What is the "Optimum f/stop" for a zoom lens?
May 9, 2012 13:26:09 #
This is 2 related questions. I've been searching through the topic boards trying to find the approximate "optimum" f/stop (in terms of sharpness) for a zoom lens. I've read that the optimum setting for prime lenses to avoid diffraction phenomenon is around 2 f/stops past wide open. Does that rough rule of thumb hold true for zoom lenses as well? If I wanted my most-used aperture opening to be at a smaller setting (for more DOF 'apparent sharpness'), would a f/4 lens (optimum sharpness around f/8) be a better choice than a faster f/2.8 lens (optimum sharpness around f/5.6)?
May 9, 2012 14:16:49 #
cecilia delacroix wrote:
This is 2 related questions. I've been searching through the topic boards trying to find the approximate "optimum" f/stop (in terms of sharpness) for a zoom lens. I've read that the optimum setting for prime lenses to avoid diffraction phenomenon is around 2 f/stops past wide open. Does that rough rule of thumb hold true for zoom lenses as well?
Yes as a "generality"
cecilia delacroix wrote:
If I wanted my most-used aperture opening to be at a smaller setting (for more DOF 'apparent sharpness'), would a f/4 lens (optimum sharpness around f/8) be a better choice than a faster f/2.8 lens (optimum sharpness around f/5.6)?
If I wanted my most-used aperture opening to be at a smaller setting (for more DOF 'apparent sharpness'), would a f/4 lens (optimum sharpness around f/8) be a better choice than a faster f/2.8 lens (optimum sharpness around f/5.6)?
No...there is no correlation. Wherever your lens starts (2.8, 1.4, 4.5 or whatever)....up two stops is generally considered to be it's sharpness peak.
Keep in mind that this is a VERY GENERAL rule...I have lenses that behave differently.
May 9, 2012 21:58:32 #
May 9, 2012 22:37:23 #
Just finished reading Bryan Peterson's "Understanding Exposure" (3rd editon). His book gave him great credibility in my eyes. He gives an explanation as to why for most lenses f8-f11 comprises the "sweet spot".
I don't want to ruin it for you so suggest you read his book to understand why.
If, like I, you think you know about exposure but haven't read his book I suggest you might find it a real treat.
I did.
I strongly recommend the latest edition.
I don't want to ruin it for you so suggest you read his book to understand why.
If, like I, you think you know about exposure but haven't read his book I suggest you might find it a real treat.
I did.
I strongly recommend the latest edition.
May 10, 2012 06:33:24 #
May 10, 2012 08:26:00 #
Hi, I bought his book and realy got a greta understanding about aperture and fstops.
May 10, 2012 14:39:51 #
cecilia delacroix wrote:
This is 2 related questions. I've been searching ... (show quote)
Every lens has it's sweet spot. My 500mm f4L shoots best at f5.6-f8 depending on how much DOF I need or want.
My 100-400mm f4.5-5.6L lens works just as good wide open as it does at f8 if the light is good. If the light is poor it's a different story.
My 24-70mm f2.8L works great wide open but DOF is a problem if I don't keep my subject framed and focused properly. I don't usually shoot wide open for this reason - especially if I have the light.
May 10, 2012 16:01:43 #
cecilia delacroix wrote:
This is 2 related questions. I've been searching ... (show quote)
If you have a particular lens in mind, detailed online reviews often rate the lens at different openings.
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