Lens of 2.8 vs. 4.0

Dear Floyd:

Thanks for replying. The two lenses I am considering are Canon EF-S 18-55mm
vs a Canon EF-S 17-85mm. I would like the extra telephoto function of the
second lens, but I'm concerned that the one higher f-stop that is has might
give me trouble in low light situations. I hope this is the info you are
seeking. Supposedly, the camera I am considering, the Canon EOS 30D,
creates very little noise at ISO 400.

Went to Alaska on a cruise this past summer. You live in an absolutely
beautiful State. I live in the Las Vegas valley in Nevada, where the
mountains are nice but not gorgeous.

Regards,

Pedro

"Floyd L. Davidson" <floyd RemoveThis @apaflo.com> wrote in message
news:871wo5119b.fld@apaflo.com...
> "Pedro" <NOpedro65SPAM RemoveThis @cox.net> wrote:
>>I am thinking of buying a dslr, and I have a choice of one of two lenses.
>>One has less of a telephoto capacity but with a 2.8 f-stop. The other has
>>better capacity but has a 4.0 f-stop. Does the 1.2 difference mean much?
>
> The actual difference is 1 fstop. But you don't mention the
> focal length, so is impossible to actually provide much
> perspective on the significance of your two choices. Likewise,
> there are circumstances where 1 fstop is everything, and others
> where 2x the focal length is everything. Also it makes a
> difference which camera you are using, because alternate (e.g.,
> less expensive) lenses may or may not be available.
>
> Hence, if you want more useful answers you will have to provide
> more useful information about your situation.
>
> --
> Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
> Ukpeagvik (Barrow, Alaska) floyd RemoveThis @apaflo.com
 >> Stay informed about: Lens of 2.8 vs. 4.0 

"Pedro" <NOpedro65SPAM.TakeThisOut@cox.net> wrote:
>Dear Floyd:
>
>Thanks for replying. The two lenses I am considering are Canon EF-S 18-55mm
>vs a Canon EF-S 17-85mm.

I can't really comment on those particular lenses, as I don't
use Canon equipment. There might be other differences that
Canon users will want to point out as significant.

>I would like the extra telephoto function of the
>second lens, but I'm concerned that the one higher f-stop that is has might
>give me trouble in low light situations. I hope this is the info you are
>seeking. Supposedly, the camera I am considering, the Canon EOS 30D,
>creates very little noise at ISO 400.

What kind of photography do you like to do? If a flash doesn't
bother you, go for the 17-85mm and get a good flash. If you
don't like flash... think in terms of other options (which are
not necessarily restricted to the 18-55mm lense).

If you are one of those "wide angle, get half into the picture
yourself" photographers, I'd bet on the 18-55mm being more
useful, flash or no flash.

If you want to be more of a fly on the wall, an f/2.8 zoom with
an even longer focal length might be better (I don't know what
is available for Canon).

Spend the money on what you do the most. And then find cheaper
ways (perhaps less convenient too) for things you don't do so
often. For example, acquire one really good zoom with a wide
aperture in the focal length range you use the most, then take
your pick of things like non-zoom high speed lenses at other
focal lengths and/or slower zooms (either of which will cost less).

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd.TakeThisOut@apaflo.com
 >> Stay informed about: Lens of 2.8 vs. 4.0