So long Compact flash: a new camera

re: So long Compact flash: a new camera

Melissa — Thu, 06 Sep 2007 08:13:10 GMT

You say "More pixels in a smaller area and higher ISO rating and higher ISO rating mean Canon need to be aggressive with noise reduction".

I'm also not sure I follow your logic about sensor size. I'd have said that, all other things being equal, the same amount of light falls on the sensor, regardless of its size. Visualize the cone of light coming from the lens -- if you replace the sensor with one 2/3 the size, you'd put it closer to the lens not keep it where the old one was. Thus, it doesn't need to be *much* better at all, it just needs to get the same performance out of CCD elements that are 2/3 the size. In five years of advances, it is quite reasonable to assume that that is quite possible.

Also, although I don't follow these things closely, but I seem to recall that Canon is one of the least aggressive brands w.r.t. noise reduction. Obviously, high ISO settings will be grainy, but then so is high-ISO film.

I don't see a review on my usual source, dpreview.com, but dcresource writes:

"The PowerShot A570 has the kind of image quality one expects from Canon: very good. It took well-exposed photos, with accurate, saturated colors. Photos have a smooth look to them which is more common [for] digital SLRs than compact point-and-shoots. As the tests above showed, noise levels in good lighting are quite low, even at ISO 400. Purple fringing was minimal."

In other words, no actual problems.

Anyway, it sounds like a nice enough Camera to me, so congratuations on buying it -- even if you do seem to think it's only good enough to be your back-up/risk-zone camera.

Have fun on your next dive...

re: So long Compact flash: a new camera

jamesone — Thu, 06 Sep 2007 10:16:18 GMT

If the pixels are smaller (and more Pixels in a smaller area means they are) less light falls on each one.

If the sensor is smaller you DO move it closer to the lens. However the lens apperture is expressed as size of the hole relative to focal length, hence "f over ...". So an f/4 lens will deliver the same amount of light to a tiny digital sensor or a 10x8 plate camera: with ISO 100 film and the lens at f/4 uses the same shutter speed as a digi set to ISO 100 and its lens at f/4

If the Pixels are smaller the voltage you get for the light arriving is smaller. (Unless you can increase what sensor makers call quantum efficiancy). Getting high ISO means turning up the gain, and that means more intrusive noise. New sensors are more efficiant, and do have lower background noise, but as someone once said "you cannye change the laws of physics".

Getting decent output from them at high ISO depends on NR, and it has to be pretty agressive. Whether canon are a bit more or a bit less agressive than the others I can't say. That was meant to be {The manufacturer} not Canon-in-particular.

The test shots I've done show that *if I pixel peep* I can find noise reduction artifacts even at low ISO. And as Dcresource is right that the picures looked smooth with low noise. That smoothness is actually a loss of detail: but there is more than enough detail in these shots for any size print I'm likely to want from this camera. It's not just a "Risk zone" camera. It's also the "I need a small camera to take on this trip" camera. And my SLR isn't just "I need the last drop of quality and or interchangable lenses". A compact is a better proposition underwater - power zoom and LCD viewfinder see to that. If someone gave me the SLR housing (and insurance against flooding) I still would prefer a compact.

The point was really that you can't sell a 4MP camera any more - but the thing that makes a modern 7MP camera ISN'T the greater number of pixels. It's everything else. The same is true of my new SLR. The fact it has 10MP and the old one had 6 is the least significant improvement. In both cases the cameras are a lot better - the technical quality of the image they make is only a small part of that - the important question on a camera is "Will this camera help me get more pictures which are good", not "Will this camera improve the resolution of my images".

USB Battery

James O'Neill's blog — Fri, 14 Dec 2007 21:57:42 GMT

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