Q. I have a question regarding Canon's Picture Styles. What is the difference between Neutral and Faithful? Both are said to have post-processing in mind. I've read the descriptions at

http://www.usa.canon.com/content/picturestyle/shooting/index.html

and

http://www.canon.co.jp/imaging/picturestyle/editor/understanding.html.

These descriptions "sell" the style but don't plainly spell out the differences and why you might prefer one over the other. The Canon Japan site gave me the impression that Neutral emphasizes detail and Faithful emphasizes accurate color. Is this correct? Also, Faithful references accuracy under 5200K lighting, so how does this affect pictures with typical indoor lighting?

A. There's no difference in default sharpness settings between "Neutral" and "Faithful," so there would be no difference at all between them in terms of detail. The significant difference between these Picture Style settings is about the same as the difference between "Perceptual" and "Relative Colorimetric" rendering intents. If you are unfamiliar with those terms, please review the following Web page for a good explanation:

http://www.cambridgeincolour.com/tutorials/color-space-conversion.htm.

Of the two Picture Style settings, "Faithful" attempts to reproduce colors as accurately as possible (similar to "Relative Colorimetric"), as long as the colors are within gamut and the white balance is properly set. "Neutral" attempts to produce a pleasing color balance (similar to "Perceptual"). As long as the colors being compared are within gamut, "Faithful" and "Neutral" will be almost identical, but you may see some differences between them in terms of out-of-gamut color reproduction. The reason that Canon's documentation references 5200K for Faithful is to provide a clear definition of the shooting conditions under which accurate color reproduction is calibrated. Differences in color reproduction between daylight and indoor lighting are subtle at best as long as you establish an accurate white balance for each environment.

If you want to get a better feel for the similarities and differences between "Neutral" and "Faithful," there are a couple of ways to do it. One quick and easy way is to visit a Web site like DP Review and check out one of their SLR test reports. Taking the Rebel T1i as an example, look at the top of page 18:

http://www.dpreview.com/reviews/canoneos500d/page18.asp.

You can roll over the Picture Style settings below the color chart and see how (or whether) the color patches change for each setting. This is only a rough comparison, though, and it doesn't necessarily give you the whole picture, so to speak. In order to do that, you really need to make some high-quality prints using each Picture Style you're interested in. If you've got a photo-quality color printer with photo inks and papers, it's relatively easy to do this from a single RAW image using Canon's Digital Photo Professional software. If you're not using DPP, it might be better to work from in-camera JPEGs shot with each Picture Style to see the differences, because working from RAW files with independent software applications like Adobe Lightroom, Apple Aperture, etc., introduces a completely additional set of variables. To gain the most comprehensive understanding of differences in Picture Style settings for printing, I would suggest experimenting with color space as well. Printing gives you a good opportunity to see the difference between the sRGB and Adobe RGB color space settings that you may not be able to appreciate any other way, since most computer monitors are incapable of displaying a color space as large as Adobe RGB.

Q. I was curious about how the video feature functions on the newer SLRs that Canon has released. "Full HD" being 1920x1080, that is much smaller than the normal resolution for, say, a 5D Mark II. So when you are capturing video, is the camera taking the full 21MP image and resizing/cropping it down to 1920x1080 or is it actually only capturing the HD-size resolution? And if it is ONLY capturing the HD-size image, is it only using a small portion in the middle of the sensor to do so? I guess this would be the same question as, what happens when you change the setting on your camera to "medium" JPEG instead of "large" JPEG? Is it capturing the large size and then resizing it down before it saves it on the memory card? The reason that I ask is because, if it is taking the full size and resizing it down, then I would guess that would greatly improve the noise performance. For instance, if I have a 15mp image that I shot at ISO 1600, and I resize it down to 1920x1080, I can't really see the noise that was in the original image.

A. Canon does not disclose a complete description of the methods used to produce Full HD movies with EOS Digital SLRs like the 5D Mark II, 7D and Rebel T1i/500D. But here is a brief description:

1. Original image data is captured by the entire image sensor, which has a 3:2 aspect ratio.
2. The image data is cropped to 16:9 to match the aspect ratio of Full HD (1920 x 1080) and HD (1280 x 720) movies.
3. The cropped data is downsampled to reduce resolution to either 1920 x 1080 or 1280 x 720 pixels, depending on the camera's feature set and the user's choice of camera settings.
4. The downsampled data is compressed according to an H.264 AVC data compression algorithm and written to the .MOV recording format.

The EOS camera's LCD screen displays the full image that the image sensor is seeing, but a semi-transparent overlay is superimposed at the top and bottom of the screen to indicate the portions of the original image that will be cropped out to change the aspect ratio from 3:2 to 16:9 for HD movies as indicated above. Concerning your noise question, the data compression method for movies is different than it is for still photos. In other words, H.264 AVC uses a different algorithm than JPEG, so it does not necessarily follow that EOS HD movies have less noise than still images that have been downsampled. It would be more accurate to say that EOS HD movies have a different noise pattern than still images. Nevertheless, it's true that EOS HD movies have noticeably less noise at comparable ISO speeds than HD footage from capture devices with smaller image sensors. And it is also true that EOS cameras with HD capability can shoot movies at very high ISO speeds that are often unavailable with other HD capture devices. For example, the 5D Mark II can shoot movies at ISO speeds up to 12,800. But the lower the ISO, the lower the noise, just like other HD capture devices.

Q. You touched some time ago on the question of flash duration for different Canon flash units but I would like to know if you could revisit this. Specifically, I sometimes mix 430EX (version I) and 550EX Speedlites in multi-flash setups for hummingbirds where I live and work in Costa Rica. I normally use 1/8 or 1/16 power in manual mode. Since the 550EX has a higher GN, does it stand to reason that it has a longer flash duration at, say, 1/16, than the 430EX does at the same power setting? If so, can you put a number of the different durations?

A. It does stand to reason that a 550EX or 580EX at 1/16 power would have a longer flash duration than a 430EX or 430EX II at the same power setting, but as I mentioned in the April 2009 Tech Tips response, Canon never provides official durations for fractional power settings. Also, the actual durations at lower power settings are not directly proportional to higher settings. (According to Wayne Schmidt: "In the real world, as the flash duration for xenon flash lamps becomes very small their efficiency decreases. To compensate for this loss of light the flash is programmed to remain on long enough so that the output is what it should be.") Therefore, it wouldn't make sense to apply a simple mathematical reduction factor to calculate the fractional power durations for smaller Speedlites like the 430EX or 430EX II. My best advice would be to test the equipment yourself to see which settings meet your needs. I suspect that if you use a higher power setting on the 430EX to match the output of the 550EX, the flash durations from both Speedlites will end up being very similar if not identical.

Q. I find Auto ISO to be a great feature on the latest Canon digital SLR cameras. My question is this, why has Canon limited Auto ISO while in Manual mode to ISO 400? Why have a limit at all especially as results on my 5D Mark II look great at high sensitivities? I would like to set a fast shutter speed to freeze action and shoot at the sharpest but largest aperture – i.e., f/2.8 on my EF 50mm f/1.4 lens. Surely a firmware upgrade could rectify this creative handicap.

A. It already has, at least to some extent. Whatever the reasons may have been for restricting the Auto ISO function in Manual mode on earlier EOS models, Canon seems to have reversed that trend with newer products. The first EOS with variable Auto ISO in Manual mode was the EOS 5D Mark II when updated to Firmware Version 1.1.0 and used in Live View or Movie Mode. The newly released EOS 7D goes one step further by making Auto ISO in Manual mode fully variable even when Live View is turned off.

Q. I would like to know what settings you recommend for shooting high-speed aircraft during air shows. I have problems with consistent sharp frames when using burst mode with AF on. I have tried several different settings, but lately I have switched to Tv (~1/1500th s or less if possible), IS off, manual focusing set close to infinity with better results. But I really would like to use AF because it is quite difficult to focus manually when [an] aircraft is coming towards you. Equipment used is EOS 40D and EOS 5D with EF 100-400 f/4.5-5.6L IS and EF 500 f/4L IS. I also use a monopod sometimes.

A. I recommend AI Servo AF for most kinds of ground-to-air photography. In the case of the 40D or 5D, select the center focusing point manually and try to keep at least part of the aircraft targeted with it at all times. With the 5D, you may want to experiment with Custom Function 17-1 to activate the invisible "Assist AF" points around the visible center point. It would be a very good idea to collect focusing data (i.e., start tracking the subject) by pressing the shutter button halfway for at least 1 second prior to pressing it all the way for the exposure. Try panning with the aircraft moving from left to right or vice versa rather than just straight-on shots. I would also suggest that you use Image Stabilizer Mode 2 for panning with both of your lenses. If the aircraft is relatively slow moving, you should try shooting one shot at a time rather than high-speed continuous bursts. But if you're dealing with a fast moving jet or group of jet planes, then high-speed continuous for a burst of 3 to 5 frames may be more productive. A few more tips:

• Try to fill the frame as much as possible before taking photos. There are few images more boring than a tiny aircraft against a huge expanse of sky, unless there's something particularly interesting about the cloud formation.
• Consider using the camera's spot metering function to isolate exposure metering to the aircraft itself. Use your histogram to determine a pleasing exposure level.
• Consider using manual exposure to keep your exposure levels consistent from shot to shot.
• If you're photographing propeller-driven aircraft, try using a relatively slow shutter speed such as 1/125 or 1/250 while panning with the movement to blur the propeller while keeping the fuselage and other portions of the airplane sharp.

Hope that helps!

Q. I bought a 7D the first day they were available here in Kansas City, and I have to say I love it. It's my seventh EOS DSLR, and by far my favorite. But there's one aspect of it that I wish was different, and that's the lack of interchangeable focusing screens. I have been using the Ef-S focusing screen in my 40D for about two years, and I like how it more accurately displays the true DOF of my fast lenses. The viewfinder in the 7D is big and bright, but the image on the focusing screen displays a depth of field of about f/5.6, even when an f/1.4 lens is attached to the camera. This can make it hard for me to visualize how an image will really look. Does the transmissive LCD make a replacement screen impossible? Might a third party be able to market one, as they did for the 20D and 30D?

A. The actual DOF level of the 7D focusing screen is about f/4 rather than f/5.6, but I understand your point. There's no doubt that Canon's Service Department could replace a broken 7D focusing screen if they had to, so I wouldn't say that changing it is impossible. However, the LCD overlay and its supporting circuitry is positioned so close to the screen that I'm sure changing it is a very delicate and time-consuming job, whether it's done by Canon or a third-party screen manufacturer. That's probably the main reason why user-interchangeable focusing screens are unavailable for the 7D camera. As a workaround when using fast lenses, your best bet would be to use the camera's Live View function. This method will display the actual depth of field at all times, and it has the added benefit of being able to magnify any portion of the picture area, either 5X or 10X, for critical manual focusing.

Q. Question on Auto Exposure Bracketing (AEB): Both the 7D and 5D Mark II are limited to 3 frames per AEB sequence, whereas, the EOS-1D/1Ds models allow up to 5 frames. Do we just have to live with this 3-frame limitation on the lower models, or is there a remote control unit that will enable further adjustments without touching the camera and risk changing the composition slightly in between sets of bracketed shots? What other solutions or techniques would you suggest to get around this problem? Thanks.

A. The EOS-1D class cameras can set AEB sequences up to 7 frames. However, you can shoot up to 15 exposures per bracketing sequence with almost any EOS Digital SLR by using DSLR Remote Pro software from Breeze Systems for various flavors of Microsoft Windows or Mac OS X. See their Web site for details:

http://www.breezesys.com/DSLRRemotePro/features.htm.

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

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