By Chuck Westfall

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I hope you can answer a question because I haven't been able to get a definitive response elsewhere. I recently purchased an external power pack for my 580EX flash -- namely, the Lumedyne TinyCycler. Would I still need to install four working AA batteries in the 580EX?

As you may know, there is a custom function on Speedlite 580EX that allows recycling from an external battery pack only. However, even when this C.Fn is activated, it is still necessary to use four AA batteries in the flash itself to operate the LCD display and the zoom head.

I'd like to suggest custom modes for Canon DSLRs. Sports, portrait, landscape, etc., are useful for beginners but it would be nice if we could set (maybe via software?) these modes for our preferences. For example, I could set the sports mode to say 1/500, ISO 400. Could Canon address this with a firmware or software update?

You may be interested to learn that Canon has already taken a step in that direction. With the EOS 5D, you can register a number of camera settings including ISO, drive mode, metering pattern, white balance, etc. according to personal preferences. Then, while shooting in your regular exposure mode, Manual for example, you can quickly switch to your registered settings by selecting "C" on the camera's exposure mode dial. EOS-1D-class cameras do not have a "C" mode, but they have various Personal Functions that can be helpful. On a Mark II body, for instance, you can use Personal Function 6 to register some basic camera settings (shooting mode, metering mode, shutter speed, aperture or exposure compensation) ahead of time, and then switch back and forth between your current settings and your registered settings by pressing and releasing your thumb off the camera's Assist button. With the EOS-1D Mark III, this same feature works with the AE lock button when Custom Function I-14 is activated.

I own (among other Canon flashes) a Speedlite 580EX, and am thinking of buying another one or the new Speedlite 580EX II. I have some compatibility questions; which of these two flashes can be used with which ones of the following?:

– SB-E1 and SB-E2 Brackets
– CP-E3 and CP-E4 Battery Packs
– CPM-E3 and CPM-E4 Battery Holders
– OSCS2 and OC-E3 Off-Camera Shoe Cords

I am hoping they are freely combinable, but in the worst case, only the TTL cables are (which means I must stick with only one kind of flash) – please clarify!

The SB-E1 and SB-E2 brackets are fully compatible with both the 580EX and 580EX II Speedlites. The same is true for Compact Battery Packs CP-E3 and CP-E4 and the Off-Camera Shoe Cords. However, the battery magazines for CP-E3 and CP-E4 are only compatible with their respective battery packs. This is because the gaskets on the CP-E4 and its battery magazine have a different shape than the corresponding parts of the CP-E3.

I recently noticed that there is no dedicated WIA driver for the EOS-1D Mark III on the EOS Digital Solution Disk CD supplied with the camera, and there is no WIA driver for the 1D Mark III on the Canon's Web site. Could you please advise where I can download the WIA Driver for the 1D Mark III for use in Windows XP Pro?

Canon does not plan to release a proprietary WIA driver for the EOS-1D Mark III camera. It is unnecessary for the following reason:

"When an EOS-1D Mark III, EOS 30D or EOS Digital Rebel XTi is connected to a PC with Windows XP or Windows Vista installed, the standard OS functions are used so there is no separate driver."

Translation: Microsoft's OS-level WIA driver can recognize the 1D Mark III once the PTP TWAIN driver supplied with EOS Solutions Disk 14 is installed.

Canon has now posted PTP TWAIN Driver 1.4 for current EOS Digital SLRs including the 1D Mark III to their Web Self-Service System, which is normally accessed from the Drivers/Software link on this page:

http://www.usa.canon.com/consumer...

My work deals with low-light shooting a lot, like wedding banquets in rooms that are as dark as a cave. Sharp (correctly auto focused) images are very important because my prints are mostly 8" x 10." My EF24-70mm, f/2.8L autofocuses a bit slowly in extremely low light. When focusing a subject about 25 feet @ 70mm, it doesn't hunt, but it takes a while for the focus point (a non-cross type) to focus. To improve autofocusing performance in low light, I have been considering getting either a f1.2/85mm or f1.8/85mm and/or a f1.4/35mm or f2/35mm. However, I am concerned that in extremely low light the EOS-1D Mark II will be slow to autofocus even with an f/1.2 lens because the subject matter has very low contrast. I think the f/1.8 lens would have higher contrast which leads to better autofocusing. I am also concerned that the f1.2/85mm or f1.4/35mm will autofocus slower than the f/1.8 and f/2 alternatives. Could you tell me which lenses will autofocus faster and more accurately between lenses have a larger f-stop vs. lower f-stop, please?

When it comes to AF speed in low light, the first issue is whether the camera can autofocus at all without a focusing aid such as an AF Assist beam. If it can, then differences in AF speed (without the AF Assist beam) are going to be affected primarily by differences in lens design. Generally speaking, lenses with a rear-focus optical design, such as the EF85mm f/1.8 USM, are going to autofocus faster than lenses that move their entire optical formula, such as the EF85mm f/1.2L II USM. In that particular comparison, the difference in maximum aperture is irrelevant. In the case of EF35mm f/1.4L USM vs. EF 35mm f/2, both lenses have similar AF speed despite differences in focusing systems, so there's no particular advantage to one lens or the other in the specific area of low-light autofocus performance,

If the light levels are such that all of these lenses can autofocus, then the clear advantage of the faster lenses will be the ability to use faster shutter speeds when shooting without flash. On the other hand, if light levels are so low that AF is difficult or impossible without a focusing aid, my recommendation would be to use a good flash such as Speedlite 580EX II and then pick the lenses you're most comfortable with. The AF Assist beam will minimize any differences in AF speed, especially when you're working with stationary subjects, and it will ensure that you can achieve sharp focus no matter what kind of lighting conditions you encounter.

An important concept to understand about the Speedlite's AF Assist beam is that the camera has to fire it at least twice before it allows the shutter to be released. The first time the AF Assist beam fires, the subject is typically out of focus. After that, the camera reads the focusing data and drives the lens to the calculated distance setting. Then the AF Assist beam fires a second time, to see if the subject is now in focus. If it is, then the shutter will fire. If it is not, the whole process is repeated. It works reasonably well with stationary subjects, but not so well with moving subjects since the subject distance may change between the first and second readings.

Bottom line, what you're really dealing with is the fact that the camera's AF system tends to be faster in low light without an AF Assist, as long as there's enough light for it to autofocus at all. But when there isn't enough light, the Speedlite's AF Assist beam is your only alternative, and slow AF becomes better than no AF. Hope this helps!

NOTE: Canon has recently posted some new firmware for the EOS-1D Mark III, but the situation concerning this camera's autofocus performance is still evolving as of this writing. In light of the many inquiries that have been received, Canon has decided to produce a new edition of the pamphlet entitled, "Getting the Most Out of Your EOS-1D Class Digital SLR," with detailed information on the EOS-1D Mark III. Watch this space for more information as it becomes available.

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

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.)