Facts About Lenses For Digital
Cameras
The thing which confuses most people is that lenses for digital
cameras are quite different from the older, and perhaps more
familiar, 35mm cameras. The reason for this is that digital
cameras, especially Single Lens Reflex (SLR) cameras, have sensors
much smaller than traditional cameras. For example, the diagonal of
most sensors is almost twice as small as 35mm film!
Now if you were using a regular 35mm lens on a digital camera,
the smaller sensor would capture only the middle portion of the
projected image. This will effectively crop the image, so you will
need a lens with a larger focal length to create the same effect.
We use the term 'Focal Length Multiplier' (or FLM) to convert
between digital and 35mm format. For example: a Digital telephoto
200mm lens with a FLM of 1.5 is equivalent to a super-telephoto
300mm (200 x 1.5) lens on a 35mm film.
The better digital SLR cameras are able to use conventional 35mm
lenses. Besides the problem with image size, these older lenses are
significantly heavier than there digital equivalents.
In the pre-digital world, names such as Karl Zeiss were famous
the world over for high quality lenses. You still get these brands
today, but they are probably over-rated and certainly don't justify
there high price-tag. Brands such as Canon and Nikon are getting a
superb reputation for high quality digital lenses. These lenses
also have features which are particularly useful for digital
photographers, features such as auto-focus and vibration
reduction.
Cleaning Digital Camera lenses is no different to cleaning the
lenses of regular cameras: you can purchase a purpose-built lens
cleaning kit from camera stores or online at ebay or amazon.
Alternatively, use a cotton swab with some alcohol. Clean in a
circular motion, and don't apply too much pressure.
Finally, we consider repairing or maintaining lenses. The most
common problem is removing scratches on lenses. Follow these steps:
dismantle lens and each lens element, locate the scratch, you might
get away with a simple repolish , otherwise you'll need to reground
or replace it, reassemble the lens. You might also need to
Relaminate the lens grouping.
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