E-5 Raw noise performance = E-30/ ballpark E-3's

Started Dec 18, 2010 | Discussions thread
bobn2 Forum Pro • Posts: 61,123
Re: Look at this

luisflorit wrote:

bobn2 wrote:

luisflorit wrote:

Look at this comparison between JPG and RAW exposures:

I can't see what the exposure is from these - they are processed shots and the tonality depends entirely on the tone mapping (in the broad sense - mapping of output tones to recorded light values) that has been applied.

As you see, they have essentially the same exposure, but the RAW file was pushed by 1.2 stops.

Is the EXIF in there, then at least I can look at the settings and see if the exposure is the same (assuming that the light is the same)

What do you mean? It is the same shot, so obviously the exposure is the same.

That's what I was wondering - actually the same capture with raw+JPEG? In that case I'm wondering just what happened. Usually raw converters are rigged so the default processing is the same as the in-camera JPEG - how come this hasn't happened - which tools are you using?

There are other manufacturers that decided to do this also. It seems that the D7000 does this to the highest degree. The point is that this makes perfect sense when the sensor has very low read noise (like the D7000). If not, then you are buying big trouble.

I'm not sure what you think has been done. The D7000 seems on first sight to rely exclusively on digital tone mapping for the whole range of exposure values it can be set for. The K-5, which uses the same sensor, retains some analog gain variation over the range.

This is what I meant.

Interestingly, it does yield the Pentax a small advantage at higher ISO's, somewhat negated by their decision to NR their raws irretrievably at high ISO's. I think there's an agreement between the camera manufacturers that none of them is allowed to get it all right with any single camera.

Which is used is really only of interest to geeks like me, for the photographer the issue is the quality of the output, and the manufacturer will have chosen the balance between digital and analog tone mapping to get what they think is the best advantage. I don't think they're always right in their choices.

I agree. The point is that electronic gain almost always gives you noticeably better results, and not only for 'geeks like you'.

It only give better results in the cases where the ADC is not good enough to digitise the whole sensor DR. I guess what's happened with the A580/D7000/K-5 sensor is that Sony designed a genuine 14 effective bit ADC system, only to produce a pixel design that could give 15 bits DR. But generally you need to set the ISO as high as possible - up to the point when the analog gain gives out. I've said this frequently but generally get castigated by those who don't understand what's going on

Otherwise, no one would care about adding electronic gain to sensors. Maybe soon we will have sensors for which this is not noticeable (D7000?),

As Nikon has decided to use it, by throwing away the extra bit of DR that Pentax used. That's why the Pentax is showing up with slighty better low light (and then there's that NR - the engineer that decided on that should get the lunkhead of the year award)

but Oly is light years from that.

Closer than you think, but unfortunately for the wrong reasons.
This is the E-5

There's really only a half a stop in it (15.4 electrons at 200 versus 9.1 when the analog gain gives out). Panasonic's electronics do a bit better with the same sensor

13.2 dropping to 5.9.

Actually they're doing better than that, because they place the exposure further up the sensor characteristic (see, we are on the same page) so they give the sensor twice the exposure at the same gain setting, so the 200 ISO figure is 15.4 plays 9.5

BTW, if you're wondering why the noise goes up at very high ISO's, I think its due to the rounding errors involved in digital arithmetic with small ADC counts. They could gain with more analog gain there, or using floating point or a longer word length

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