Saturday, May 17, 2008

Canon PowerShot SD890 IS and SD850IS compared

Canon has released a lot of new cameras since my last post. Today I'll discuss the SD890, which appears to be an update to the SD850. Like it's predecessor, it has a 2.5" LCD, an optical viewfinder, and image stabilization. The Sd890's major improvement over the older camera is that it features a 5x optical zoom. That's the highest zoom I've heard of in a compact camera. Unfortunately, Canon did have to make the camera slightly larger in every dimension, at 3.8 x 2.3 x 1.1 in (vs 3.6 x 2.2 x 1 in. for the sd850). The SD850 is already about as big as I'm willing to carry around in a pocket, so for my money I'd go for the SD850 instead (which is only $240, vs $350 for the SD890). An interesting side note is that the SD850's price hasn't dropped much from when I bought it, 5 months ago, at $250.

The only other advantage to the SD890 is the shots (CPIA) per charge is better: 320 (vs 240). With the LCD off it goes up to 800!

So far I've only found one review. They found the ergonomics surprisingly poor: not easy to hold, and difficult to navigate between pictures. I hope to put my hands on on one soon, and post my own review. They also found that at the widest setting, the lens was rather distorted, and produced photos with blurry corners (see ttp:// Given the higher zoom of this lens, it's not surprising, and likely it's worse than for the SD850, though there are not enough sample pics out there to be able to judge this yet. The only real positive I found in this review is that the noise level at ISO 800 is notably better than on the SD850. That's at least something.

Oh, and did I mention that it's a 10 megapixel camera (up from 8MP on the SD850)? But who cares, these days, about the mega pixel rating?

Sunday, May 4, 2008

Innovating at the color filter level

As I've discussed before, the way your camera produces color images is by placing a color filter over what is essentially a monochrome sensor. The redness of a particular pixel, for instance, depends on how much light passed through the red filter above the nearest CCD element to that pixel. The big disadvantage is that the filter must discard a lot of the light entering the lens. I never thought about it before, but apparently there exist many different possible color filter layouts, with different advantages and disadvantages.
has some really nice examples of the possible trade-offs.

Hack your PowerShot camera's firmware

I just found this amazing website where several camera enthusiasts have figured out how to hack the firmware for the Canon PowerShot cameras (most cameras from the last few years are supported, and many recent models are supported). The hacks range from the mildly useful, such as live histograms, to the amazing, such as enabling 1/10,000th of a second exposures. Also particularly notable is the added ability to save pictures in RAW mode.

In particular, check out the high-speed photography pictures.

I'm going to try this out my SD850 soon. In the mean time, I encourage PowerShot owners to give it try, as the firmware hacks are non-destructive; you have to enable them each time you turn on the camera, so there's no risk to giving them a try.