DP2 Merrill sensor read noise finally measured

Started Sep 5, 2012 | Discussions thread
Truman Prevatt
Truman Prevatt Veteran Member • Posts: 6,611
Re: Do you even look at images?

No Roland,

DR is well defined. It is from the noise floor to the max signal level. I agree that DPR does not do a good job since they don't use raw. DXOMark uses the same process on all cameras using raw data. In reality the place this should be measured is at the sensor level. DXO cannot get the data at the sensor level and they make the argument that since the photographers see the data not at the sensor level but at the raw level, that is what they see makes a lot of sense.

However, DPReview measures apples to apples, the DR of the JPEGS and all the versions of the JPEGS. The Foveon sensor is probably 4 stops behind the current best offerings. A big issue with DR is read noise and read noise is a function of many factors including the chip design and the chip manufacturing.

While I am sure Sigma is working hard, I expect not many semiconductor houses wants to take on such small runs. Semiconductor houses make their money on volume. Sigma can promise volume. Would Sony mess with Sigma - doubtful. It would not be worth their time. Sony seems to have one of the better fabrication processes for digital sensors today. I also expect the Foveon sensor taxes a semiconductor facility. Bottom line the three level sensor is much more difficult to produce than a single level sensor with a CFA on top.

The SD1 is a fine camera with some warts which have been well discussed on this site. The SD1 is not a high DR camera - although some want to believe it. That's fine - no skin off my nose. Sigma will have some significant issues going forward. They have a non- standard sensor which requires high fabrication tolerances that will not produce a high volume in runs. Fabrications facilities make their money on large volumes of runs - that's thats the business model.

Sigma is caught between a rock and a hard place. They have a sensor that is more expensive to produce combined with a low projected volume. I wish them luck. I hope they can keep going to keep those loyalist in cameras. However, don't look for a whole lot of converts to increase the market share. Without an increase in market share don't look for the Sony's of the world to be courting them.


Roland Karlsson wrote:

Truman Prevatt wrote:

While DP review does not do a test on the raw data, it does do an apples to apples against other camera. What you find on the DPreview review of the SD1 is about 3 stops below the D7000 and the SD-1 with the least DR of the other three, one from Canon, one from Sony and one from Nikon.

Yeah ... maybe.

But it is not really interesting. The JPEG DR number is anything the camera maker choose it to be. And its often possible to tweak.

And it spreads misconceptions regarding the DR of cameras.

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