The Lightweight Photographer:
Canon Powershot S90 Real World Camera Review

Despite the Powershot middle name they share, the Canon Powershot S90 is but a distant cousin to Canon’s top-of-the-line Powershot G11. While the G11 keeps company with low-end digital SLR cameras, the S90 finds itself barely able to stay ahead of the point-and-shoot multitude. Still, the S90 has a personality of its own and a few good qualities that make it worth a closer look.

UPDATE 5-25-2010. In response to one reader’s comment, I’ve added information about the effect of different raw processors on the purple fringing mentioned in this article. Scroll to the end of the article.

Lighten Up

This is the third in a series of reviews of compact cameras for serious photographers. Read the other reviews – and all articles in this series – here: The Lightweight Photographer.

User Reviews and Prices

Read user reviews and check the latest prices on these compact cameras for pros and serious amateurs:

	Canon Powershot S90
	Panasonic Lumix DMC-LX3
	Canon Powershot G11

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Over the past few weeks, I’ve been testing three compact cameras which, on paper, seem to be good substitutes for my Nikon D300 and the 20-pounds of lenses and accessories that go with it.

I’m looking for a camera that will  fit in a pocket for those times when I don’t want to carry the big rig. I don’t expect it to handle like the D300, but I do expect it to be capable of producing publication-quality images.

The camera I choose has to capture raw files, since I rarely shoot jpegs. That requirement eliminates all but a handful of compacts. Those listed here are the only three that capture raw files, are pocket sized (or nearly so) and are reasonably priced.

The first camera I reviewed was the Canon Powershot G11. It is without a doubt the best of the bunch. But it’s not pocket-sized, so the search goes on.

Canon Powershot S90 Overview

The Canon S90 is the smallest of the three cameras I’ve reviewed. It’s so small, you can slip it into a pocket and forget that it’s there. Unlike the other two cameras, when the S90 is turned off the lens is nearly flush with the camera body: the whole camera is less than 1-1/4 inches thick! In height and width, it’s about the size of a deck of cards.

The menu system and some of the controls have a lot in common with the G11. It has a pop-up flash which I prefer over the built-in flash on the G11, yet it’s not as convenient as the one on the Panasonic LX3.

And the S90 has a funky control dial around the lens that is reminiscent of the aperture dials we used in the bygone film days; but this one can be programmed to adjust more than just aperture.

Image Quality

Publication-quality image

Image quality is big deal to me. The S90 has major issues in this department.

First, the good news: the Canon Powershot S90 is capable of making publication-quality images. I was able to get one image from this camera – of Mesquite Dunes in Death Valley – accepted by my stock photography agency.

Unfortunately, the keepers-to-rejects ratio is ridiculously low. The main problem is color aberration. Any image that has a high-contrast edge – where a dark area meets a bright area – results in a purple fringe along the edge.  The only reason the dunes photo made it through quality control at Alamy is that the edges are relatively low in contrast.

Purple fringe

Images with high-contrast edges do not fare so well. For example, I photographed a statue in Balboa Park against a cloudy blue sky. Because the statue is not black, but a medium-toned green, the contrast between the dark statue and the bright sky is not all that high. Still, there are purple fringes around many of the edges.

More purple fringe

Or, how about another Balboa Park scene including several tall palm trees? Every tree trunk has a thick purple line along its entire length.

I’ve tried to illustrate the problem with the two photos shown here. The purple has been emphasized to make it easier to see, but trust me, in the original raw image at 100% enlargement and no extra saturation, the fringe is impossible to ignore.

The fringe is less obvious when viewing the image on the camera’s LCD screen. Out in the field, the images often look good even when highly magnified. But once they’re viewed on the computer monitor, it’s a different story.

You might think that you can correct the problem in post-processing. Adobe Lightroom, for example, has a Chromatic Aberration module specifically designed to handle this sort of thing. But the S90′s images have such extreme purple fringing that, in the process of eliminating the purple in one part of the picture, you’ll create colored fringes (most often blue) in other areas.

The purple fringing is probably a result of poor lens design. It occurs at all ISO settings, focal lengths and aperture settings. I’ve photographed in raw-plus-jpeg mode and even noticed the problem in the jpegs which were processed by the camera. In some of these jpegs, the fringe had been reduced by the camera’s internal processing,  but not eliminated.

Raw vs. JPEG

I prefer to shoot raw. But after noticing problems with the S90′s output, I decided to give JPEG a try. I set the camera to record raw-plus-jpeg which records a large jpeg along with the CR2 raw file. The photographer has no choice in this matter, it’s a large jpeg or none at all. Since I would have chosen the large jpeg anyway, in this case the camera designers made a good decision.

The lack of choice does cause problems in other areas when shooting in jpegs. There is no way to control the amount of sharpening and most other jpeg parameters are also off-limts.  The camera is in control and the photographer is only able to view the results. The amount of sharpening applied is excessive: you’ll notice telltale outlines around sharpened edges – typical of over-sharpening. For this reason, I would not recommend this camera for shooting jpegs.

Pros and Cons

The Good

• The S90 is truly pocket-sized and light (7 ounces including battery, SD card and strap), so it’s easy to carry.
• Good performance in low light. The noise level is acceptable up to ISO 400.
• ISO can be set in fine increments: 80, 100, 125, 160, 200, 250, 320, 400, 500, 640, 800, 1000, 1250, 1600, 2000, 2500, 3200.
• 28mm to 105mm zoom range with maximum aperture of f/2.0 at 28mm and f/4.9 at 105mm.
• Pop-up flash.
• Good customization options:
  • Customizable control ring around lens can be set to adjust aperture value (in Av mode), ISO, exposure compensation, focus (in manual-focus mode), white balance or focal length/zoom.
  • One custom setting position on mode dial to instantly choose your preferred settings.
  • Shortcut button can be customized to one of up to 13 functions depending on mode.
• Large and bright 3-inch LCD.
• Excellent self timer makes it easy to use as a substitute for a remote release (which cannot be attached to this camera).
  • Set the self-time in one second increments from one to 30 seconds.
  • Self timer stays active until you cancel it: it doesn’t turn itself off after each use as do some other compacts.
• White balance is easy to customize by adjusting levels of green, blue, amber and magenta. White balance can also be preset by photographing a gray (or white) card.
• Unlimited continuous shooting of raw images at about 2 seconds per image. I took 20 images in a row without any slowdown. For a compact, that’s pretty good.

The Not So Good

• Image quality is unacceptable due to purple fringing in most photos.
• No way to move the focus point – it is locked to the center of the frame.
• The tripod mounting hole conflicts with the battery and SD card door. If you mount a tripod quick-release plate to the camera, you have to remove it every time you want to change the card or battery.
• No optical viewfinder.
• No flash shoe or any way to use an external flash.
• Customizable “My Menu” is a good idea, but why not allow me to place any menu item in “My Menu” instead of limiting me to a short list of choices?
• Shutter speeds from 1/15 to 1/1600 and no “bulb” mode for long exposures.
• Black-and-white mode not available when shooting raw.
• No way to attach a polarizer or other filter.
• Movies are low-quality VGA (640×480 resolution).
• No choice of color modes (sRBG vs. Adobe 1998).
• In jpeg mode, no control over the amount of sharpening applied.

Conclusion

As you can probably tell from the brevity of this review, it’s hard for me to work up much enthusiasm for the Canon Powershot S90. I want to like this camera, but its small size and other nice features are overshadowed by its one glaring fault: poor image quality. I ‘d feel uneasy about any critical use of images from this camera such as submissions to my stock photography agency. So, I cannot recommend this camera to any serious photographer.

Some people seem to love the S90 and I don’t know why. Maybe I expect more than other S90 owners. I’ve downloaded full-resolution images from other S90 reviewers such as those at dpreview and seen the same purple fringing in their photos. It’s apparent, then,  that this is a design flaw and not simply a problem with my particular camera.

For other opinions, read the user reviews of the S90 at B&H Photo and Amazon. Then, decide for yourself. Both of these companies have liberal return policies.

I look forward to the next version of this camera (the S91?). With a better lens to eliminate the purple fringe, Canon would really have something. I’m not holding my breath.

If you have photographed with the Canon S90, what do you think of its  picture quality? Share your experience: leave a comment below.

For two cameras that are worth considering, read my reviews of the Canon Powershot G11 and the Panasonic Lumix LX3. Thanks to B&H Photo for lending me the S90 for this review.

Update: Raw Processing and Purple Fringing

Thanks to  a comment by Dan, I’ve experimented with different raw processing software to see if there was any improvement in the reduction of purple fringing I noticed in the S90′s images. Unfortunately, the results are the same: every raw-processing software I used exhibited the same purple fringe.

The only image that does not exhibit this color anomaly is the JPEG produced by the S90 itself when I shot in the raw + jpeg mode. The camera’s internal processing covers up the purple fringe by desaturating the edges where the purple appears. So, you get a gray fringe instead of a purple one. This is still not acceptable.

All of the images below were processed with no corrections: each raw processor was set to affect the image as minimally as possible. I used the following software: ACDSee Pro 3, DxO Optics Pro 6,  Adobe Photoshop CS4, Adobe Lightroom 2 and Adobe Lightroom 3 Beta. Because there was no noticeable difference between the two Lightroom versions, I’ve only included the Lightroom 2 images here.

Click on an image below to view a 200% crop of an image of a bagpiper. I did not exaggerate any of the colors in these images; the large crop should make it easy to see the fringing. It’s especially noticeable on the tops of the white pipes to the left (you’ll notice the gray fringe in the original S90-processed jpeg here) and running down the side of the black cord on the right.

ACDSee Pro 3	Photoshop CS4	DxO Optics Pro
Lightroom 2	Canon S90 jpeg

Tagged as: camera, Canon, compact, digital, equipment, photography, point and shoot, Powershot, raw, s90