Sigma SD-9 vs. Nikon D100

O-dark-thirty. I'm awake without an alarm clock and the sounds from outside are ominous. Opening the door to the hotel only confirms what I already know - heavy weather in the form of big splattering raindrops. There's little wind and water is running through the parking lot in a torrent. The cloud cover is low enough that I can't see cliffs that are no more than 200 yards away. There'll be no sunrise shots this morning.

Back inside I curl up with a book and relax for a while. The storm may pass or at least the clouds may lift. In a bit I'll head out for breakfast and go in search of whatever the weather gods decide to toss my way.

The Showdown
It sounded like a good idea back in a warm dry office in New Jersey. I'd be flying down to Las Vegas to cover PMA. That would put me within easy driving distance of Zion National Park. Why not fly down a couple of days early with a Sigma SD-9 and Nikon D100 and do a shoot off in Zion?

Gary Stanley and I had visited Zion last year and gotten some spectacular shots. It would be a great location. We'd hit snow and abnormally cold weather the previous trip but the weather had been mild in Zion this year. Temperatures were in the 60's and even the 70's at times. I could re-shoot areas I was familiar with and the milder weather would allow me to hike into parts of the park I hadn't visited before.

That was a couple of weeks before. As the day of the trip approached a front came in off the Pacific bringing moisture and storms. Back in Las Vegas a 70 year record for consecutive days of rain would fall; and the leading edge of that storm would follow me to Zion.

The Test
An hour later the sky was beginning to lighten and I began the drive up to Zion Lodge for breakfast. As I entered the park the rain began turning to sleet and then to giant white flakes that quickly turned into a full-blown snowstorm as the temperature took a dramatic plunge. Weather happens quickly in the mountains. Breakfast forgotten I headed up the canyon looking for opportunity. The low clouds roiled and boiled down cliff walls; at times reducing visibility to as little as a few hundred yards.

It was unfortunate that I really didn't have more time to familiarize myself with these cameras before getting on the plane. They literally arrived the day before my flight and my undying thanks go out to the folks at Sigma (Tom), Nikon (Saurabh), and Lexar (Kim) for getting everything out to us last minute. The upside is that it's a long flight from Philadelphia to Las Vegas so there was time to read through manuals and fiddle with controls.

To keep the test fair I wanted to mount the same lens on both cameras. Since the SD-9 uses Sigma's SA mount that meant using Sigma lenses for the test. Sigma obliged with their 20-40mm f2.8 EX DG DF lens in both SA and Nikon F mounts. That way I'd be sure that I was comparing cameras and not lenses. Additionally Nikon sent along its AFS 24-85mm f3.5-4.5G IF-ED. I would have the opportunity to shoot with a variety of lenses on the Nikon, which would give me a relative feel for the quality of the Sigma lens.

The significant fly in the ointment was the fact that there just weren't that many SD-9's available - and every journalist wanted to get their hands on one. That meant returning the SD-9 on the first morning of PMA for use in the Sigma booth - which left only four days for testing in the field.

The idea was to shoot them together. Record my impressions of using the two and do some large prints when I returned to the office. Those prints would provide a feel for the actual differences in image quality between the two cameras. After all Foveon is making some pretty large claims for its technology. Side by side images shot using the same glass from the same tripod would show just how much difference there really is.

First Impressions
Nikon has several generations of digital SLR designs under its belt and it shows with the D100. Like other mature designs such as the D1 series and Canon D series cameras; the D100 just feels right in your hands. It's well balanced and feels of a whole. If you've ever handled an SLR and a digital camera the D100 will immediately feel comfortable and you can start shooting with little preamble.

As captured

With Contrast Adjustment

Horsetail falls appear out of the porous cliff of Zion's canyons whenever there is heavy rain or snow.

Both cameras overexposed this scene, fooled by the mist and cloud hanging in the air. Either the auto contrast adjustment in Nikon's software or the auto contrast adjustment in Photoshop returned the color of the cliff's saturated, wet look.

The SD-9 by contrast feels big and blocky and a little bit awkward. It's not that the Sigma is badly designed. In fact it works quite well when you get acclimated to it. But that's just the point - you need a bit of time to get acclimated to it. Ergonomics are a difficult thing to quantify. When a design is "right" everything just seems to flow. The D100 is there. The Sigma is close, and we expect the next generation to be better, but that indescribable something in this first generation camera is just a hair off.

When you look through the viewfinder you notice another difference. The D100 has a traditional viewfinder providing 95% image coverage. The Sigma on the other hand shows you well over 100% of the image with its sports finder. Everything outside the capture area is darker but still visible. This can be an aid in composition but it can also be a distraction until you get used to it. It's just one more little way in which the Sigma is different. Whether this is good or bad is up to the individual. But in any case it doesn't take long to get used to these small differences.

The D100 is compatible with the new Write Acceleration cards (WA) from Lexar. The SD-9 is not. For an explanation of write acceleration and why you should care see Big Memory in last month's issue. Neither camera is currently compatible with Lexar's new 2 & 4GB memory cards.

In Use
Into my Lowepro Trekker backpack went both cameras and their respective lenses, an F100 as a reference camera, and a compliment of Nikon lenses. Then it was off into the heavy wet snow of Zion.

This added an unexpected component to the test - especially on our final day there. At one point three to four inches of heavy wet snow fell in a little over a half hour. Throughout the day the weather transitioned from snow to sleet to rain and back to wind driven snow. Temperatures swung with the storms and our location in the park. There was nothing you could do to really protect your gear short of putting it in an underwater housing. By the end of the day everything was thoroughly wet. Neither camera is advertised as a rugged, weather resistant pro body. But neither missed a beat due to the soaking, a commendable performance by both cameras.

One thing I particularly liked about the Sigma was its LCD. It was clear and bright and it's lower contrast and wider viewing angle made it the more useful tool for previewing images. Bigger LCD screens would be a welcome improvement on either of these cameras.

I mentioned the difference in ergonomics between the two. While I quickly dialed in to the Sigma I found that it's "different" feel translated into increased confidence in the Nikon. This was unfounded as both cameras were providing high quality images and handling well, yet whenever I was jumping out of the car or reaching into my pack to try and capture fast moving light I found myself reaching for the D100. I didn't even realize I'd been doing it until I started looking at images back in the hotel. Comfort equals confidence!

In use it felt as though the D100 focused a bit faster than the SD-9 (particularly in continuous focus mode), though the 20-40mm focal length of the only lens I had common to both bodies is a poor focal length to use for judging focusing speed. Bear in mind that there is a focal length multiplier with digital cameras. The D100's is 1.5x the SD-9's is 1.7x. I found that I've become accustomed to having multiple focus points and missed not having them on the SD-9.

Lens and Flash Compatibility
The D100 works will all current Nikon autofocus lenses and all previous Nikon and Nikon compatible AF lenses with a CPU (except the early F3AF lenses). It will function with manual Nikon lenses but the in-camera TTL meter will not. That gives you a range of focal lengths from 14mm to 600mm in the current Nikon line-up and from 8 to 800mm from 3rd party lens makers (Sigma). It is fully compatible with all DX flash units. Non-DX flash units will work with the D100 in manual (non-TTL flash) mode, and are still compatible with specialty modes such as repeating flash and rear curtain sync. Connection to a studio flash setup requires an AS-15 PC Sync Adapter.

The built-in flash on the D100 (GN17 @ ISO 200) works surprisingly well for fill flash and provides coverage of up to 20mm. Flash metering produced well exposed images.

The SD-9 uses the Sigma SA mount. That means you'll be buying all your lenses from Sigma. The good news is that Sigma makes lenses that range from 8mm to 800mm. The SD-9 is fully compatible with Sigma SA flash units and a PC Sync adapter (AX1000) is available for studio work. The SD-9 has no onboard flash.

The bottom line to all this is that the Sigma won't limit your capabilities in terms of lens focal lengths, flash capability or even your ability to take it into the studio. It will however limit your choices. There is a huge array of lenses available for the Nikon F-mount from both Nikon and third party manufacturers. In some cases those lenses may be of superior quality to what you can get from Sigma.

Batteries
One of the reasons that the SD-9 is larger and heavier is that its sporting two sets of batteries to the D100's one.

In the handgrip go two CR123's. In the base go your choice of 4 AA's or two CR-V3's. That's a lot of batteries. We don't know how much use the Sigma got prior to coming to us but the Olympus CR-V3's died when the temperature took a severe drop. Some spare rechargeables kept me going until I came down off the mountain. When they were used up I popped the CR-V3's back in and they again showed a full charge on the SD-9's battery indicator. The temperature was quite a bit warmer by then and those same CR-V3's continued to work without complaint for another day shooting in Las Vegas. But it made me wonder about battery life with the SD-9. That still remained an open question when I dropped the camera at Sigma's booth early the next morning and again left me wishing I'd had more time with the camera.

The D100 came to us brand new and I did the initial charge of the EN-EL3 battery pack before we left. Over 300 images later the camera was still working fine on the battery's initial charge. The cold weather in the mountains had no effect on the batteries. However, very few of those images used the camera's internal flash which would shorten battery life.

Work Flow
The D100 gives you a choice of JPEG, TIFF, or raw (NEF) formats when shooting, and many photographers shoot in JPEG for it's smaller image size and ease of use. The SD-9 shoots only in raw mode (X3F format). That means that you'll have to convert the file to JPEG or TIFF before you can work with it in Photoshop or any other image editor. If you always shoot in raw mode this is no big deal, but if you're accustomed to shooting JPEGs its an issue.

It's also an issue with archiving. Five or ten years from now it's likely that I'll still be able to read a JPEG file on almost any computer. I wouldn't bet on being able to read ANYONES proprietary data format five or ten years from now. Shoot in raw mode if you must, but if you're shooting for a living I'd think long and hard about doing batch conversions and backing up images in both formats.

The software provided with both cameras was easy to use, loaded without a hitch, and worked without a problem (this is not something we take for granted). A feature we really loved was the loupe feature in Sigma's software. It allows you to turn the mouse cursor into an onscreen loupe that you can move around the image vs. zooming in tight and scrolling around. This works so well we're hoping it becomes a standard (are you listening Adobe?).

Low Light
After dodging snow in the mountains Vegas seemed tame indeed and offered a chance to try out the cameras with some very different types of scenery. Foveon claims that its image capture chips are able to capture more accurate color information than competing chip designs but they have a narrow ISO range. How would the SD-9 perform in low light?


D100	SD-9
The D100 nailed this low light exposure in the lobby of the Luxor hotel. The SD-9 was unable to capture the image. Correct exposure 7 seconds @ f22 ISO 400

The entrance foyers of Las Vegas casinos are extravagant places and the Luxor's is no exception. But it was perfect for my purposes since their foyer has particularly dim light. I again shot with all three cameras including the F100 loaded with Provia as a benchmark.

As expected the Provia returned excellent results in terms of sharpness. Exposure was spot on, but the image had an excessively warm colorcast from the incandescent lighting that would have to be corrected on scanning. The D100 handled the long exposure with aplomb. The resulting image was sharp and held detail well. Noise, which looks like grain in a digital image was well controlled at both 200 and 400 ISO settings. White balance was manually set to incandescent which returned accurate colors. Digital has a definite edge over film in this situation.

The SD-9 was another story. I was unable to get a correctly exposed image no matter what the exposure time. Dialing in additional exposure compensation made seemingly no difference - even when cranked up to three full stops of overexposure !

The entrance to the casino is a difficult shot for point and shoot cameras, even for handheld SLRs because of the length of exposure. But for a tripod mounted SLR this shot should be a piece of cake (7 second exposure, f22 at ISO 400). It was only afterwards, reading through the manual that I found the SD-9 has an upper limit of 1 second at ISO 200 and 400. I could have switched to ISO 100 on the SD-9 which would have given me a 15 second exposure. But that still would have left me with an underexposed image (correct exposure in this situation being 28 seconds at ISO 100). Having to go to a lower ISO setting for low light conditions seems a bit counter intuitive to us.

The right light?

With good light the SD-9 can produce stunning results. Color reproduction was dead on in the image at left.

Below is a close-up of the Sphinx face at 100% resolution. The shot on the left is untouched. On the right is the same shot after sharpening and a slight adjustment to curves & levels. This is standard procedure with digital images to achieve the kind of depth you see in your slides.

SD-9, 20-40mm, 1/60th @ f22, ISO 100

It points out a difference in the working specs for these two cameras. The ISO range for the Sigma SD-9 is ISO 100, 200, and 400. For the Nikon D100 the range is a much wider ISO 200 to 1600 (with higher equivalent ISO settings available). While we're on the subject of ISO settings we were surprised at the amount of noise in the Sigma's images at ISO 400. There was a noticeable "grain" effect. At ISO 400 the D100 showed virtually no noise and at 1600 was still slightly cleaner than the Sigma at 400. Noise reduction was left off for these images.

Overall Image Quality
There is a bottom line here. If you're considering the SD-9 you're doing so because of the claims that Foveon has made for its image sensor. (for an overview of the Foveon image sensor technology see the article in this issue).

We shot images using both cameras from the same tripod through the same lens. When we got back to the office we scrutinized images from both in Photoshop and produced prints from both on an Epson printer to gauge the results. We produced prints directly from each cameras bundled software that were untouched and we produced prints from image files that were brought into Photoshop for sharpening and tweaking (such as contrast adjustments).

Both cameras produced excellent results though each has a quirk or two in it's metering. Both produced sharp images, though both benefited from a slight touch of unsharp masking in Photoshop. Tones and colors from both were smooth and we didn't detect any color artifacts in images from either camera at low ISO settings. Some red/purple artifacts showed up in the sky in a couple of shots from the SD-9 at ISO 400, but you had to be zoomed in very close, or be very close to a print before they were noticeable.

I don't know about you but I know for certain that I can't remember the exact colors and tones of a scene a day later (let alone two weeks later). So to determine color accuracy I went back to the images taken with the F100 and compared images from both cameras against the slides (which we know to reproduce accurate color). This is an area where Foveon claims an advantage because of their chip technology but the more accurate colors were actually recorded by the D100!

The real news is that the Sigma SD-9 and its Foveon chip did not blow away the D100 in terms of image quality. I'll say it again - both cameras produced excellent images. The caveat is that the SD-9 produces its best images at ISO 100. Noise picks up considerably at ISO 400 as well as some color fringing.

So why have I seen reviews that rave about the capabilities of the SD-9? I'm ashamed to admit it but if I hadn't shot the two cameras back to back I might have written a similar review. Open the image files from the SD-9 and your first reaction is "Wow!"

Though I hate to admit it even a dyed in the wool cynic like me was a little taken in by all the marketing hype. So when you see an image pop on the screen you're wowed because you're expecting to be wowed. The difference was that I had the D100 to do a direct comparison. Open up images from the D100 and your first reaction is "Wow!"

Then you start comparing the two. There are definite differences but both look great initially. Thankfully I had some of the same images captured on film in the same light. That allowed me a benchmark for color. The film, it should be noted, had more saturated colors, and a bit more contrast than either of the digital cameras.

Conclusion
Neither the Sigma SD-9 nor the Nikon D100 are "bargain" cameras ($1,500 & $1,700 respectively); and while the SD-9 might be $200 less initially you'll have the expense of buying SA mount lenses and a compatible flash (unless you already own a Sigma SLR). That said it's unlikely that many photographers will choose one of these cameras based solely on price.

Our test showed that both cameras were capable of producing high quality images. The compelling reason for purchasing the Sigma is the Foveon chip. In our side-to-side test we found that the Foveon chip didn't produce a noticeable advantage. Not only that but when you factor in the limitations shooting in low light the advantage is squarely with the Nikon.

In the end the D100 is our choice. We found it to be the more flexible of the two cameras, it supports a vast array of lenses, offers more flash choices, is more compact, lighter, better in low light and it just plain works well. Now if we could only get Nikon to bring the price down to $999!


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