 Jnaneshwar Surabathula |
Hyperfocal Distance, Exposure
I am not satisfied with the sharpness of the image. The purple tulips in the foreground don't appear sharp enough compared to the red & white ones (2nd row). I used my theory of Hyperfocal distance and focussed between the reds and red & white ones. What best could be done? If there is a flaw in what I have done, could that be pointed out.
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Who Me? |
Is that a kit lens? I don't see anything in focus. I would use a prime lens for a shot like that if you want better sharpness.
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Alan N. Marcus |
Hi Jananeshwar, Could it be that your theory regarding hyperfocal distance and mine might differ? Say the camera is focused to some specific distance. Now it is unrealistic to think that only objects precisely at this distance will be in sharp focus. Depth-of-field always exists, however shallow. This is a span of acceptable focus extending both fore and aft from the point focused upon. As you stop the lens down to smaller and smaller apertures, that span of acceptable sharpness expands in both directions. Now at some point, as you continue to stop the lens down, the far limit of sharpness will eventually embrace infinity (as far as the eye can see). When this occurs you have set the camera to a position that maximizes depth-of-field, retaining infinity in acceptable focus. The distance focused upon as indicated by the camera’s focusing scale is the hyper focal distance. Knowing by calculation, the hyperfocal distance enabled makers of fixed cameras like the “Brownie” to be preset so the span of depth-of-field made picture taking trouble-free i.e. this is the heart of the simple non-adjustable camera. The hyperfocal distance is difficult to calculate. When you use a zoom lens the variable focal length adds perplexity. Some cameras may have a depth-of-field scale engraved on the lens barrel. If present you can use it to set the hyperfocal distance. Short of this, I don’t think one can do these calculations in the field. OK then, what to do? Use apertures like f/16 – f/22. Tiny apertures maximize depth-of-field. Focus upon objects around the 15 foot mark. The secret is in the knowledge that span we call depth-of-field is not split down the middle. It extends 2/3 further away from the camera and 1/3 towards the camera as measured from the point focused upon. If the lens is set to f/22 and the focus is set to 15 feet, the span of depth of field extends from 6 feet to infinity. Try it, you’ll like it. Alan Marcus
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Christopher A. Vedros |
Short answer - f/6.7 didn't give you enough depth-of-field. Many lenses that show DOF marks on the lens barrel only show the marks for f/16 and above.
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Jnaneshwar Surabathula |
Thanks for the response. I guess I should have used a small aperture to gain depth. I shall try that next time.
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Lynn R. Powers |
I still haven't seen the tulip fields in full bloom. I have lived 40 miles from them for over ten years. When shooting at f16 or 22 please remember not to focus at infinity. Do not try this by focusing at 15 feet with a telephoto lens. Use a lens that is a wideangle to normal length. It is much easier with a prime lens because you can look at the lens and it will tell you what is in focus. Experiment and have fun. Lynn
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