Category Archives: Equipment

Questions about the Canon EF-S 10-22mm f/3.5-4.5 USM

Alex writes to ask about the Canon EF-S 10-22mm f/3.5-4.5 USM:

I’ve been reading your blog for a while now and have noticed that you haven’t commented on the Canon 10-22mm lens on a crop camera. I have a 350D with the 10-22mm lens. I’m curious as to your opinion on using this lens on a crop body compared to the 17-40mm. I’m considering upgrading to the 5D at some point and would obvioulsy need to purchase a WA lens as well. You seem to be satisfied with your result of using the 17-40 on a crop body in the past or did it make a noticeable difference to you when you moved from the crop body to the full frame on the 5D with your 17-40mm?

Thanks for writing, Alex. You are right that I haven’t written about this lens, but only because I don’t have any direct experience with it. Being an EF-S lens, it is designed for use only on crop sensor Canon bodies (like the 350D/400D series and the 20D/30D/40D series), and I’m using full frame these days.

You are also correct that I’m a big fan of the Canon EF 17-40mm f/4 L lens. I used this lens on the crop sensor camera that I had until about a year ago, and I continue to make a lot of use of this lens on my 5D. On my crop sensor body, the 17-40 always produced excellent center sharpness, though it could be a bit soft in the corners, especially when shot wide open. I find it to be even better on full frame where I frequently shoot it at f/11 or even f/16, thus controlling the corner softness/fall-off issues more effectively.

On a crop sensor body, the 10-22mm focal length range is essentially equivalent to the 16-35mm range on a full frame body – in other words just a tiny bit wider than my 17-40mm lens on full frame. Although I had thought that 17-40mm was “wide enough” on my crop sensor body, once I started shooting full frame with this lens I really came to appreciate the much wider coverage provided by this combination. I think that the combination of the 350D and the 10-22mm lens could very useful – for example, it could be a wonderful small and lightweight setup for doing landscape photography while hiking or backpacking.

With that in mind, I guess you could say that I was satisfied with the 17-40 on the crop sensor camera at that time, but that I know realize that if I were going to again use a crop sensor body I would almost certainly want to get a lens providing the coverage of the 10-22. Although I haven’t used the EFS 10-22mm lens myself, almost everything I’ve read about it has been positive.

When you do move to that full frame body you might find that the 17-40 really comes into its own, especially if you shoot landscapes and similar subjects. As to whether you would want to get this lens now or wait, I think that depends upon what kind of coverage your other lenses currently provide in that range.

Follow-up On A Post From Yesterday

Yesterday I posted a short piece about timing a move to full frame, particularly in relation to the possibly arrival of an upgraded version of the Canon 5D and dropping prices on the existing model. (“A Good Time to Move to Full Frame DSLR?“) I may have left a false impression that I was mulling over my own decision about this. Nope, I already shoot with a 5D.

Which perhaps raises a couple questions. First, what do I think of the camera? I like mine a lot. It is pretty much the perfect camera body for the sort of work I do most of the time.

Would I trade my 5D for a 16MP replacement model? Unlikely, at least until prices drop as they always do after a new camera has been out for awhile. The difference between 12MP and 16MP (if that is what comes out) is less than you might think, and in most cases it wouldn’t result in a noticeable difference in my photographs. I might change my mind if a new body is introduced that is significantly better in other important ways, but even then I don’t think I’d be in any big rush to do so.

That said, it is starting to look like a better market for those who are looking up upgrade to full frame.

DSLR Sensor Cleaning – My Approach

Update: June 14, 2023I just returned to this article after not reading it for quite some time, perhaps years. I still think it contains useful information, and the steps I describe still represent more or less what I would do today. However, things really have improved when it comes to the dust issue. Back when I had a Canon 5D, dealing with sensor dust was a major issue that required frequent cleanings (often with wet cleaners) AND a lot of spot removal in post. But today that is hardly ever the case. It is actually pretty rare to encounter visible spots, and when they do show up the cameras dust reduction system often takes care of them and they disappear a few frames later. I still firmly believe in tolerating a tiny bit of dust and dealing with it when necessary by using the least intrusive methods first.

When I got my first DSLR (1)  I was very upset if I got any sensor dust in a shot. I was also very paranoid about cleaning the sensor (2), having read too many posts about how one can damage the sensor during cleaning. Now that I’ve used digital cameras for quite some time I’ve gotten over it and life is much, much easier.

Here is a summary of my approach (3) to dealing with sensor junk…

Rule #1: Modern cameras typically include dust-reduction systems that vibrate the sensor to dislodge dust particles. I set mine to operate automatically each time the camera is turned on or off. In addition to ensuring that the process runs regularly, this automatically runs it after every lens change, the time when you are most likely to pick up dust. You can also manually trigger a dust-reduction system cycle from the control menus, and I do this if I notice a dust spot while shooting. (If you have ever shot for a day or a few days without checking, only to realize that you had picked up a big dust bunny on day one and that it appears in all of your several hundred or more photographs, you will adopt this practice!)

Rule #2: I don’t worry too much about a small amount of dust in my images. I rarely can get a sensor clean enough to get perfect, dust-free shots at smaller apertures, and when I do the dust will soon return. Rather than obsess about dust-free perfection I quickly fix most small spots in post-processing. I can usually deal with most dust spots in a matter of a few seconds in Adobe Camera Raw (ACR) or Photoshop. (My preference is to do this in ACR during the raw conversion process. This fits better with my workflow which relies on the use of smart layers in Photoshop.)

Rule #3: When the dust gets to the point that dealing with it in post is no longer efficient, I try the easiest thing first. I use a blower to try to clean out the worst of the stuff. More often than not this is enough and I can go back to relying on rule #2. Point the tip of a good blower bulb into the chamber but keep the tip itself just outside. As you blow a few dozen puffs into the chamber and toward the sensor, change the angle of the bulb to ensure that you get full coverage. It is probably best to hold the camera with the open chamber facing down. (Don’t overdo it, since the blower can move some dust onto the focus screen of some cameras, leaving annoying bits of dust that do no real harm and will not affect your photographs but which are very difficult to remove.)

Rule #4: Sometimes rules #1-#3 aren’t enough and a more direct cleaning of the sensor itself becomes necessary. At this point I used to try a static charged sensor brush, being very careful to avoid letting the brush touch anything but the sensor* glass itself. Yes, the brush can pick up other stuff in the chamber, and I have learned from experience to avoid this. I still occasionally use the brush, but with the availability of the sensor gel products (4), these days I’m more likely to try them before I try a brush, though the brush can still be useful sometimes for stuff caught right up against the edges/corners of the sensor.

Rule #5: On rare occasions rule #4 fails, too. If the contamination is adhering too firmly to the sensor surface I resort to wet cleaning with Eclipse fluid and PecPads. I can rarely get it right in one attempt, so I plan on having to work at this a bit, but eventually I get a reasonably clean sensor with no streaks. Be very cautious to not use pressure, to not “scrub” the sensor glass, and to not use too much liquid. Let the fluid loosen and/or dissolve the material and gently wipe it off with the pad attached to the “spatula” tool. Read the instructions for this cleaning method very carefully before attempting it. It isn’t terribly difficult but there are a few ways you could go wrong including: pressing too hard and damaging the coating on the sensor glass, transferring lubricants to the sensor from other parts of the camera chamber, leaving streaks on the sensor.

Rule #6: On very rare occasions a combination of methods is required. Often the wet cleaning works well for me but leaves a few spots of dust on the sensor. For this reason I frequently follow the wet cleaning with a quick once-over with the static charged brush and/or the sensor gel stick.

From all of this, it might sound like I’m sensor-obsessed. I’m not. Remember rule #1 is the one I follow most. I usually go many months between real sensor cleaning sessions, and it is very rare for me to have to resort to a wet cleaning.

In my opinion, it is not necessary to fear the sensor cleaning operation as long as you are reasonably careful. Once you do it a few times it becomes quite quick and easy. Taking your camera to the shop or sending it to the repair facility is going to cost you a significant sum, take considerable time, and probably not result in a cleaner sensor in the end.

However, one photographer pointed out that he has a service plan that includes six free sensor cleanings per year. A few years ago, I would have counseled against relying on this – since early cameras without sensor cleaning systems often needed to be cleaned frequently and on short notice. However, the newer cameras rarely need a serious sensor cleaning – and in this case I can see how simply sending the darn thing in (while you keep shooting with your backup camera) could make sense for some people. (I still feel that you should be able to clean the thing in the field if necessary.)


Notes

(1) Interchangeable lens mirrorless cameras have become widely available since I first wrote this article about sensor cleaning. I use one along with my DSLR system, and both need occasional sensor cleaning — to the techniques described here are also broadly applicable to mirrorless cameras, too.

(2) I’ll anticipate that someone might feel obligated to write, “You aren’t really cleaning the SENSOR! You are cleaning the glass cover over the sensor, you nitwit!” Yes, I know that. It is just easier to refer to the whole assembly as “the sensor.” :-)

(3) Disclaimer: This report describes what I do, but I am not any sort of certified expert on these things – as I wrote, this is “my approach.” I strongly urge you to seek out and learn from other official sources of information on sensor cleaning and related issues. The inside of your camera contains fragile and sensitive electronic and mechanical components and it is possible to cause damage while working there. You should read and carefully consider warnings from the manufacturer of your camera and any accessories and tools you use on it. If you are not convinced that you are competent to do this work on your camera, you can always take it to a professional. I do not claim that my methods are the best or most appropriate, nor that they meet the standards of the manufacturers of the camera equipment nor do I recommend that you use my methods in place of manufacturers’ official recommendations.

(4)  The Sensor Gel product (available here) is a cube of a sticky gel attached to the end of a plastic “wand.” The gel cube is placed in contact with the surface of sensor’s glass cover, and the dust adheres to it. Since the cube is smaller than the sensor, this process is repeated across the sensor surface. Press the cube against a supplied sheet of “sticky paper,” to clean it. I tried the Sensor Gel Stick partially out of desperation, as my aging Canon 5DII had picked up a ridiculous number of dust specks that were resistant to other methods of cleaning. After the first cleaning there were no noticeable spots left on the sensor. I continued to use it during a four-day shoot in Death Valley, a location known for dust—and, again, the result was impressive. The product is not cheap, costing about $50 for the gel stick and the sticky papers. Frankly, I think it is overpriced—but because it works so well I was willing to pay the price. I have recently seen similar products online from other distributors at lower prices, though I cannot vouch for their quality.  I understand that two versions are currently available. One is the “blue” version that I have. The other “pink” version is apparently designed for certain camera brands, particularly for some Sony cameras. Check the product descriptions and make sure you get the right version for your camera.

(Most recent update: June 2023)

Articles in the “reader questions” series:

G Dan Mitchell is a California photographer and visual opportunist. His book, “California’s Fall Color: A Photographer’s Guide to Autumn in the Sierra” is available from Heyday Books and Amazon.
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Canon EF 17-40mm f/4 L: Testing a Claim About Sharpness and Focal Length

Today I read a claim in a photography forum thread that “some 17-40’s are soft on the long end.” Having not noticed that on my copy I went back to some test shots I did earlier this year to compare sharpness at 40mm and 24mm with this lens.

The two images below are 100% crops – in other words, they are very small sections of a much larger print that would be something like 5 feet wide if printed at this resolution! The crop came from an area just below the center of the frame. Both were shot on a Canon 5D a 1/125 second and f/11. The camera was on a tripod and I used mirror lockup and a remote release. Both were converted from RAW using ACR with no adjustments to the original settings. The same sharpening process was applied to both.

24mm: 40mm:
17-40at24mmf11.jpg 17-40at40mmf11.jpg

My verdict? There doesn’t seem to be a lot of difference in terms of sharpness. And if there is a difference, it would hardly be significant in even a pretty decent sized print. I don’t think a difference would be noticeable in a 12″ x 18″ inch print, and frankly I doubt that anyone would notice even at a larger print size.

What do you think?

There is one other possibility. The person who posted the original message claimed that “some” copies of this lens exhibit this problem. There is no way for me to rule that out with only one sample.

One other related idea. Any zoom lens is going to perform differently at different focal lengths, and there will likely be some focal length or focal length range in which the “quality” may be measurably “best.” But this doesn’t mean that the other focal lengths are not good – in some cases so good as to provide virtually the same quality.

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