the dots or the lens?

I recently decided to buy a digital camera, and it came down to a choice between two brands. They had these characteristics:

Ohmygoshi-2000: 3x zoom lens, 2 Mpixel

WhizBang-47: 2x zoom lens, 3 Mpixel

The cameras were pretty much identical in all other regards including price. One of the cameras only records 2 million pixels, but can zoom 3 times closer. The other can only zoom 2 times closer, but it records 3 million pixels.

Assuming I want to zoom all my pictures, which is going to give me higher quality: 3x zoom onto 2M pixels, or 2x zoom onto 3M pixels? By higher quality, I mean more detailed output.

Please explain the reasoning behind your answer.

If we assume that: 1) you want to 2x (or less) zoom all your pictures, you're going to have better results with the 2x3M because you'll have more information than with the 3x2M because it will record more pixels. 2) you want to zoom all your pictures more than 2x, you're going to have better results with the 2x3M because you won't be able to use the latter at all

But seriously, I would go for the pixels. You can always use software to 'zoom' the final product to whatever factor you want. Zooming does not provide more information. Pixels do. It's like with binoculars and telescopes: what counts is the diameter of the lens. Not the magnification: it can only makes the picture bigger. It doesn't create more information.

You could also try your luck on a specialized newsgroup like rec.photo.digital. You'll find more information than you could ever dream of

Good luck,

Dirk Vdm

If the lens can focus your image onto the sensor, then the sensor with 3M pixels will capture more detail. Most digital camera lenses can focus well enough if the subject is more than 1-2 meters away. It's at close range, I think, where things get interesting.

There are 3 critical elements to a digital camera. They are spatial resolution (pixels per inch) and dynamic range (the range and number of colors) and the lens. I don't know of any consumer digitals cameras thay reveal all necessary imformation. Without a very good dynamic range, and the good chips are expensive, you're not going to get great photos. The lens is also a critical element. A small plastic lens will not perform anywhere near what a high quality lens will.

If you want it all in a digital camera, get a Scitex. I think they're down to about $20,000 now (lens extra).

)> I recently decided to buy a digital camera, and it came down to )> a choice between two brands. They had these characteristics: )> )> Ohmygoshi-2000: 3x zoom lens, 2 Mpixel )> )> WhizBang-47: 2x zoom lens, 3 Mpixel )> )> The cameras were pretty much identical in all other regards including price. )> One of the cameras only records 2 million pixels, but can zoom 3 times closer. )> The other can only zoom 2 times closer, but it records 3 million pixels. )> )> Assuming I want to zoom all my pictures, which is going to give me higher )> quality: 3x zoom onto 2M pixels, or 2x zoom onto 3M pixels? )> By higher quality, I mean more detailed output. )> )> Please explain the reasoning behind your answer. ) ) If we assume that: ) 1) you want to 2x (or less) zoom all your pictures, you're going to have ) better results with the 2x3M because you'll have more information than ) with the 3x2M because it will record more pixels. ) 2) you want to zoom all your pictures more than 2x, you're going to have ) better results with the 2x3M because you won't be able to use the latter ) at all ) ) But seriously, I would go for the pixels. You can always use software ) to 'zoom' the final product to whatever factor you want.

This is nonsense. If I use software to zoom the 3Mpixel image so that it's as large as the unzoomed 2Mpixel image, that would mean I have to enlarge the image by 50% (to get from 2x to 3x zoom) and then crop the image to cut out the part I zoomed in on (by 33%) _but_ that means I have to cut off 33% in _both_ directions. So I'm left with 66%^2, or 44% of the original image. So if I use the 3Mpixel camera and then use software to zoom from 2x to 3x, I'm left with 44% of 3Mpixels, or 1.33Mpixels.

To put it completely differently: The viewing angle that one pixel covers depends more on the zoom factor (which works in both the X and Y directions) than on the number of pixels (which already has both directions in it)

) Zooming does not provide more information. Pixels do.

Zooming doesn't provide more information, but it _does_ provide more _detail_. When you zoom you map a smaller piece of the world onto the same amount of pixels, and/or you map the piece of the world you're interested in onto more pixels.

) It's like with binoculars and telescopes: what counts is the diameter of ) the lens. Not the magnification: it can only makes the picture bigger. It ) doesn't create more information.

This is complete and utter nonsense. The only reason you want a big lens is to catch more light. When looking at faint stars this is an issue, but when looking at planets, the moon, a sail on the horizon, the cute chick across the street, or whatever you want to see, it doesn't matter. What you want is for the desired object to be projected on as large an area of your retina as possible.

) You could also try your luck on a specialized newsgroup like ) rec.photo.digital. You'll find more information than you could ever ) dream of

You didn't happen to note the makes of the cameras he mentioned, did you ?

Detail _is_ information. But information is no use unless you record it.

Which would you prefer, a camera with 1MPixel and no zoom at all, or a camera with 1000x zoom but only one pixel?

)> Zooming does not provide more information. Pixels do. )> )>Zooming doesn't provide more information, but it _does_ provide more )>_detail_. ) ) Detail _is_ information. But information is no use unless you record ) it.

Very well, then. Zooming _does_ provide more information. It maps the interesting bit of an image onto a larger amount of pixels, thus providing more information. You can either get more information by mapping the interesting bits on a larger area of the imaging chip, or by putting more pixels on it. So you can either zoom 2x, or double the amount of pixels. In both directions. So that's actually _quadrupling_ the amount of pixels.

) Which would you prefer, a camera with 1MPixel and no zoom at all, or a ) camera with 1000x zoom but only one pixel?

This is an absurd analogy, as 1000x zoom is way too much to be useful in practise, and you _also_ cheated by squaring the pixel-difference, which was the whole point of the original problem.

_If_ I want as much _detail_ as possible, I'd rather have a camera with 1000 pixels and 1000x zoom than a camera with 1MPixel and no zoom. Of course, 1000x zoom is only useful in microscopes, but those are real-world details, while this is a rec.puzzles problem.

I do hope you noted the makes on the cameras. If not, read back and take a look at them.

you could take multiple pictures and stitch them together into a panorama

Given a reasonable level of fitness then (for most of one's shots) it is possible to actually advance forward a few steps to get the desired level of detail - and then whiz, bang you've got it.

I'm a bit ignorant on how many steps it might be for the range of focal lengths involved, but I've found if you go too far forward, then you can actually go backwards again.

We'll need a few more assumptions... I assume that by 'more detailed output' you mean that you want to resolve finer detail