Fast lenses, and High ISO

Started Jul 18, 2014 | Discussions thread
Austinian Veteran Member • Posts: 6,545
Re: Understanding ISO

Great Bustard wrote:

Austinian wrote:

mosswings wrote:

Good recasting of the subject, GB.

And the reason why sensors aren't getting rapidly better anymore.

Which is bad news for those expecting major sensor improvements in the immediate future, but good news for those fearing their existing gear will soon become obsolete.

Lowering the read noise, however, is important for increasing pixel counts. For example, the read noise at high ISOs for modern sensors is typically in the 2-3 electron range. Let's see the effect this has on various pixel counts over the same area of the photo (I like to use the µphoto, which is a millionth of a photo -- for example, 1 µphoto on a 24 MP sensor is 24 pixels) using a read noise of 2.5 electrons / pixel:

12 MP: 8.7 electrons / µphoto

24 MP: 12.2 electrons / µphoto

48 MP: 17.3 electrons / µphoto

96 MP: 24.5 electrons / µphoto

As we can see, every doubling of pixel count increases the read noise by 41%, assuming that the read noise per pixel is the same. If the read noise pixel were to be half as much for 4x as many pixels, then the read noise µphoto would remain unchanged.

So, there additional improvements in sensor tech with regards to read noise are very important with regards to increasing pixel counts.

Ah! I'd read that for identical technologies, sensor area was the most important factor, but it was implied that it wasn't the only factor. Good to know this is another.

What other significant aspects should digital camera buyers consider, and is such specific sensor information readily available?

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Sony a77 II Sony Alpha a7 II Sony DT 55-300mm F4.5-5.6 SAM Sony DT 16-50mm F2.8 SSM Sony FE 28mm F2 +3 more
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