A new way of measuring camera performance

Started Dec 15, 2008 | Discussions thread
Cax Regular Member • Posts: 245
Re: A new way of measuring camera performance

CommanderSpike wrote:

I also had another thought - what exactly is so troublesome and
expensive about a large sensor in a compact camera?

Big sensors have absolutely no advantage over smaller sensors unless you are pushing the focal length to aperture ratio, or ƒ-number, down below ƒ 2 on the smaller sensor.

Nothing has anything to do with the sensor, really, it is all about lens size, or lens aperture. The DP1 has a larger sensor than the LX3, but with the same size lens, it captures the same light at a longer focal length and at ƒ 4 instead of ƒ 2.

This thread has an example:

With the same aperture, 50mm/2.8 = 25mm/1.4 = 17.9mm and the same shutter speed, the four times larger sensor has to be used at four times the sensitivity.

So, don't get hung up on sensor size. Sure, it has to grow with the lens aperture to avoid making the optics too complicated or expensive, but it is the lens that is doing the light-collecting.

I had a thread on this here:

I also made a spreadsheet where I make up some new (at least to me) metrics for measuring photographic systems, giving each one a light index in the rightmost columns. I can't guarantee its correctness, as I am no optician, but it shouldn't be all crazy either:

(sorry about the poor hosting, couldn't think of anything else)

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