Yakumo Mega Image 55cx vs. Praktica Dpix 750z

Comparison

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Mega Image 55cx image
vs
Dpix 750z image
Yakumo Mega Image 55cx Praktica Dpix 750z
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Megapixels
5.00
7.21
Max. image resolution
2592 x 1944
3027 x 2304

Sensor

Sensor type
CCD
CCD
Sensor size
1/1.8" (~ 7.11 x 5.33 mm)
1/2.5" (~ 5.75 x 4.32 mm)
Sensor resolution
2579 x 1939
3096 x 2328
Diagonal
8.89 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
1.53 : 1
(ratio)
Yakumo Mega Image 55cx Praktica Dpix 750z
Surface area:
37.90 mm² vs 24.84 mm²
Difference: 13.06 mm² (53%)
55cx sensor is approx. 1.53x bigger than Dpix 750z sensor.
Note: You are comparing cameras of different generations. There is a 3 year gap between Yakumo 55cx (2005) and Praktica Dpix 750z (2008). All things being equal, newer sensor generations generally outperform the older.
Pixel pitch
2.76 µm
1.86 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: 0.9 µm (48%)
Pixel pitch of 55cx is approx. 48% higher than pixel pitch of Dpix 750z.
Pixel area
7.62 µm²
3.46 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: 4.16 µm² (120%)
A pixel on Yakumo 55cx sensor is approx. 120% bigger than a pixel on Praktica Dpix 750z.
Pixel density
13.16 MP/cm²
28.99 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: 15.83 µm (120%)
Praktica Dpix 750z has approx. 120% higher pixel density than Yakumo 55cx.
To learn about the accuracy of these numbers, click here.



Specs

Yakumo 55cx
Praktica Dpix 750z
Crop factor
4.87
6.02
Total megapixels
Effective megapixels
Optical zoom
Yes
Yes
Digital zoom
Yes
Yes
ISO sensitivity
Auto, 50, 100, 200, 400, 800
Auto, 50, 100, 200, 400, 800, 1600
RAW
Manual focus
Normal focus range
23 cm
40 cm
Macro focus range
10 cm
15 cm
Focal length (35mm equiv.)
34 - 102 mm
38 - 113 mm
Aperture priority
No
Yes
Max. aperture
f2.6 - f3.4
Max. aperture (35mm equiv.)
f12.7 - f16.6
n/a
Metering
Centre weighted
Centre weighted, Spot
Exposure compensation
±2 EV (in 1/2 EV steps)
±2 EV (in 1/3 EV steps)
Shutter priority
No
Yes
Min. shutter speed
1 sec
8 sec
Max. shutter speed
1/2000 sec
1/2000 sec
Built-in flash
External flash
Viewfinder
Optical
None
White balance presets
7
Screen size
1.6"
2.5"
Screen resolution
85,000 dots
Video capture
Max. video resolution
Storage types
CompactFlash type I
SDHC, Secure Digital
USB
USB 1.1
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
4x AA
2x AA
Weight
367 g
140 g
Dimensions
108 x 67 x 46 mm
90 x 61 x 27 mm
Year
2005
2008




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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

Yakumo 55cx diagonal

The diagonal of 55cx sensor is not 1/1.8 or 0.56" (14.1 mm) as you might expect, but approximately two thirds of that value - 8.89 mm. If you want to know why, see sensor sizes.

w = 7.11 mm
h = 5.33 mm
Diagonal =  7.11² + 5.33²   = 8.89 mm

Praktica Dpix 750z diagonal

The diagonal of Dpix 750z 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.

55cx sensor area

Width = 7.11 mm
Height = 5.33 mm

Surface area = 7.11 × 5.33 = 37.90 mm²

Dpix 750z 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

55cx pixel pitch

Sensor width = 7.11 mm
Sensor resolution width = 2579 pixels
Pixel pitch =   7.11  × 1000  = 2.76 µm
2579

Dpix 750z pixel pitch

Sensor width = 5.75 mm
Sensor resolution width = 3096 pixels
Pixel pitch =   5.75  × 1000  = 1.86 µm
3096


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

55cx pixel area

Pixel pitch = 2.76 µm

Pixel area = 2.76² = 7.62 µm²

Dpix 750z pixel area

Pixel pitch = 1.86 µm

Pixel area = 1.86² = 3.46 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

55cx pixel density

Sensor resolution width = 2579 pixels
Sensor width = 0.711 cm

Pixel density = (2579 / 0.711)² / 1000000 = 13.16 MP/cm²

Dpix 750z pixel density

Sensor resolution width = 3096 pixels
Sensor width = 0.575 cm

Pixel density = (3096 / 0.575)² / 1000000 = 28.99 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

55cx sensor resolution

Sensor width = 7.11 mm
Sensor height = 5.33 mm
Effective megapixels = 5.00
r = 7.11/5.33 = 1.33
X =  5.00 × 1000000  = 1939
1.33
Resolution horizontal: X × r = 1939 × 1.33 = 2579
Resolution vertical: X = 1939

Sensor resolution = 2579 x 1939

Dpix 750z sensor resolution

Sensor width = 5.75 mm
Sensor height = 4.32 mm
Effective megapixels = 7.21
r = 5.75/4.32 = 1.33
X =  7.21 × 1000000  = 2328
1.33
Resolution horizontal: X × r = 2328 × 1.33 = 3096
Resolution vertical: X = 2328

Sensor resolution = 3096 x 2328


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


55cx crop factor

Sensor diagonal in mm = 8.89 mm
Crop factor =   43.27  = 4.87
8.89

Dpix 750z 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).

55cx equivalent aperture

Crop factor = 4.87
Aperture = f2.6 - f3.4

35-mm equivalent aperture = (f2.6 - f3.4) × 4.87 = f12.7 - f16.6

Dpix 750z 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 Praktica Dpix 750z, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Praktica Dpix 750z is 6.02

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