ctxkevin wrote:
對焦是對人，你怎麼讓背後的葉子清楚...(恕刪)
我當然知道對焦是在人上面
指不夠利的地方當然也是指對焦點上的部份
這應該不用特別提吧
有人會去注意散景夠不夠犀利清晰嗎?
另外我主要疑問的重點是擺在
這樣高的像素是否已經超越鏡頭的解析度了
並不是在照片是否清晰
davyhsieh wrote:
哇哩咧
D3才...(恕刪)
這篇參考一下, 這應該是D3 高ISO時 畫面純淨的原因.
http://www.astrosurf.com/buil/nikon_test/test.htm
其中結論如下
Conclusion
The readout noise of the Nikon and Canon CMOS detectors is very similar. The high ISO sensitivity displayed by Nikon is for the marketing: Nikon D3 CMOS (and also the CMOS D300 CMOS - Sony origin) is a very high quality sensor, but in the end, Nikon just rises now the level of Canon technology.
The behaviour of Nikon DSLR are radically different from the Canon ones for long exposure:
- For Nikon, the hot pixels are eliminated by a sophisticated digital processing external to the sensor. During this digital processing, the signal of the neighboring pixels is also affected. The damage of such processing is well-known in astronomy: the weak stars are also eliminated and the image loose photometric qualities on stellar like objects.
- For Canon, the thermal signal is reduced for each pixel by a differential reading method. The thermal signal level measured at the output of the sensor is very low. The residual can efficiently be removed during the image processing (a simple substraction of a reference dark signal map).
It is tragic to see that Nikon solved the problem of thermal signal by a digital processing of the RAW files (i.e. NEF files do not contain true raw data). This processing can surely meet the daytime users and the high performance for main application is evident. But by repeating the same mistake made on the D70 and the D200 (equipped with a CCD) on the news Digital SLR Nikon probably divorces once more with the astronomical community.
Today the Canon and Pentax cameras seem to be the only ones useable digital SLR for efficient and advanced astronomy.
這篇文章 就是CANON CMOS技術白皮書
http://www.the-digital-picture.com/Reviews/Canon-Full-Frame-CMOS-White-Paper.pdf
其中Page 17-19 有提及 CANON的On-Chip降躁技術 即是前面文章中所提及的 "differential reading method"
有興趣的可以讀一下~~
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