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Canon EOS-1D Canon leaps into the professional SLR arena, with the fastest digital SLR on the planet! Select a topic Reference: Datasheet --------------------------------- 1. Overview 2. Specifications 3. Spec Comparison 4. Features: Speed 5. Features: Image Quality 6. Features: General 7. Features: Color 8. Features: Ruggedness 9. Operating Details 10. Summary --------------------------------- Print-Friendly Review Version Additional Resources and Other Links Reader Comments on EOS-1D Review --------------------------------- Digital Camera Comparometer (TM) --------------------------------- <-- Digital Cameras (Home) <-- Digital Camera Reviews Index <<Features: Speed :(Previous) | (Next): Features: General>> Page 5:Features: Image Quality Review First Posted: 09/24/2001

Features: Image Quality

In talking about the EOS-1D, Canon also touts several features and design elements relating to image quality. In this section, we'll discuss a couple of these, relating to resolution and image noise, leaving color-related issues for a later section.

Large Sensor
One of the first things that leaps out of the EOS-1D's specs is the unusually low focal length multiplier of 1.3 (It's actually closer to 1.25, we're not sure why Canon chose to round it up to 1.3 in their literature.) At 28.7 x 19.1 millimeters, the CCD in the EOS-1D is a good bit larger than most. Spreading its roughly four million pixels out across that area results in a pixel size of 11.5 microns. This is larger than most current pro digicams, which should translate into lower noise levels than those found in some of the competition. We'll definitely have to wait to see a test sample though, since there are a lot of factors that can affect noise apart from the pixel size. (By way of example, Nikon completely surprised us by reducing the noise in the D1x relative to that of the earlier D1, while simultaneously cutting the pixel size in half.) Canon seems to have learned a lot about noise reduction in their consumer digicam line over the past year, and we're told that all of that technology will appear in the EOS-1D as well.

Noise Reduction
Speaking of noise reduction, the specs from Canon indicate that the EOS-1D will (optionally) use dark-frame subtraction to reduce fixed-pattern noise from the CCD for any exposures longer than 1/15-second. (Dark-frame subtraction is a technique whereby a second "exposure" is taken immediately following the photograph of the subject, only with the shutter closed. This basically produces a "picture" of the fixed-pattern noise of the sensor. Subtracting this noise pattern from the just-captured photo of the subject can dramatically reduce noise levels in the final image.) We find this interesting, because we've only seen dark-frame subtraction applied to much longer exposures in the past. Most manufacturers using this technique generally only apply it to exposures longer of one second and longer. The fact that Canon is choosing to apply it to exposures as short as 1/15-second implies to us that the random noise of their sensor and signal-processing chain is very low indeed. Again, we'll have to wait until we can get a sample of the EOS-1D into our lab, but our reading between the lines of Canon's specs and marketing literature leads us to expect great things from the 1D in the noise arena.

No CMOS?
One of the biggest surprises in the EOS-1D is that Canon abandoned the CMOS sensor technology that was so successful in the EOS-D30. The reason apparently has to do with speed. There was simply no way Canon could get the image data off a four-megapixel CMOS array fast enough to keep up with an eight frames-per-second frame rate. It'll be very interesting to see what the EOS-1D's images look like, because one of the hallmark characteristics of the EOS-D30's images was their exceptional smoothness, and almost total lack of noise. (Apparently a result of Canon's active-pixel CMOS technology.)

New approach to low-pass filtering
A persistent bugaboo in digital camera design is the need for an optical "low pass filter" between the camera lens and the sensor. These filters blur the image slightly, to prevent too-abrupt brightness transitions from creating color artifacts in the final image. (To understand, consider this simplified explanation. Individual Red, Green, and Blue sensor pixels are used to make up the final, full-color image pixels. If a sharp white/black transition occurred on the image such that the red and green pixels of a trio were illuminated, but the corresponding blue pixel was not, the camera would think it was seeing a bright yellow pixel, rather than the intermediate gray that should result from a transition between black and white.) Once color artifacts like this appear in the final image, they're very difficult to get rid of in software without also compromising fine image detail. The problem though, is that the low pass filters frequently produce visibly soft images, effectively throwing away some of the potential resolution of the sensor.

Some manufacturers (Kodak) have taken the approach of making the low pass filters removable, allowing the user to remove them (replacing them with a simple IR filter) if they want. This is a risky proposition though, potentially exposing the sensor to dirt and damage when the filter is changed.

With the EOS-1D, Canon claims to be taking a slightly different approach, combining a weaker optical low pass filter with new image-processing algorithms to reduce the impact of color aliasing. We admit we're a little skeptical about this, since it's axiomatic that once bad data (aliasing) has crept into your image information, there's little you can do to get rid of it. (At least, without also risking throwing away part of the image information as well.) Again, we'll see what we see when we get a test unit in our lab, but Canon seems to think they have something up their corporate sleeves in this area. Stay tuned...