BenQ DC C740 vs. BenQ DC C840

Comparison

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DC C740 image
vs
DC C840 image
BenQ DC C740 BenQ DC C840
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Megapixels
7.00
8.00
Max. image resolution
3072 x 2304
3264 x 2448

Sensor

Sensor type
CCD
CCD
Sensor size
1/2.5" (~ 5.75 x 4.32 mm)
1/2.5" (~ 5.75 x 4.32 mm)
Sensor resolution
3051 x 2294
3262 x 2453
Diagonal
7.19 mm
7.19 mm
Sensor size comparison
Sensor size is generally a good indicator of the quality of the camera. Sensors can vary greatly in size. As a general rule, the bigger the sensor, the better the image quality.

Bigger sensors are more effective because they have more surface area to capture light. An important factor when comparing digital cameras is also camera generation. Generally, newer sensors will outperform the older.

Learn more about sensor sizes »

Actual sensor size

Note: Actual size is set to screen → change »
vs
1 : 1
(ratio)
BenQ DC C740 BenQ DC C840
Surface area:
24.84 mm² vs 24.84 mm²
Difference: 0 mm² (0%)
DC C740 and DC C840 sensors are the same size.
Pixel pitch
1.88 µm
1.76 µm
Pixel pitch tells you the distance from the center of one pixel (photosite) to the center of the next. It tells you how close the pixels are to each other.

The bigger the pixel pitch, the further apart they are and the bigger each pixel is. Bigger pixels tend to have better signal to noise ratio and greater dynamic range.
Difference: 0.12 µm (7%)
Pixel pitch of DC C740 is approx. 7% higher than pixel pitch of DC C840.
Pixel area
3.53 µm²
3.1 µm²
Pixel or photosite area affects how much light per pixel can be gathered. The larger it is the more light can be collected by a single pixel.

Larger pixels have the potential to collect more photons, resulting in greater dynamic range, while smaller pixels provide higher resolutions (more detail) for a given sensor size.
Relative pixel sizes:
vs
Pixel area difference: 0.43 µm² (14%)
A pixel on BenQ DC C740 sensor is approx. 14% bigger than a pixel on BenQ DC C840.
Pixel density
28.15 MP/cm²
32.18 MP/cm²
Pixel density tells you how many million pixels fit or would fit in one square cm of the sensor.

Higher pixel density means smaller pixels and lower pixel density means larger pixels.
Difference: 4.03 µm (14%)
BenQ DC C840 has approx. 14% higher pixel density than BenQ DC C740.
To learn about the accuracy of these numbers, click here.



Specs

BenQ DC C740
BenQ DC C840
Crop factor
6.02
6.02
Total megapixels
Effective megapixels
Optical zoom
Yes
Yes
Digital zoom
Yes
Yes
ISO sensitivity
Auto, 50, 100, 200, 400
Auto, 50, 100, 200, 400, 800, 1000
RAW
Manual focus
Normal focus range
80 cm
50 cm
Macro focus range
15 cm
15 cm
Focal length (35mm equiv.)
37 - 112 mm
37 - 112 mm
Aperture priority
Yes
No
Max. aperture
f2.8 - f5.2
Max. aperture (35mm equiv.)
f16.9 - f31.3
n/a
Metering
Centre weighted
Centre weighted
Exposure compensation
±2 EV (in 1/3 EV steps)
±2 EV (in 1/3 EV steps)
Shutter priority
Yes
No
Min. shutter speed
8 sec
8 sec
Max. shutter speed
1/2000 sec
1/2000 sec
Built-in flash
External flash
Viewfinder
None
None
White balance presets
6
6
Screen size
2.5"
2.5"
Screen resolution
150,000 dots
150,000 dots
Video capture
Max. video resolution
Storage types
Secure Digital
SDHC, Secure Digital
USB
USB 2.0 (480 Mbit/sec)
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
2x AA
2x AA
Weight
140 g
140 g
Dimensions
91.5 x 61.5 x 26 mm
91.5 x 61.5 x 32 mm
Year
2006
2007




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Diagonal

Diagonal is calculated by the use of Pythagorean theorem:
Diagonal =  w² + h²
where w = sensor width and h = sensor height

BenQ DC C740 diagonal

The diagonal of DC C740 sensor is not 1/2.5 or 0.4" (10.2 mm) as you might expect, but approximately two thirds of that value - 7.19 mm. If you want to know why, see sensor sizes.

w = 5.75 mm
h = 4.32 mm
Diagonal =  5.75² + 4.32²   = 7.19 mm

BenQ DC C840 diagonal

The diagonal of DC C840 sensor is not 1/2.5 or 0.4" (10.2 mm) as you might expect, but approximately two thirds of that value - 7.19 mm. If you want to know why, see sensor sizes.

w = 5.75 mm
h = 4.32 mm
Diagonal =  5.75² + 4.32²   = 7.19 mm


Surface area

Surface area is calculated by multiplying the width and the height of a sensor.

DC C740 sensor area

Width = 5.75 mm
Height = 4.32 mm

Surface area = 5.75 × 4.32 = 24.84 mm²

DC C840 sensor area

Width = 5.75 mm
Height = 4.32 mm

Surface area = 5.75 × 4.32 = 24.84 mm²


Pixel pitch

Pixel pitch is the distance from the center of one pixel to the center of the next measured in micrometers (µm). It can be calculated with the following formula:
Pixel pitch =   sensor width in mm  × 1000
sensor resolution width in pixels

DC C740 pixel pitch

Sensor width = 5.75 mm
Sensor resolution width = 3051 pixels
Pixel pitch =   5.75  × 1000  = 1.88 µm
3051

DC C840 pixel pitch

Sensor width = 5.75 mm
Sensor resolution width = 3262 pixels
Pixel pitch =   5.75  × 1000  = 1.76 µm
3262


Pixel area

The area of one pixel can be calculated by simply squaring the pixel pitch:
Pixel area = pixel pitch²

You could also divide sensor surface area with effective megapixels:
Pixel area =   sensor surface area in mm²
effective megapixels

DC C740 pixel area

Pixel pitch = 1.88 µm

Pixel area = 1.88² = 3.53 µm²

DC C840 pixel area

Pixel pitch = 1.76 µm

Pixel area = 1.76² = 3.1 µm²


Pixel density

Pixel density can be calculated with the following formula:
Pixel density =  ( sensor resolution width in pixels )² / 1000000
sensor width in cm

One could also use this formula:
Pixel density =   effective megapixels × 1000000  / 10000
sensor surface area in mm²

DC C740 pixel density

Sensor resolution width = 3051 pixels
Sensor width = 0.575 cm

Pixel density = (3051 / 0.575)² / 1000000 = 28.15 MP/cm²

DC C840 pixel density

Sensor resolution width = 3262 pixels
Sensor width = 0.575 cm

Pixel density = (3262 / 0.575)² / 1000000 = 32.18 MP/cm²


Sensor resolution

Sensor resolution is calculated from sensor size and effective megapixels. It's slightly higher than maximum (not interpolated) image resolution which is usually stated on camera specifications. Sensor resolution is used in pixel pitch, pixel area, and pixel density formula. For sake of simplicity, we're going to calculate it in 3 stages.

1. First we need to find the ratio between horizontal and vertical length by dividing the former with the latter (aspect ratio). It's usually 1.33 (4:3) or 1.5 (3:2), but not always.

2. With the ratio (r) known we can calculate the X from the formula below, where X is a vertical number of pixels:
(X × r) × X = effective megapixels × 1000000    →   
X =  effective megapixels × 1000000
r
3. To get sensor resolution we then multiply X with the corresponding ratio:

Resolution horizontal: X × r
Resolution vertical: X

DC C740 sensor resolution

Sensor width = 5.75 mm
Sensor height = 4.32 mm
Effective megapixels = 7.00
r = 5.75/4.32 = 1.33
X =  7.00 × 1000000  = 2294
1.33
Resolution horizontal: X × r = 2294 × 1.33 = 3051
Resolution vertical: X = 2294

Sensor resolution = 3051 x 2294

DC C840 sensor resolution

Sensor width = 5.75 mm
Sensor height = 4.32 mm
Effective megapixels = 8.00
r = 5.75/4.32 = 1.33
X =  8.00 × 1000000  = 2453
1.33
Resolution horizontal: X × r = 2453 × 1.33 = 3262
Resolution vertical: X = 2453

Sensor resolution = 3262 x 2453


Crop factor

Crop factor or focal length multiplier is calculated by dividing the diagonal of 35 mm film (43.27 mm) with the diagonal of the sensor.
Crop factor =   43.27 mm
sensor diagonal in mm


DC C740 crop factor

Sensor diagonal in mm = 7.19 mm
Crop factor =   43.27  = 6.02
7.19

DC C840 crop factor

Sensor diagonal in mm = 7.19 mm
Crop factor =   43.27  = 6.02
7.19

35 mm equivalent aperture

Equivalent aperture (in 135 film terms) is calculated by multiplying lens aperture with crop factor (a.k.a. focal length multiplier).

DC C740 equivalent aperture

Crop factor = 6.02
Aperture = f2.8 - f5.2

35-mm equivalent aperture = (f2.8 - f5.2) × 6.02 = f16.9 - f31.3

DC C840 equivalent aperture

Aperture is a lens characteristic, so it's calculated only for fixed lens cameras. If you want to know the equivalent aperture for BenQ DC C840, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for BenQ DC C840 is 6.02

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