Question on Aperture


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mrericlee

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Sep 27, 2008
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#1
Hi Guys,

I have a dumb question about Canon L lens.

Comparing the f2.8 lens vs. the f4 lens (both L lens), would performance be the same if I am taking landscape and I set to f11 using aperture priority? All else equal.
 

Jan 20, 2009
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#2
sure will be different.... especially 24-105 vs 16-35... two off this lens will get the different even you set the same aperture and speed... mean different lens got different dept of field... did i answer you question and any pro can give advice?
 

Rashkae

Senior Member
Nov 28, 2005
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#3
sure will be different.... especially 24-105 vs 16-35... two off this lens will get the different even you set the same aperture and speed... mean different lens got different dept of field... did i answer you question and any pro can give advice?
He said all else being equal. I think a better example would be a 70-200 f/2.8 vs. a 70-200 f/4.
 

Jan 20, 2009
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#4
if for 70-200mm F4 the main different i think mostly in sharpness of image.... actually i also not very sure with canon equipment, but i think most likely with nikon...!
 

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Rashkae

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Nov 28, 2005
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#5
Hi Guys,

I have a dumb question about Canon L lens.

Comparing the f2.8 lens vs. the f4 lens (both L lens), would performance be the same if I am taking landscape and I set to f11 using aperture priority? All else equal.
In theory, it should be exactly the same if the focal length is the same; but the reality is that the different design constraints can lead to different results. Some manufacturers use higher-quality glass or better coatings in their larger aperture lenses, so you may get slightly better colors or contrast in the "native" 2.8 lens.

If you compare these 2 lenses:

http://www.photozone.de/canon-eos/199-canon-ef-70-200mm-f28-usm-l-is-test-report--review?start=1

http://www.photozone.de/canon-eos/196-canon-ef-70-200mm-f4-usm-l-is-test-report--review?start=1

You'll notice the 70-200 f/4 actually has a higher resolution than the 2.8 at the smaller apertures!
 

Jul 27, 2008
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#6
If both stepped down to say f11, then there should be not much a difference....
However, some lenses have their "sweet spots" at different aperture....(meaning that the lens when stepped down to a certain aperture, they are said to be sharper and etc.)
 

mrericlee

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Sep 27, 2008
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#7
So, reading all your replies... my understanding is the advantage (more light, faster shutter speed) only sets in when I have my aperture set between 2.8 to 4.

Anything above 4, the 2 lens should be equal meaning that my shutter speed can achieve same speed for the same light conditions.
 

Jan 20, 2009
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#8
step down like F4 vs F2.8, the sharpness and detail most performance in good result with F4 lens...! it's correct sir?
 

Rashkae

Senior Member
Nov 28, 2005
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#9
step down like F4 vs F2.8, the sharpness and detail most performance in good result with F4 lens...! it's correct sir?
Depends on the lens. Best to read up on sites like photozone (the link i provided).
 

Rashkae

Senior Member
Nov 28, 2005
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#10
But I guess, the real question is... Can you tell the difference yourself if you saw the pics side by side? I bet not.
 

Jan 20, 2009
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#11
yup... i also hope to get know more about canon equipment...! thx ya
 

mrericlee

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Sep 27, 2008
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#12
But I guess, the real question is... Can you tell the difference yourself if you saw the pics side by side? I bet not.
Honestly, for sure I cannot tell the difference if on a tripod.

But, for sure I think I can tell difference if taken at a dinner outing handheld... right (due to shutter speed causing image blurring for the f4)?
 

Jul 27, 2008
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#14
So, reading all your replies... my understanding is the advantage (more light, faster shutter speed) only sets in when I have my aperture set between 2.8 to 4.

Anything above 4, the 2 lens should be equal meaning that my shutter speed can achieve same speed for the same light conditions.
Wrong.... i think you better read this: http://www.clubsnap.com/forums/showthread.php?t=309544
You need to take note that every aperture opens the hole bigger or smaller....
f2.8 vs f4 = bigger hole vs smaller hole
therefore, f2.8 can afford to have a faster exposure/ shutter speed. therefore chances of hand shake syndrome can be reduced.

Aperture number getting bigger = hole getting smaller. therefore even after the aperture f2.8 and f4, the aperture will also affect the amount of light getting into the camera....

Suggest you read the guide ba~
 

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mrericlee

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Sep 27, 2008
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#15
Wrong.... i think you better read this: http://www.clubsnap.com/forums/showthread.php?t=309544
You need to take note that every aperture opens the hole bigger or smaller....
f2.8 vs f4 = bigger hole vs smaller hole
therefore, f2.8 can afford to have a faster exposure/ shutter speed. therefore chances of hand shake syndrome can be reduced.

Aperture number getting bigger = hole getting smaller. therefore even after the aperture f2.8 and f4, the aperture will also affect the amount of light getting into the camera....

Suggest you read the guide ba~
Hi, thank.. this is exactly what I was asking...

Under low light conditions... if I set aperture priority for both lens at f11, would the shutter speed on the f2.8 lens still be faster? or equal to the f4 lens?

My understanding from reading the guide is SAME SHUTTER SPEED cos already forced both to f11.

Is this not correct?
 

Jul 27, 2008
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#16
Hi, thank.. this is exactly what I was asking...

Under low light conditions... if I set aperture priority for both lens at f11, would the shutter speed on the f2.8 lens still be faster? or equal to the f4 lens?

My understanding from reading the guide is SAME SHUTTER SPEED cos already forced both to f11.

Is this not correct?
I think this is where you have mistaken....
1) when the camera's f-stop specifies for example f2.8 as the largest size the "hole" can open. By setting the aperture in the camera, you are basically commanding the lens "hole" to open at a certain size.

With that said, one f4 lens and f2.8 lens when stepped down to say f11, their "hole" basically opens up at the same size.

Whats different between the two is when one camera sets the aperture at f2.8 (big hole) rather than the f4(smaller hole.)

Hope you get the drift....hahaha i quite suck when it comes to explaination.

Hope this helps
 

Rashkae

Senior Member
Nov 28, 2005
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#17
step down like F4 vs F2.8, the sharpness and detail most performance in good result with F4 lens...! it's correct sir?
Oh! Are you talking about the lenses being wide open? Like if you shoot at f/2.8 and f/4.0?

Well of course there will be differences! For one thing, lenses are known not to be at their sharpest wide open. Next, you'd have different depth of field and shutter speed.
 

Rashkae

Senior Member
Nov 28, 2005
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#18
Under low light conditions... if I set aperture priority for both lens at f11, would the shutter speed on the f2.8 lens still be faster? or equal to the f4 lens?

My understanding from reading the guide is SAME SHUTTER SPEED cos already forced both to f11.
Would be the same.
 

ZerocoolAstra

Senior Member
Mar 13, 2008
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#20
The only difference is that the f2.8 one will give you a brighter picture thru the viewfinder....
hmmmmm yeah. Didn't think of that.
You're right about that.
I'm pretty sure that the difference between the 2 lenses @ f/11, all other settings being equal, would not be noticeable at all by even experienced eyes... :) [especially if both are high-end lenses, e.g. 24-105L @ 50mm, and a 24-70 f/2.8 @ 50mm]
You buy the f/2.8 lens for the ability to shoot at f/2.8 in low light, or when you want a super- thin depth-of-field.
 

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