Tech Tips
November 2008

by Chuck Westfall

I've been combing the web for insights as to the best way to shoot flash with a Canon EOS 5D and 30D. We use them for weddings, and are having inconsistent results. Are there optimum settings to use for best results? I've adjusted custom function for evaluative and average flash metering, adjusted camera metering modes, etc., but seem to always be changing exposure compensation. As you can imagine, shooting a wedding is a fast-paced job, and there's not a lot of opportunities to make constant adjustments, or re-shoot. Any help you could provide me with would be appreciated.

With your experience, I'm sure you understand how difficult it can be to get consistently accurate flash exposures with wedding photography. The typical subject matter is either all white, as in the bride's dress, or all black as in the groom's tuxedo. This is problematic for flash metering systems because they are designed to expose for mid-tones, and there just aren't many of those in the typical wedding photo.

The E-TTL II flash metering system used in current and recent EOS Digital SLRs including the 5D and 30D works very well at its default settings with most subjects, but it has overrides that are intended to help it overcome unusually bright or dark subject matter. One of the overrides that I've found most helpful for wedding photography on these particular models is Custom Function 14-1. This C.Fn changes the flash metering pattern from Evaluative to Average. The reason I like it is that Averaged flash metering looks at the entire scene and reduces the possibility that any single element will be overemphasized.

Another technique that I find helpful for flash photography at weddings is bounce flash rather than direct illumination, because it softens the light for a more pleasing effect. There are plenty of commercially made diffusers around, but my favorite is the Ultimate Bounce Card by Peter Gregg. It's easy to use, and the quality of the illumination is outstanding, in my opinion. For more information, visit Peter's web site at:

If you're going to do a lot of bounce flash photography at a wedding and you're using either the Speedlite 580EX or 580EX II, I would strongly suggest using an external battery pack such as the Compact Battery Pack CP-E4. Not only will this accessory speed up recycling times and increase the number of flashes per set of batteries, it can also minimize the possibility of overheating the flash unit. In order to make the most of that feature, set Custom Function 12 on the flash itself. This C.Fn reduces the drain on the batteries in the flash itself by recycling from the external pack only.

The decision on ambient metering during dedicated flash photography should be based on the shooting conditions. There is no "one size fits all" answer. With a heavily backlit subject in a fill-flash situation, either evaluative or centerweighted average metering would be good choices. Spot metering might be problematic in a heavily backlit situation, since you'd run the risk of blowing out the background. Indoors or at night in an "all flash" situation where the ambient light is making no significant contribution to the overall exposure, choice of ambient metering pattern will make no difference. The good news is, there's usually have enough time to take a test shot or two in a given lighting condition so you can evaluate your results quickly on the camera's LCD screen and make an adjustment if necessary.

Last but not least, you might want to consider shooting your wedding photography in RAW mode on the camera. This setting requires post-processing in your computer, but the advantage is that you can adjust your highlight and shadow detail to a far greater degree than is possible with in-camera JPEGs. Most of the professional wedding photographers I know use a RAW workflow for this reason, and it's also helpful for tweaking white balance for better color accuracy when desired.

These are just brief comments on a subject that could be explored in much greater depth, but I think your results will improve if you try some of these techniques. Hope this helps!

The standard zoom lens for the new EOS 5D Mark II is the EF24-105mm f/4L IS USM lens. Are there EF lenses that work better with the camera than others? Also, with the new sensor in this camera, are f/2.8 lenses really made obselete and f/4 truly sufficient for low-light photography?

The EF24-105mm f/4L IS USM is probably the most flexible general-purpose zoom lens for the EOS 5D Mark II camera. It would be a good choice as a "walk around" lens that you can depend on for a wide variety of typical photos. However, before purchasing any new lens, you should take the time to consider your personal priorities. What are your main interests in photography? Landscapes? Architecture? Portraiture? Sports? Birds? Macro? Weddings? Low Light without flash? etc. Answers to these questions will go a long way towards guiding you to the lenses you should consider. With more than 50 EF lenses to choose from, there's bound to be a few of them that will fit your needs and budget. The high ISO capabilities of the EOS 5D Mark II really make low light photography without flash a lot easier even with an f/4 lens, but faster lenses will give you more control over depth of field while at the same time extending the range of lighting conditions you can work in. If you're interested in trying a large aperture lens without investing a lot of money, consider the EF50mm f/1.8 II.

I wonder if you can give us the maximum exposure time for each camera in the current line-up. I want to do star-trails and other long exposure pictures, which require 3-5 hour long exposures. Are there any settings (such as noise reduction) which will shorten the possible exposure time because of lengthy post-shot processing? What happens to a photo that runs out of juice half-way through - will the camera save whatever it's got in it's memory, or will the shot be lost?

Realistically, maximum bulb exposure time for an EOS Digital SLR is going to depend on the type of power supply and to some extent the ambient temperature conditions. By far the longest exposures are enabled when using the optional DC Couplers and AC Adapter Kits, since these accessories eliminate concerns about battery life. If you're doing astrophotography from your back yard or any other location where AC power is accessible, this is probably the most feasible solution. When AC power is not accessible, the next best solution is to use an optional battery grip and load it with two lithium-ion rechargeable battery packs. The battery grips and battery packs will vary according to the camera model involved, but in moderate temperatures it would be reasonable to expect no more than approximately 4 to 6 hours of battery life for time exposures with a two battery power supply. In situations where only one battery pack is available, the total bulb exposure time in moderate temperatures will be somewhere in the range of 2 to 3 hours. Cooler temperatures down to the cameras’ minimum rated operational range of 32 degrees Fahrenheit will reduce battery life somewhat. In answer to your second question, any image data in the camera's buffer memory will be lost if the camera loses power before the file is written to the memory card. Since long exposure noise reduction in the camera can last as long as the actual exposure, you’ll need to factor that into your decision on setting the length of time exposures.

Will the new Canon EOS 5D Mark II have interchangeable viewfinder screens? I am interested in a split-image rangefinder type as I hope to use the new Zeiss manual focus lenses on this camera if I purchase it.

Canon offers 3 interchangeable focusing screens for the EOS 5D Mark II, but none of them has a split-image rangefinder manual focusing aid. Frankly, I don't expect this option to be offered for the 5D Mark II because of the possibility of exposure errors in certain metering patterns that could be caused by the different brightness levels passed through to the exposure metering system by a split-image rangefinder. The best options Canon offers for critical manual focusing with the EOS 5D Mark II are Live View, Angle Finder C, and Super Precision Matte Focusing Screen Eg-S:

1. Live View features a choice between full screen viewing and magnification settings of 5X and 10X for critical focusing. The focusing frame can be moved anywhere in the picture area depending on the portion you wish to magnify.

2. Angle Finder C is an optional accessory that slips over the optical viewfinder's eyepiece. It features a choice between full screen viewing and a magnification setting of 2.5X for the center of the picture area.

3. Super Precision Matte Focusing Screen Eg-S does not have a split-image focusing aid, but it does display a shallower depth of field with fast lenses than the 5D Mark II’s Eg-A standard focusing screen. This makes manual focusing easier with f/2.8 or faster lenses, especially when used in combination with Angle Finder C’s high magnification setting.

I use Wireless File Transmitter WFT-E2A with two Mark III cameras, an EOS-1D Mark III and an EOS-1Ds Mark III. On two occasions, the camera lost the wireless PTP communication with my computer and stopped working with the buffer full of untransferred images (total camera freeze). The images in the buffer were not written to the camera’s memory card and the only way to bring the camera back to life was removing and resetting the main battery. In both situations I immediately noticed that the tightening screw of the module got loose probably due to shutter/mirror vibrations during normal camera use. After tightening the connection, the problem never appeared again. Do you think that a loose physical connection between WFT-E2A and a Mark III camera can cause such camera behavior and prevent saving the images to the card as well? I also noticed the WFT-E2A gets slightly warm during normal use and the camera battery in the EOS-1Ds mark III lasts for some 800-900 shots (transmitting small JPG files only). Is it normal for wireless PTP communication to require that much power consumption?

Have you updated the firmware on your Wireless Transmitter WFT-E2A? For best results, it's important to use firmware version 1.0.1 as described here:

This firmware update is intended to save images to the memory card in the camera if wireless transmission is interrupted due to an unstable wireless connection. Also, it is important to use the lock lever on the WFT-E2A together with the screw-in connection at the base of the unit to ensure a tight fit between the WFT-E2A and the camera. Once these steps have been taken, normal use of the camera should not loosen the connection. Regarding shooting capacity, the WFT-E2A manual states that a fully charged battery pack in the camera can transmit up to 1,100 images through the WFT-E2A (presumably via Ethernet), but "fewer images can be captured when transferring over wireless LAN." Therefore, your report of approximately 800 to 900 images transferred on a single battery charge is normal. And it also normal for the WFT-E2A to warm up slightly during extended usage.

Thank you very much for your response. My WFT-E2A transmitter came already with firmware version 1.0.1 preinstalled. In my case it was not regular loss of wireless connection (as the firmware update would indeed help here) but it was rather sudden physical disconnection of the entire module during its work in progress, which probably resulted in some kind of malfunction in electronics causing the pictures in the buffer to be lost. Good news is that for the last 6 months now the problem has never appeared again since I'm now much more careful about the connection screw during use.

I’m glad the information was helpful.

Thanks for reading Tech Tips! That’s it for now. See you in December!

You are invited to submit questions about photo equipment, imaging technology, or photo industry trends that may have a bearing on your work or interests. I cannot promise to answer everything, but I pledge to do my best to address the issues that concern you. (Please use the e-mail link provided at the end of this article.)

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© Chuck Westfall

After earning a degree in Professional Photography from the Rochester Institute of Technology and accumulating some valuable on-the-job experience during a 10-year stint in commercial photography and photo retail, Chuck Westfall began his corporate career with Canon U.S.A. in 1982 as a Technical Representative. He has steadily advanced through the ranks to achieve his present position as Technical Advisor for the company's Consumer Imaging Group, working out of Canon U.S.A.'s headquarters office in Lake Success, NY. Among his many assignments, Chuck Westfall is currently Canon USA’s main media spokesman for new camera products. He also provides a unique insider’s perspective to financial analysts who follow the company’s CIG sales and marketing activities.

Chuck’s involvement with digital cameras began in 1994, when he assisted Canon and Kodak engineers in developing the EOS-DCS series of professional SLRs. Since then, his responsibilities have expanded to include participation in the development and launching of many other Consumer Imaging Group products including Canon's professional and consumer-oriented digital cameras. Most recently, he has been developing content for online and on-site consumer education projects in Canon USA’s Professional Products Marketing Division.

On the personal side, Chuck enjoys sightseeing, photography, reading, music, and family life with his wife Ying and their beautiful daughter Anna.