I purchased a Sony NEX F3, and it came with a 16mm lens and a 18-55mm lens. It seems to me that the 18-55mm lens produces better picture.

Does the bigger lens opening in the 18-55mm lens produce better image quality because it allows more light to pass through so that the sensor of the NEX F3 is fully utilized? And the 16mm doesn't fully utilize the power of NEX F3 sensor?

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  • \$\begingroup\$ If you are getting "better image quality" with the 18-55mm over the 16mm lens(as you noted in a comment below), I suggest setting up a test of the same subject and shoot in manual mode, keeping the settings the same for both shots - post the results to a new topic here and let us evaluate. \$\endgroup\$
    – dpollitt
    Jan 20, 2013 at 6:13

1 Answer 1


No. Lenses are designed to cover a certain image circle which is larger than the camera's sensor. All lenses with the same or larger image circle use the full surface area of the sensor.

The amount of light that reaches the sensor is dictated by the aperture used to take the picture and the shutter-speed. More light results in a higher signal-to-noise ration and therefore less apparent image noise.

The size of the rear opening is dictated by the lens design and has nothing to do with the quality of images it produces. Ideally, the size should exactly match the projection of the sensor based on the angle of incidence of light falling on it.

  • \$\begingroup\$ from here (shortcourses.com/use/using5-2.html) I understood it as that smaller lens allows smaller image? And can you explain why I'm getting better image quality with the 18-55mm lens than the 16mm? \$\endgroup\$
    – user133466
    Jan 20, 2013 at 3:31
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    \$\begingroup\$ This is in the case of a lens designed for a smaller sensor. For example if you would take a Micro Four-Thirds lens and plug it on a NEX camera (with a suitable adapter which probably does not exist), then the m3/4 would project a too small image circle. This is much more common when mounting a cropped-sensor (DX in Nikon terms) lens on a full-frame camera (FX camera in Nikon terms). \$\endgroup\$
    – Itai
    Jan 20, 2013 at 3:38
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    \$\begingroup\$ @user133466 - It is impossible to explain because we do not know what you are seeing. One or both of your lenses may even be defective for all we know! In theory a prime lens can be built better than a zoom but the reality depends on specific models. \$\endgroup\$
    – Itai
    Jan 20, 2013 at 3:41

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