out with my camera set to RAW+JPEG. The images above (from left to right) are the original RAW with no modifications, the RAW corrected in Lightroom by using the eyedropper and clicking on the gray part of the tripod head, and the last is the JPEG treated the same way. Notice how the RAW looks perfect, but the JPEG has a blue tone to it still? You can play with that JPEG all you want, but you aren’t going to get it to have the high quality results of the RAW image. Which would you prefer as your starting point? Now you see why having an accurate white balance is so critical when shooting JPEG only (or video)!

White Balancing and Video

In what is certain to be the most boring and lame video you’ll see in all of 2009, I proudly present my masterpiece video that quickly shows you the before and after results of white balancing using the ExpoDisc on a video:

Cool, huh? Sorry folks, it was 3:00 AM and I wasn’t able to whip up some cool video footage in time for the release of this review. You should get the point though that the ExpoDisc made a HUGE difference and applying the custom white balance was identical to what you do for the still images. If you are moving into the world of DSLR Videography, then you can improve the quality of your videos (especially indoors) using this one improvement alone. Even this crappy video taken at ISO 6400 with Canon 7D, at least shows some color quality improvements (even if it is a bit over exposed such that the black paper background now renders as gray).

Serious Videographers will be happy to know there is special version of the ExpoDisc designed specifically for high end video cameras.

White Balance and Metering Challenges

Lots of colors going on here, so the only choices are to introduce more gel’ed
flashes to try to get one color or to embrace it and make the most with what you have.

While ExpoDisc is great at setting a white balance reference point, there’s several problems you may still face that will require some post-processing help. For example, you might be shooting a flash which emits white light into a room lit with tungsten (household bulbs) light, so you have two colors introduced into the scene. White balancing for one, doesn’t necessarily help the area impacted by the other color so your only feasible solution is to use an orange gel on your flash to get one tone going on in the whole scene. A full discussion of how to accomplish this in this scenario or or in more complex scenarios outdoors (i.e., a building lit with tungsten light against a moonlit sky; street lights and house lights; etc…) is beyond the scope of this article, but you get the idea here. White balance is most effective when dealing with one tone across the entire image is incorrect, so that a reference point may be used to remove that tone and return everything to a proper color.

Having a correct white balance is also just part of the challenge in photography as your camera’s light meter will also look to expose the image to an 18% gray which may not result in a faithful reproduction of your image. This is especially common in black objects and snow, even if when you are perfectly white balanced. In the case of black objects, you might find that they tend to look a little faded on perfectly white balanced images. In the case of things like snow, you might find that it feels a bit gray instead of a nice bright white. For these, and other scenarios (like a cloudy day where white balance results in the drab reality) you might find that you’ll have to apply different techniques to get the best results in camera. This may include, but is not limited to, decreasing your exposure a stop (or –1 EV exposure compensation) to make dark objects (blacks) darker, increasing your exposure (+1 EV) to make bright objects like snow brighter.

The point here, is that products like ExpoDisc are a tool, but not a magic bullet. You may find that a cloudy day benefits from the Cloudy white balance (or even Auto White Balance) setting on your camera, much more than a properly white balanced image. You might choose to apply a creative white balance such as tungsten on a twilight evening shot to make the sky look more blue than it was in reality. Joe McNally has some great examples in his books The Moment It Clicks and The Hot Shoe Diaries on how to make creative uses of the white balancing system features built into your camera to express your artistic intent at capture time to avoid post-processing hassles.

Conclusion

After having the ExpoDisc for about a month, I find myself using it about 90% of the time before I shoot. Even though my original methodology for using it was inaccurate, the results were good enough to be a better starting point for me than the in-camera AWB setting. I like it more now that I better understand how to get the most out of it (by taking your test shot from the subject with the lens pointing back to where the camera will be).

Sometimes, I’ll look at the custom white balanced test image versus the Auto White Balance (AWB) test image and choose to go with the AWB image for artistic reasons (when shooting RAW only). However, for video or when shooting JPEG (or in my case RAW+JPEG) I always go with the custom white balanced version as I’ve yet to find a real-world scenario for the subjects I shoot where that wasn’t a good starting point down the road.

I think the price is a tough pill to swallow for some, but I’d say that some of its value can be recouped in time saved in post-processing (especially if you do video or JPEG only). You can also help spread out the cost by getting one large enough to fit your largest lens (the diameter of the front of your lens – not focal length mm). For example, most of my lenses use a 77mm filter, but my 16-35mm uses a 82mm filter size. As a result, I got a 82mm ExpoDisc and just hold it in front of all my other lenses, so this one ExpoDisc serves all of my needs.

This article does prove that there are other less expensive options that will get you reasonably accurate results, so for those of you who fall in this camp you can use the information in this article to help you decide what you do (or don’t do) with respect to white balancing. You should study the images and the tools featured here and get the one that is right for you, and don’t forget to consider your output target (i.e., 4x6 prints will be more forgiving than 30” LCD’s or huge city billboards).

Special Offer

 image

Save 15% on all ExpoImaging Store products like the ExpoDisc or RayFlash when you enter ronmart09 in the “Enter Redeem Code” box and click Redeem in the ExpoImaging Store’s shopping cart as shown above.

REMEMBER when ordering, that you should get the largest size you’ll then you’ll realistically need. My recommendation for Canon shooters is to not get one smaller than 82mm, because if you ever shoot with the 16-35mm lens you’ll have to own it, and you’ll want a ExpoDisc that works with it. I’d never, no matter what brand you shoot with, get one less than 77mm (unless you can afford one for every filter size you have). You also don’t need to worry about step up/down rings as you can simply hold this in front of your lens as needed (be sure to keep your fingers out of the way <g>).

But I found this cheaper alternative on eBay, isn’t it the same thing?

No, there’s a science to this and few take the process of white balancing more seriously than ExpoImaging. In fact, you even get a card with hand written calibration values for your disc that were tested on a transmission color densitometer. This provides peace of mind that your unit has been tested to be accurate and within the specs required to produce accurate results. Before buying that similar looking disc elsewhere, find out if they’ll be including transmission color densitometer values with your unit so you can ensure it is going to actually do the job you are paying money for it to do – produce accurate results!

What about ExpoCap?

Great question – I asked the same thing to ExpoImaging as I thought the idea of just having my disc as a lens cap was a brilliant one. The short answer here is that the ExpoCap has been discontinued so if you want one, get it now as they will only exist while current supplies last (and you’ll notice popular sizes are forever out of stock). ExpoCap was very good, but not as accurate as ExpoDisc and the cost of making the cap was on the rise so the decision was made to discontinue it rather than having two products that were similarly priced with one (ExpoDisc) being substantially better than the other. If you have one, great – there’s no need to replace it, but if you are a first time buyer then go for the ExpoDisc – it’s the better long-term solution.

Disclosure

I was provided an evaluation copy of the ExpoDisc for this review and I will earn a commission when you use my discount code (thanks for supporting the blog).

If you enjoyed this article, please support future articles like this by donating a dollar or saving several dollars by using my discount coupon codes. Either way, your support is greatly appreciated!

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1 comment:

mobius32 said...

Well, I have an ExpoDisc. It works well if things are bright enough to give you a good custom reading. But I've been in many situations where I couldn't get a reading (or get it easily). I also bought the WhiBal card ($30) and have found I use it more than the ExpoDisc.