f8 VS f22? whats the difference?


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Wenjin

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Aug 7, 2004
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#1
I noticed that the camera lens can bring the f-stop to 8
but the camera enables you to set it to f22 or even higher~~

does f8 mean the same depth-of-field as f22?
does the camera lower the sensitivity of the ccd to achieve f22??
 

#2
f8 is not the same as f22.
I'm assuming you are using a DSLR because there is no PnS or prosumer that has f22 aperture settings.

f22 will give you more depth of field but it will also result in diffraction which softens the final result, assuming that's the min aperture setting.

I'm not sure what you mean by "the lens can bring the f-stop to 8 but the camera enables you to set it to f22 or even higher."

The sensor is not involved in any f-stop setting.
 

Wenjin

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#3
hmm think i got mixed up
cuz usually i see that lenses state the they can go from e.g. 2.8-6.3.
but i suppose that the can go up to 22~~ or higher
 

night86mare

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#4
hmm think i got mixed up
cuz usually i see that lenses state the they can go from e.g. 2.8-6.3.
but i suppose that the can go up to 22~~ or higher
No no no. What I'm thinking is that you see the 2.8 - 6.3 is the maximum aperture (or rather, smallest f-stop number) that the lens can go from a certain range.

i.e. when a lens is 70-300, f/2.8~6.3, it means that maximum aperture at 70mm will be 2.8, and at 300mm will be 6.3.

But anyways, f/8 and f/22 - f/22 will definitely give you a lot more DOF, but more often than not this is not discernible or evident if you're shooting landscapes - more evident when you're shooting stuff like macro.
 

grantyale

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Oct 4, 2004
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#5
hmm think i got mixed up
cuz usually i see that lenses state the they can go from e.g. 2.8-6.3.
but i suppose that the can go up to 22~~ or higher
Usually we say go down to F/22 because it's 1/22 = openning/focal length, meaning only a small hole is open for light.

The F/2.8-6.3 is likely the maximum aperture range at the wide and tele end of a zoom lens, meaning 1/2.8 max at wide angle, 1/6.3 max at telephoto.

==editted==

night86mare you're quick ~

To add one more point - normally beyond F/11 defraction starts to set in so don't close it down too much unless you really need the DOF badly.
 

#6
What is stated on the lens is the maximum aperture that the lens is limited to at a particular zoom length.

At the widest, it is 2.8
At max telephoto zoom, it is 6.3

typically, lenses of 35mm cameras will stop at f22 though there are exceptions
 

night86mare

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#7
To add one more point - normally beyond F/11 defraction starts to set in so don't close it down too much unless you really need the DOF badly.
Also to add on, sometimes you stop down to do stuff like.. Smooth out waves for that blurry smoothed out effect.

That is when you cannot afford ND filters, of course.. =) But in any case, I think the resultant image degradation from ND filters will be almost the same as diffraction effect, so it's not much loss, though I could be wrong. =D
 

surge

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#8
hmm think i got mixed up
cuz usually i see that lenses state the they can go from e.g. 2.8-6.3.
but i suppose that the can go up to 22~~ or higher
what you are looking at must be a zoom lens. some zoom lens have a constant max aperture...say 2.8 meaining when you zoom say from 28 -70mm the max aperture is still 2.8

most cheaper zoom lens do not have a fixed but a variable aperture. say a 28-70/3.5-5.6 it means at 28mm the largest available aperture is 3.5, when you zoom the lens, the largest aperture also changes and at 70mm, you will get 5.6 and nothing lower that that.

think of it like fast cars...a 2.8 constant is like a fast car that can hit 200km/h, but that doesnt mean it can go slow at 50km/h

whereas 5.6 is a slower car, it can go 100km/h or slower but can never reach that of a 2.8.
 

ihub88

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Mar 3, 2007
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#9
No no no. What I'm thinking is that you see the 2.8 - 6.3 is the maximum aperture (or rather, smallest f-stop number) that the lens can go from a certain range.

i.e. when a lens is 70-300, f/2.8~6.3, it means that maximum aperture at 70mm will be 2.8, and at 300mm will be 6.3.

But anyways, f/8 and f/22 - f/22 will definitely give you a lot more DOF, but more often than not this is not discernible or evident if you're shooting landscapes - more evident when you're shooting stuff like macro.
ya lor...shoot spider sometime f32 also not enough
 

zac08

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Feb 21, 2005
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#10
ya lor...shoot spider sometime f32 also not enough
Tat brings me to a point... What is the minimum aperture that a lens is capable of?

I just tried my Tamron macro and it allows me to take it down to f64 when the lens aperture ring only shows up to f32. :think: :dunno:
 

Artosoft

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Aug 31, 2005
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#11
Tat brings me to a point... What is the minimum aperture that a lens is capable of?

I just tried my Tamron macro and it allows me to take it down to f64 when the lens aperture ring only shows up to f32. :think: :dunno:
Macro lens is different. It is the design of macro lens you will lose the stop. At minimum distance (macro distance), the aperture will stop down (1 or 2 stop IIRC, depend on what macro lens) from aperture it can achieve in long distance.

Regards,
Arto.
 

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