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Aperture 'Sweet Spot' on small sensor compacts.

Discussion in 'Ask B&H Photo' started by Toonman, Apr 14, 2011.

  1. Toonman

    Toonman Regular

    Here is a question. On larger sensor cameras the 'sweet Spot' is usually around f8 to f11. So how does this work with smaller sensor compacts? My Canon G11 bottoms out at F8. By using this minimum aperture am I compromising image quality or not?
  2. pictor

    pictor All-Pro

    Jul 14, 2010
    f/8 is too small for a compact because of diffraction. It is better to stop down one stop to get the sweet spot.
    • Like Like x 1
  3. Chuck-B&H

    Chuck-B&H B&H Photo Specialist

    Aug 5, 2010
    New York

    Just like you should always process film at 68 degrees, the wisdom has always been the best f stop to use is 2 stops down from wide open. I've Used the G12 and own a P7000 and an older Panasonic LC5 and while I've never tested it, I have never noticed a loss in image quality stopping down to f8 or smaller. I looked at some of the on line reviews for the camera and I could not find any f stop comparison tests. Sorry, I could not be more helpful.
    • Like Like x 1
  4. Amin Sabet

    Amin Sabet Administrator Emeritus

    Jul 3, 2010
    It varies by camera, but 1-2 stops from wide open is generally the sweet spot for small sensor compacts. With a typical zoom that starts at f/2.8 on the wide end, ~f/4.5 is a safe bet.
    • Like Like x 2
  5. Will

    Will All-Pro

    Aug 30, 2010
    I heard somewhere that the GRD cameras are best at between about f/3.5 and f/6 ish and that smaller than that they tail off. There was some long technical reason why this should be so on a small sensor camera but I cant remember what it was.
    • Like Like x 1
  6. BBW

    BBW Administrator Emeritus

    Jul 7, 2010
    betwixt and between
    Gee, I often have my LX5 at f/8...though, of course, it depends upon the lighting. I have not found f/8 on my camera to cause anything negative at all.
    • Like Like x 1
  7. Djarum

    Djarum All-Pro

    Jul 10, 2010
    Huntsville, AL
    With my old Panasonic FZ3, diffraction becomes noticeable past f4.0. Its not to bad. At F5.6 things get ugly. Its got an old 1/3.2" sensor in it. With my Canon A560, I have found the real sweet spot at F5.6.

    I've used this website before:
    Digital Camera Sensor Sizes: How it Influences Your Photography

    They have a calculator to determine the aperature limit before diffraction starts to effect image quality when viewed at 100 percent.

    There really are two issues here that come into play. The diffraction by the airy disc at a particular aperature. This is defined by the sensor size. The larger the sensor, the slower the f stop that can be used before diffraction effects image quality.

    Then there is the actual resolution of the lens at a given f number. I've seen some lenses that are actually sharper stopped down past the diffraction limit.
    • Like Like x 1
  8. On a small sensor camera, you are probably looking at a sweet-spot of around f/4 to f/5.6. Note that most compact cameras don't give you a full range of apertures but often employ a mix of a ND filter and maybe a 2-stage aperture so you may have something like f/2.8 and f/5.6 at short focal lengths although you may be able to select f/4 and f/8 as well if you have manual control. Of course at the long end, you frequently have stuff like f/5.6 and f/11 etc.
    • Like Like x 1
  9. Will

    Will All-Pro

    Aug 30, 2010
    That was the technical stuff I was referring to!
  10. Streetshooter

    Streetshooter Administrator Emeritus

    Jul 12, 2010
    Philly, Pa
    The old school Leica shooters go 3 stops from Wide Open.
    Summicrons @ 5.6
    Of course, it really depends on the DOF you want.... but when you need that tack sharp image ... 3 stops from wide open.
    I still adhere to that and every lens I ever had proved it correct including my m4/3 stuff.

    If your a youngster, this may prove wrong.
    If your olde school, you know it's right but don't care anyway.
    • Like Like x 1
  11. Crsnydertx

    Crsnydertx Top Veteran

    Jan 21, 2011
    Houston, TX
    If you're as old as I am, you care, but you won't remember it tomorrow....:redface:
    • Like Like x 2
  12. Mayank

    Mayank Veteran

    Jul 16, 2010
    f4 or f4.5 has been the sharpest on several compacts I've owned.
    • Like Like x 1
  13. Luckypenguin

    Luckypenguin Hall of Famer

    Dec 24, 2010
    Brisbane, Australia
    Any small sensor compact I own is permanently set on 'P'. I think it was mentioned earlier that some compacts actually only have one or two physical aperture settings anyway, with the rest done through built-in ND filters.
    • Like Like x 3
  14. linkedit

    linkedit Rookie

    Nov 7, 2010
    Morris County, NJ
    As a rule of thumb, 2 stops down from wide open is generally the sharpest point. If you want an exhaustive explanation of why, get your hands on a copy of "Applied Depth of Field" by Alfred Blaker.
    • Like Like x 1
  15. Toonman

    Toonman Regular

    Thanks everybody for your input.

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