Could you please clarify the operation of Mode 2 (panning) IS on the Canon EF70-200mm f/2.8L IS USM lens? Does it work correctly only when panning across the long axis of the frame (horizontally) or is it smart enough to detect a smooth pan in any orientation/direction and correct for vibrations perpendicular to that detected axis (even diagonally, for instance)?

Every Canon Image Stabilizer lens has two "gyro sensors" oriented at right angles to each other. If the IS lens has a Mode 2 setting, it compensates for panning by shutting off image stabilization in the direction that is parallel to the panning movement. With this system, it's entirely possible to compensate effectively for panning in any direction, even diagonally. It also makes no difference whether the camera is held horizontally, vertically, or diagonally with respect to the horizon line of the image.

I own an EOS 30D and an EOS 40D. When I first got the 30D, the brightness of the display in the viewfinder appeared just fine. Over time it has gotten very dim to the point that it is only visible on a sunny day if I cover the viewfinder area with my other hand. The difference in the 40D and the 30D viewfinder brightness is like night and day. I read in the forums that the display being dim on the 30D is a common problem. Is there anything I can do about it? I love the camera but it's to the point where I may want to sell it because of this one problem.

It is difficult at best to diagnose equipment problems without seeing the equipment first-hand, but based on your description, I wonder if there might be a problem with the LED backlighting system behind your EOS 30D's LCD screen. There's no reason why the screen should become dimmer over time. That being said, it is often difficult to see images or menus on an SLR's LCD screen in bright sunlight, even when the equipment is functioning correctly. And there is no question that the EOS 40D's LCD screen is brighter than the EOS 30D's, due to the fact that the 40D with its larger 3-inch display uses more LEDs in its backlight mechanism. If there is a problem with the backlight in your EOS 30D camera, you'll need to have it repaired by a Canon Factory Service Center. But before you send in your camera, I would recommend that you do a side-by-side comparison in indoor lighting with another EOS 30D or even 40D body. Be sure the camera's battery pack is fully charged, and check the LCD brightness adjustment settings on the camera's menu screen. If you're convinced that there's a problem after that, then go ahead and send in the camera. The Factory Service Center will be able to replace the backlight if necessary in order to bring the camera back to its design specifications.

I am trying to use an 8GB SD card in the #2 card slot of an EOS-1D Mark II and when I try to format the card I get the message 'Cannot format or change card #2." Is this because I am using too large of a card in the second slot or is there another reason?

Check to see what version of firmware is installed on your 1D Mark II. It has to be 1.2.6 in order to format SDHC memory cards in the camera, i.e., SD cards with capacities higher than 2GB. If you need 1.2.6, you can download it here:

http://web.canon.jp/imaging/eos1dm2/eos1dmk2_firmware-e.html

I have a PowerShot G9 and it does a remarkable job for its size, so refreshing to take on family trips etc. The one thing that is really cool for me is the live histogram. When shooting in M, you can adjust the setting and watch the histogram move back and forth to get it just right; wish my EOS-1D Mark III had that.

Live histograms are available with the EOS-1Ds Mark III, EOS-1D Mark III, EOS 40D EOS Rebel XSi and EOS Rebel XS when those cameras are set to their Live View mode. It shows up on the LCD screen just like it does on the G9, only bigger, and with an option to display either RGB or Luminance. I can't imagine many photographers preferring Live View at its current feature level for the bulk of their work, but it's nice to have it available when it can be useful, such as this situation.

After learning of the EOS-1Ds Mark III's feature for setting the aspect ratio of captured images, I tried it on my camera, thinking it would help show what an 8x10 crop would look like on my LCD screen. After downloading the card and processing in DPP, I find that the images are cropped in that aspect ratio which I really didn't want. Is there a way to turn the images back to 2x3 ratio? They show the full picture with the lines in it but after processing they are 4x5s.

Here's how to clear the crop marks in DPP:

1. In DPP's Main Window (not the Edit Image Window), select the image(s) you want to work on.

2. From the Tools menu, start the Trimming Tool.

3. Locate "Clear" in the menu to the right of each image and click on it.

That will get rid of the crop marks and allow you to print the full frame, or allow you to select any of the other cropping alternatives.

I have some question regarding the handling of the TS-E45mm f/2.8 lens. Should I always take care to lock down the tilt and shift pressure knobs? Would the internal gears get damaged if I keep them loose all the time? I noticed that when the pressure is off, any moderate force on the camera body will cause the tilting lens element to snap around. Would it also be safe to manipulate the tilt and shift directly by hand instead of turning the knobs?

Leaving the tilt and shift adjustments unlocked won't damage a TS-E lens directly, but I would suggest tightening them up at least partially when the lens is not in use. This will prevent the mechanisms from unnecessary wear and tear that might be caused by inadvertent movement. It's no problem to adjust the movements directly by hand as long as the camera and lens are mounted on a sturdy tripod and the tilt and shift mechanisms are completely unlocked, but you may find that the shift movement in particular is easier to control precisely with the adjustment knob. Once you've made an adjustment, it's good practice to lock the mechanism to prevent further movement.

Is it possible to rename the file prefix for Canon EOS Digital SLRs (30D, 40D, 1Ds Mark II)? I use at least two bodies on assignment. I like to send selected photos into a work file at the end of the assignment. I sometimes find that I want to send images from different bodies with the same name to a single work file. Of course, the second image can't be saved. I'd rather rename the prefix in the camera than rely on a renaming utility on my computer.

In-camera file prefix renaming is available in the EOS-1Ds Mark III and EOS-1D Mark III as well as the EOS-1D Mark II N, but I do not anticipate that it will be retrofitted to older or lower-category models like the 1Ds Mark II, 40D or 30D. For those cameras, the best available option is file renaming during or after download. EOS Utility software supports customized renaming during downloads, including the ability to use the camera's serial number as an identifier when desired. Selecting the file renaming options is essentially a one-time procedure, and once it's been done you can concentrate on shooting, knowing that your files will be renamed automatically as soon as they enter your computer system.

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 all inquiries, 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.)