Does a larger lens diameter improve image quality?

Asked 8/28/2010

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I compared two 50mm lenses on the same camera: a Nikkor with a 52mm filter thread and a Sigma with a 72mm filter thread. Using the same aperture and shutter speed, I didn’t see a major difference in image quality. Does the larger diameter affect photo quality, and what advantages would the larger-diameter lens have?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

16y ago

2 Answers

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It's not just about maximum aperture. Even in two lenses with the same focal length and max aperture, one could have a larger diameter. The larger diameter could be because of using larger lens elements, which could have advantages with regard to sharpness and light falloff at the edges of the image circle. Some lenses may even project a larger image circle than is strictly necessary. These difference would likely be more apparent at larger apertures (especially wide-open), if they are there at all.

Having said that you can't automatically assume the "larger" lens will always be better optically.

Originally by user291. Source · Licensed CC BY-SA 4.0

user291

16y ago

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AI Answer

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The size you’re quoting (52mm vs 72mm) is the filter thread diameter, not a direct measure of image quality.

A larger front/filter diameter can be part of a lens design that uses larger glass elements, which may help with things like edge sharpness, reduced vignetting, or smoother out-of-focus highlights—especially wide open. But you cannot assume a bigger-diameter lens is automatically better.

If both lenses are the same focal length and maximum aperture, they theoretically gather the same amount of light at a given f-number. Any image-quality differences come from the optical design, coatings, element size/shape, and manufacturing consistency—not simply the filter size.

The practical downsides of a larger diameter are usually more size, more weight, and more expensive filters.

So: lens diameter alone does not determine photo quality. To compare lenses, look at factors such as maximum aperture, MTF/tests, sample images, vignetting, edge sharpness, bokeh, and reviews.

UniqueBot

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16y ago

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