I hope you enjoy this month's column, and encourage you to submit questions of your own via the e-mail link at the end of this page.

I am a DPP user for RAW conversion and I noticed recently that the JPEG conversion in the latest version is giving me much larger file sizes than earlier versions (around 4-5 times bigger). I usually convert to "9" setting which has previously resulted in a file size of around 1-2MB from a RAW image from my EOS-1D Mark II N. Now the same image will typically be around 5MB under the latest version of DPP.

Canon Inc. has confirmed that the JPEG compression algorithms were changed in DPP 2.1 compared to 2.0 and earlier. Their comments were as follows:

"We improved the curve of the JPEG compression rate so as to change file sizes more smoothly. The attached is data of JPEG compression setting in DPP 2.1 and DPP 2.0 in case of 20D. We expect the data will be helpful for your understanding."

At this point, I am not permitted to release the chart that Canon Inc. provided, but I can tell you that Level 7 in DPP 2.1 is roughly equivalent to Level 9 in DPP 2.0 and earlier, in terms of JPEG compression ratios.

The interesting point for me was to see how drastically the older versions of DPP changed the compression ratio going from Level 10 to Level 9. Also, there was relatively little difference in compression ratios stepping down from Level 9 in the older software. With DPP 2.1, each step down the scale reduces file size by approximately 40 percent, so there's a much greater degree of flexibility to work with.

I have a problem when using my EOS 20D at high ISO (1600 and 3200) with sporadic white balance and exposures. I manually set exposures, preset white balance and sometimes even use manual focus (as an example at a recent gymnastics meet), but I am getting exposures and white balance all over the place when shooting several exposures in a row. This happens with all my lenses and with both of my 20D's. Any suggestions?

When you shoot under discontinuous spectrum lighting (such as fluorescent and mercury vapor, etc.), the light pulses on and off at 60 Hz. The human eye compensates for this, but still cameras do not. Color temperature changes drastically over the course of each pulse, and fast shutter speeds only pick up one portion of each lighting cycle. Net result: some shots will look OK for color, while others will look very yellow or green, depending on the spectral characteristics of the light source. In some cases, you may even see a form of banding that shows different colors in the same image.

One way to minimize or eliminate the problem is to shoot at slower shutter speeds, so that the number of lighting cycles captured in the image increases. Another solution is to use flash to replace the available light. But other than converting the images to black and white, there's no way I know of to eliminate the color issues of discontinuous spectrum lighting if your shutter speed is set too high.

I am the owner of a Canon EOS 20D. I also happen to have the new Apple MacBook Pro with an Intel Core Duo inside. I have been unable to accomplish tethered shooting with Canon's myriad of confusing software. Every application I've tried merely hangs when launching with a connected camera (spinning beach ball mode). I have been unable to find any information about why this happens or how to rectify it. I'd really appreciate it if you could provide some insight into this mystery.

The solution to your problem may lie with the 20D's "Communication" setting. You'll find this setting on the camera's LCD menu screen. When Communication is set for "PTP," which is the default, the camera can be recognized by Apple software such as Image Capture and iPhoto, as long as the Preferences for those programs are properly set. But if you want to use Canon software, the Communication has to be set for "Normal." This is spelled out in the software instructions, but it's easy to miss. If you continue to experience connection problems after making this change (and if you are a USA resident), I would suggest calling Canon USA's Customer Support Center at 1-800-828-4040 for further assistance. They are currently open from 8 a.m. to 12 midnight Eastern USA time), Monday through Friday, and 10 a.m. to 8 p.m. on Saturdays, excluding holidays.

Incidentally, if you haven't done so already, I would suggest updating your Canon software to the latest versions for maximum compatibility with Mac OS X including 10.4.6. Go to the Support Index page for EOS 20D on Canon USA's Web site:

Canon USA Support Index

...and click on the Drivers/Software link. Follow the prompts from there. The latest versions for 20D are:

DPP 2.1.1

EOS Utility 1.0

ImageBrowser 5.6.1a

You don't need anything earlier than these updaters. Be sure to read the download pages for information on which software must be installed on your system before these updaters can be installed.

The new version of the EF85mm f/1.2L USM lens has come out, and I have been able to "play" with it. I have also used the older version of this lens, so I can comfortably comment on both lenses and their differences. Two things strike me as strange about the newer lens. Why was the filter thread not increased to 77mm, seeing as 80 percent of L lenses use this filter thread? Secondly why wasn't the weather seal ring around the bayonet mount included, unlike other recent L lenses? Either of these two changes might have mitigated in part the $600 price increase for a slightly faster USM motor, and a bit of lens coating on the rear element. Whereas in other areas Canon is quite radical and forward-looking, in this lens re-release, they have kept as close to the original recipe as possible. Why? I realize these are not really technical questions, but rather marketing issues at stake, but your input on the reasoning behind this lens release and Canon's philosophy in general would be appreciated.

The designers of the EF85mm f/1.2L II USM started out under the condition that the optical formula of the lens was not going to be changed. (The image quality of this formula is exceptional. Not only was there no need to change it, it's likely we would have had a revolt on our hands if we did.) This in turn led to the decision to use the original mechanical components of the lens to the greatest possible extent, in order to control manufacturing costs and ultimately, retail pricing. Had the lens been redesigned with a larger filter mount and/or a rubber gasket at the mount, it would have involved additional retooling, which would have increased the price even further. (Retooling the mechanical components of a precision, limited-production camera lens is no trivial matter in terms of cost.)

I would further argue that the improvements Canon made in this lens are far more significant than you seem to imply. The focusing speed (auto and manual) of the lens was increased 1.8x compared to the original version. The improved lens coatings are far more extensive than just the rear element, and they significantly reduce ghosting in backlit situations when the lens is used with digital SLRs. The shape of the diaphragm blades was made more circular to improve bokeh at wide apertures. To summarize, we changed what needed to be changed, without compromising optical or mechanical performance. For what it’s worth, the overall market reaction to this lens has been overwhelmingly positive, and sales are brisk.

Do you have any recommendations for top-notch repair centers for F-1n and F-1 products?

Canon no longer offers repair service for FD system cameras like the F-1, so at this point your best bet is to work with an independently owned and operated Canon Authorized Service Facility (ASF). If you are a USA resident, Canon USA provides ASF information through its toll-free Customer Support Center at 1-800-828-4040. The lines are open Monday-Friday from 8 a.m. to 12 midnight EST, and Saturdays from 10 a.m. to 8 p.m., excluding holidays.

Are we very likely to see a firmware upgrade to the EOS-1D Mark II that would allow the camera to see and recognize a 4GB SD card? I can't help but think that with the falling price of these cards, I'm not the only one to have requested this. What do you think? Will it happen?

I've already commented on this topic in an earlier edition of Tech Tips. The gist of the information was that as of January 2006, the SD Card Organization had not yet ratified a standard for SD cards with capacities higher than 2GB. They issued a press release confirming that fact, and announcing that they were working on a new standard to be called SDHC, for "SD High Capacity." The good news is that the SDHC standard has finally been ratified, and we are expecting firmware updates for all Mark II EOS digital SLRs over the next few months. The potentially bad news is that at least some of the currently available 4GB SD cards may not meet SDHC standards. If you have any questions on this, I would suggest that you contact the card manufacturer or distributor.

Is it possible to enlarge the eyepiece on the Canon 1DsMkII? I notice the eyepiece is smaller than the one on my Canon 1V, and much smaller than the eyepiece on my 30-year-old Olympus OM 10. The files produced by the camera are terrific, but using the viewfinder is not as enjoyable as with my older cameras.

The physical size of the viewfinder eyepiece is the same on an EOS-1Ds Mark II as it is on an EOS-1V, so you must be referring to the finder magnification, which is the apparent size of the viewfinder image. The finder magnification of the 1Ds Mark II at 0.70x is quite similar to the EOS-1V at 0.72x, but you are right that the image seen through the 1V's viewfinder is slightly larger. Older cameras like the OM-10 and indeed earlier Canon 35mm SLRs like the FTb from the 1970s had finder magnifications closer to 0.85x, which is considerably higher than today's digital SLRs. Perhaps the biggest reason why the current cameras don't magnify the viewfinder image as much as the older models is to make it easier for eyeglass wearers to see the entire image at once without having to mash their faces into the rear of the camera. EOS users desiring higher magnification of the focusing screen for manual focusing can use the optional Angle Finder C, which provides a built-in magnifying lens and dioptric adjustment.

I am writing regarding the parfocal property of Canon lenses. I have read on many forums that the EF24-70mm f/2.8L lens is supposed to be parfocal (including a list of parfocal lenses that you or someone posing as you wrote). My 17-40 and 70-200 are both parfocal and I find this property to be extremely useful. My 24-70 is not remotely close to parfocal (which I noticed since purchasing it). I would like to get it fixed, but I called Factory Service in Irvine and they indicated to me that they couldn't find in any documentation that the lens is parfocal. They indicated that if I were to send the lens for repair, they would test it for factory specifications, most likely find nothing wrong with the lens, and mail it back to me. Is there anything I can do short of selling the lens in order to buy a new one?

I included the EF24-70mm f/2.8L USM on a list of EF zoom lenses that in my experience are parfocal. However, there is more to the story with this particular lens. It turns out that while the lens itself is reasonably if not perfectly parfocal, it is very difficult to calibrate for autofocus over the entire zoom range. There's no way to diagnose the issue properly without having the equipment examined by a Canon Factory Service Center technician, but you can do some troubleshooting on your own:

1. Use a tripod and a cable release or self-timer.

2. Set the camera at ISO 100 and One-Shot AF.

3. Use a flat target with plenty of detail. (Do not use an angled chart.) Make sure the camera is parallel to the target.

4. Position the camera about 6 to 10 feet from the target.

5. Set Custom Function 4-1 so that the AE lock button only operates AF.

6. Set Custom Function 12-1 for mirror lock.

7. Use the Standard Picture Style setting.

8. Use manual exposure or aperture-priority (with exposure compensation if necessary) to get an accurate exposure at f/2.8.

9. Manually select the center focusing point and make sure that Custom Function 17 is set to 0.

10. Perform the test in lighting conditions that are at least as bright as office lighting.

11. Zoom in to 70mm, autofocus and shoot. The self-timer is a good method to reduce potential vibration, since it automatically provides a 2-second mirror lock prior to the exposure when CF12 is on.

12. Check your results on a computer at 100 percent magnification. If the photo is sharp, the camera's AF system is functioning properly.

If the test photo is not sharp, then send in your camera and lens with a sample image and an explanation of your testing method.

Assuming the test photo is sharp, then continue testing as follows:

13. If necessary, refocus using the AF system at 70mm.

14. Zoom the lens to 24mm.

15. Take another test shot without refocusing. (IMPORTANT). The camera will not refocus as long as you followed Step 5 above.

16. Take yet another test shot after refocusing with the camera's AF system.

17. Examine the results at 100 percent magnification.

If the test photo taken at step 15 is sharper than the test photo taken at step 16, it is a clear indication that the lens needs to be calibrated for autofocusing by the Canon Factory Service Center.

I was wondering if you could comment on a 1DmkII phenomenon I was made aware of recently. This is a case where the 1DmkII or 1DmkIIN seems to switch to center-weighted metering mode whenever a flash is mounted and turned on, regardless of which metering mode the 1D was initially set to. For example, let's assume that the camera is in Manual mode (this happens in the other creative modes, too, but is easier to see in M mode) with metering set to spot mode. Let's also assume that we want to take a picture of a white poster board with a black lens cap in the center of the board. Zoom the lens so that the black lens cap completely fills the center spot metering circle and adjust the shutter and aperture so that the meter "needle" is at "0." Now, mount a flash set to ETTL mode but do not turn it on yet. (Note: If the shutter speed that was set on the camera is above sync speed, make sure to set the flash to HSS mode, too.) After mounting the flash, observe the exposure meter through the viewfinder. It should still be at 0. Now, while looking at the exposure meter, turn on the flash. You should see the exposure needle drop about 1 1/3 stops. Turn the flash off and the needle goes back to 0. Similar observations can be made for the other ambient metering modes except for CWA. I have tried this on my 10D and 30D and they do not exhibit this behavior; only the 1DmkII does. Thanks for taking the time to read this and looking into it for me.

In the case of the 5D and all EOS digitals other than the 1 series, ambient metering with dedicated flash is done in the pattern selected by the user. In the case of the 1 series, ambient metering with dedicated flash is done in Evaluative as if the center focusing point were selected (similar but not the same as center weighted average) regardless of the pattern selected by the user. Exposure compensation set by the camera when the flash ready light is on is a separate issue, and like the situation outlined above, one that Canon Inc. elects not to discuss in detail. Under the circumstances, I suggest that photographers familiarize themselves with the way their particular equipment combination handles these issues and select the exposure settings they prefer based on their own testing and preferences.

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

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.)