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Not all pixels are created equal

As mentioned above, the physical size of lenses and image sensors affect the quality of images they create.  Consider that many image sensors and lenses have not changed in size while the number of individual pixels continue to increase with each model year, as technology allows them to be made smaller.  Pixels are becoming so small that less light falls directly into them, instead some of it bounces off the raised walls of each cell, reducing quality and increasing digital noise.

Digital Single-Lens-Reflex (DSLR) & Interchangeable Lens Cameras' (ILC) image sensors are several times larger than Point & Shoot (P&S) or Compact camera sensors.  Rather than cramming more tiny pixels onto a bigger sensor, DSLR & ILC manufacturers make the pixels larger allowing more light to fall into each one.  In combination with large lenses that are easier to manufacture to high standards, image quality is much better than with P&S models of the same megapixel rating.



Point & Shoot (P&S) or DSLR / ILC?

Most folks will be happy with a compact P&S camera, combining portability and affordability.  In general, long-time Japanese camera brands are the best choice for performance and housing options, but make sure to research whether or not a compatible housing is available.  Touch-screen cameras won't allow much control in a housing, so avoid those.  Superzoom models tend to have a large lens making housings either impractical or the lens port severely obstructs the built-in flash.  Cameras with a 3 or 4x zoom are ideal.  Canon, Olympus, Sony, and Casio sell housings for some but not all current models. These are ideal in terms of size, cost, and access to most camera functions.  Price of a decent camera and housing should be somewhere between $400 - $700 dollars.  In the USA Ikelite builds housings for a wide range of current models and expanded options for an external flash and wide conversion lenses.

P&S cameras are especially good for close-ups of stationary or slow-moving subjects, some cameras able to produce nearly life size magnification while maintaining a comfortable working distance between 3 - 5 inches from the lens.  Macro capability with flash varies so I recommend you try out a few models before buying.

Using the built-in lens and flash, these cameras are poor to good for normal and wide scenes.  Some housings accommodate add-on lenses and flash for better wide-angle performance at considerable cost.  Because the flash is so close to the lens, backscatter or light reflected by particles in the water, are a major problem.

In general, images taken with even the best P&S camera are just marginally acceptable for publication.  This is due to physical limitations of tiny lenses and image sensors when compared to DSLR's of identical megapixel (Mp) rating.  Reduced sharpness, optical aberrations, and noise are problems apparent with most P&S images.  However these shortcomings are not obvious to the untrained eye and most users will be satisfied with their work.

ILC cameras are a recent introduction with image quality on-par with DSLR's and prices to match.  Unfortunately just a few models are supported with underwater housings.  As this market segment grows there will undoubtedly be more options available.  The biggest advantage of the ILC format is full-time rapid autofocus while shooting video, a feature only available with Sony DSLR's with a transparent mirror.

Cost LO HI
Size SM LG
Image Preview YES NO
Acc. Lenses FEW YES
Acc. Flash FEW YES
Shutter Lag YES NO
Image Quality


RAW format