Q: I'm going to be photographing Yellowstone this February from a snow coach. The average temperature ranges from 13 to 34 degrees F. Extreme low temperatures can get to -20 to -40 F, although I'm guessing that we won't venture out when the temperature is much below -5 F. I have a 1D Mark II and a 5D. I've used both in the winter but never at these extremes. I plan to take the normal precautions such as keeping spare batteries in warm pockets, putting cameras into plastic bags when I get into the snow coach and go back to the motel. I have bought one new battery for the Mark II since the 5-year old batteries are pretty weak and only last for a few minutes in the cold. I have four spares for the 5D. Can you suggest anything else I ought to do?

A: You've got the most important issues (condensation, spare batteries) covered, but there are a couple of other tips worth considering for cold weather photography:

• Consider using a hand warmer to keep your hands and the spare batteries warm.
• Don't forget to check your cameras' histograms to ensure that your exposure level is accurate; it's sometimes necessary to apply exposure compensation, but not always. Consider using manual mode to keep your exposures consistent.
• Dress appropriately for the weather. Warm clothing including high-quality boots, a warm coat and scarf, and warm headgear is essential, and it's also a good idea to use customized gloves so you can still operate the camera comfortably. Here are some links to point you in the right direction for gloves:

http://gizmodo.com/220182/photographers-gloves-keeps-your-fingers-toasty

http://products.lowepro.com/product/Photo-Gloves,1990.htm

http://www.campmor.com/outdoor/gear/Product___88537

Q: How likely is it that Canon would respond if lots of EOS-1D(s), 7D & 5D users really supported the re-introduction of Eye Controlled Focus? Do you know the story behind its demise?

A: Eye Controlled Focus in future Canon products cannot be ruled out, but there is no evidence to support the notion that it will reappear anytime soon. In the meantime, Canon will continue to study the market and gauge the interests of its customers in all sorts of camera features including ECF.

Similarly, I can't provide details on why the feature was discontinued after the EOS Elan 7NE. But I can tell you that it was more advanced in that camera than any of its predecessors. By the time the Elan 7NE came around, ECF supported vertical as well as horizontal camera orientations; it was much faster than before, and it had the "self-teaching" function that allowed as many as 20 individual calibrations per user for horizontal and vertical orientations according to variations in light levels, for up to three users.

From that description, it's fair to say that the implementation of ECF had become rather complex and memory-intensive, and Canon had received reports indicating that many customers were not using it for various reasons such as:

• Their eyes did not move normally so the feature didn't work for them;
• Their eyeglass lenses were too thick or they habitually wore sunglasses, so the camera couldn't detect their eye movement;
They didn't know it was necessary to recalibrate the system for each and every light level and/or camera orientation, so they couldn't understand why the system was only working every once in a while for them.

Finally, sales figures indicated that the majority of customers weren't willing to pay for ECF if they could buy the same camera, as in Elan 7N, without ECF for less. Considering all the obstacles, it's not too surprising to me that Canon eventually decided to drop the feature. But again, if you think ECF is worthwhile, then by all means make your wishes known. I am happy to pass them along, and you can also contact Canon's Customer Support Centers (e-Mail: carecenter@cits.canon.com) to let them know as well.

Q: This question is about using DOF preview with Live View on the 5D Mark II. In the instruction manual on page 110 it says, "The image brightness displayed will be close to the actual brightness of the resulting image." When I stop down to f/16, shooting outdoors or shooting out the window indoors, the Live View display is bright; however, when shooting indoors the display is a lot darker. It's as if I'm viewing thru the viewfinder. When I called Tech Support, they found the same behavior, and they couldn't tell me why. I was wondering if you could provide a technical reason for this.

A: Based on your description, it sounds like you probably have the camera set to Manual rather than Aperture Priority, with Exposure Simulation turned off. With that combination, the LCD screen will brighten or darken when you press the Depth of Field Preview button depending on the light level vs. the shutter speed, aperture and ISO combination you've selected. If you leave the camera set to M, you can keep the screen at a usable brightness level under most lighting conditions during DOF preview regardless of the exposure settings by turning on Exposure Simulation in the Live View menu. Or, if you don't mind switching to an AE mode like Av, Tv or P, the screen brightness will be usable in almost all light levels, no matter how Exposure Simulation is set. It's your call. For what it's worth, I prefer to turn on Exposure Simulation so that the LCD screen will remain at a usable brightness level most of the time, even when using DOF preview in Manual mode.

Q: So there's nothing wrong with my camera; good. Yes, it is a normal viewable range indoors with low light on the LCD; looks like the view through the viewfinder. With good light, the LCD is nice and bright using DOF preview; MUCH better than the viewfinder. I'm still wondering, what is the technical reason for darker LCD images in low light? Maybe a future feature?

A: I haven't seen any technical documentation to support it, but here is my hypothesis: When Exposure Simulation is turned on, the 5D Mark II has to be using Auto ISO to control the brightness of the screen during DOF preview. (What else could it be? The aperture value is fixed and the low-end "shutter speed" of the LCD in Live View is limited during DOF preview.) Therefore, there's going to be a limit to how high the sensitivity can go at a fixed aperture value in low light. Once that limit is reached, the image has no choice but to become darker as light levels fall.

Q: I've been reading your columns for almost two years now. It's been a great time, and I've discovered lots of things about our cameras that I would never figure out by myself. But now I've been having a consistent problem with my EOS-1D Mark III. The camera does not let me use higher ISO speeds than 3200 - which, in Brazil, where I live, is really necessary to shoot soccer pictures for instance - and lower ISO than 200. I can't change that setting using the camera controls. I doubled-checked Custom Function I-3 for the lowest and highest ISO speeds. And it's adjusted for H - highest ISO - and L - for lowest. Do you have any suggestions or clues on that?

A: You'll need to shut off Highlight Tone Priority (C.Fn II-3) to regain the full ISO range of your EOS-1D Mark III. Check page 164 in the instruction book for details.

Q: Right after powering on my new EOS 7D camera, I've noticed some strange squeaking noise. After some investigation it turned out that this noise is coming from the "sensor cleaning mechanism." I've never noticed or heard this noise with any other camera I've used or owned before. After some searching on the Internet I found a forum where some people say that they can hear this "squeaking noise" in their cameras also. Even though some hear it on 1D Mark III or 40D cameras it seems that 7D camera is less silent in this matter. Please take look at this forum, where the audio file is also posted:

http://photography-on-the.net/forum/showthread.php?t=760912

Please give us a brief explanation of this phenomenon. Also, should we be concerned with this squeaking noise? Should the camera be repaired? If this is expected manner how come some percentage of the cameras have this and some do not?

A: The list of EOS models with self-cleaning sensor units now includes:

1. EOS Digital Rebel XTi (400D)
2. EOS Rebel XSi (450D)
3. EOS Rebel T1i (500D)
4. EOS Rebel XS (1000D)
5. EOS 40D
6. EOS 50D
7. EOS 5D Mark II
8. EOS 7D
9. EOS-1D Mark III
10. EOS-1Ds Mark III
11. EOS-1D Mark IV

All of these cameras use one or more piezoelectric vibrators to shake the front plate of the cameras' low-pass filter in order to dislodge dust particles. There have been several variations in the design of the piezoelectric components according to the vintage of the camera, but the operating principle is basically the same for all of them. There is nothing particularly unique about the self-cleaning sensor unit of the 7D; in fact, it uses the same hardware as the self-cleaning sensor unit of the 50D. With both of these cameras, the operating sound of the self-cleaning mechanism is audible, but the sound level is quite low. Many people can hear it, but for various reasons many others cannot. This may account for the variety of reports one can find on the Web concerning this topic. In any case, because it is a normal operational sound, it is not a cause for concern.

Q: I am trading my 50D for a 7D and would like to use the Lexar cards from the 50D. When I format the cards will the numbering sequence start at zero? I have several cards and would like to use them but start at zero. Thanks.

A: When you get your 7D, go to Setup Menu 1 (wrench icon with one dot) and change "File numbering" from "Continuous" to "Auto reset." This will reset the camera's file numbering system to "100-0001." Then format your CF cards. Once this task is complete, go back and set "File numbering" to "Continuous," load one of your freshly formatted CF cards, and start shooting. That's all there is to it!

Q: With the EOS 7D, is it possible to combine spot metering with focusing points other than the center one?

A: Spot metering is always linked to the center focusing point with the EOS 7D camera, but you can use AE lock or manual exposure control to hold the reading and recompose before capturing an image. Focusing point-linked spot metering is available with EOS-1 class digital SLRs.

Q: The data from turning on High ISO noise reduction isn't used by third party software like Lightroom, but what about Long Exposure NR? Does the long exposure noise reduction change the actual pixel data in the RAW file or is it separate data that isn't used by Lightroom?

A: Long exposure noise reduction applies to RAW data as well as in-camera JPEGs. Adobe software such as Lightroom and ACR (Adobe Camera RAW) will "see" it because it's already in the image data before RAW conversion.

Q: I've been a Canon shooter since the early '90s, and have been a digital user since '99 with the Kodak/Canon DCS 560. I currently use two EOS-1Ds Mark IIIs, and one EOS-1D Mark III. Here's my question. Is there anyway I could use a digital frame hooked to the camera to show clients what I've shot? Video output from small TV sets is poor plus it disables the camera's screen. Thanks for your input.

A: To the best of my knowledge there's no way to display high-res images on a digital frame that's connected to an EOS-1D Mark III or 1Ds Mark III. There are two connectors on those cameras: composite video and Hi-Speed USB. If you're not satisfied with the resolution of composite video, the only other option is the USB port. But there's not enough computing horsepower in most digital frames to run EOS Utility software, and you can't see images through the camera's USB port without it. So, the average digital frame is not a good choice for connecting to the camera.

Some additional thoughts: Most of the digital frames I've seen are limited to VGA resolution (640 x 480 pixels) or less, so you'll never get an image that's as sharp as the file that an EOS Digital SLR can produce. If your digital frame has a built-in CF or SD card reader, you might be able to display JPEG images directly from the memory card after you remove it from your camera. However, even the smallest in-camera JPEGs are much higher in resolution than the average digital frame can display, so viewing files straight out of the camera is inefficient at best. It is far more efficient to download the images to your computer, then batch-process a set of JPEG copies at the maximum resolution that your digital frame can support, then transfer those files to the digital frame, either into its internal memory or via its built-in card reader. That's how I'm handling it with the digital frame I use at home, which has a roughly 6 x 8-inch screen that displays VGA. Keep in mind that you can get away with fairly high JPEG compression when you downsize the images to VGA for use in a digital frame. I typically set Level 6 in Photoshop for this purpose, and the resulting files are usually under 100KB apiece. That's roughly 1,000 images per GB, so it's easy to store as many images as you need on a relatively inexpensive memory card.

Thanks for reading this edition of Tech Tips! That's it for 2009. I sincerely appreciate all the comments I've received from readers of this column, and hope that the information I've provided here has been helpful.

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.)

P.S.: The purpose of the Comments section is to allow readers to respond to the content of each month's edition of Tech Tips. New topics or questions should be submitted by e-mail (using the link at the end of each column) in order to support the development of future monthly editions. I appreciate your kind support and cooperation. Thanks!