Цифровое фото и аппараты для оного

Joseph Wisniewski Prolific Poster, jan 29, 2004; 11:55 a.m.
Yes. Some sensors are capable of "electronic shutter" operation, others are not. If the sensor has this capability, you get 1/500 sec x-sync, like D1X, D1H, 1D, or D70. If it doesn't, you get whatever sync speed the mechanical shutter on the camera is capable of: 1/250 for the F100 shutter in the D2H or the EOS-1V shutter in the 1D II, 1/180 for the N80 shutter in the D100.

Currently no CMOS sensors have electronic shutter capability, which is why Canon lost this capability when they moved from CCD on 1D to CMOS in 1D II.

Some CCD sensors don't have it, either. Supposedly, the Fuji Super CCD has it, but Fuji didn't choose to use the capability in S2. The Sony ICX413AQ sensor used in Nikon D100 and Pentax *ist D didn't have it, but the design of the sensor should have permitted it. The D70 appears to use a new version of ICX413AQ that does have electronic shutter, so you get a 1/500 sec electronic shutter x-sync, instead of the 1/90 that the N75 shutter in D70 is capable of.

 

Joseph Wisniewski Prolific Poster, jan 26, 2005; 03:34 p.m.
There are different types of sensors. Some can do electronic shutter, and some can't. In general, the extra circuitry needed to do an electronic shutter takes silicon area away from the photosites, making hte sensor a little noisier.

The D70 uses an "interline transfer" CCD. This sensor can do electronic shuttering. The mechanical shutter is that of a Nikon N75, capable only of 1/90 second shutter speed. The D70 always (sorry Thom Hogan) waits for the first mechanical shutter curtain to open before tripping the electronic shutter, then waits for the electronic shutter to "close" before starting to close the second curtain of the mechanical shutter.

With excessive light exposute, the D70 CCD can overload to the point where it would be a real mess, beyond the sensor circuitry's ability to clean up in time for a good electronic exposure, so using the mechanical shutter as a "light blind" is necessary.

Other cameras use different sensor types. Nikon D100, Oly E-1, Pentax *ist, Minolta 7D use "full frame transfer" CCDs, which don't have the extra circuitry for electronic shutter. (Supposedly, D100, *ist, and 7D have the circuitry, it just doesn't work right. Kind of the worst of all worlds).

No DSLR sized CMOS sensor on the market has electronic shutter capability. CMOS sensors are random access devices. They are capable of "rolling shutter" operation, where they start exposing cells at one time, then reading those particular cells at one "exposure time" later. The exposure and read chase each other across the sensor, just like the moving curtains of a regular mechanical shutter. Except much, much slower. It would only be useful on most cameras for long exposure times, up over 1 second.

 

The CCD sensor the D50 uses is unique. No, it's not the one used in the D100 or D70 models, though it is certainly derived from the same technology. The D50 sensor consists of a 3008 x 2000 array, and it has massive (compared to consumer cameras such as the Coolpix) 7 micron pixels. That's just one reason why the D50 can produce 12-bit RGB images with rich color and low noise. Like virtually all digital cameras, a filter array is placed over the D50's CCD. This filter has four purposes:

1.
Provides the Bayer pattern. The Bayer pattern is named after the Kodak engineer who invented it. Basically, this is a set of color filters that results in an alternating pattern of RG (on odd-numbered rows) and GB (on even-numbered rows) pixels. The final image is rebuilt by interpolating the actual pixel values at each position.
2.
Filters out infrared. CCDs are sensitive to infrared light, and to keep infrared energy from affecting image quality, most (but not all) of this light i filtered out.
3.
Realigns the light. CCDs don't like light hitting them at any angle other than 90 degrees, so the filter also focuses the light rays from the lens directly into the sensors using a set of what are called microlenses.
4. Provides a low-pass anti-aliasing filter. Digital sampling is subject to color fringing (artifacts) when high frequency detail in a scene approaches that of the sensor pitch.

On a D50, some of these things appear a bit changed from the D70 and D70s. The near IR filtration seems a bit more aggressive. Some small spectrum changes I see could mean that the Bayer dyes are a bit different, too. Overall, it appears that Nikon may have tweaked the layer that sits on top of the sensing part of the CCD. On the other hand, none of these changes are dramatic, so it could be sample variation, too.

 

The GN of the 5600HS at 1/4000 HSS is 5.6 for a 50mm lens.
at 1/500 HSS is 12 for a 50mm lens.
(ISO 100)

 

stas27>> Кстати, ссылочкой, доказывающей идентичность 6MP чипов, идущих в Никоны, Минольты и Пентаксы поделимся? Если уж все вокруг опять дураки...

Никон Д50/70/1X может стрелять вспышкой на 1/4000 без режима ФП/ХСС, Минольты и Ко нет. Для среднего пользователя ПРИЧИНЫ этого играют мало рояли.

 

D80 @ ISO 200, f/3.5, 1/2
D80 @ ISO 1600, f/3.5, 1/20
a100 @ ISO 200, f/3.5, 1/8
a100 @ ISO 1600, f/4.5, 1/40