[JimmyDranox]

What Digital Camera says that is Sony sensor, not Toshiba.

[Smeggypants]

Yes. More MP on the same sized sensor means smaller sensels, but more of them. For the same level of sensor technology, small sensels are individually noisier than large sensels. But if you were to print out the same sized output images, say A4 or 11"x8.5" sized prints, then more sensels reduce the overall noise level. So, if the fill factor is the same (how much of the sensor's surface is actually capable of generating a signal from the light, rather than "wasting" some of the sensor's area with connecting traces and other structural elements), both trends tend to cancel out. In the old days, when fill factors were low, more MP meant overall noisier images. But today, with very high fill factors due to efficient micro-lens designs, there's not much in it.

To test this assertion, compare the DxoMark SNR 18% graphs of the the D7100 vs the K-5II:

Compare cameras side by side - DxOMark

Look at the SNR 18% curves. These show the shot/photonic noise performance of the sensors, and are a good indicator of the sensor's QE (quantum efficiency). The "Print" tab shows the outputs normalised to the same printout size, and the two curves are very close. Now click on the "Screen" tab and you are comparing the same number of MPs (like 100% pixel peeping) and you'll see a difference in noise performance due to the smaller sensels: 3.9µm vs 4.75µm distance between the centre of each sensel.

It comes down to how you want to use the extra MPs. If you want to produce a proportionally larger printout with the the D7100, and look closely at it, then yes, it will appear noisier. But if you use the extra MPs to increase the fine detail in the same-sized printout, extra noise should not be an issue.

However, there is a flip side to this. While the extra MPs means you can crop an D7100 image more, for the same number of overall pixels in the resultant image, the D7100 image will look noisier than a K5II image.

Finally, there's an argument that, for the same overall image SNR, since smaller sensels produce smaller sized "grains" of noise, the noise is therefore more film-like and thus more aesthetically acceptable. This assumes that the two cameras have the same ratio of luminance noise to chroma noise. Many designers more heavily filter the chroma (colour) noise as it's more noticeable, and the loss of colour resolution caused by the filtering is unlikely to be noticed. The luminance (B&W) noise is less objectionable than chroma noise and heavily filtering it tends to produce a noticeable loss in resolution.

Dan.

LOL

[Alizarine]

What Digital Camera says that is Sony sensor, not Toshiba.

The one in the A77? That's... a little old. But who knows? Given that Pentax can't use the Sony sensors as early as Nikon can... (but why did Nikon opt for the Toshiba one instead?)

[Caat]

The one in the A77? That's... a little old. But who knows? Given that Pentax can't use the Sony sensors as early as Nikon can... (but why did Nikon opt for the Toshiba one instead?)

Not besmirching the magazine but I would believe Adam before I would believe What Digital Camera.

Is this Toshiba's first widely commercially available sensor? Maybe they gave Nikon a good price to help get the sensor out there

[D1N0]

Not besmirching the magazine but I would believe Adam before I would believe What Digital Camera.

Is this Toshiba's first widely commercially available sensor? Maybe they gave Nikon a good price to help get the sensor out there

Nikon probably went to Toshiba because the 24mp in the a77 a65 nex-7 would be a step back. Sony probably went back to 20mp because of that. Toshiba is a huge company, bigger than Sony, I don't now wether they have supplied other dslrs before but they make a lot of sensors for smartphones and for video camera's. When te K-3 has the old sony iq at high iso will be disappointing (check dpreview comparison tool). When sony would have had a newer 24mp sensor then they would have already replaced the a77 and nex7 and not given it to Pentax first is my guess.

[traderdrew]

Yes. More MP on the same sized sensor means smaller sensels. For the same level of sensor technology, small sensels are individually noisier than large sensels. But if you were to print out the same sized output images, say A4 or 11"x8.5" sized prints, then more sensels reduce the overall noise level. So, if the fill factor is the same (how much of the sensor's surface is actually capable of generating a signal from the light, rather than "wasting" some of the sensor's area with connecting traces and other structural elements, both trends tend to cancel out. In the old days, when fill factors were low, more MP meant overall noisier images. But today, with very high fill factors due to efficient micro-lens designs, there's not much in it.

Hi Dan, I think you know a lot more than me so let me ask you this.

My thinking is more megapixels are friendlier to post processing as long as you captured your subject sharp enough. Simply put, more information is more editor friendly. As you say 100% crops are more noisy with the D7100 relative to the K-5 II but I think they are easier to manage for a good editor. I would rather not work with a 100% crop with the K-5. I would be happy with 80% or so because it seems some birds only let me get that close at 700 to 900 mm or so.

[Winder]

When sony would have had a newer 24mp sensor then they would have already replaced the a77 and nex7 and not given it to Pentax first is my guess.

Its not that simple. The A77 replacement is on the way, but according to Sony rumors it was held up because Sony was working on other support technologies like image processors and AF. Probably the same issue with the NEX-7. Sony needs to improve a lot more than just the sensor, and with the A7 launch their focus this year and part of next year appears to be on FF bodies.

There is a lot more to a camera than a new sensor.