Tech question - sensor performance

[@imagesBV]

According to the DXO tests....which I know a lot of people don't think credible...the low light ISO figure quoted ranges widely between sensors.
i.e. low light ISO figure for the 50D is 696, 7D is 854, 5DMKII 1815.

My question is ...does this equate to exposure f stop/shutter speed benefits.....i.e. if camera A is rated at 2000 and camera B at 1000, does that mean camera A has a one stop advantage?

[DrJon]

Re: Tech question - sensor performance

I don't know the answer to that, but low-light performance generally just goes with sensor size, so a FF camera with a sensor 4x the area of a m43 camera should be about 2 stops better. There is some wiggle room for sensor design and micro-lens coverage, but size is generally the main thing. (This is looking at an image at the same size, not the pixels.)

FF is 2.6x the size of a 7D sensor, so a stop and change, note the 50D figure is 1/2.6 of the 5DmkII, the 7D is better than that, suggesting intervening improvements, and hopefully tomorrow's 5DmkIII will be up around 2300+.

So I guess I'm concluding that yes, a result one stop better will show one stop better low-light performance.

Oh, and I'm generally cool with DXO, they actually do scientific tests while their detractors tend to say, ah yes, but my chosen system is really better than that so they must be rubbish. I'm not so sure about their final single numbers (or a single lens resolution number), but the broken-out numbers (like ISO) seem useful.

John

[@imagesBV]

Re: Tech question - sensor performance

Just checking the DXO site explanation it says
25% better low ISO figure equates to 1/3 stop.....so 75% would be about one stop
So I could conclude that at say the 5DMKII (1800) against the 7D (850) is about 110% based improvement on the 7D as a starting point and therefore around 1.5 stops better at best.

hence the noise on an ISO 1000 shot on a 7D will equate to that of a 5DMKII at ISO2500.......I think! or £400/stop improvement.

[briansquibb]

Re: Tech question - sensor performance

From experience I would say that the 5DII is a stop faster than a 7D