感光器比一比 - D3 v.s. 40D

今天看到這篇文章, 結論大概是 D3 那種嚇死人的高 ISO 其實是用軟體做成的. 延伸的意思是, 只要有相同能力的演算法, 40D 大概可以打平 D3, 而 5D 在超高 ISO 時, 大概可以海扁 D3.

這大概可以讓眾 Canon 使用者對自己的相機多一些信心, 在和 Nikon fans 打嘴炮時, 多一分自慰的快感

原文與翻譯

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.

從 Nikon 與 Canon 的感光器讀出的數據十分接近. D3 的高 ISO 數據比較像是廣告手法: D3 (與 D300) 的 CMOS 是一個很好的感光器, 但是追根究底, 它只能算追平 Canon 的程度.

The behaviour of Nikon DSLR are radically different from the Canon ones for long exposure:

Nikon DSLR 長時間曝光的做法和 Canon 系統很不一樣:

- 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.

 

在 Nikon,熱噪點從 Sensor 讀出來之後, 再由複雜的影像處理演算法抹處, 這樣的抹處過程會影響旁邊的畫素. 這會造成一個常見的天體 (是星空, 不是光屁屁的那種) 攝影問題: 亮度低的星體會當成噪點被抹掉.

- 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).

在Canon, 機身會使用不同的讀取方法從 sensor 讀取資料. 所以讀出來的熱噪值比較低, 較利於在後製時抺除.

 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.

Nikon 使用軟體除噪真是一個悲劇(原諒我全然酸葡萄的翻譯) (所以 NEF 並不是真正純然不加料的raw 檔). Nikon 的做法在一般攝影可以過得去, 但在天體攝影(again, 不是光屁屁的那種), 它重覆了 D70 與 D200 的問題而無法使用.

 Today the Canon and Pentax cameras seem to be the only ones useable digital SLR for efficient and advanced astronomy

看起來, Canon 與 Pentax 的還是唯二比較勝任天體攝影的相機.

(迷之音, 那到底那一種比較適合光屁屁的那種天體攝影?)

原文出處

http://www.astrosurf.com/buil/nikon_test/test.htm