where is the sharpest f-stop for landscape?

Discussion in 'Beginner Questions' started by chi_siu|1, Feb 19, 2009.

  1. I just went through wiki for f-stop just to reassuring myself. I have been thought using to use smaller aperture for sharpness, so I always stay at f16 or f22 when taking landscape shots with long exposure. On the other hand, the content in wiki describes the sharpest aperture is at the medium opening like f5.6-f8. Older lenses at f/11. Is it true?
    Thanks,
    Chi
     
  2. This is going to depend on what camera (format) you're using, the focal lengths involved, the distances involved, etc. But the short message is: when you're stopped down to f/16 or f/22 on, say, an APS-C format digital camera, you're actually introducing diffraction, which robs you of some sharpness. Without anything else to go on, I'd say f/8 or f/11. But where you focus it (distance-wise), and the focal length of the lens will have a lot to do with the results, too. Well, that and good tripod technique!
     
  3. Very few lenses perform at their peak at either extreme of aperture settings. I find that f8-f13 is often "best".
     
  4. It really will depened on the lens and format of camera you are using. Even within a given model of lens, there may be some slight performance differences between individual lenses. The best thing to do is to go out and try a bunch of different apertures, focal lengths, and focus points. Take good notes to go along with EXIF (assuming digital), and you will reach a conclusion that you know is pertinent to your lens/camera combination.
     
  5. Not only does it depend on the factors already mentioned but it also depends on the size of your final output.
    Use the aperture you need to achieve the DoF and shutter speeds you want.
     
  6. In basic terms, yes. However I usually have no problem at f11 and some times higher
     
  7. The best way to find out is to do your own testing and then decide for yourself, as it varies from lens to lens and from person to person. Personally I use the widest f stop I can because I don't like the lower contrast and resolution diffraction always introduces.
     
  8. It also depends on your subject matter and requirement for a deep depth of field.
     
  9. There are two different concepts being discussed here--sharpness and depth of field. As a rule of thumb, a lens will be sharpest (the in-focus areas will be rendered with the greatest clarity and resolution) somewhere around two stops down from wide open. As you begin to stop down further, some of that sharpness will be lost to diffraction effects. In modern DSLRs, diffraction typically starts to be a significant issue somewhere past f/11. Larger format cameras begin to experience troublesome diffraction at smaller apertures while small format cameras like point and shoot cameras may begin to see diffraction at fairly wide apertures.
    Depth of field refers to the depth of the zone (near to far) in which the image appears to be in focus. Depth of field will increase as you stop down, but at some point you will lose the practical benefit of the increased depth of field as diffraction becomes more and more of an issue. That is, the zone of focus will continue to increase but the softness from diffraction will make it seem like it is out of focus.
    In a traditional landscape photo, you are interested in rendering as much of the scene sharply and in focus as possible. The particular aperture that will give you that result will necessarily be a compromise, depending on the scene and the particular lens and camera you are using. If you are using a lens with a maximum aperture of f/2.8, the sharpest result for that lens might be f/5.6; and if you are photographing a subject, like a rock wall, that is all at the same distance from you then f/5.6 might be your best choice. But if you have a scene stretching into the distance, you may need to stop down to get it all into focus, even if that means compromising a bit on sharpness in some parts of the scene.
    With landscape shots, it is usually easy to shoot the same scene multiple times on a tripod, using different settings, so you can determine what works best. Bear in mind that some of the differences are subtle and may be evident only when you take a photo with a high quality lens and view it at very large sizes. If you take a shot hand-held and print it at a small size, changes in critical sharpness may not be visible at all.
     
  10. Thank you so much, all of your answers lead to one last question. I shoot medium format using a hassy 503cx w/ 80mm f2.8, if I use f/5.6 or f/8 in this case instead of f/22, then I can't get the long exposure time that I want. What can I do to obtain both sides?
     
  11. To increase exposure times, you can add a neutral density (ND) filter. ND filters are intended to subtract light without otherwise affecting the shot. They are available in different strengths that change the exposure by a specified number of stops-- 1, 2, 3 etc. They are very useful for slowing down exposures so you can blur moving water, for example.
    With a medium format camera, I wouldn't hesitate to stop down beyond f/11 which was the rule of thumb I mentioned for a current DSLR. On a small sensor like an APS sized digital sensor, it takes only a small amount of softness from diffraction to affect the result because the image will be magnified so many times when it is printed at a large size. In your medium format camera, the area of the film is much greater than the size of the DSLR's sensor so the image does not have to be magnified so much for an equally large print so the effects of diffraction are not magnified so much. Short answer is that I think you can use f/22 on your camera without much worry.
     
  12. Thanks John, you're the man!!
     
  13. For 645/6x6 cameras max sharpness usually occurs around f8 for most lenses so the ND filters mentioned above would be your best bet as long as you don't stack them.
     
  14. Chi, the best way to find the sharpest aperture setting is to test your lenses yourself, as they're all a bit different. There is even some variation among 'identical' lenses, due to production tolerances. Set up on a tripod, use a fine-grained film, and shoot at something with a lot of detail like tree branches or a brick structure at a middle distance. I find a straight section of railroad tracks with trees close by perfect for this kind of test.
    Focus carefully, and take a shot at each aperture with each lens you have. Take notes, and maybe put a piece of paper with the aperture & shutter speed info marked on it in the frame somewhere. Review the pics carefully, like with a loupe, and you'll have your answer. You'll see the actual depth-of-field results, and you'll also see where sharpness begins to fall off due to diffraction for YOUR lenses. Tedious, yes, but then you'll know for sure what your equipment will do without any guesswork. That will save you at least one important shot someday.
    Besides using ND filters, a polarizing filter will cut down on the light a good bit. You can also use slower speed films to lengthen exposure times, or if using a digital back on your Hassy, a lower ISO setting. I've used all of these methods separately or in combination, depending on the shot.
     
  15. Hey, you might want to try the hyperfocal point. That's the way we used to do it before the lost art of photography got lost. It's basically infinity over aperature.
    Your best bet when it comes to questions like the one you pose is the library. There should be lots of photo technique books gathering dust there and they're stuffed with correct answers to difficult questions.
    Good luck with the search.
     
  16. Most photographic lenses for 35mm and APS-C are at their sharpest at f5.6 - f8. However that often does not give enough depth of field for landscapes. So for any 'all-in'focus' shot I suggest you set the aperture initially to f5.6 then check whether you are getting the right depth of field. If you are then fine, if not then reduce the aperture until you have the right depth of field.
    You can get quite a good idea of the characteristics of any lens by looking up the MTF curves either from the manufacturer (Sigma publish MTF curves for their lenses) or on sites such as
    www.photozone.de
    That way you can assesss where each of your lenses works best and, for zooms, which focal lengths work best.
    I don't think there is much difference between modern and older lenses, they all work best about f5.6 - f8. If you are in any doubt just set up your camera/lens on a tripod and shoot at all apertures in sequence and observe the performance differences.
     
  17. Other things than f stop affect sharpness. Camera movement and the effects of wind blown foliage may also make pictures appear less sharp. For 35mm cameras I use a minimum of 1/250 sec with a 50mm lens if possible (which often puts you at an ideal f stop, depending on your film speed).
     
  18. Tripod, and two or three stops down from maximum aperture, provided the depth of field is sufficient (Use DOF scale, focus and close down one stop more than it says).
     
  19. david_henderson

    david_henderson www.photography001.com

    Where is the sharpest f stop for landscapes?​
    I'm tempted to respond "its right on top of your tripod" as perhaps the most useful thing for you.
    Beyond that you have a bit of a problem. Clearly you have to trade off depth of field, which increases as you reduce aperture size, and diffraction, which makes photographs less sharp overall as apertures get smaller. If it was as simple as that, then you could for any particular scene have an "optimum" aperture that for your format and lens would probably most often lie in the range f8-f16.
    But it often isn't as simple as that. You often run the risk or grasses, leaves or whole trees blowing and clouds moving with long exposures. You might need to use differential sharpness to draw the eye to or away from a particular part of the image. You might need to blur water . In fact there are lots of reasons why you may not be best served by the deemed "optimum" f stop.
    And so in general I think its best not to approach landscapes with a mind set to use a particular f stop if you can, but to examine every scene on its merits and do what you have to do. Your camera and lens is capable of delivering good results at any aperture provided that your judgments are right and to be frank I don't think you're going to notice a difference of a stop or two on a print a lot of the time. People like me have picture editors crawling all over their work at 100% to assess dof and sharpness. You have more freedom than that. Use it.
    I find that having an extra back with different film speed loaded gives me more control over the apertures I use. Having a depth of field table handy in the field is useful too.
    Finally I wanted to say that if you want your pictures to appear sharp there is little substitute for focussing on the right thing. Whilst hyperfocal techniques (mentioned above) offer a route to maximising dof that is not the same as maximising sharpness. IMO the best way to make your pictures look sharp is th be aware of the most important part of your subject and focus on that. It is only the point on which you focus that will be as sharp as it can be.
     
  20. the sharpest fstops will be in the rsnge from f5.6 to f11.0. below f5.6 the lens is letting mnore light through but is noit performing at its best. above f11.0 the lens is running into diffraction distorsion in ever increasing amounts.
    as someone mentioned, the best fstop for sharpness in the use of a good tripod. whenever i take the gear and go sxhooting both my tripods come with me. ALWAYS RPT ALWAYS RPT ALWAYS. never are they left home. if there is anyway that the tripod can be used for a shot it will. i have a treipod with a panorama head and that pod is always used for any panoramas i shoot. i have never shot a hdr or panorama without the use of the tripod and never will. there ks just too much degrading of the image handheld. please do not talk about SR, it is only good for 2 stops worth of REAL shutter speed.
    if you are talking critical sharpness, which is the ability of picture to be enlarged to any amount desired without any concern over how sharp the print will be, you need cxritical shrapness to do this. SR is jnust not good enough, you need the use of a good tripod to lock down that camera.
    it should be noted hat on a c sensor dslr you are gettijng about one fstop more dof than a film slr or FF dslr is at the same fstop. so you do not need to go to f16 or 22. you should check with a dof chart to see how much dof you are really getting at the different fstops. also, since landscapes are shot with wideangle lenses, thta type of lens has inherently more dof that a regulkar or normal length lens. see-
    http://www.dofmaster.com/dofjs.html
    lastly consider the use of a hyperfocal setup for landscape shots this makes the issue of dof nonexistant. you will end up with dof from just infront of your feet to infinity.
    i shoot almost all my shots, landscape or otherwise, at f8.0 to f11.0 and get all the dof i need, and the lens is performing at its best in that range. for portraits i will back off the fstop to f4.0-5.6.
    00SWrH-110932684.jpg
     
  21. I was wondering about this myself. I am fairly new to photography, and I am still learning many of the technical aspects. I assumed that the tighter the aperture, the more sharpness would be achieved throughout the photograph. I decided to perform my own test to see if I could discern this for myself, and I am convinced.
    at f/29:
    [​IMG]
    at f/11:
    [​IMG]
    This doesn't address depth of field, but it definitely does exhibit effects due to diffraction. The photo shot at f/11 is clearly much sharper. Both of these are straight-out-of-camera, except for the zoomed-in selections, but of course no sharpening has been applied.
     
  22. Seems the pictures didn't post, I'll try that again.
    At f/11:
    [​IMG]
    At f/29:
    [​IMG]
     

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