F-stops in lens vs F-stops in camera


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Jan 17, 2003
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#1
Hi,

There is something that is always bemusing me. In SLR or DSLR, we need to attach lens to the camera body. And at the same time, these lens come with F-stops like F1.8, F5.6 etc... However, the the camera body, we can also select the F-stops. So for instance, I can attach a 50mm F1.8 lens to my camera body, yet still select F5.6 in the camera. In a normal digital camera, I can simply just select the F-stop from the camera to have the DOF I want... but in SLR and DSLR, there are two F-stops.... :(

So what is the difference between the F-stop in the lens, and the F-stop in the camera?

TIA

Trendmatrix
 

ckiang

Senior Member
#2
Originally posted by trendmatrix
Hi,

There is something that is always bemusing me. In SLR or DSLR, we need to attach lens to the camera body. And at the same time, these lens come with F-stops like F1.8, F5.6 etc... However, the the camera body, we can also select the F-stops. So for instance, I can attach a 50mm F1.8 lens to my camera body, yet still select F5.6 in the camera. In a normal digital camera, I can simply just select the F-stop from the camera to have the DOF I want... but in SLR and DSLR, there are two F-stops.... :(

So what is the difference between the F-stop in the lens, and the F-stop in the camera?

TIA

Trendmatrix
Same. On most cameras, you typically set it on the camera. The camera will set the lens to the desired f-stop. On some Nikon cameras, you can choose to set the f-stop on the lens as well.

Regards
CK
 

Jan 17, 2003
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#3
Originally posted by ckiang
Same. On most cameras, you typically set it on the camera. The camera will set the lens to the desired f-stop. On some Nikon cameras, you can choose to set the f-stop on the lens as well.

Regards
CK
Hi CK,

thank you for your reply. IF there are the same, then what does it means if I attach a 50mm F1.8 lens to a camera body which I have selected a F5.6? Does it means the F-stop is now 1.8 or 5.6? Or do I add/multiply/divide them up :dunno: ?

Or is it the F-stop in the lens is no use one? And everything will be over-ridden by the camera settings?

Regards,
TM
 

ckiang

Senior Member
#4
Originally posted by trendmatrix
Hi CK,

thank you for your reply. IF there are the same, then what does it means if I attach a 50mm F1.8 lens to a camera body which I have selected a F5.6? Does it means the F-stop is now 1.8 or 5.6? Or do I add/multiply/divide them up :dunno: ?

Or is it the F-stop in the lens is no use one? And everything will be over-ridden by the camera settings?

Regards,
TM
Oh sorry I think I might have misunderstood your question. ;p

The 1.8 in 50mm f/1.8 refers to the maximum aperture of the lens, i.e. f/1.8. The lens can probably do f/1.8 to f/22. If you set f/5.6 on the camera or on the lens (if the camera support that), you get same results.

Regards
CK
 

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#5
Originally posted by ckiang
Oh sorry I think I might have misunderstood your question. ;p

The 1.8 in 50mm f/1.8 refers to the maximum aperture of the lens, i.e. f/1.8. The lens can probably do f/1.8 to f/22. If you set f/5.6 on the camera or on the lens (if the camera support that), you get same results.

Regards
CK
Oh I see... the F1.8 is the max aperture... That solves my query.. Thanks CK for your help.

Regards,
TM
 

klein

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Feb 18, 2003
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#6
so if my lens fstop is 4-5 does it mean my max aperture i can select is also 4-5??? what if i select another? will the pics blur out or something?
 

eos

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Jan 13, 2003
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#7
Those are the max apertures you can have for both extremes of a zoom range. For example, a 28-105mm f/3.5-4.5 means you can get max apertures of f/3.5 at 28mm and f/4.5 at 105mm.
 

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