With tiny, high pixel count chips noise is always going to be an issue, and to a large degree this is more a test of the effectiveness (both measurable and visible) of a camera's noise reduction system. Designers have to balance the desire to produce smooth, clean results with the need to retain as much detail as possible (if you blur away the noise, you blur away image detail too).
Like its predecessors the TZ5 has very low measurable noise at all ISO settings. Of course this is not the result of some superior sensor design but due to the application of strong noise reduction even at low sensitivities. Panasonic has slightly changed its noise reduction with this new TZ generation and the adoption of the Venus IV engine. While noise reduction is still strong compared to most of the competitors it is not as heavy-handed as it was on the TZ3. The result is a fairly soft image (although not as soft as the TZ3's output) that unfortunately even at base ISO shows a touch of noise. While this is acceptable for normal printing / viewing sizes from ISO 400 upwards the images start lacking a large proportion of fine detail and get visibly softer and noisier.
If the scenes you capture include a lot of fine detail and textures you're stuck with very small print sizes, the image quality is simply not good enough for anything bigger than postcard size. ISO 1600 is so noisy, blurry and full of artifacts that frankly I cannot see the point of even offering this setting.
Like its predecessor the TZ5 has a special 'high sensitivity' mode that offers higher than ISO 1600 sensitivity, but since it uses pixel binning the results are very, very low resolution, and have not been included in our test procedure.
|ISO 100||ISO 200||ISO 400||ISO 800||ISO 1600|
Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity is on the vertical axis. The graph indicates very low noise levels at all sensitivities, in fact black luminance noise even decreases from ISO 400 onwards. This of course has nothing to do with Panasonic's sensor but is all down to its in-camera noise reduction software which at higher ISOs generates soft, blurred images which are lacking most of the fine image detail. It's not significantly worse than most other compact cameras but we definitely have seen better results.
Low contrast detail
What the crops and graph don't show is the effect of noise reduction on low contrast fine detail such as hair, fur or foliage. An inevitable side effect of noise removal is that this kind of detail is also blurred or smeared, resulting in a loss of 'texture'. In this test the crops below show the effect of the noise reduction on such texture (hair) as you move up the ISO range.
|ISO 100||ISO 200||ISO 400|
|ISO 800||ISO 1600|
The detail blurring caused by noise reduction is pretty evident at ISO 100 already and only gets worse from there. At ISO 200 the smearing will be visible even in smaller prints and at ISOs higher than that our subject hair has been converted into an undistinguishable yellowish mess.
The smearing of fine detail is common to almost all compact cameras but the TZ5 (like its predecessors) is located towards the worse end of the spectrum. If fine details and textures are important in your images you should really stick to base ISO, otherwise you won't be happy with your results. High ISO output is good enough for the occasional party picture but certainly not for any type of serious photography.