Lens Newbie

[Nabil-A]

Im preparing for my DSLR debut and would like to know a little more about lens for DSLR's.

Im a G6 owner at present, planning on purchasing a 20D soon, ive reviewed through the lens recommendations sticky, but am curious about the following issue. Please be gentle i am new to this.

On a P&S aperture settings are adjustable ie F2-F8 etc.. just wondering with a lens say EF 50 f/1.8, does this mean this lens is only able to provide one aperture setting? or is it the largest aperture possible with this lens?

What are the main differences, please someone kind enough to explain without putting the torch to me..

[CRE@TE]

1.8 is the largest. I think the smallest on the 1.8 is f - 22

[Dante King]

SLR lenses alway list the largest apeture.

[tiching99]

How about when there are 2 aperture sizes?
eg.
28-105mm 3.5-4.5 II USM
Does that mean that the minimum aperture size is f3.5 and maximum is f4.5?

and yes .. im a newbie

oh and .. what do people mean when they say "prime" .. in relation to lenses (i think)

thanks guys/gals

[DAMphyne]

The 3.5-4.5 means the lens has a variable Maximum F-stop, at 28mm the max is F3.5, at 105mm the max is F4.5. This happens with zoom lenses, the lens elements inside the lens move and vary the largest opening because of their distance from the sensor.

A "prime" lens is NOT a zoom, simple as that.

[robertwgross]

SLR lenses alway list the largest apeture.

Sometimes SLR lenses list the ONLY aperture.

Case in point, I had a cheap mirror lens one time. One aperture is all you get.

It was better than nothing, but not much better.

---Bob Gross---

[Dante King]

I guess that still makes it the largest then! LOL. What lens was that Bob?

[CyberDyneSystems]

All those mirror lenses have a fixed aperture as far as I know.