Which aperture is the sharpest in the lens that come with Nikon d3100?

Question

Wich aperture is the sharpest in the lens that come with Nikon d3100? I'm new to photograpy and I read about the "sharpest aperture" property that lenses have, but I read it changes depending on the lens. I have the kit that comes with the Nikon d3100. Wich is the sharpest aperture? Is there a practical way to find it by myself?

Answer 1

Using the dpReview lens widget it appears the AF-S DX Nikkor 18-55mm f/3.5-5.6G VR is sharpest at f/8 for most focal lengths. There are some points in the zoom range that center sharpness is better at f/5.6 but usually at a much greater expense to edge sharpness.

At DxO Mark, the results for the AF-S DX Nikkor 18-55mm f/3.5-5.6G VR are similar to those at dpReview. The older AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6G ED II seems to do a little better at f/5.6 on the wider end and at f/8 on the longer end.

Both the dpReview and DxO Mark tests were conducted using a D300 rather than a D3100, but the results using a D3100 should be fairly close.

Answer 2

Please see the charts here. The sharpest aperture depends on the focal length. As you can see, at 18mm, the center is barely sharper at f/5.6. At 35mm and longer, it is sharper at f/8. The differences in jpegs posted to the web or in prints at 8x10" or smaller is unlikely to be perceptible. The advice above, if in doubt, use f/8, is sound. I would add a sturdy tripod.

Answer 3

As a general rule of thumb:

• f/8 is often sharpest for lenses designed for full-frame coverage
• f/5.6 is often sharpest for lenses designed for Nikon DX or APS-C coverage
• f/4 is often sharpest for lenses designed for Micro 4/3 or similar coverage.
• Wide open is often sharpest for compact cameras or cellphone cameras.

However, being a general rule of thumb, this will obviously vary according to each lens, but the sharpest point for most lenses should usually be within a stop or two of the above figures - especially if they are of relatively normal focal length (ie, not ultra wide angle or very long telephoto).

Tests done by places such as photozone.de or DxO Mark can help you get specific figures for a particular lens model. Note however that even individual lenses of the same model might vary a little.

Important note: The above also assumes that depth of field is not an issue for you. If you need a wider depth of field in order to put multiple subjects in focus, a smaller aperture than the above may result in more subjects being within acceptable focus. Thus it would be incorrect to say you should always avoid shooting narrower apertures than the above. Sometimes, it will be needed.

Answer 4

That's definitely depends on your lens. Usually, using the widest aperture won't produce the sharpest image. A thumb rule: Use 1-2 stops down from the widest aperture possible. This should give you good results. I guess you won't need more accuracy than that. Most of the times, I set the aperture size according to the DOF and the available light and using the thumb rule.

Note that a smaller aperture will give you a greater DOF (depth of field) and so, more areas in the photo will be in focus.

At some point, smaller aperture will cause diffraction. Usually it goes around F/13-16, depending on your camera and lens.

You can read more about these terms here: Diffraction, DOF.