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Old Dec 11, 2005, 7:29 PM   #1
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I'm looking for a subcompact that's really small and light as it will be mainly in my pocket whilst snowboarding; my Olympus D580Z is just too heavy and bulky for this. However I also want more than the usual 3x optical zoom. I've always felt limited by it as I often can't get close enough to the subject.

So ideally I want something like the Canon PowerShot SD450 (Digital Ixus 55) but with better zoom, weighing a max of 160g. I'm pretty sure this camera doesn't exist yet, so I was wondering if a camera with more megapixels can offset the lack of a 4x or 5x optical zoom. I have no idea about the technicalities of this, so sorry if it sounds stupid, but if for example I'm forced to use the digital zoom on top of the optical to get a good shot, will the resulting image or video be significantly better on a 7mp than a 5mp camera? In other words, if I'm stuck with 3x optical, will extra megapixels make a digitally zoomed shot higher quality?

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Old Dec 11, 2005, 8:06 PM   #2
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Generally more megapixels means you have a larger file to work with.

Rather than digitally zooming, your better off to "crop" the photo afterwards using photo software.

You could probably crop half the image away, and still have a print that makes a good 8x10.

You can overcome the difference between a 3x zoom and a 4x zoom by using your feet to get closer to your subject.

-- Terry


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Old Dec 11, 2005, 9:55 PM   #3
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The Pentax Optio SV is fairly small (150g), has 5MP, and 5X zoom. It's not super-slim but I'd say it qualifies as pocket-size.

As for the resolution thing: Sure, if you crop a high-megapixel image, then the crop will have fewer pixels (be a smaller area), but if you started out with a lot of megapixels to begin with, then the crop might still be quite high-resolution. However:

1) Cropping by a certain factor will reduce the area, and thus the pixel count, by the square of that factor. So cropping an 8MP image and taking the middle half (if you imagine a grid of 16 rectangles, 4x4, then I'm talking about cutting out the "edge" 12 rectangles and keeping the middle 4) will leave you with a two-megapixel image. This is why a few more "X" of optical zoom usually gives much better image quality than cropping by that amount, even in a high-megapixel camera.

(The pixel number in the cropped area goes down real fast as you crop in. For example, take a 5-megapixel camera with 6X zoom. For another camera, one with 3X zoom, to produce images that could be cropped to look like 6X zoom images and still have 5 megapixels, then that other camera would need to have 20 megapixels).

2) When you crop, the grain/noise becomes more evident. Since the pixel density of higher-megapixel cameras tends to be higher, this grain tends to be worse, so a two-megapixel crop from a five-megapixel image will usually look a lot worse (more noisy/grainy) than an image taken with a camera that has a maximum resolution of two megapixels. This is especially true in compact cameras. So even if you COULD crop and keep a high resolution, it would look worse than having that resolution as your camera's maxiomum. You can see this demonstrated (with examples) at

http://www.airshowfan.com/guide-to-d...eras.htm#grain

So the Optio SV would be my recommendation (or something else with good optical zoom), so that you don't have to crop significantly, if you can avoid it. The Casio P505 and the Panasonic LZ2 both have a lot of zoom and are not huge, so those are two others to check out.

(And of course I crop most of the shots that I like, in order to adjust the composition a bit and so on. But I never crop out more than 1/4 of each edge, which means the area never goes below 50% of the original area. Even that looks pretty bad - I try to not crop out any more than 10% of each edge if I can help it at all).
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Old Dec 12, 2005, 8:41 AM   #4
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excellent advice there, and I'll be sure to read the guide.

I forgot to mention that a high quality movie mode is a very important factor for me, due to the type of action you get on a ski slope, so I'm also hoping for a camera with 640x480 @ 30fps movies. Looks like I can't have it all!

So just in terms of shooting video when I can't get close to the subject, would I be better off with the SD450 (640x480 @ 30fps and a 3x optical zoom), or something with 320x240 @ 30fps and a 5x- 7x optical zoom?

(It's a shame the Konica Minolta Dimage X1 is only 20fps, as that can optically zoom during filming and is also a subcompact.)

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Old Dec 12, 2005, 10:29 AM   #5
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cragside wrote:
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(It's a shame the Konica Minolta Dimage X1 is only 20fps, as that can optically zoom during filming and is also a subcompact.)

Just a reminder -- when you go to the movies and watch Star Wars on the big screen, the movie is being shown at 20 fps. Don't get caught up in spcsmanship. You may very well find 20 fps perfectly appropriate. The big "gotcha" might be if you're showing your movie on a television, where it has to contend with interlacing and a 30 fps rate that would make the 20 fps, noninterlaced video a bad fit for the display medium. But, on a computer screen, 20 fps should be every bit as good as faster rates for just about everything you can imagine.
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Old Dec 12, 2005, 5:32 PM   #6
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I downloaded a sample 20fps clip and it was pretty poor quality, but I suppose that could have been due to aggressive compression.
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Old Dec 12, 2005, 7:14 PM   #7
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Quote:
So just in terms of shooting video when I can't get close to the subject, would I be better off with the SD450 (640x480 @ 30fps and a 3x optical zoom), or something with 320x240 @ 30fps and a 5x - 7x optical zoom?
It would be a wash at 3X optical with 640 X 480 and 6X optical at 320 X 240. The image is four times as large with 640 X 480 but the 2X crop factor gives you ¼ of the frame.

It is a tad larger than you are looking for and the movies are 640 X 480 but only 15fps, but you might want to look at the new Nikon S4. It has a 10X optical zoom and is 225g with batteries. Steve hasn't finished his review, but the movies should be up in a few days. It is interesting that Steve already has it on his best cameras list and hasn't finished the review yet. He must like it. The long zoom would be a bear with only the LCD as a viewfinder though.

Movies in the theater are 24fps BTW. I've read a couple of articles why you need a little more for a computer display but can't remember the details. I know you can see the difference between 20 and 30 fps from a digital camera.

The X1 has true mechanical image stabilization, which would make for much smoother movies. Might make up for a little slower frame rate in the movies, and would certainly make it more versatile as a camera. On a sunny day on the slopes it might be hard to follow action at 3X without an optical viewfinder though.


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Old Dec 13, 2005, 6:22 AM   #8
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slipe wrote:
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It would be a wash at 3X optical with 640 X 480 and 6X optical at 320 X 240.
sorry slipe, what does a 'wash' mean?!




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Old Dec 13, 2005, 10:11 AM   #9
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slipe wrote:
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Movies in the theater are 24fps BTW. I've read a couple of articles why you need a little more for a computer display but can't remember the details. I know you can see the difference between 20 and 30 fps from a digital camera.

Right you are. Thanks for the correction on frame rates of film. However, on a typical LCD computer screen, I seriously doubt that you could tell the difference between 20 and 30 fps. As a quick experiment, you can take a 30 fps video clip that you may have and play it on your computer monitor. Most viewing programs will let you adjust the frame rate. Set the frame rate to 15 fps. You probably can't tell the difference at all. Most folks can tell the difference between 10 fps and 30, but that seems to be pretty close to the threshold for most people to actually notice.
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Old Dec 13, 2005, 1:45 PM   #10
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tclune Download some 15fps movies from Steve's samples. I can see a lot of jerkiness compared to 30fps. Perhaps you are using more sophisticated viewers. I just use the Windows Media Player.

cragside Sorry – I assumed your secret location was in the US. A wash means it comes out even.

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