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Old Aug 31, 2006, 1:46 AM   #1
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Can you explain why a video cam has or can have such a far longer zoom
than a still camera? I'm not technically knowledgable as you might assume
from this question. Sorry if it's elementary or if comparing apples to melons (in
season)! Thanks.
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Old Aug 31, 2006, 1:53 AM   #2
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Its because the video cam has such as tiny sensor, the "crop" factor kicks in and enables a tiny focal length lens to act as if it had the same field of view of a much larger lens.

As an example, my camera has a 1/2.5" sensor ( 5.76mm x 4.29mm) and the lens has a focal length of 6-72mm, but due to the small sensor acts as a 36-432mm length lens, focal length multiplier x6.

The sensor on a video cam is even smaller thus has an even larger crop factor (focal length multiplier) eg some vidcams have a minute sensor 1/6" thats about 2.15mm x 1.61mm !
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Old Aug 31, 2006, 2:00 AM   #3
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Sintares,

Thanks for response. I don't really grasp or understand all that info and
explanation but I'll work on it!

Can't they put the same size sensor in still cams? With same result?

Thank you kindly.

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Old Aug 31, 2006, 2:11 AM   #4
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See

http://www.dpreview.com/learn/?/Glos...r_sizes_01.htm


http://www.dpreview.com/learn/?/Glos...tiplier_01.htm

The smaller the sensor the bigger the focal length multiplier so the smaller the lens can be and yet give the same field of view of a much larger lens.

Yet the smaller the sensor, the lower the quality of the final image, the more noise the sensor suffers, the less light each photosite embedded into the sensor can take in etc. Which is why even a modern superzoom (non dslr) camera with a small sensor struggles compared to the large sensors used in dslrs.

Professional class video cameras do use bigger sensors, but the bigger the sensor then the bigger the lens needed to get the same zoom etc.

Thats why a modern superzoom camera (SonyH series, Canon S series, Pany FZ series etc) can have zooms reaching 432mm in a small sub slr style body.

Youcan even get shirt pocket sized cameras with x10 zooms these days, though obviously with smaller inferior lens.

Next time you are in a camera shop , find an old slr and find a zoom lens reaching 400+mm, look at the sheer size of it.

It probably bigger and heavier than my entire 36-432mm equivalent camera plus for that range you would be looking at at least two lens and they would cost more than my camera..

Then look at the tiny lens on a video camera, andtry comparing that to the lens on a Canon S3 or Sony H 1 etc , its tiny, and then compare the lens on the Sony/Canon to a dslr/slr lens and seehow small they are in comparison.




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Old Aug 31, 2006, 9:59 AM   #5
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Sintares,

Again thank you very much for your further response. That really helps and
I will do as you suggest next time in a camera store. Those links really
helped. Seems steve's site is down so don't know when you will see this.

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Old Aug 31, 2006, 10:05 AM   #6
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Video is a really low resolution format compared to modern digital cameras. That's why they can have such small sensors - they don't have to fit in anywhere near as many pixels. Just look at a still from a home-made movie!
High res video cameras with a lot of zoom like the ones they use to shoot sports events for tv are gigantic in comparison.
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