Sony Alpha SLT-A33 vs. Sony Alpha SLT-A77

Comparison

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Alpha SLT-A33 image
vs
Alpha SLT-A77 image
Sony Alpha SLT-A33 Sony Alpha SLT-A77
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Megapixels
14.20
24.30
Max. image resolution
4592 x 3056
6000 x 4000

Sensor

Sensor type
CMOS
CMOS
Sensor size
23.5 x 15.6 mm
23.5 x 15.6 mm
Sensor resolution
4631 x 3067
6058 x 4012
Diagonal
28.21 mm
28.21 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)
Sony Alpha SLT-A33 Sony Alpha SLT-A77
Surface area:
366.60 mm² vs 366.60 mm²
Difference: 0 mm² (0%)
Alpha SLT-A33 and Alpha SLT-A77 sensors are the same size.
Pixel pitch
5.07 µm
3.88 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: 1.19 µm (31%)
Pixel pitch of Alpha SLT-A33 is approx. 31% higher than pixel pitch of Alpha SLT-A77.
Pixel area
25.7 µm²
15.05 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: 10.65 µm² (71%)
A pixel on Sony Alpha SLT-A33 sensor is approx. 71% bigger than a pixel on Sony Alpha SLT-A77.
Pixel density
3.88 MP/cm²
6.65 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: 2.77 µm (71%)
Sony Alpha SLT-A77 has approx. 71% higher pixel density than Sony Alpha SLT-A33.
To learn about the accuracy of these numbers, click here.

Specs

Sony Alpha SLT-A33
Sony Alpha SLT-A77
Crop factor
1.53
1.53
Total megapixels
14.60
24.70
Effective megapixels
14.20
24.30
Optical zoom
Digital zoom
No
No
ISO sensitivity
Auto, 100, 200, 400, 800, 1600, 3200, 6400, 12800, 25600 with boost)
Auto, 100, 200, 400, 800, 1600, 3200, 6400, 12800, 16000
RAW
Manual focus
Normal focus range
Macro focus range
Focal length (35mm equiv.)
Aperture priority
Yes
Yes
Max. aperture
Max. aperture (35mm equiv.)
n/a
n/a
Metering
Multi, Center-weighted, Spot
Multi, Center-weighted, Spot
Exposure compensation
±2 EV (in 1/3 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
1/8000 sec
Built-in flash
External flash
Viewfinder
Electronic
Electronic
White balance presets
6
8
Screen size
3"
3"
Screen resolution
921,000 dots
921,000 dots
Video capture
Max. video resolution
1920x1080 (60p/24p)
Storage types
SD/SDHC/SDXC/Memory Stick Pro Duo/ Pro-HG Duo
SD/SDHC/SDXC/Memory Stick Pro Duo/ Pro-HG Duo
USB
USB 2.0 (480 Mbit/sec)
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
Rechargeable NP-FW50 battery
Rechargeable NP-FM500H battery
Weight
500 g
732 g
Dimensions
124 x 92 x 85 mm
143 x 104 x 81 mm
Year
2010
2011



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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

Sony Alpha SLT-A33 diagonal

w = 23.50 mm
h = 15.60 mm
Diagonal =  23.50² + 15.60²   = 28.21 mm

Sony Alpha SLT-A77 diagonal

w = 23.50 mm
h = 15.60 mm
Diagonal =  23.50² + 15.60²   = 28.21 mm


Surface area

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

Alpha SLT-A33 sensor area

Width = 23.50 mm
Height = 15.60 mm

Surface area = 23.50 × 15.60 = 366.60 mm²

Alpha SLT-A77 sensor area

Width = 23.50 mm
Height = 15.60 mm

Surface area = 23.50 × 15.60 = 366.60 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

Alpha SLT-A33 pixel pitch

Sensor width = 23.50 mm
Sensor resolution width = 4631 pixels
Pixel pitch =   23.50  × 1000  = 5.07 µm
4631

Alpha SLT-A77 pixel pitch

Sensor width = 23.50 mm
Sensor resolution width = 6058 pixels
Pixel pitch =   23.50  × 1000  = 3.88 µm
6058


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

Alpha SLT-A33 pixel area

Pixel pitch = 5.07 µm

Pixel area = 5.07² = 25.7 µm²

Alpha SLT-A77 pixel area

Pixel pitch = 3.88 µm

Pixel area = 3.88² = 15.05 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

Alpha SLT-A33 pixel density

Sensor resolution width = 4631 pixels
Sensor width = 2.35 cm

Pixel density = (4631 / 2.35)² / 1000000 = 3.88 MP/cm²

Alpha SLT-A77 pixel density

Sensor resolution width = 6058 pixels
Sensor width = 2.35 cm

Pixel density = (6058 / 2.35)² / 1000000 = 6.65 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

Alpha SLT-A33 sensor resolution

Sensor width = 23.50 mm
Sensor height = 15.60 mm
Effective megapixels = 14.20
r = 23.50/15.60 = 1.51
X =  14.20 × 1000000  = 3067
1.51
Resolution horizontal: X × r = 3067 × 1.51 = 4631
Resolution vertical: X = 3067

Sensor resolution = 4631 x 3067

Alpha SLT-A77 sensor resolution

Sensor width = 23.50 mm
Sensor height = 15.60 mm
Effective megapixels = 24.30
r = 23.50/15.60 = 1.51
X =  24.30 × 1000000  = 4012
1.51
Resolution horizontal: X × r = 4012 × 1.51 = 6058
Resolution vertical: X = 4012

Sensor resolution = 6058 x 4012


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


Alpha SLT-A33 crop factor

Sensor diagonal in mm = 28.21 mm
Crop factor =   43.27  = 1.53
28.21

Alpha SLT-A77 crop factor

Sensor diagonal in mm = 28.21 mm
Crop factor =   43.27  = 1.53
28.21

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).

Alpha SLT-A33 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 Sony Alpha SLT-A33, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Sony Alpha SLT-A33 is 1.53

Alpha SLT-A77 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 Sony Alpha SLT-A77, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Sony Alpha SLT-A77 is 1.53

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