Summer come and is time for vacation. One of the tools you will use to store those wonderful moments is Digital camera. But the question is how to choose one(in case that you still do not have one)?
This guide is not intended to replace other published guides, but to stress on “forgotten” parameters often crucial for the resulting image.

Main parameters:

  • Number of matrix pixels
  • Zoom

Other parameters:

  • Noise
  • Optics
  • Auto-focus
  • Manual white balance
  • Storage type
  • Interface type
  • Time to run on batteries
  • Usability

Number of matrix pixels

This is one of the most advertised part of Digital camera specifications. Image resolution and from there quality depend on it.

But what is needed matrix size? It usually depends for what the acquired image will be used. In most cases this image will be printed.

“Standard” quality printing is 300 dpi (dots per inch). Standard photo is 10×15 cm (4×6 in) from there (with simplification) we can calculate 4×300=1200 pixels and 6×300=1800 so for ordinary photo you will need image 1200×1800=2.2 Mpixels (approximately).

If we do the same calculation for 20×25 cm(8×10 in) the result is: 7.2 Mpix. And following this procedure you could calculate the needed resolution for desired resulting print size.

NOTE: Probably best will be to have spare pixels if you need to crop the image. More you have – better.

WARNING: Some Digital cameras use interpolated resolution in their specifications, so you need ro read carefully.

ATTENTION: There is no linear dependency between matrix resolution and image quality.

Zoom

Very useful function included in almost all Digital cameras allowing you to Zoom on the object without the need to change the distance between the camera and the object.

In addition this function will allow to crop from initial image everything that is not needed.

Zoom could be “optical” and “digital”.

Optical zoom is “the old school” zoom used in classical 35mm cameras. It uses optical lens to bring the object closer.

Digital zoom is not zoom in definition – instead it enlarges portion of the image using numerical algorithm or if matrix has more pixels than resulting image image is cropped(not common).

Typical numbers for digital cameras are from 3x to 10x for optical zoom and 3x-30x for digital one. Often the two are multiplied (when advertised) resulting 10x-300x zoom.

Quality wise optical zoom is much better than digital. Don’t wonder why your photos are not as sharp when using digital zoom – just use low resolution image for your desktop wallpaper and stretch it to full screen to see the results.

To be continued…

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