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Lens focus The place to talk about your camera's glassware.

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  #1  
Old 28th February 2008
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F Stop Value

Hi All,

Just a real quick question if you don't mind.

Whats the oly F value Equivalent of Canon 400D F22?

Cheers
G
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Old 28th February 2008
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Re: F Stop Value

I maybe wrong, but I though the F value was for the amount of light let though the lens, so shouldn't it be the same?
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Old 28th February 2008
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Re: F Stop Value

sorry I meant aperture F value
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Old 28th February 2008
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Re: F Stop Value

The equivalent of f22 is f22. An f number is an f number no matter the system neg/sensor size or focal length. It is a ratio of the width of the aperture to the distance to the film/sensor plane.

Ian C.
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Old 28th February 2008
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Re: F Stop Value

Garrie

Are you asking about DOF???
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Old 28th February 2008
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Re: F Stop Value

Hi Andy,

Yeah I thats what I'm meaning, I'm rubbish at explaining stuff

Cheers
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Old 28th February 2008
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Re: F Stop Value

Try these from Andrzej Wrotniak brilliant site.I believe DOF is greater for 4/3 cameras due to the smaller sensor.


http://www.wrotniak.net/photo/tech/dof-43.html

http://www.wrotniak.net/photo/tech/dof.html
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Old 28th February 2008
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Re: F Stop Value

MINT - Cheers Andy
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Old 28th February 2008
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Re: F Stop Value

Please remember that from F5.6 onwards your lens will deliver softer and softer images - f/22 is to be avoided if at all possible. f/5.6-f/6.3 is the sweet spot for Four Thirds cameras. The softness as the aperture gets smaller is due to the effects of diffraction along the edges of the aperture blades at very small physical aperture sizes.

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Old 28th February 2008
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Re: F Stop Value

Quote:
Originally Posted by Ian View Post
Please remember that from F5.6 onwards your lens will deliver softer and softer images - f/22 is to be avoided if at all possible. f/5.6-f/6.3 is the sweet spot for Four Thirds cameras. The softness as the aperture gets smaller is due to the effects of diffraction along the edges of the aperture blades at very small physical aperture sizes.

Ian
Thanks Ian - I didn't know that Maybe that's why I'm often disatisfied with the sharpness of my E-1?
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Old 28th February 2008
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Re: F Stop Value

Quote:
Originally Posted by Ian View Post
Please remember that from F5.6 onwards your lens will deliver softer and softer images - f/22 is to be avoided if at all possible. f/5.6-f/6.3 is the sweet spot for Four Thirds cameras. The softness as the aperture gets smaller is due to the effects of diffraction along the edges of the aperture blades at very small physical aperture sizes.

Ian
Thats interesting, I have been led to believe the sweet spot on the 14-54 was nearer F16 before diffraction set in? Any landscape togs here wish to comment? Also does this differ with different lenses. I have had what I consider poor results on anything landscape wise where DOF was needed.

Last edited by Scapula Memory; 28th February 2008 at 04:24 PM. Reason: spelling
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Old 28th February 2008
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Re: F Stop Value

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Originally Posted by Scapula Memory View Post
Thats interesting, I have been led to believe the sweet spot on the 14-54 was nearer F16 before diffraction set in? Any landscape togs here wish to comment? Also does this differ with different lenses. I have had what I consider poor results on anything landscape wise where DOF was needed.
Here is a plot of the sharpness of a 50mm f/2 Digital Zuiko through its aperture range. The smaller the (DxO Blur Experience Unit or BXU the less blurred (more sharp) the lens is) :


There probably isn't a lens much sharper than this in Four Thirds and the edge/edge sharpness is very uniform, even at full aperture.

You can see that sharpness peaks at f/2.8 here, but f/16 is quite a way down.

Ian
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Old 28th February 2008
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Re: F Stop Value

Quote:
Originally Posted by E-1 fan View Post
Thanks Ian - I didn't know that Maybe that's why I'm often disatisfied with the sharpness of my E-1?
E-1s, by default, have minimal sharpening set, so you should have plenty of sharpening latitude in post processing.

Ian
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Old 28th February 2008
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Re: F Stop Value

I hate using it though Ian - I know it's daft but still feels like cheating

I'd much rather get the basics right in camera if possible.

Do you have similar charts for the 35mm ZD and the 40 -150mm?

I'd love to know the optimum aperture for both of these too
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  #15  
Old 28th February 2008
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Re: F Stop Value

Excellent post Ian, thanks, that is very interesting to see. Quite a difference from F11 onwards. This explains a few things about some of my pictures from the Lakes last year.
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