neuroanatomist said:
LetTheRightLensIn said:
There is not such thing as a top end, digital sensors are all but entirely used in a linear range.
Where did you study mathematics? Remind me to never hire someone educated there, much less even consider it for my kids. A range, by definition, has bounds. A numerical range has an upper bound – a top end.
For a camera, by convention we also define 'middle gray' and that's used as the set point for metering. The point being made is that with Exmor, 'middle gray' isn't in the middle. If a metered exposure on Canon blows highlights, so will a metered exposure on SoNikon. So, to use the additional couple of stops of low ISO DR on Exmor, you must chronically underexpose (relative to metered exposure).
Exactly. But it gets worse.
Having used an Exmor sensor alongside the Canon for a couple of weeks now I am really surprised by what is going on in reality compared with the hyperbole that is quoted on the Internet, not just from the EE crowd on CR ( that's the Exmor Evangelists), but also the likes of DxO and DPR etc.
I will try and explain:
As Neuro has pointed out above, 'correct' exposure in placing the recorded image on the response curve of the film or chip according to the intensity of the light falling on the subject. If we are wanting to record and image that has different levels of light intensity falling on it we have to compromise on where we set the exposure. As both sensors have precisely the same highlight limit to record more highlight we have to under expose proportionally, thus pushing the darkest areas deeper down the sensor anyway. So because you are having to push those dark tones further down to get more highlight range you are losing some of the potential benefit.
Think of the range of both sensors as being equal but the final bottom end of the Canon is unusable. In other words the extra DR you have is all bottom end, all two stops of it. Two stops sounds a lot. How often have we heard people on CR stating what a difference two whole stops can make. We hear them say that when you lift by two stops and look at the difference what a wonderful thing two extra stops would be to have in the first place.
Here's the rub: we all know that exposure isn't linear, a stop more is double the light and so forth. Do you see where this is going ? Your two stops extra is buried in the bottom end of the sensor, so a two stop advantage at the bottom is minuscule advantage in reality.
To make the Exmor look better than the Canon you really have to try to set up a situation that can show that advantage and it only really comes from lower read noise. It's still greatly reduced in tone and saturation.
I'm finding that I'm really having to work harder on the Exmor images to get them to have the 'pop' I want, for use of a better word. They are very flat, in fact all the things digital was critiqued so much for in the beginning. Also the blues are not handles as well as the Canon, though I think the greens are handled better.
In short I would say that for my kind of shooting the overall IQ of the Canon sensor is better than the Exmor at low ISO.