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EF-S 18-55mm f/3.5-5.6 IS lens problem?
#1
I recently purchased this lens based on Photozone's review.



My problem is that with my Canon 350D in manual mode the lens will not allow me to set the aperture to f3.5. Is this dependent on focal length even in manual mode?
#2
aperture 3.5 is only available at 18mm focal length (maybe until 20mm) the further you zoom in, the smaller the maximum available aperture gets. at 55mm you can select f/5.6 at the widest. (you know that large apertures carry small numbers e.g.: f/1.4, F/2.8, f/3.5 etc while small apertures carry large numbers, f/5.6, f/8, f/11 etc?)
#3
It's not a bug, it's a feature, so to say.



Lenses like your 18-55/3.5-5-6 are called "variable aperture" zooms for this reason.

Also the lens name is reflecting this fact ... the maximum aperture of f/3.5 is only reached

at (or near) the 18mm setting, while f/5.6 is the maximum aperture available at the 55mm settings.

For focal lengths in between, the maximum aperture is somewhere inbetween f/3.5 and f/5.6.



Opposed to this, a "constant aperture" zoom, like the 70-200/4 can reach f/4 at each and every focal length.



... Rainer
#4
[quote name='Rainer' timestamp='1281014666' post='1508']

It's not a bug, it's a feature, so to say.



Lenses like your 18-55/3.5-5-6 are called "variable aperture" zooms for this reason.

Also the lens name is reflecting this fact ... the maximum aperture of f/3.5 is only reached

at (or near) the 18mm setting, while f/5.6 is the maximum aperture available at the 55mm settings.

For focal lengths in between, the maximum aperture is somewhere inbetween f/3.5 and f/5.6.



Opposed to this, a "constant aperture" zoom, like the 70-200/4 can reach f/4 at each and every focal length.



... Rainer

[/quote]
#5
Yes, as jenbenn says. The maximum aperture is not dependent on the mode you use the camera or lens in, it is purely dependent on the focal length it is set to with this variable aperture zoom lens.

This lens is an 18-55 F/3.5 -F/5.6, which means that it is a zoomlens from 18 to 55 mm, with an aperture of F/3.5 at 18 mm and F/5.6 at 55, and when you zoom from 18-55 the aperture will gradually decrease in size (and go up in number) from 3.5 to 5.6.



There are zoom lenses out there which have a constant maximum aperture throughout their zoom range, but these generally cost a multiple of what you paid for the 18-55 IS, which BTW is a a very good lens, especially for the money.



Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....
#6
Thanks to all for the replies and it look like I screwed up and reposted Ranier's reply by accident.



I thought that a "variable aperture" feature might be true, but I wasn't totally sure not having much experience with lenses of this type.
#7
[quote name='bwoodrum' timestamp='1281015294' post='1511']

I thought that a "variable aperture" feature might be true, but I wasn't totally sure not having much experience with lenses of this type.

[/quote]



Well, Wim had put it even more correct than I did ... the really correct term is a "variable maximum aperture" lens ...

since a "variable aperture" would just mean, that it is not a fixed aperture (like in a mirror lens).
  


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