Canon Legria HF S21

Low Light Sensitivity (4.96)

The HF S21 did a decent job in our sensitivity test. The HF S21 needed 13 lux of light to produce a viable image (50 IRE on our waveform monitor), which is slightly worse than the 12 lux required by the HF S100 last year. Now, the performance by the HF S21 isn't anything spectacular—we'd really like to see a sensitivity result below 10 lux—but it does represent an improvement for Canon. (More on how we test low light sensitivity.)
 

Required Illumination *

* the lower the lux required, the better the performance

In addition to testing the HF S21's low light sensitivity in auto mode, we also tested it using the camcorder's alternate frame rate. With the lower frame rates the camcorder uses a slower shutter speed, which often results in an improved sensitivity. The sensitivity on the HF S21 was much better when using the PF25 mode. Check out the table below for the full set of results.
 

Low Light Colour (6.55)

There wasn't anything special about the HF S21's low light colour performance. The camcorder had  a lackluster colour error of 5.59 and a saturation level of 65.13%. These numbers are on par with the HF S100, but we were hoping Canon had improved things for 2010. Based on our tests, however, they didn't.  (More on how we test low light colour.)
 

Auto Low Light Colour Performance
Colour Test Chart (above), Colour Error Map (right)
The Canon HF S21 produced a colour error of 5.59 and a saturation level of 65.13% in our low light colour testing. (The map on the right is a diagram of the colour error. The length and direction of each line indicates how the camcorder processed each particular colour.)

Like last year, the Canon HF S21 produced a fairly dark image in our low light testing. However, its colours still looked strong, despite the darkness of the overall image. In the comparisons below you can see that the Panasonic HDC-TM JVC GZ-HM1 captured a brighter image, but its colours don't look as vivid as what the HF S21 produced.

Low Light Comparison
Canon HF S21	Panasonic HDC-TM700
JVC GZ-HM1	Canon HF S100

Low Light Colour Across Frame Rates

If you want to improve low light performance you can always shoot with the alternate frame rate. The chart above shows the colour error and saturation levels we measured when using the camcorder's two frame rate options: 50i, and PF25. Below, you can see actual comparison images for each frame rate option on the HF S21. Notice how much brighter the image is when shooting with PF25.  

Canon HF S21 Frame Rate Comparisons (Low Light)
Canon HF S21 50i Frame Rate	Canon HF S21 PF25 Frame Rate

Low Light Colour Score Comparison		Compare the Canon HF S21 to the Panasonic HDC-TM700
		Compare the Canon HF S21 to the JVC GZ-HM1
		Compare the Canon HF S21 to the Canon HF S100

Low Light Noise (6.05)

The Canon HF S21 averaged 1.99% noise in our low light test, which is more noise than most high-end HD models measure in this test. You can actually see the noise in the crops below, although we should point out that the HF S21 did retain a lot of sharpness in low light despite its elevated noise levels. (More on how we test low light noise.)
 

Noise at 60 lux Auto
Canon HF S21 100% Crop	Panasonic HDC-TM700 100% Crop	JVC GZ-HM1 100% Crop	Canon HF S100 100% Crop

The Panasonic HDC-TM700 measured the least amount of noise in this test, and its image was also sharper and crisper than the Canon HF S21 or Canon HF S100. You can also see some of the fine specks of noise in the 100% crop image above from the Canon HF S21 (look at the vertical trumpet). As we saw with our low light colour test, the Canon HF S21 performed much better when shooting with its alternate frame rate. The images below tell this story, but the hard number is 1.1% noise.

Canon HF S21 at 60 lux Auto: Alternate Frame Rate
Canon HF S21, 50i 100% Crop	Canon HF S21, PF25 100% Crop

Low Light Noise Score Comparison		Compare the Canon HF S21 to the Panasonic HDC-TM700
		Compare the Canon HF S21 to the JVC GZ-HM1
		Compare the Canon HF S21 to the Canon HF S100

If you come away with anything from these low light tests it should be this: the Canon HF S21 is a decent low light camcorder in auto mode, but an excellent low light performer when shooting with its alternate frame rate. The camcorder measured better colour accuracy, less noise, and stronger sensitivity when shooting in 25p.