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Thread: does stopping down always make image sharper?

  1. #1
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    Default does stopping down always make image sharper?

    i read alot of reviews which commented that stopping down the lens to f5.6 or f8 makes the image sharper compared to f2.8

    now i was wondering if stopping down to f22 or f32 will also keep the image sharp or does it start to coz the image to also lose its crispness??

    (speaking for general lens)

    thanks

  2. #2

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    http://www.bobatkins.com/photography...ffraction.html

    This short article may help you understand the technical explaination of the practice.

    In summary, stopping down from the lens' biggest aperture is to reduce the lens' aberrations, while stopping down too much will introduce diffraction.

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    Quote Originally Posted by haagen_dazs
    i read alot of reviews which commented that stopping down the lens to f5.6 or f8 makes the image sharper compared to f2.8

    now i was wondering if stopping down to f22 or f32 will also keep the image sharp or does it start to coz the image to also lose its crispness??

    (speaking for general lens)

    thanks
    Lens has sweet spot, so stopping down does improve the sharpness from corner to corner. For optimal sharpness, need to refer to MTF chart, but usually from ~f8 onwards.

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    Yup... that's true. The sweet spot of the glass is usually towards the center, stepping down the aperture concentrates the light towards the center of the glass.

    The f/2.8 glasses normally perform well at f/2.8, but when stepped down to f/4 and down, the quality does get better.

  5. #5
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    Always? No. Like others have said, each lens design has it own sweet spot, the optimal point in lens performance. An example is the 58mm Noct. If you step down past f/5.6, the quality degrades significantly...

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    thanks for some of the replies

    how do i find the sweet spot?is it from literature and the MTF charts or from trial and error?

  7. #7

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    Quote Originally Posted by haagen_dazs
    i read alot of reviews which commented that stopping down the lens to f5.6 or f8 makes the image sharper compared to f2.8

    now i was wondering if stopping down to f22 or f32 will also keep the image sharp or does it start to coz the image to also lose its crispness??

    (speaking for general lens)

    thanks
    From what I read, most lens sweet spot (sharpness) is f8-11. Subject will never be sharp/focus if it falls outside dof.

    So some form of judgement is required for the kind of subject of interest & selecting optimal composition helps keep subject of interest in focus/sharpenss/

    my pov only.

  8. #8

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    any good lens review website that shows 100% crop of f2.8 zoom lens at various aperture settings?

    I only found one

    http://www.jasonlivingston.com/sigma-review/

  9. #9

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    morng all, i played with 1.4 and 1.8 on the 50, keeps finding that sometime in focus sometime out...accdg some posts on the internet its becos the plane of focus is very thin, a slight miscalibration or shift its out.

    does anyone here have any experience to share on this, how best counter? as no one can really tell for sure if a shot is dead on in a smallish LCD display as vs the monitor. one thing i can think of myself is at such low apt do everything on manual, but sometime i cant even trust my own eyes (no spects) to ascertain the exact focal pt!

    thks bros

  10. #10

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    Quote Originally Posted by haagen_dazs
    thanks for some of the replies

    how do i find the sweet spot?is it from literature and the MTF charts or from trial and error?
    Without trying to be too technical, (And which I am not capable of anyway)

    as a general guide, it is about two stops from its widest aperture.

  11. #11

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    Quote Originally Posted by itisnottheendorg
    morng all, i played with 1.4 and 1.8 on the 50, keeps finding that sometime in focus sometime out...accdg some posts on the internet its becos the plane of focus is very thin, a slight miscalibration or shift its out.

    does anyone here have any experience to share on this, how best counter? as no one can really tell for sure if a shot is dead on in a smallish LCD display as vs the monitor. one thing i can think of myself is at such low apt do everything on manual, but sometime i cant even trust my own eyes (no spects) to ascertain the exact focal pt!

    thks bros
    well, one way is to change/modify your camera focus screen to a split-screen one! This's what i did.

    to check whether is the image OOF or sharp from the LCD, use the zoom function. after every picture if you feel it's important and want to check on the spot, just zoom the preview pic to the max. If it's deemed blur to you, take again on the spot!

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    Quote Originally Posted by haagen_dazs
    thanks for some of the replies

    how do i find the sweet spot?is it from literature and the MTF charts or from trial and error?
    May be this site can help
    http://medfmt.8k.com/mf/resolution.html
    photography makes one sees things from all angles.

  13. #13

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    Quote Originally Posted by student
    Without trying to be too technical, (And which I am not capable of anyway)

    as a general guide, it is about two stops from its widest aperture.
    Surely that would depend on the camera format, and the lens

  14. #14

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    Quote Originally Posted by haagen_dazs
    i read alot of reviews which commented that stopping down the lens to f5.6 or f8 makes the image sharper compared to f2.8

    now i was wondering if stopping down to f22 or f32 will also keep the image sharp or does it start to coz the image to also lose its crispness??

    (speaking for general lens)

    thanks
    stopping down the lens means shooting at slower shutter speeds. if you hand-hold your camera, you are more likely to get unsharp photos due to camera shake. if you are using a tripod, and are shooting a static subject, for example a landscape, then stopping down the lens will give you a sharper image. i suppose that's why the f64 club was formed....the obtain the ultimate sharpness and detail in a photograph.
    you can buy better gear but you can't buy a better eye

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    Quote Originally Posted by kahheng
    Surely that would depend on the camera format, and the lens
    very true...

    and also the "sweet spot" of the lense, which actually becomes bigger and more apparent as you go further into bigger formats.

    I'm using 2 different Fujinon EBC lenses for my 4x5 and when stopped down to F64.... WHHHOOOOOOHHH... it's sharp like siao.. can even see the bi sai of the tourist at the opposite side of the lake. (hehehehe)

    BUT.. with a different Rodenstock i use as a tele, the sweet spot comes into play at around F22-32...

    just my input here...

    on how to achieve the sweet spot, go through the links above .... very helpful.

  16. #16
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    Quote Originally Posted by bigmouse
    From what I read, most lens sweet spot (sharpness) is f8-11. Subject will never be sharp/focus if it falls outside dof.

    So some form of judgement is required for the kind of subject of interest & selecting optimal composition helps keep subject of interest in focus/sharpenss/

    my pov only.
    Stopping down increases the DOF, so that you get better sharpness for every part of your subject. Unless you're shooting roti-prata or some other flat item, and with the plane of the subject parallel to the film plane/sensor plane, then no diff. For portraits for example, stopping down would give you sharper focus on all parts of the body, including nose, ears, arms and legs.

    So stopping down get you to the optimum aperture and increase DOF - better result due to 2 reasons.
    I love big car, big house, big lenses, but small apertures.

  17. #17
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    after reading the articles. i guess you are using a larger format camera for f64..
    coz pass f22, image degrades for 35mm cameras..


    Quote Originally Posted by F5user
    very true...

    and also the "sweet spot" of the lense, which actually becomes bigger and more apparent as you go further into bigger formats.

    I'm using 2 different Fujinon EBC lenses for my 4x5 and when stopped down to F64.... WHHHOOOOOOHHH... it's sharp like siao.. can even see the bi sai of the tourist at the opposite side of the lake. (hehehehe)

    BUT.. with a different Rodenstock i use as a tele, the sweet spot comes into play at around F22-32...

    just my input here...

    on how to achieve the sweet spot, go through the links above .... very helpful.

  18. #18

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    Quote Originally Posted by kahheng
    Surely that would depend on the camera format, and the lens
    You are right!

    But we are addressing haagen_dazs. question. He/she is talking about an aperure of f2.8.

    I think there are very few 4x5 lenses that have a wide aperture of 2.8.

    And since he asked such a question, my assumption is that he is relatively new. All these led me to conclude that he is talking about 35 mm lenses.

  19. #19

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    Quote Originally Posted by F5user
    very true...

    and also the "sweet spot" of the lense, which actually becomes bigger and more apparent as you go further into bigger formats.

    I'm using 2 different Fujinon EBC lenses for my 4x5 and when stopped down to F64.... WHHHOOOOOOHHH... it's sharp like siao.. can even see the bi sai of the tourist at the opposite side of the lake. (hehehehe)

    BUT.. with a different Rodenstock i use as a tele, the sweet spot comes into play at around F22-32...

    just my input here...

    on how to achieve the sweet spot, go through the links above .... very helpful.
    I think there are two different things here.

    "Optimum performance of a lens" and "Depth of field".

    When you talked about f64 you are talking about depth of field, not optimum performance of the lens.

  20. #20

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    Quote Originally Posted by student
    You are right!

    But we are addressing haagen_dazs. question. He/she is talking about an aperure of f2.8.

    I think there are very few 4x5 lenses that have a wide aperture of 2.8.

    And since he asked such a question, my assumption is that he is relatively new. All these led me to conclude that he is talking about 35 mm lenses.
    As usual, your reply so very 'considered' one

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