Saturday, January 12, 2013

Re: Please can you give me some advice

Hello william,

"While there is no specific meaning for high-definition,"

First lets understand the question.

When I think definition, there is resolution and then is image quality in terms of sharpness, contrast, color saturation and noise level. 

The smallest lens is effectively a pin hole camera.  If you are unsure what that is, it's a fun kids science experiment to google or YouTube search for.

Pixel Resolution is unaffected by the lens size and it purely about the sensor.

Sharpness actually. Increases as a smaller lens can be less accurate and produce a shaper image.  In addition focus is also less of an issue, a pin hole camera is in focus for all distances.
In a larger lens light entering the one side of the lens must match light from the other. The precision of the alignment is determined by the lens quality, focus.  Things like chromatic aberration and many other factors come in to play and become more of an issue the larger the lens.

What does happen with the smaller lens is less light.  What that means is the image sensor is getting less signal.   This means less color resolution, gray scale resolution and sensor noise becomes more of a factor. The classic signal to noise ratio.

To deal with noise longer sample times are needed, meaning longer exposure times and slower frame rates on things like cheap USB web cams. 

In astronomy techniques like cooling the cameras sensors to reduce noise, extremely long exposure times and digital post processing of many successive images to produce a higher contrast low noise image is done. All of which can be applied to even a web cam.

Also high resolution sensors need more light to produce a good image.

So a small lens is a trade off, cheaper lens but less light coming in work with.

There are 1080p cameras with 1mm or smaller lenses.

Here is another extreme example of small lenses.

Sent from my iPad

On Jan 12, 2013, at 6:47 AM, John Sokol <> wrote:

---------- Forwarded message ----------
From: W.E.
Date: Jan 12, 2013 5:59 AM
Subject: Please can you give me some advice
To: <>

I wonder if you can help.
I am trying to figure out what is the highest definition i can get from a video camera with a smallest lens.
Can you enlighten me on this at all.
Thank you.

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