MIZZI Computer Software

Noise comparison between a DLSR and a Super-Zoom-Digicam

    

There is a long discussion about noise of DSLR versus Super-Zoom-Digicam. Let me compare now two of them. To make a fair comparison we should compare two models with nearly the same size. So I use a semi-professional DSLR Canon EOS 300D with 6 megapixel detector and the standard kit zoom lens (18-55mm,f/3.5-5.6) and one of the most popular super-zooms from Panasonic FZ-20 with a 5 megapixel detector and a fixed mounted lens (6-72mm,f/2.8).

For the comparison we had used a printed version of a simple test sheet shown below and all shots were taken at the same light and the same distance from the object. The zoom factor was nearly the same for both cameras and was about 80mm (35mm equivalence). In this situation the smallest aperture number was for the 300D f/5.6 and for the FZ-20 f/2.8. Also note that due to the much smaller detector of the FZ-20 the depth of sharpness is for both cameras nearly the same at the smallest aperture number. Also we make the shot under tungsten conditions because this is most often a problem when having low light and we use tungsten white balance in both cameras. Please do not compare the colors in this test. The difference arises form the different white balance of both cameras and are not an indicator for the quality of the picture.

But let me show the test sheet first....

click to enlarge it

Then we make a macro shot (FZ-20) of the region we compare. You may click to it to the get the full resolution of the inkjet printout and you can see the resolution of the inkjet printer very well. However in this test you will see that the resolution of the cameras is much lower than the quality of the printout.

FZ20
f/5.6,
1/15 sec,
ISO 80

Now let us discuss the noise and quality when using the cameras at low light. To make our shot we use an aperture that the depth of sharpness is the same for both cameras and we want to make the shot with the same exposure time. So we use for 1/100 sec for both and as aperture f/2.8 for the FZ-20 and f/5.6 for the 300D. Because now the FZ-20 gets about for times more light than the 300D we must use ISO 400 for the 300D and ISO 100 for the FZ-20 to produce the same brightness at the image. However the original images of the FZ-20 are a bit darker so we increased the brightness by a computer program by 15%. To make the images the same size we had scaled the 300D images down by 10% because the 300D has a slightly higher resolution (6 megapixel) than the FZ-20 (5 megapixel). All these effects are not really tremendous. There are done for a better comparison only. You can click to the images to get the original version of the total images. But now compare the results.

FZ20,
f/2.8,
1/100 sec,
ISO 100
300D,
f/5.6,
1/100 sec,
ISO 400

You see that the images have a much lower resolution than our orginal printout but both cameras produce nearly the same results in noise and sharpness. The 300D seem a bit more blurry but also shows slightly lower noise. You can click to the images to get the uncorrected images for both cameras but note that the jpeg files had been limited to 1MB size. So you miss the EXIF information in these images.

Now let us compare the shots at lower exposure times and higher ISO sensitivity. We use a 1/400 sec for both and an aperture f/2.8 for the FZ-20 and f/5.6 for the 300D. Using the same light now we increase both ISO values. ISO 400 for the FZ-20 and ISO 1600 for the 300D.

FZ20,
f/2.8,
1/400 sec,
ISO 400
300D,
f/5.6,
1/400 sec,
ISO 1600

Also in this example both cameras show nearly the same result. The 300D seem a bit more blurry but also shows slightly lower noise.

At this point it seems that noise is nearly the same for both cameras, but this is not really true. We should discuss the cameras in situations when light is not the problem and we can use the 300D at ISO 100. So we make our shot at the lowest ISO value available for both cameras. This is ISO 80 for the FZ-20 and ISO 100 for the 300D. The 300D now uses 3 times longer exposure time. These are the results ....

FZ20,
f/2.8,
1/80 sec,
ISO 80
300D,
f/5.6,
1/25 sec,
ISO 100

Also the sharpness seems not to be higher for the 300D the overall performance is much better for the 300D than for the FZ-20. The noise is much less, the letters and numbers are clear and without any blemish.

However we can now apply our noise filters to the images and see what the effect is.

FZ20,
f/2.8,
1/80 sec,
ISO 80,
noise reduction level 1
300D,
f/5.6,
1/25 sec,
ISO 100,
noise reduction level 1

The 300D is a bit more blurry but with a little bit less noise. But over all the images are marginal different.

Conclusions

The comparison shows that it is not the question how good your sensor performs rather than what is the best combination of sensor size and lens. Clearly a big sensor needs a big lens. If the lens has the same size the light reaching the sensor is the same for a camera with big or a small sensor. Noise results always from not having enough light. It depends on the number of photons which hit the detector only and this is the reason why under low light conditions the front diameter of the lens is the determining factor only.

Clearly the 300D produces better results under bright conditions, but what we have compared is still rather unfair. The 300D with a kit lens of 28-90mm/f3.5-5.6 (35mm equiv) costs 1000$, weights 1 kg, the zoom has a factor of 3. The FZ20 has 35-430mm/f2.8 (35mm equiv) costs 600$, weights 500g and the impressive zoom has a factor of 12 with an unbelievable aperture of f/2.8, and an optical image stabilizer which lets you extend the exposure times to ranges a 300D user only dreams from.

What we have learned too: noise reduction is very important for small sensor cameras. It should be applied not only to images captured with ISO 400 rather than all images down to ISO 100 will be improved if using small sensor cameras. If you need a zoom up to 400mm (35mm equiv.) and you don't want a heavy weighted camera the only way out is to buy a FZ-20 or a similar one because this cameras have a nearly perfect very small sensor and a big lens in front of it!