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Old Jul 3, 2010, 9:25 PM   #1
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Default How come camcorders have so much zoom?

Back in the days where digital cameras all have 3-4x zoom, ALL camcorders had at least 20x zoom. Now superzooms are really popular because they have, what, >10x zoom? The highest zoom a digital camera currently has is 30x, while the highest for a camcorder is 78x (I think).

Why does camcorders have so much more zoom?
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Old Jul 3, 2010, 9:33 PM   #2
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Because they have small, low resolution image sensors.
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Old Jul 3, 2010, 9:44 PM   #3
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Because they have small, low resolution image sensors.
Please elaborate. How does that affect zoom? Thanks

Last edited by chengbin; Jul 3, 2010 at 9:49 PM.
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Old Jul 4, 2010, 2:47 AM   #4
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The higher the resolution the better the quality of the lens/glass that is needed for the sensor to attain that resolution. With the far lower resolutions of video compared to still then you can have a lens that isn't so good. By nature a very broad range of zoom makes a lens 'weaker' in its performance.

It's like when I shoot video with my dSLR, I don't have to be quite so concerned with using a lens at a point where it is softer as it full HD resolution of only 1920 x 1080 is nothing compared to the still resolution of 5616 x 3744 so you can't see the reduced sharpness or other undesirable elements.
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Old Jul 4, 2010, 6:37 AM   #5
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In addition to the issue of resolution Mark1616 explained so well, there is also the issue of the smaller image sensor.

A small image sensor has a narrower anle of view for the same focal length lens. In order for a dSLR to have a lens capable of, for instance, a 78X zoom ratio, it would have to have a focal length of from, for instance, 10mm to 780mm, which would be a monster of a lens to carry around. For the smaller image sensor in a camcorder, the same zoom ratio could be achieved with a lens of, for instance 2mm to 156mm, which would be a lot easier to carry around. And, given the lower resolution of the image recorded by a camcorder, as Mark1616 explained, a 2-156mm lens wouldn't have to be very good, so it would be cheaper and easier to make. Conversely, that 10-780mm dSLR lens, if it were useable at all on the higher resolution image sensors in dSLRs, would be difficult to design and make and therefore quite expensive.
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Old Jul 4, 2010, 8:34 AM   #6
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Quote:
Originally Posted by Mark1616 View Post
By nature a very broad range of zoom makes a lens 'weaker' in its performance.
Could you explain why?

Quote:
Originally Posted by TCav View Post
In addition to the issue of resolution Mark1616 explained so well, there is also the issue of the smaller image sensor.

A small image sensor has a narrower anle of view for the same focal length lens. In order for a dSLR to have a lens capable of, for instance, a 78X zoom ratio, it would have to have a focal length of from, for instance, 10mm to 780mm, which would be a monster of a lens to carry around. For the smaller image sensor in a camcorder, the same zoom ratio could be achieved with a lens of, for instance 2mm to 156mm, which would be a lot easier to carry around. And, given the lower resolution of the image recorded by a camcorder, as Mark1616 explained, a 2-156mm lens wouldn't have to be very good, so it would be cheaper and easier to make. Conversely, that 10-780mm dSLR lens, if it were useable at all on the higher resolution image sensors in dSLRs, would be difficult to design and make and therefore quite expensive.
Why does the minimum focal length affect image quality.

Thanks
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Old Jul 4, 2010, 8:38 AM   #7
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Quote:
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Could you explain why?
Without going into too much detail it's all about the ability to bend light well (what a lens does). The best lenses are those that don't zoom (prime) as they only have to bend light for the desired focal length. The more the focal length can vary the harder it is be bend the light as accuracy so you will start getting less sharpness/more distortion/aberrations/vignetting/reduced contrast etc.
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Old Jul 4, 2010, 8:46 AM   #8
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Quote:
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Why does the minimum focal length affect image quality.
The minimum focal length doesn't; the range of focal lengths does.

A lens with a single focal length can and probably will be better at that focal length than a zoom of comparable size and cost. Similarly, a 3/4" open-end wrench will work better on a 3/4" nut than an adjustable wrench will. And a lens with a smaller zoom ratio will work better than a lens with a larger zoom ratio, just as an adjustable wrench will work better on a 3/4" nut than a pipe wrench will.

When you try to make a tool that does a lot of things, it doesn't do many of them well.
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Old Jul 4, 2010, 8:47 AM   #9
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Lemmee try. It's not the minimum focal length. It's the quality requirement. Videos are awful quality. If you grab a still out of one, you'll see. Stills are expected to be high quality. So a quality high-power zoom (like 50X or more) would be HUGE and too expensive to be practical. Huge, like REALLY HUGE.

i.e. a pretty good full-frame Canon picked almost at random goes for $750 at Henry's Canada ( Canon ef-s 18-200mm 3.5-5.6 IS ). That's approx a 10X. I doubt if there is a 50X dslr lens even made.

So it's related to differing requirements. Video doesn't need to be good quality so can have big zoom. Stills are another game.
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Old Jul 5, 2010, 8:51 AM   #10
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Thanks everyone for your answers. I understand now.
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