Tech Tips
October 2008

by Chuck Westfall

On a recent trip, I used two different cameras depending upon the circumstances – one, a Canon PowerShot A630 compact digital camera and the other, my EOS-1D Mark II digital SLR. Almost without exception the A630 took tack sharp and seemingly perfectly exposed images. All with a snap to them. In order for me to get the same quality or look, I must do post processing in Adobe Photoshop CS2 using levels and un-sharp mask adjustments. The 1D Mark II images look flat (flash would not be a help in these cases) and don't represent what I saw when I made the image. The only exception may be in sunlight with the 1D Mark II; those seem to be OK. Is there an adjustment or custom function I am missing?

The results you achieved are the results you should expect when using these cameras at their default image quality settings. I've written a detailed article on this topic in a PDF document about the EOS-1D Mark II camera, which is available online here:

Feel free to read the whole thing, but the section that's most relevant to your inquiry begins on page 25 and continues on page 26. Please pay attention particularly to the diagram on page 26 that shows the default settings of the EOS-1D Mark II in terms of sharpening, contrast, saturation and color tone versus other cameras including compact digital models like the PowerShot A630.

I shoot concerts and magazine work as well as landscape photography. Now that Canon has announced the EOS 5D Mark II, what would be the logic of keeping my EOS-1Ds Mark III besides faster frame rate and superior weather sealing? How different is the shutter lag? Is there anything else to consider?

With its superior low noise performance and Full HD movie recording capability, the EOS 5D Mark II is a remarkable camera that raises the bar for image quality in the EOS system. However, the EOS-1Ds Mark III still has the edge over the 5D Mark II in the following areas:

  • More durable camera body with better weather resistance. (5D Mark II has better weather sealing than 5D or 50D, but not as good as the Mark III SLRs.)
  • 300,000 cycle shutter durability vs. 150,000
  • Dual memory card slots
  • 100% viewfinder at .76x magnification vs. 98% viewfinder at .71x magnification
  • Longer lasting battery (1700 shots per charge vs. 850)
  • 45-point AF sensor with 19 high-precision cross-type AF points vs. 15-point AF sensor with 1 high-precision cross-type AF point
  • 15 interchangeable focusing screens vs. 3
  • 5 fps vs. 3.9 fps
  • X-sync 1/250 vs. 1/200
  • Shutter lag and blackout between frames is 55 ms/87 ms for 1Ds Mark III vs. 73 ms/145 ms for 5D Mark II

There are other feature differences in favor of the 1Ds Mark III, but these are some of the biggies. They're basically two different kinds of cameras that are targeted towards different market segments.

I am interested in your opinion on the subject of white balance being incorporated into a flash. I'm thinking the simplest way to do this would be to have a couple of colored flip-out panels built in (much like the 14mm diffuser). Otherwise, do you think it's possible to change the temperature (Kelvin) output of the flash internally to match the white balance of the camera?

Most shoe-mount flash units are capable of controlling automatic flash exposure very precisely by varying the duration of the flash burst. This method has the disadvantage that color temperature levels vary slightly according to the duration. Battery power levels also have an effect, with higher power levels resulting in slightly cooler color temperatures than lower power levels. For these reasons among others, installing colored gels or panels over a flash head can only control color temperature to a limited extent. Canon recognized this issue several years ago and resolved it by adding a feature called automatic color temperature compensation to its EX-series Speedlites starting with the 580EX. With this feature, a circuit in the flash reads the battery power level and the flash duration for every shot, and then applies a color temperature compensation factor to the white balance data in the resulting image files. This has the effect of equalizing the color temperature for all flash photos taken with the 580EX or newer Canon Speedlites with EOS digital SLRs.

I have read that when used as a focus-assist device, Speedlite Transmitter ST-E2 is compatible with lenses of focal lengths 28mm and longer. Is this true for lenses on 1.6x factor camera bodies, such as my EOS 40D? Or can I use lenses with focal lengths that are equivalent to 28mm and longer? I was hoping to use the ST-E2 as a focus-assist device when shooting with my 24mm f/1.4L.

Speedlite Transmitter ST-E2 is effective as an AF Assist beam with any Canon lens regardless of focal length as long as the camera's central focusing point is manually selected. But its effectiveness with peripheral focusing points is limited to lenses with focal lengths of 28mm and longer, regardless of the size of the camera's image sensor.

I own an EF70-200/2.8L and an EF100-400L lens, both members of the "white family" of Canon L-series lenses. When looking at the Olympics last month, the white lenses stood out from the crowds of photographers. But is the white color more than just a marketing gimmick? On, Canon says there are technical reasons for "white," and with some imagination we all understand about the heat problems with electronics and lubricating fluids. But does it have an optical advantage too? Are there test results out there that support this?

The first "white" Canon lens was the FD600mm f/4.5 S.S.C., which was announced in July of 1976. At that time, Canon Inc. described the lens barrel color as "Silver Grey." They said that the new finish was selected due to the suggestions of professional photographers who felt that the lighter color would absorb less heat than a black lens barrel, thus reducing the likelihood of condensation in humid environments. Over time, the color of subsequent "white" lenses became brighter and slightly warmer in tint than the FD600mm, but the functionality has remained the same.

I have owned / extensively used a number of Canon DSLRs, including the 1D, 1D2, Rebel, Rebel XT, Rebel XTi, and 20D. I continue to notice over the years that when looking at screen saver photos, shots taken with my ID are very often noticeably sharper than any of the other cameras. The degree of this phenomenon continues to surprise me. You have previously advised that the 1D's AA filter was less aggressive than newer models. My understanding is that increasing the sharpness setting, when shooting JPEGs would, to some degree, counter the newer, more aggressive AA filters. My question is whether increasing sharpness to maximum on newer models would theoretically achieve the equivalent level of AA filtering on the 1D, and whether such a degree of sharpening would be expected to have a significant negative impact on image quality in other respects, such as moire, noise, etc.?

It's difficult to make a valid comparison between the EOS-1D and other EOS Digital SLRs, if for no other reason than the fact that the original 1D at 4 megapixels had the lowest resolution of any EOS Digital except for the 3.1MP EOS D30 back in 2000. In order to make any comparison as fair as possible for all the cameras involved, we'd have to settle on a fixed output size, such as a 13 x 19 inch print, so that we're not throwing away the higher resolution of the newer cameras before we compare. Under those conditions, I'd say that any current EOS Digital model would outperform the original 1D in terms of overall image quality including sharpness and noise, assuming equal in-camera sharpness and ISO settings, etc. You wouldn't even have to change the newer camera's default sharpness settings to see the improvements, although raising the sharpness settings on a newer camera would increase its advantage over the original 1D. The higher the resolution of the newer camera, the greater its overall sharpness would be on a 13 x 19 inch print, all else being equal. The same logic would even extend to a screensaver image, as long as the image data is downsampled properly. Note that I am not saying the original EOS-1D was a slouch by any means. I am saying, though, that current EOS cameras are much better in terms of image quality including sharpness and noise levels.

When an EOS camera selects multiple focus points automatically, does it average the distance of those points and focus on the averaged distance?

Most definitely not. When multiple focusing points are illuminated in the combination of One-Shot AF with automatic focusing point selection, it means that all of them are within the same depth of focus as each other. In such cases, the camera usually selects the closest focusing point with reliable data. In the case of AI Servo AF and automatic focusing point selection, AF frames are not illuminated while the subject is being tracked. In cases where the subject is large enough that multiple focusing points are within the same depth of focus, a similar rule for focusing point selection is applied. In both cases, data from only one focusing point is actually selected and used by the camera.

My question is related to the EOS-1Ds Mark III and its standard focusing screen Ec-C IV. I shoot mostly landscape and city photos and I am interested in the Ec-D grid focusing screen. This focusing screen requires a change to the custom function. (C.Fn IV - 11 must be set to option 1.) What is behind this change? Are there any drawbacks? I am not talking about the grid on the Ec-D vs. the ellipse on the Ec-C IV here, but are there any differences in AF and/or metering performance?

The reason why individual focusing screens have different custom function settings is that their light transmission efficiency varies according to the aperture of the lens in use. Some screens like the Ec-C IV are slightly brighter with moderate aperture lenses than other screens like the Ec-D. This affects the accuracy of exposure meter readings, since the metering sensor is positioned above the camera's pentaprism, and it reads the light after it has passed through the focusing screen. Selecting the correct custom function allows the camera to modify the exposure meter reading according to the specific light transmission characteristics of the focusing screen in use. The camera's AF system is positioned in the base of the mirror box, so its performance is unaffected by the user’s choice of focusing screens.

Thanks for reading Tech Tips! That's it for now. See you in November!

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.