HP Photosmart 720 vs. HP Photosmart 945
Comparison
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| HP Photosmart 720 | HP Photosmart 945 | ||||
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Megapixels
3.34
5.10
Max. image resolution
2048 x 1536
2608 x 1952
Sensor
Sensor type
CCD
CCD
Sensor size
1/1.8" (~ 7.11 x 5.33 mm)
1/1.8" (~ 7.11 x 5.33 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 »
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 »
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| HP Photosmart 720 | HP Photosmart 945 | |
Surface area:
| 37.90 mm² | vs | 37.90 mm² |
Difference: 0 mm² (0%)
720 and 945 sensors are the same size.
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.
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.
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.
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: 3.91 µm² (52%)
A pixel on HP 720 sensor is approx. 52% bigger than a pixel on HP 945.
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.
Higher pixel density means smaller pixels and lower pixel density means larger pixels.
To learn about the accuracy of these numbers,
click here.
Specs
HP 720
HP 945
Total megapixels
Effective megapixels
Optical zoom
3x
8.1x
Digital zoom
Yes
Yes
ISO sensitivity
Auto, 100, 200, 400
Auto, 100, 200, 400
RAW
Manual focus
Normal focus range
20 cm
50 cm
Macro focus range
20 cm
10 cm
Focal length (35mm equiv.)
34 - 102 mm
37 - 300 mm
Aperture priority
No
Yes
Max. aperture
f2.6 - f4.7
f2.8 - f3.1
Metering
Centre weighted
Centre weighted, Matrix, Spot
Exposure compensation
±1.5 EV (in 1/2 EV steps)
±3 EV (in 1/3 EV steps)
Shutter priority
No
Yes
Min. shutter speed
2 sec
16 sec
Max. shutter speed
1/1000 sec
1/2000 sec
Built-in flash
External flash
Viewfinder
Optical (tunnel)
Electronic
White balance presets
6
6
Screen size
1.6"
2"
Screen resolution
61,600 dots
180,000 dots
Video capture
Max. video resolution
Storage types
MultiMedia, Secure Digital
MultiMedia, Secure Digital
USB
USB 1.0
USB 1.0
HDMI
Wireless
GPS
Battery
AA (4) batteries (NiMH recommended)
AA (4) batteries (NiMH recommended)
Weight
266 g
400 g
Dimensions
118 x 75 x 53 mm
123 x 85 x 85 mm
Year
2002
2003
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Diagonal
Diagonal is calculated by the use of Pythagorean theorem:
where w = sensor width and h = sensor height
| Diagonal = √ | w² + h² |
HP 720 diagonal
The diagonal of 720 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
w = 7.11 mm
h = 5.33 mm
| Diagonal = √ | 7.11² + 5.33² | = 8.89 mm |
HP 945 diagonal
The diagonal of 945 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
w = 7.11 mm
h = 5.33 mm
| Diagonal = √ | 7.11² + 5.33² | = 8.89 mm |
Surface area
Surface area is calculated by multiplying the width and the height of a sensor.
720 sensor area
Width = 7.11 mm
Height = 5.33 mm
Surface area = 7.11 × 5.33 = 37.90 mm²
Height = 5.33 mm
Surface area = 7.11 × 5.33 = 37.90 mm²
945 sensor area
Width = 7.11 mm
Height = 5.33 mm
Surface area = 7.11 × 5.33 = 37.90 mm²
Height = 5.33 mm
Surface area = 7.11 × 5.33 = 37.90 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 |
720 pixel pitch
Sensor width = 7.11 mm
Sensor resolution width = 2108 pixels
Sensor resolution width = 2108 pixels
| Pixel pitch = | 7.11 | × 1000 | = 3.37 µm |
| 2108 |
945 pixel pitch
Sensor width = 7.11 mm
Sensor resolution width = 2604 pixels
Sensor resolution width = 2604 pixels
| Pixel pitch = | 7.11 | × 1000 | = 2.73 µm |
| 2604 |
Pixel area
The area of one pixel can be calculated by simply squaring the pixel pitch:
You could also divide sensor surface area with effective megapixels:
Pixel area = pixel pitch²
You could also divide sensor surface area with effective megapixels:
| Pixel area = | sensor surface area in mm² |
| effective megapixels |
720 pixel area
Pixel pitch = 3.37 µm
Pixel area = 3.37² = 11.36 µm²
Pixel area = 3.37² = 11.36 µm²
945 pixel area
Pixel pitch = 2.73 µm
Pixel area = 2.73² = 7.45 µm²
Pixel area = 2.73² = 7.45 µm²
Pixel density
Pixel density can be calculated with the following formula:
One could also use this 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 |
720 pixel density
Sensor resolution width = 2108 pixels
Sensor width = 0.711 cm
Pixel density = (2108 / 0.711)² / 1000000 = 8.79 MP/cm²
Sensor width = 0.711 cm
Pixel density = (2108 / 0.711)² / 1000000 = 8.79 MP/cm²
945 pixel density
Sensor resolution width = 2604 pixels
Sensor width = 0.711 cm
Pixel density = (2604 / 0.711)² / 1000000 = 13.41 MP/cm²
Sensor width = 0.711 cm
Pixel density = (2604 / 0.711)² / 1000000 = 13.41 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:
3. To get sensor resolution we then multiply X with the corresponding ratio:
Resolution horizontal: X × r
Resolution vertical: X
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 → |
|
Resolution horizontal: X × r
Resolution vertical: X
720 sensor resolution
Sensor width = 7.11 mm
Sensor height = 5.33 mm
Effective megapixels = 3.34
Resolution horizontal: X × r = 1585 × 1.33 = 2108
Resolution vertical: X = 1585
Sensor resolution = 2108 x 1585
Sensor height = 5.33 mm
Effective megapixels = 3.34
| r = 7.11/5.33 = 1.33 |
|
Resolution vertical: X = 1585
Sensor resolution = 2108 x 1585
945 sensor resolution
Sensor width = 7.11 mm
Sensor height = 5.33 mm
Effective megapixels = 5.10
Resolution horizontal: X × r = 1958 × 1.33 = 2604
Resolution vertical: X = 1958
Sensor resolution = 2604 x 1958
Sensor height = 5.33 mm
Effective megapixels = 5.10
| r = 7.11/5.33 = 1.33 |
|
Resolution vertical: X = 1958
Sensor resolution = 2604 x 1958
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 |
720 crop factor
Sensor diagonal in mm = 8.89 mm
| Crop factor = | 43.27 | = 4.87 |
| 8.89 |
945 crop factor
Sensor diagonal in mm = 8.89 mm
| Crop factor = | 43.27 | = 4.87 |
| 8.89 |
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).
720 equivalent aperture
Crop factor = 4.87
Aperture = f2.6 - f4.7
35-mm equivalent aperture = (f2.6 - f4.7) × 4.87 = f12.7 - f22.9
Aperture = f2.6 - f4.7
35-mm equivalent aperture = (f2.6 - f4.7) × 4.87 = f12.7 - f22.9
945 equivalent aperture
Crop factor = 4.87
Aperture = f2.8 - f3.1
35-mm equivalent aperture = (f2.8 - f3.1) × 4.87 = f13.6 - f15.1
Aperture = f2.8 - f3.1
35-mm equivalent aperture = (f2.8 - f3.1) × 4.87 = f13.6 - f15.1
Enter your screen size (diagonal)
My screen size is
inches
Actual size is currently adjusted to screen.
If your screen (phone, tablet, or monitor) is not in diagonal, then the actual size of a sensor won't be shown correctly.
If your screen (phone, tablet, or monitor) is not in diagonal, then the actual size of a sensor won't be shown correctly.