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Color reproduction

Here you can see a generated GretagMacbeth ColorChecker chart, place your mouse over any of the labels below it to see the color reproduction in that mode. Select a camera/setting combination from the 'Compared to' drop-down to see comparative boxes inside each patch.

Unsurprisingly the EOS 50D delivered an almost identical color response to the EOS 40D and EOS 450D. Canon's standardized Picture Style's mean that going from one Canon SLR to another you don't need to accustom yourself with a different rendition of color.

Canon EOS 50D Compare to:  
      
      
      
      
StandardPortraitLandscapeNatural
FaithfulMonochromeAdobe RGB

Artificial light White Balance

No news at the white balance front. The 50D is as bad at automatic white balance in artificial light as its predecessors. The presets aren't great either. So if you want white whites indoors or in any mixed light situation you will almost definitely need to take a manual preset or use the Kelvin temperature option.

Something else that was mentioned in previous Canon DSLR reviews is the 'Now select manual white balance' message you are presented after taking a manual white balance reading (assuming you're not already in manual white balance). Simply switching the camera to manual white balance would remove a (rather unnecessary) step for the user.

Incandescent - Auto WB
Red: 12.7%, Blue: -15.3%, Poor
Incandescent - Incandescent preset WB
Red: 9.0%, Blue: -8.9%, Average
Fluorescent - Auto WB
Red: 7.1%, Blue: -9.2%, Average
Fluorescent - Fluorescent preset WB
Red: 7.5%, Blue: -3.2%, Average

Long Exposure noise reduction / Night shots

Our usual 30 second exposure test produced no hot pixels from the EOS 50D, so the optional long exposure noise reduction option (dark frame subtraction using an equal exposure with the shutter closed) made no difference here.

Noise reduction Off Noise reduction On
ISO 100, 30 sec, F13 ISO 100, 30 sec, F13
(Brightness boosted by 50% in these crops)

Flash

Overall the EOS 50D's internal flash performs well without any color balance issues or metering issues.

Highlight tone priority

The EOS 50D features the same 'Highlight tone priority' option as the 40D. It is activated by C.Fn II-3 and according to the user manual "Improves the highlight detail." We have already examined the effect of this option on Dynamic Range, below is a fairly good example of the difference enabling Highlight tone priority has on a real life shot. We exposed both shots to get some detail on the brickwork of the dark tunnel. Naturally this results in an overexposure of the buildings you can see outside. As you can see in the crops Highlight Tone Priority managed to retain some highlight detail that would otherwise have been lost, the effect is fairly subtle though.

Highlight tone priority off Highlight tone priority on
ISO 200, 1/25 sec, F4 ISO 200, 1/25 sec, F4 (Highlight tone priority)

Vignetting & Light Falloff

Vignetting and light falloff aren't something we would normally test in our digital SLR reviews, primarily because cropped sensor digital SLR's and don't exhibit much falloff. However, the EOS 50D is the first Canon APS-C DSLR to come with a 'Peripheral Illumination Correction' function, so we thought we should have a closer look at this feature. When enabled this function corrects vignetting in JPEG images. On RAW images you can do the same thing using Digital Photo Pro.

Technically vignetting refers to a darkening of the corners of the frame due to a physical obstruction such as the rim of the lens barrel or a filter, light falloff refers to a reduction in the amount of light reaching the far corners of the frame due to the angle of incidence of the light reaching there. Light falloff is sometimes referred to as cos4 vignetting. In this section of the review we will refer to this effect as falloff for simplicity (and more likely accuracy) however it could well be either or both vignetting / light falloff.

When enabled Peripheral Illumination Correction corrects vignetting in JPEG images. On RAW images you can do the same thing using Digital Photo Pro. The camera detects the lens attached and applies the adequate amount of correction. According to the manual the 50D can detect 20 lenses but you can add data for further lenses through the EOS Utility software.

Testing


Measurement Areas
We aim the camera at a white wall (about 0.5 m away) which is evenly lit by two soft boxes (producing about 10 EV across the entire wall), and a heavy diffuser placed over the front of the lens. For this test we then took a sequence of shots at maximum aperture and at different Vignetting Control settings.

These images are then processed by our own analysis software which derives an average luminance (Lum) for the four corners of the frame (5% each) as well as the center (10%), the corners are averaged and the difference between this and the center of the frame is recorded. This value can then be plotted (see graphs below) as a representation of the approximate amount of falloff.

Hence falloff of -30% would mean that if the luminance center of the frame was at exactly 100% (pure white) the average luminance of the corners would be 70%. Anything more than -20% may well be visible in everyday shots, although this depends on the framing of the shot and the exposure.

Range of falloff

The chart below demonstrates the difference that these figures above can make, we took the blank wall luminance value of 75 (about 190,190,190 RGB) as our normal level. Remember that these patches are solid and the actual effect of shading is a softer gradual roll-off which would never be so obvious. The thumbnails are created by breaking the fall off into the same bands for clarity, so the same comment applies to them.

Vignetting Correction test results

As mentioned above vignetting is not usually a massive problem on crop DSLRs but at wide angles and large apertures it might become visible in your pictures. The results below illustrate that the Peripheral Illumination Feature Works near-perfectly, eliminating almost all corner-shading in JPG images. It works just slightly conservatively, leaving behind about 1/3 stop falloff. This is presumably to avoid over-correcting. More correction can be applied in Digital Photo Pro if needed.

Vignetting Correction Settings thumbnails for Canon EFS 17-55 F2.8

 
Peripheral Illumination Correction
Disabled
Peripheral Illumination Correction
Enabled

@
17mm
F2.8

@
17mm
F8

@
55mm
F2.8

@
55mm
F8

Overall Image Quality / Specifics

The EOS 50D is the latest incarnation of a product line that has always reliably delivered on image quality and you won't find any nasty surprises in this review either. The 50D delivers a lot of detail and clean images with well balanced contrast and colors that leave some latitude for 'customization' in post processing. Canon's standard-across-the-range Picture Style tone and color combination also produce consistent performance between models, which is useful if you're moving up from a 'smaller' model.

Having said that, in terms of detail the 50D is not quite the step up from the 40D that we would have expected. After all the new model's nominal resolution has increased by approximately 22% in both dimensions. There is only a very small amount of extra detail in the 50D output though (in fact even at 100%, if you scale the 40D's output up to match the 50D the results are almost indistinguishable). While the new sensor makes the 50D the highest megapixel APS-C DSLR currently on the market it also makes it the one with the highest pixel density and it appears that Canon has reached the limit of what is sensible, in terms of megapixels, on an APS-C sensor (using current technology). At a pixel density of 4.5 MP/cm² (40D: 3.1 MP/cm², 1Ds MkIII: 2.4 MP/cm²) the lens becomes the limiting factor. Even the sharpest primes at optimal apertures cannot (at least on the edges of the frame) satisfy the 15.1 megapixel sensor's hunger for resolution. The result is images that look comparatively soft at a pixel level and only show marginally more detail than images from a good ten or twelve megapixel DSLR. If all you end up with is a larger image (and file) one starts to wonder what the whole point of pushing the resolution up to these dizzying heights is.

Considering the disadvantages that come with higher pixel densities such as diffraction issues, increased sensitivity towards camera shake, reduced high ISO performance and the need to store, move and process larger amounts of data, one could be forgiven for coming to the conclusion that at this point the megapixel race should probably stop.

Just to make it clear, the 50D's image quality is (at identical viewing size) and by no means worse than the competition's but it's also not significantly better than the 40D's (Dynamic range and high ISO performance are even slightly worse) and that simply makes one wonder if the EOS 50D would have been an (even) better camera if its sensor had a slightly more moderate resolution.

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