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Camera

# Parameters

## 快门

### 光圈与快门

A档也就是光圈优先档，在光圈优先的情况下，我们可以通过改变光圈的大小来轻松地控制景深，相机会在保证曝光量的前提下自动为其配备合适的快门速度。

# Concepts

• 单反：digital single-lens reflex cameras (DSLRs).
• Mirrorless interchangeable-lens cameras (MILCs).

## APS-C

Advanced Photo System type-C (APS-C) is an image sensor format approximately equivalent in size to the Advanced Photo System "classic" negatives of 25.1 × 16.7 mm, an aspect ratio of 3:2.

The quality of the image from an APS-C sensor is higher when compared to a smaller sensor due to its larger size which allows it to collect more light. However, compared to a full-frame camera, image quality is lower, particularly at high ISO values (shooting with little light).

SENSOR SIZE:

Full Frame = same size as a 35mm film frame
APS-C = same size as APS-C film. Approximately a 1.5x crop factor vs 35mm or Full Frame.
APS-H: Same size aS APS-H Film. 1.3x crop factor.


The birth of 35mm film is the result of Thomas Edison bargaining with George Eastman (Kodak) for film for his Kinetoscope (first motion picture system 1889), when Kodak was making roll film in 70mm width. Edison needs sprocket holes on each side to transport the film in his movie camera. The space between the sprocket holes allowed an image 24mm wide. The film travel was vertical; the height of the image was set to 18mm. For years the standard for motion pictures was 24mm by 18mm. Then Leica manufactured the full frame: 24 by 36mm image (Full Frame).

In 1996, Kodak headed a consortium (Kodak - Fuji - Konica - Nikon -others) to make a still camera utilizing 24mm film. The idea was a hybrid camera with film that carried both a chemical and a digital image. The classification was Advanced Photo System or APS for short.

The 24mm wide film (APS) had three aspect ratios. H for High Definition 16:9 (same as today's HD TV's), C for Classic format 16mm x 24mm ratio 1.5 (same as 4x6 print). P for Panoramic 4 x 11 prints.

The APS System was a failure mainly because the 35mm cameras of the day were advancing due to onboard chip logic and the introduction of the digital camera.

## BSI

A traditional, front-illuminated digital camera is constructed in a fashion similar to the human eye, with a lens at the front and photodetectors at the back. This traditional orientation of the sensor places the active matrix of the digital camera image sensor on its front surface and simplifies manufacturing. The matrix and its wiring, however, reflect some of the light, and thus the photocathode layer can only receive the remainder of the incoming light; the reflection reduces the signal that is available to be captured.

A back-illuminated sensor contains the same elements, but orientates the wiring behind the photocathode layer by flipping the silicon wafer during manufacturing and then thinning its reverse side so that light can strike the photocathode layer without passing through the wiring layer.

### Compared to CCD

CCD (charge-coupled device) sensors are typically used in compact cameras because there's nothing obstructing the light and keeping it from hitting the photo diodes. That means even at smaller sizes, CCDs are more sensitive than FI (front-illuminated) CMOS sensors. BSI CMOS sensors solve that problem, though.

At the same time, CMOS sensors offer faster performance than CCDs as well as better battery life and heat dissipation, so BSI CMOS sensors are a popular choice.

## CCD, CMOS

The CCD (Charged Coupled Device) has on its surface, photosites in a grid pattern. Each sight consists of a photodiode to capture light and storage area to hold the electric charge generated by a photon hit. The charge is moved out of the photosites into another chip for processing into an image.

The CMOS (Complementary Metal Oxide Semiconductor) consists of photosites and an area in the chip to process the signals into an image. Thus the CMOS saves power and processes the data faster.

The CCD requires additional chips and consumes more power. Because the CCD must move charges around, it takes more time to assemble an image.

## TFT

Active-matrix LCDs depend on thin film transistors (TFT).

thin-film transistors (TFTs).

# Fujifilm

## X-trans sensor

Fujifilm says, X-Trans avoids the Anti-alising filter, thus adds more photons to sensors.