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Sensor/pixel Size


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#1 Aaron Solomon

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Posted 13 September 2010 - 04:35 PM

So aside from being able to cram more pixel's on a larger sensor, what's the advantage of having a larger sensor? Depth of field? And what about having more pixels? Why not smaller pixels on a larger sensor to produce a "finer" image?

Thanks,
Aaron
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#2 Adrian Sierkowski

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Posted 13 September 2010 - 04:52 PM

It's a trade off. the smaller your pixel, or in the case of film even, your crystal, the less of a chance it has of being struck by a photon, and hence the less light is recorded. So if we have a given chip size and want to add in more pixels, say going from 2K to 4K, we loose sensitivty to light.
Having a pixel of a certain size is therefore a way of getting higher resolution and the same or greater sensitivity to light. In the case of digital cinema, sensory sizes want to closely match the physical sizes of motion picture film to allow for one to use the same lenses and accessories which already exist. Depth of Field Characteristics are also important in terms of film-making, but a larger sensory doesn't necessarily mean a shallower DoF which is based on many other factors, such as subject/object distances.
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#3 Aaron Solomon

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Posted 13 September 2010 - 04:56 PM

So ideally we want a huge sensor to cram tons of pixels on for high resolution and make the sensor big enough that the pixels are still large enough to be hit by photons?
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#4 Adrian Sierkowski

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Posted 13 September 2010 - 05:02 PM

Yep, Ideally we want larger sensors, to a point, to give us enough room for good sized pixels and good enough resolution.
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#5 Aaron Solomon

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Posted 13 September 2010 - 05:04 PM

Sorry I know this is off the topic, but about field of view, how is that determined? What affects it? Are the different distances between objects that we apparently see when lenses have different focal lengths results of changes in field of view?
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#6 Aaron Solomon

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Posted 13 September 2010 - 05:10 PM

Thanks for everything by the way.
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#7 Adrian Sierkowski

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Posted 13 September 2010 - 05:14 PM

http://en.wikipedia....i/Field_of_view

and no problem.

Field of view is essentially what the lens can see, so you're on target with your summation of it.
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#8 Aaron Solomon

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Posted 13 September 2010 - 05:25 PM

I just have a question, when you're planning out a shot, do you actually take into account angle of view? and do you use a light meter when you're shooting digital? or just play it by eye?
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#9 John Sprung

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Posted 13 September 2010 - 05:32 PM

So aside from being able to cram more pixel's on a larger sensor, what's the advantage of having a larger sensor? Depth of field? And what about having more pixels? Why not smaller pixels on a larger sensor to produce a "finer" image?

Thanks,
Aaron


We like big chips for shallow DOF -- up to a point. Go significantly bigger than, say, VistaVision, and the focus puller's job becomes damn near impossible.

We like big photosites (pixel isn't really the right word, but it gets misused a lot) for high dynamic range, and because there's necessarily some non-light-sensitive space between the photosites, which can't be scaled down any smaller. Make the pixels smaller, and you have to give more silicon to the dead area between them. That results in a more severely undersampled image.

So, there's a tradeoff between more pixels and better pixels.





-- J.S.
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#10 Aaron Solomon

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Posted 13 September 2010 - 08:32 PM

Thanks!
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