stupid question?

[Jimmy The Bat]

I own a Nikon d40 with the 18mm-55mm lense.the aperture on the lense says 3.5-5.6,but I can adjust aperture from 3.5-34 manually.I'm pretty sure this is a stupid question,but I guess i just dont understand why this is. thanks for any help.

 

[tirediron]

The only stupid question is the one you don't ask. The 3.5 - 5.6 refers to the maximum aperture (largest opening) that the lens has. At a focal length of 18mm the maximum aperture is f3.5, if you zoom all the way out to 55mm, the maximum aperture will reduce to f5.6.

 

[kundalini]

The f/3.5-5.6 are the maximum apertures (smallest number) at the extents of your zoom range.

f/3.5 at 18mm and f/5.6 at 55mm.


EDIT
^^ beat me to it.

 

[Jimmy The Bat]

So when I go past f5.6, say to like f.22 , Is that really not f22?Sorry if this seems rediculous,I guess I just dont understand why it will go to f36,Thanks

 

[overparduffer]

Let's try this again. I was a little confused myself when I bought my DSLR a couple months ago.

The lens is supposed to adjust to all the way to F36. As the other two said, the 3.5-5.6 is not the full range of the lense. It is only the maximum aperture... and that maximum changes from 3.5 to 5.6 as the lens is zoomed in.

So yes, it will adjust from 3.5 to 36 depending on the zoom.

 

[kundalini]

The maximum aperture f/3.5 at 18mm describes the maximum amount of light (largest opening) that lens will allow to hit the sensor, it is also limited to f/22 (the smallest opening).

At focal length of 55mm, the maximum aperture is f/5.6, which is 1 1/3 stopped down - less light hitting the sensor and will stop down to f/36.

It's all about how much or how little light reaches the sensor....... and of course, the DOF.

 

[ann]

you will be able to use the larger numbers with all focal lengths on the lens. the small numbers will change as you rack the zoom out.

just try this; put your focal lens at 18mm your fstop on 3.5, zoom the lens out to it's longest range and you will see the fstop change on the LCD

 

[Jimmy The Bat]

Thanks for the advice, I definatly understand it better now.