Help, different Lens

[morpheus]

Hi all, i'm newbee and just one question about lens. Why sometime i see
CANON 100 - 400 / 4.5 - 5.6 L IS USM

and sometime the aperture is just a number (not a range)
CANON 135 / 2.0 L USM

or sometime like this
CANON 16 - 35 / 2.8 L USM

Can you help me to understand, pls
Thanks

[Hellashot]

More expensive lenses will have better apetures. A low to medium cost lense will have an increasing minimum apeture value when you increase your zoom. More expensive lenses will allow you to keep the lowest apeture value even when zooming. It all comes down to what you want to pay for.

[morpheus]

More expensive lenses will have better apetures. A low to medium cost lense will have an increasing minimum apeture value when you increase your zoom. More expensive lenses will allow you to keep the lowest apeture value even when zooming. It all comes down to what you want to pay for.

hi thanks,
u mean that with the 135mm, I can't zoom then?? (the second lens in the list)

[izzypizzy]

correct, the 135mm is fixed at 135mm..

[morpheus]

correct, the 135mm is fixed at 135mm..

and how about EF 50mm f1.4,is this for macro or portrait. I'm said that the 100mm 2.8 is for macro and 50mm F1.4 is good for portrait. I don't understand much. I though that F1.4 is for macro mode. Why the aperture decide these mode ? Help ;-)

[morpheus]

correct, the 135mm is fixed at 135mm..

and how about EF 50mm f1.4,is this for macro or portrait. I'm said that the 100mm 2.8 is for macro and 50mm F1.4 is good for portrait. I don't understand much. I though that F1.4 is for macro mode. Why the aperture decide these mode ? Help ;-)

Someone can help me to understand this, pms :-) Thank you very much

[Jon]

Macro refers to extreme close-ups, generally between 1/2 life-size and 10 x life size (at the sensor/film plane). The 100 mm macro wil focus from infinity all the way down to 1:1 (life-size).

The 50 mm f/1.4 or 50 f/1.8 is a "normal" lens for a 35 mm camera (which means the angle of view is approximately the same as your stereo field of view through your eyes), covering an angle of about 46 degrees. On a Digital Rebel, 10D, 20D it would be a short telephoto. It won't focus close enough to be used as a macro lens unless you buy an accessory (extension tubes, close-up lens, bellows).

A portrait lens is typically a short telephoto, so on the DR et. al. the 50 would qualify as a portrait lens. The 100 mm macro could also be used for portraits; because of the different focal lengths of the two, the effects will be different. Which to use for portraits is a matter of individual preference.