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Sensor update possible?


Guest bwcolor

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This picture says it all.

An angle of 30 degrees means one stop less light in the corners,

Probably most wide angle lenses on the M8 are coming close, or even exceeding this angle.

 

Coming from 30 degrees with the Leica Sensor, you would go to 37 degrees with a FF sensor

But, 37 degrees means already three stops in vignetting, which is unacceptable.

 

Hans

 

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Guest volkerm

If you look at other sensors in the Kodak portfolio, you will find big state-of-the-art sensors like the KAF-50100 which have only 1/2 EV vignetting at an angle of 40 degree.

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Hi Volker,

 

You are right, I missed this one, but it creates another question.

What puzzles me here is that this is a sensor without microlenses.

According to Kodak, "microlenses are added to improve sensitivity".

The sensor for the S2 will also have microlenses.

It almost seems as if microlenses do more harm than good for vignetting, exactly the opposite to what one would expect.

 

Hans

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Hi Volker,

 

You are right, I missed this one, but it creates another question.

What puzzles me here is that this is a sensor without microlenses.

According to Kodak, "microlenses are added to improve sensitivity".

The sensor for the S2 will also have microlenses.

It almost seems as if microlenses do more harm than good for vignetting, exactly the opposite to what one would expect.

 

Hans

 

Maybe the problem is that a camera doesn't do mathematics. All it does is take pictures.

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The primary purpose of microlenses is to redirect light falling on a pixel onto the part of the silicon that is actually sensitive to light - the "well".

 

Most sensors only use a part of the surface to actually produce signal (the proportion that does so is called the "fill factor" - i.e. a sensor with a fill factor of 45% doesn't respond to light over the other 55%, and that light is wasted unless is can be redirected to the "well". CMOS sensors especially use a lot of the surface area for non-light-gathering circuitry like per-pixel preamplification of signal or noise reduction, but CCDs are "blind" over a significant part of each pixel, as well.

 

That's how they "improve sensitivity" - by steering light from the circuit parts of the pixel site to the location that actually responds to it.

 

However, it's the steering process that puts limits on the direction from which light can hit the microlens and still actually fall in the right place (think of Indiana Jones' staff projecting the sun in the Map Room in "Raiders of the Lost Ark" - wrong angle, wrong answer)

 

To solve THIS issue, one must either use telecentric, digital-friendly lenses (Olympus's argument) - or progressively offset the microlenses towards the center of the frame as one moves towards the corners of the sensor (Leica/Kodak's technique for the M8)

Edited by adan
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