25 April

I recently had a look at the new Canon Powershot SD890 IS digital camera. It is part of Canon's ELPH line, and also known as the IXUS SD890.

It has one impressive feature: a 5x optical zoom. This is a higher zoom factor than any prior camera in the ELPH line, which I favor due to their small size and generally good quality. It has image stabilization as well, which is nice, but isn't really that significant in practice, I find (see below). I also use them for some sensing projects, and they can be partially computer controlled, which is a benefit.

The SD890, however, seems to suffer from a noisy CCD. In comparison with the slightly older SD900 (superseded by the SD950), I found the 890 to be disappointing. A series of comparisons photos is provided below.
In all the image pairs, the results from the SD890 are given on the left side, the SD900 on the right.

I often take pictures of documents, using my camera as a hand-help
quickie scanner, a selected such a scene as a good test. Shown below
is a photo of a paper document. No flash was used (in general, a flash produces far too much glare in such cases anyhow). Notice how blurred
the image from the sd890 (on the left) is, but worse yet, observe the color speckles on the white surface. I this is a case of "Bayer noise".

SD890 looks much worse than the older SD900
Paper document, significant zoom, major color artifacts from SD890 (on left).

Here is my son's face in a not-well-lit room. Notice the awful color
variations due to thermal noise on the CCD array (on the left). I almost wrapped the SD890 up and returned it to the box then and there, when I saw this.

SD890 looks much worse than the older SD900
SD890: left. SD900: right. Dim scene, blotchy colors.

Here is a case where the SD890 shines. A well-lit scene that I zoomed in on to an extreme degree, and then digitally zoomed as well. With the SD890 you can almost read the writing on the cables, which are just a blur for the SD900.

SD890 lets us really zoom in.
Great zoom with the SD890. Image stabilization probably was a helpful factor here.

The SD890 does seems to do nicely with respect to color balance and
sharpness. It's a tie between the two cameras, who knows which set of colors is correct? Here's a whole image, shrunken to fit.

Full scene, good color from sd890

How about a couple more examples, before we conclude?

Now I zoomed in (to the same scene shown) above as much as possible, and adjusted both images so the
physical object was the same size. That means the image on the
left is digitally zoomed less, because it was optically magnified more
before being recorded.
The sd890 wins here. This was taken standing on the balcony holding both cameras at once, yet I don't see
much benefit from the image stabilization.

Zoomed content

Here both images have been resized by the same factor to see the actual pixel
quality. What do you think?

Both images zoomed the same amount

And finally, one more try at writing on white paper, this time under daylight illumination. I even tried manually adjusting the color balance for the SD890. We're pretty brutally digitally zoomed into both images here.

Writing on white paper under daylight illumination.

All in all, it's a very mixed performance. It's not clear from these tests that the SD890 is really worth getting, since the noise problems are so severe.

By Gregory Dudek at | Leave a comment |    
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