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I have tried several apertures, but I still can't get the entire body of the subject to be super-sharp. When the subject extends the arms, I find the hands to be less sharp than the eyes. I'm using a Nikon D500 with Nikkor 35mm, I've tried various speeds from 1/250 to 1/2000. If this is not possible, how far do I need to be to get the entire body sharp ?

The subject is extending the arms sideways.

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  • Possible duplicate of Why are my photos not crisp? – Olivier Jan 16 '17 at 19:08
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    Please be more specific: which Nikkor 35mm? (is it the kit lens that came with the camera?) Also, what aperture are you using? – scottbb Jan 16 '17 at 19:52
  • I tried all apertures from 1.8 to 16. My lens is AF-S NIKKOR 35mm 1.8 G ED – user83522 Jan 16 '17 at 19:56
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Depth of field is just an illusion. There is only one distance that will be in sharpest focus.

The further away from that distance, the blurrier things get. If you look at any image closer (greater magnification or closer distance) the depth of field for the exact same image is reduced. If you look close enough at any image either the DoF is reduced to pretty much nothing on either side of the focus distance or the loss in sharpness due to diffraction at narrow apertures makes everything a blurry mess..

To get full bodied portraits that are incredibly sharp from head to toe requires many things:

  • Very good lenses. If the lens is significantly better in the center than away from center then you'll never get things as sharp on the edges as in the center. The larger the image format is, the less critical the resolution limits of the lens become. (e.g. large format>medium format>full frame>Aps-C>4/3>etc.)
  • Good lens/camera/sensor alignment. Manufacturing tolerances are becoming more and more of a factor as lenses and sensors are capable of ever increasing resolution and we are viewing them at ever increasing enlargement ratios at 100% on our computer monitors.
  • Very good light. Poorly lit subjects will be rendered more noisily by digital sensors. To manage the noise we have to sacrifice detail.
  • Critical manual focus on the right parts of the subject.
  • Appropriate aperture selection for the lens in question as well as for the specific scene/composition. Many lenses have a distinctive "sweet spot" that give the best sharpness as measured at the center. Many lenses have a "sweet spot" that gives the best sharpness over the largest percentage of the frame. The best lenses have a "sweet spot" that does both at the same aperture.
  • Composition that places the entire body at or very near the focus distance in the shape of the lens' field of focus (curved, flat, or wavy shaped). If part of the body is significantly closer to the camera than another, then perhaps a perspective shift/tilt-shift lens or a large format camera with adjustable movements must be used.
  • Very good post processing done by a skilled operator who understands that making the parts our eyes/brain expect to see sharper the sharpest is just as important as making everything equally sharp.

It only takes missing one of the above elements to make an image less than acceptable.

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  • Thanks a lot for that. By very good light, do you mean light intensity, or light that covers the whole spectrum, i.e. is regular flash light never going to be good enough ? – user83522 Jan 17 '17 at 9:57
  • @user83522 Both intensity and quality make a difference. – Michael C Jan 17 '17 at 9:59
  • What do you mean by "regular flash light?" A "regular" photographic flash is usually fairly good in terms of full spectrum output. How you shape it is dependent on what you place between the light and the subject. – Michael C Jan 17 '17 at 10:05
  • I mean studio flash heads. So with studio flash heads I just need enough intensity to fulfill the criteria about light if I understand correctly. – user83522 Jan 17 '17 at 19:26
  • You need both enough intensity and the proper distribution of that intensity. – Michael C Jan 18 '17 at 8:36
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Since I imagine subject is extending his arms forwards I imagine your depth of field is too shallow to cover the whole body.

Depth of field is area that remains sharp in front and behind your focus point. Shallow depth of field means that area is smaller.

The way you can regulate depth of field is by changing your camera's aperture, for example aperture of f8 will give you more detail (bigger depth of field) than for example f2.8. Distance from your focus point also changes depth of field, moving closer to your subject will make depth of field more shallow.

There are many online calculators to calculate your depth of field based on what you're using, one of them you can find here: http://www.dofmaster.com/dofjs.html

Also keep in mind that 1/3 of depth of field is in front of your focus point, and 2/3 is behind. Meaning if your depth of field is 3m, something 2m behind your focus point will be sharp, while something 2m in front won't be as sharp.

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    I meant the subject is extending the arms sideways, not forward / backward. – user83522 Jan 16 '17 at 18:49
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In short : try to put all your subject in the middle of the frame and choose the correct aperture.

At least 2 explanations might explain your problem (assuming it isn't a shutter speed to low with moving hands).

Distance

The eyes and the hands are probably not at the same distance from the camera. If you are using a very wide aperture, your DoF will be very shallow (see What exactly determines depth of field?) so it might have an influence.

Lens

In most cases, lenses are sharpest in the center and softer in the corner (Why are some photos sharp in the center, but soft on the edges?). As an illustration, you can look at this image (from http://www.discoverdigitalphotography.com/2015/lens-problems-field-curvature/): Field curvature You can see that the center is sharp and the corner blurry.

For more info about good/bad lenses : What image-quality characteristics make a lens good or bad?

What to do ?

As you are taking an image of a moving subject, a single shot is probably the simplest solution. Be sure to follow the indications of Why are my photos not crisp? (and How to achieve sharpness on image. Yes, it's self-promotion !). Mostly, try to put all your subject in the middle of your frame and choose the correct aperture.

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  • Thanks for the links, looks like the sharpest aperture for my lens is 5.6 according to this review site. They also have this awesome feature where you can see the variations in sharpness and focus between apertures for my lens.Still I wonder how people get portrait sharp from head to toe, because the distance difference between head and feet is similar to right hand / left hand when arms are spread out, so field curvature would also come into play. – user83522 Jan 16 '17 at 21:13
  • Can you post an uncropped example ? – Olivier Jan 16 '17 at 21:28
  • I can't because I am doing tests, the subject is myself, I trigger with a remote. – user83522 Jan 16 '17 at 22:21
  • Well, I assure you that we already have received a few autoportrait on this website :) You can anonymize yourself (black band on eyes in post) – Olivier Jan 16 '17 at 22:24
  • Believe me, you don't want to see me in my testing outfit :) Anyway, this site you were linking to made me think that I can calculate the difference in distance between eyes and feet and the camera using simple trigonometry, and then see how that impacts DOF, and then relate to their DOF tool to see how I could achieve whole body near-focus from a distance of 10 to 15 feet. – user83522 Jan 16 '17 at 22:38

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