Pentax K100D vs. Canon EOS Rebel T3i
Comparison
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| Pentax K100D | Canon EOS Rebel T3i | ||||
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Megapixels
6.10
18.00
Max. image resolution
3008 x 2008
5184 x 3456
Sensor
Sensor type
CCD
CMOS
Sensor size
23.5 x 15.7 mm
22.3 x 14.9 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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| Pentax K100D | Canon EOS Rebel T3i | |
Surface area:
| 368.95 mm² | vs | 332.27 mm² |
Difference: 36.68 mm² (11%)
K100D sensor is approx. 1.11x bigger than Rebel T3i sensor.
Note: You are comparing cameras of different generations.
There is a 5 year gap between Pentax K100D (2006) and Canon Rebel T3i (2011).
All things being equal, newer sensor generations generally outperform the older.
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: 41.97 µm² (228%)
A pixel on Pentax K100D sensor is approx. 228% bigger than a pixel on Canon Rebel T3i.
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
Pentax K100D
Canon Rebel T3i
Total megapixels
6.31
18.70
Effective megapixels
6.10
18.00
Optical zoom
Digital zoom
No
Yes
ISO sensitivity
Auto, 200, 400, 800, 1600, 3200
Auto, 100, 200, 400, 800, 1600, 3200, 6400, (12800 with boost)
RAW
Manual focus
Normal focus range
Macro focus range
Focal length (35mm equiv.)
Aperture priority
Yes
Yes
Max. aperture
Metering
Centre weighted, Multi-segment, Spot
Multi, Center-weighted, Spot, Partial
Exposure compensation
±2 EV (in 1/3 EV, 1/2 EV steps)
±5 EV (in 1/3 EV, 1/2 EV steps)
Shutter priority
Yes
Yes
Min. shutter speed
30 sec
30 sec
Max. shutter speed
1/4000 sec
1/4000 sec
Built-in flash
External flash
Viewfinder
Optical (pentamirror)
Optical
White balance presets
7
6
Screen size
2.5"
3"
Screen resolution
210,000 dots
1,040,000 dots
Video capture
Max. video resolution
1920x1080 (30p/25p/24p)
Storage types
Secure Digital
SDHC, SDXC, Secure Digital
USB
USB 2.0 (480 Mbit/sec)
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
AA (4) batteries (NiMH recommended)
Li-Ion
Weight
560 g
570 g
Dimensions
129.5 x 92.5 x 70 mm
133.1 x 99.5 x 79.7 mm
Year
2006
2011
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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 |
Pentax K100D diagonal
w = 23.50 mm
h = 15.70 mm
h = 15.70 mm
| Diagonal = √ | 23.50² + 15.70² | = 28.26 mm |
Canon Rebel T3i diagonal
w = 22.30 mm
h = 14.90 mm
h = 14.90 mm
| Diagonal = √ | 22.30² + 14.90² | = 26.82 mm |
Surface area
Surface area is calculated by multiplying the width and the height of a sensor.
K100D sensor area
Width = 23.50 mm
Height = 15.70 mm
Surface area = 23.50 × 15.70 = 368.95 mm²
Height = 15.70 mm
Surface area = 23.50 × 15.70 = 368.95 mm²
Rebel T3i sensor area
Width = 22.30 mm
Height = 14.90 mm
Surface area = 22.30 × 14.90 = 332.27 mm²
Height = 14.90 mm
Surface area = 22.30 × 14.90 = 332.27 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 |
K100D pixel pitch
Sensor width = 23.50 mm
Sensor resolution width = 3026 pixels
Sensor resolution width = 3026 pixels
| Pixel pitch = | 23.50 | × 1000 | = 7.77 µm |
| 3026 |
Rebel T3i pixel pitch
Sensor width = 22.30 mm
Sensor resolution width = 5196 pixels
Sensor resolution width = 5196 pixels
| Pixel pitch = | 22.30 | × 1000 | = 4.29 µm |
| 5196 |
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 |
K100D pixel area
Pixel pitch = 7.77 µm
Pixel area = 7.77² = 60.37 µm²
Pixel area = 7.77² = 60.37 µm²
Rebel T3i pixel area
Pixel pitch = 4.29 µm
Pixel area = 4.29² = 18.4 µm²
Pixel area = 4.29² = 18.4 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 |
K100D pixel density
Sensor resolution width = 3026 pixels
Sensor width = 2.35 cm
Pixel density = (3026 / 2.35)² / 1000000 = 1.66 MP/cm²
Sensor width = 2.35 cm
Pixel density = (3026 / 2.35)² / 1000000 = 1.66 MP/cm²
Rebel T3i pixel density
Sensor resolution width = 5196 pixels
Sensor width = 2.23 cm
Pixel density = (5196 / 2.23)² / 1000000 = 5.43 MP/cm²
Sensor width = 2.23 cm
Pixel density = (5196 / 2.23)² / 1000000 = 5.43 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
K100D sensor resolution
Sensor width = 23.50 mm
Sensor height = 15.70 mm
Effective megapixels = 6.10
Resolution horizontal: X × r = 2017 × 1.5 = 3026
Resolution vertical: X = 2017
Sensor resolution = 3026 x 2017
Sensor height = 15.70 mm
Effective megapixels = 6.10
| r = 23.50/15.70 = 1.5 |
|
Resolution vertical: X = 2017
Sensor resolution = 3026 x 2017
Rebel T3i sensor resolution
Sensor width = 22.30 mm
Sensor height = 14.90 mm
Effective megapixels = 18.00
Resolution horizontal: X × r = 3464 × 1.5 = 5196
Resolution vertical: X = 3464
Sensor resolution = 5196 x 3464
Sensor height = 14.90 mm
Effective megapixels = 18.00
| r = 22.30/14.90 = 1.5 |
|
Resolution vertical: X = 3464
Sensor resolution = 5196 x 3464
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 |
K100D crop factor
Sensor diagonal in mm = 28.26 mm
| Crop factor = | 43.27 | = 1.53 |
| 28.26 |
Rebel T3i crop factor
Sensor diagonal in mm = 26.82 mm
| Crop factor = | 43.27 | = 1.61 |
| 26.82 |
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).
K100D 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
Pentax K100D, take the aperture of the lens
you're using and multiply it with crop factor.
Crop factor for Pentax K100D is 1.53
Crop factor for Pentax K100D is 1.53
Rebel T3i 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
Canon Rebel T3i, take the aperture of the lens
you're using and multiply it with crop factor.
Crop factor for Canon Rebel T3i is 1.61
Crop factor for Canon Rebel T3i is 1.61
More comparisons of Pentax K100D:
- Pentax K100D vs. Pentax K10D
- Pentax K100D vs. Pentax K100D Super
- Pentax K100D vs. Nikon D70
- Pentax K100D vs. Canon EOS 40D
- Pentax K100D vs. Canon EOS 300D
- Pentax K100D vs. Nikon D200
- Pentax K100D vs. Fujifilm FinePix S5 Pro
- Pentax K100D vs. Canon EOS 5D Mark II
- Pentax K100D vs. Canon EOS 50D
- Pentax K100D vs. Canon EOS Rebel T3i
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