How Many Mp Camera Is Good

Don't be seduced by the megapixel counts touted in advertising materials and on camera packaging. It's no longer true that the higher a camera'south megapixel count the meliorate.

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Chapter 02
How Many Megapixels Do You REALLY Need?
Don't exist seduced by the megapixel counts touted in advert materials and on camera packaging. It's no longer true that the higher a photographic camera's megapixel count the better. The only thing more than megapixels will give you is the ability to enlarge and crop pictures without private pixels condign visible. Other factors are much more important in determining overall picture show quality.
Output Size
Megapixel resolution plays an important role in how big you can print your pictures. Considering the more megapixels you have, the more particular is recorded, high-resolution cameras allow you to make larger prints or crop shots without worrying most the image's pixel structure becoming visible.

graph
The diagram above provides a guide to the ideal resolutions for 3 popular print sizes. Note that output resolution decreases every bit print size increases because larger prints are viewed from a greater distance.

Paying for pixels yous don't demand is a waste product of money. It's better to invest in a camera with a ameliorate quality lens, larger sensor and more than effective image processor.
You should also consider how well your printer tin reproduce fine item. There's little signal in shooting or scanning pictures at high resolution and creating huge image files unless you accept a printer that can reproduce all the detail in the paradigm.
There comes a betoken across which high output resolution on its ain is irrelevant. Only the pickiest of viewers will await at an A3+ print close upwardly; well-nigh of united states prefer a viewing altitude of one-ii metres. At that distance it's very difficult to see any difference betwixt prints from a 6-megapixel and a x-megapixel camera with the aforementioned sized sensors. (The shots from the 10-megapixel camera have slightly greater potential for enlargement, however.)
Sensor Size and Picture Quality
The size of a photographic camera'south paradigm sensor is the master determinant of picture show quality and the larger the sensor area, the higher the potential for producing summit-quality digital pictures. Equally important is the size of the actual photosites on the sensor that collect the prototype-making lite. The larger the photosites, the more lite they tin can collect and, consequently, the more image information they brand available to the camera'southward image processor. (Details of how to calculate the size of sensor photosites are provided below.

Sensor "Blazon"	Imaging Area dimensions (width x height x diameter in mm)
i/2.vii-inch	5.37 10 four.04 x 6.72
1/2.5-inch	5.76 10 iv.29 ten 7.18
1/1.eight-inch	7.18 x 5.32 x viii.93
1/1.7-inch	7.6 10 v.seven 10 ix.5
2/iii-inch	viii.8 x 6.six x 11.07
4 Thirds	18.0 x 13.5 ten 22.5
APS-C (Canon )	22.two ten fourteen.8 x 26.7
APS-C (Nikon)	23.7 x 15.seven x 28.4
APS-C (Sony)	23.6 10 fifteen.8 10 28.4
(Catechism professional DSLR)	28.one x xviii.seven ten 33.eight
Total Frame (=35mm frame)	36 x 24 x 44.3

For the past couple of years Photo Review has translated the irrational 'measurements' quoted in manufacturers' specifications into dimensions in millimetres so readers know just how small most digicam sensors actually are. The tabular array in a higher place shows the dimensions of some of the most popular digicam and DSLR sensor sizes and, to emphasise the differences betwixt the two camera types we've used blood-red to highlight the digicam section of the table and green for the DSLR department.
Every bit yous tin can encounter, the sensors used in digital SLR cameras are substantially larger. The size differences are easiest to capeesh in the diagram below, which compares the areas of the near pop digicam sensor (ane/ii.five-inch blazon) with three DSLR sensor sizes sensor and a 35mm pic frame.
Calculating Photosite Surface area
If you know the size of a camera'southward prototype sensor and the pixel dimensions of the largest epitome it can produce, it's easy to calculate the surface expanse of its lite-collecting photosites. This is of import because the more light each photosite collects, the less the signal has to be amplified to produce an image and the better the prototype quality volition be.
The actual calculation is straightforward. Simply divide the length of 1 side of the imaging expanse past the number of paradigm pixels that represent to that side. For case, a vi-megapixel camera with a ane/2.v-inch imager produces a high resolution image of 2816 10 2112 pixels. Dividing the width of the sensor (5.76 mm) by 2816 pixels gives us 5.76 ø·2816 = 0.0020454 mm (or 2.045 microns).
The tabular array below shows a range of typical photosite sizes for current consumer digicams in red and DSLR cameras in green with typical examples for each resolution category.

Photographic camera Resolution	Sensor Type	Image Resolution (pixels)	Photosite surface area microns)
six megapixels (i)	one/2.5-inch	2816 10 2112	2.045 x ii.045
7.1-megapixels (2)	one/two.5-inch	3072 10 2304	1.875 x ane.875
8 megapixels (3)	1/2.5-inch	3264 x 2448	1.76 x i.76
10 megapixels (four)	1/1.viii-inch	3648 x 2736	ane.97 ten 1.97
six.ane megapixels (five)	23.7 x 15.6	3008 x 2000	7.88 ten 7.88
x.0 megapixels (six)	17.three ten 13.0	3648 x 2736	iv.74 x 4.74
ten.0 megapixels (vii)	23.five x 15.7	3872 x 2592	6.07 ten 6.07
10.1 megapixels (viii)	28.one ten 18.7	3888 x 2592	7.23 x 7.23
12.eight megapixels (9)	35.viii x 23.ix	4368 x 2912	8.19 x 8.19

(1) Nikon Coolpix L6 (2) Olympus SP550UZ (3) Sony Cyber-shot DSC-T100
(four) Canon PowerShot G7 (5) Nikon D40, (6) Olympus E-410, (7) Pentax K10D, (viii) Canon EOS-1D Marking 3, (9) Canon EOS5D

Photosite Size and Picture Quality
The surface area of a sensor'due south photosites dictates the number of photons (particles of light) it can capture. The more photons collected, the more than information the camera can process – and the less the epitome is affected by the background noise that is generated by all electronic devices, which is relatively abiding.

Image noise can affect digital photographs under a multifariousness of situations, including:

* When the number of photons (the fundamental 'particles' of light) striking the sensor is very low;
* When the photographic camera's sensitivity (ISO) is gear up to a loftier value;
* When the temperature of the sensor is high,
* When there are errors in the transmission of the signal from the sensor to the processor, and
* When the digital image signal is amplified substantially.

The diagram below illustrates why larger photosites are less afflicted past noise than smaller photosites.

PRPG12_pg12A
The larger photosite on the left tin collect many more than photons of light than the smaller photosite on the right. Simply the amount of groundwork noise is the same for both photosites. Consequently, the larger photosite has a much better signal-to-noise ratio. It tin can also collect more light with the aforementioned exposure time and, therefore, respond with higher sensitivity.

Identifying Image Noise
In nigh cases, racket tin only exist seen when the image is enlarged substantially – at least 200 times. Noise-afflicted pictures look 'grainy'. Sometimes you may encounter a blueprint of tiny white or coloured dots, scattered randomly throughout the image. Noise also reduces the sharpness of edges between bright and dark areas in the moving picture and tin make it look unsharp and a niggling apartment.
Sometimes dissonance can only be seen in shadowed areas, where exposure levels are low. It is common for this shadow noise to bear witness a design of coloured dots. Long exposures are frequently associated with 'hot' or 'stuck' pixels, which can be seen as a design of bright and coloured dots that is repeated in all shots taken under the same conditions.

PRPG12_pg12B

PRPG12_pg12C
Enlarged sections of two identical shots taken with ISO 200 (left) and ISO 1600 sensitivity, showing typical image noise.
Sensor Size and Tonal Reproduction
Sensor size can also influence the photographic camera's ability to record a total range of tones from white to blackness. Our regular camera tests consistently evidence that cameras with smaller sensors fail to achieve this in vivid conditions. It's common to notice blown-out highlights and blocked up shadows in such shots. In contrast, DSLR sensors with larger photosites tin can usually record the total dynamic range in the subject field (although you lot may need to shoot raw files in society to excerpt all the highlight and shadow details in bright sunshine).

PRPG12_pg13A

PRPG12_pg13B
The illustration above has been cropped from a shot taken with a high-resolution digicam in brilliant sunlight. Notation the lack of detail in the bright areas on the left wall of the firm and likewise nether the verandah near the front door. Dissimilarity these areas with a similar shot taken with a DSLR camera, which tin capture a full range of tones in both brightly-lit and shadowed areas because of its larger photosites.

Lens Quality
The size and quality of a camera's lens can influence image quality at least as much every bit the sensor'due south megapixel count. In that location's a big difference between a minor, inexpensive drinking glass lens that you might discover on an entry-level digicam and the loftier quality, multicoated lenses you would purchase for a DSLR. Five megapixels is probably the limit of resolving ability for most bespeak-and-shoot camera lenses. Beyond a sure point, diffraction will begin to reduce the resolving power of the lens-plus-sensor system, as nosotros take discovered from Imatest tests on many 8- and 10-megapixel digicams.
A farther consideration is the way the photographic camera'south prototype processor handles the image data. In many digicams, the image processor automatically sharpens the image past default. This can further degrade picture quality, especially if it's already been reduced past diffraction. It'south not uncommon to find a 10-megapixel digicam with worse performance than a 6-megapixel camera with a similar-sized sensor.
Subject lighting will also play a role in prototype quality, especially with small-sensor digicams. In dim atmospheric condition, photographers are forced to increase ISO speeds. However, with a modest-sensor digicam, this will increase image dissonance, thereby reducing epitome quality. As nosotros've outlined above, larger photosites produce less image noise and requite photographers more flexibility with ISO settings. Shooting at ISO 800 may be feasible on a DSLR while the aforementioned setting on a digicam will probably produce very noise-afflicted images.

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