Question regarding sensors

[Tuffcookie]

I currently have the Canon S5 IS. In the specifications it lists a 1/2,5" type CCD sensor.

The one for the Canon SX20IS, which I'm thinking about upgrading to, lists a 1/2,3" type CCD sensor.

What do these numbers mean????

TC

 

[disneyboy2003]

I currently have the Canon S5 IS. In the specifications it lists a 1/2,5" type CCD sensor.

The one for the Canon SX20IS, which I'm thinking about upgrading to, lists a 1/2,3" type CCD sensor.

What do these numbers mean????

TC

A couple things about 1/2,5". First, I believe that Europeans use commas instead of decimals, so I have a feeling that 1/2,5" actually means 1/2.5" in American terms.

Second, 1/2.5" is a fraction, just like 1/2 is a fraction. 1/2.5 is somewhere between 1/2 and 1/3. If you divide it out, 1/2.5 = 0.4.

Similarly, 1/2.3 = 0.435.

Third, 1/2.5" describes a length in inches. In this case, it's 0.4 inches.

These numbers almost indicate the diameter of the camera's sensor (not quite, but very close). So when you upgrade to the 1/2.3" sensor, you're gaining about 0.035 inches in sensor diameter!

In comparison, many crop-frame DSLRs have approximately 1.8" sensor (that's 4.5x longer in diameter!).

Here's a link that describes sensor sizes: http://www.dpreview.com/learn/?/key=sensor%20sizes

Hope I got all the technical information right. Please feel free to correct me if I'm wrong.

 

[Groucho]

A smaller number means a bigger sensor (since it's a fraction) - and the reason that you want a bigger sensor is for larger photosites, those little points that capture the actual pixels that make up your photo.

If you compare two cameras, both 10 mp, one with a 1/2.5" sensor and one with a 1/2.35" sensor, the latter one will have larger photosites. That should buy you more sharpness and better low-light performance (since each photosite can gather more light.)

However, this is often negated by increased megapixel numbers. The bigger sensor isn't such a big advantage if you are stuffing more photosites on the sensor. The ideal setup is a larger sensor with lower megapixel numbers.

There are other factors, too - some sensors are better overall than others, and point-n-shoot cameras often rely heavily on in-camera processing of the photo (especially low-light photos) to get acceptable results. So you can't automatically say that one will always be better than another. By and large though, you want a bigger sensor.

Here's a graphic I made a while ago to illustrate the relative sizes. There's no 1/2.35" one, but 1/1.8" is there and that is often found in some nicer PnS cameras.