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General discussion

Something about LENS

Mar 22, 2005 5:02AM PST

I want to buy a dig cam, and I'm relly new in this matter. I need your need to undestand something or a lot of LENS, mainly the terms: FOCAL LENGTH and LENS APERTURE.
The camera will be used for different purposes: to take pics at closed range and also for landscapes. But mainly the first. What would you recommend me???
Thanks in advance.

Discussion is locked

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Focal Length and Lens Aperture
Mar 22, 2005 7:51AM PST

Here are links to both subjects:

http://www.dpreview.com/learn/?/key=focal%20length

http://www.dpreview.com/learn/?/key=aperture

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You want to take pictures at close range.
This is where focal length is important.

"Close focus" - means how close the lens can be to the subject and still focus. Good for photographing small objects
"Macro" - a special setting on some lenses, that let you focus very close. Good for photographing insects and very small objects.

Things I need to know before suggesting a camera:

Price range in Dollars (USA)
Approximate number of megapixels (3, 4, 5, 7, Cool
Optical Zoom (3X, 4X, 5X, 10X, etc)
Camera Size (small, medium, large)

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Let's see
Mar 25, 2005 12:55AM PST

I assume that you want to get started with a new DSLR camera. Regard the scope of mentioned work, you can hang around with a variety of lenses.

For the landscapes, most likely, you need a wide-angle lense, for example lense with the 20 mm focal length or less, in order to cover the wide angle of scene. For most DSLR camera, the disadvantage comes along with the size of sensor, called " a multiplier. " For example, Canon 20D and Nikon D70 has a 1.6 multiplier. The fact is that the sensor size ( most DSLR camera ) isn't the full frame size as 35mm camera, except Canon 1DS and 1DS Mark II. Therefore, the lense you put on your DSLR will have more focal length. For examle, 24-70mm lense ( for 35mm camera ) becomes 38-112mm lense on Canon 20D. Nevertheless, the lense, when puts on DSLR , becomes a plus for telephoto.

For the aperture, there's a great deal to trade off. The brighter lense is to have the lower F-stop. For example F2.8 is 1-stop brighter than F4. It means that the lower F-stop lense allows more light to be placed on the digital camera sensor or film. But, mostly, shooting the picture below F4 is uncommon in most photography since the pictures definitely lost DOF ( depth of field ). And, here, you need a macro lense for this kind of picture. In other words, a macro lenses are designed for a close-up picture, for example, shooting flowers, insects, and a very detailed thing, at a very close-encouter from your camera.

That's all I can think of. Photographing techniques and books really help. It takes time to learn and understand the photographing information. Hang in there, and be patient. There's no absolutely right or wrong. Good luck.