Question on lens


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Dec 23, 2009
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#1
Hi, I have a EF-S55-250mm f4-5.6 IS

Does the "f4-5.6" refer to the aperture?

Does this mean that when I am using the lens, I must set the camera's apperture to within the f4-5.6 range?

What happens if I set the camera's aperture outside the range?

Thanks in advance
 

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Jul 3, 2009
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#2
it means that at 55, the biggest/ max aperture is 4, while at 250, the biggest/ max aperture is 5.6.

if you are at 55, you can still set the aperture to...say 8, that mean you will have a smaller aperture.
 

Dec 23, 2009
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#3
it means that at 55, the biggest/ max aperture is 4, while at 250, the biggest/ max aperture is 5.6.

if you are at 55, you can still set the aperture to...say 8, that mean you will have a smaller aperture.
Thanks. So if at 55 I set the camera aperture to 8, the actual aperture (camera plus lens) will be 4 (because the max aperture for the lens is 4)?

What if at 55 I set the camera aperture to 2, will the actual aperture (camera plus lens) be 2?
 

Jul 3, 2009
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#4
Thanks. So if at 55 I set the camera aperture to 8, the actual aperture (camera plus lens) will be 4 (because the max aperture for the lens is 4)?

What if at 55 I set the camera aperture to 2, will the actual aperture (camera plus lens) be 2?
huh?? if you set it to 8 at 55, then the aperture will be 8...

since the biggest/ max aperture is 4, you wont be able to go to 2. It will not show 2 on your camera no matter how you roll the scroll...

http://en.wikipedia.org/wiki/Aperture
 

Rashkae

Senior Member
Nov 28, 2005
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#5
Thanks. So if at 55 I set the camera aperture to 8, the actual aperture (camera plus lens) will be 4 (because the max aperture for the lens is 4)?

What if at 55 I set the camera aperture to 2, will the actual aperture (camera plus lens) be 2?
Have you read your manual, or tried to google "aperture"?
 

Dec 23, 2009
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#6
huh?? if you set it to 8 at 55, then the aperture will be 8...

since the biggest/ max aperture is 4, you wont be able to go to 2. It will not show 2 on your camera no matter how you roll the scroll...

http://en.wikipedia.org/wiki/Aperture
OK thanks, the camera will automatically set the max aperture based on the lens I am using.
 

Dec 23, 2009
17
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#7
huh?? if you set it to 8 at 55, then the aperture will be 8...

since the biggest/ max aperture is 4, you wont be able to go to 2. It will not show 2 on your camera no matter how you roll the scroll...

http://en.wikipedia.org/wiki/Aperture
Have you read your manual, or tried to google "aperture"?
Yup thanks. Francis kindly answered my question already.

I just keep forgetting that the bigger the f number the smaller the aperture and vice versa
 

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