Camera connections differ. All ten Sigmas offer L-Mount and Sony E-mount; Rokinon's five offer Sony E. Tamron's five have no mount detail here.
Look up the exact version for your camera before buying.
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With no preferences selected: Rokinon AF 18mm F2.8 FE is one option to compare.
Your choices are compared with each model’s product details. A missing or conflicting value stays unknown and cannot satisfy a choice you select. The starting order helps you browse; it does not rate real-world performance.
Source dates appear with each link below. A source date does not confirm today's price or stock.
Tamron 20mm F/2.8 Di III OSD M1:2 (Model F050): Source 1 ↗ · September 15, 2026
Tamron 24mm F/2.8 Di III OSD M1:2 (Model F051): Source 1 ↗ · September 15, 2026
Tamron 28-200mm F/2.8-5.6 Di III RXD (Model A071): Source 1 ↗ · September 15, 2026
Tamron 28-75mm F/2.8 Di III VXD G2 (Model A063): Source 1 ↗ · September 15, 2026
Tamron 35mm F/2.8 Di III OSD M1:2 (Model F053): Source 1 ↗ · September 15, 2026
Match the lens mount before building a filter kit
Rokinon’s AF 45 mm F1.8 E names Sony E, while Sigma’s 45 mm F2.8 DG DN names L-Mount and Sony E-mount versions. The mount is available for 15 lenses; entries with no mount here leave camera compatibility unresolved. Lens dimensions and maker descriptions are documented; charts were not photographed and autofocus systems were not used for this guide. Select the specific mount version on the product page before ordering.
A family offered in multiple mounts does not make every version fit your body.
Filter diameter is its own compatibility decision
Filter threads range from 49 to 82 mm. Rokinon’s AF 45 mm takes a 49 mm filter, while Sigma’s 45 mm DG DN takes a 55 mm filter. Equal focal lengths therefore do not mean your existing filters will fit both lenses.
Keep filter size separate from lens mount when you compare accessories you already own.
Read the aperture across the whole zoom range
Rokinon’s AF 45 mm has a maximum aperture of F1.8; Sigma’s 45 mm DG DN has F2.8. The Tamron Di III RXD zoom instead gives a maximum-aperture range of F/2.8-5.6. Preserve that range rather than comparing it as a fixed-aperture lens.
Focal length and maximum aperture describe the named version; they do not rate autofocus behavior or image sharpness.
Close-focus figures need their original qualifications
Rokinon’s AF 45 mm gives a minimum focusing distance of 0.45 m, while its AF 18 mm gives 0.25 m. Sigma zoom entries distinguish wide and telephoto settings, so carry those qualifications into any close-focus comparison. Minimum-focus information is available for 15 lenses; the blanks require a maker-page check.
Close-focus distance alone cannot determine reproduction size or sharpness at that distance.
Before you buy
Does a matching filter size mean a lens fits my camera?
Filter thread and lens mount are separate. Eight of the 20 share a 67 mm thread, including all five Tamrons, so one set of that thread size’s filters could cover many of them, but the mount still has to suit your body.
Why does the Aperture f/2.8 choice show nine lenses?
It combines the makers' F2.8 and F/2.8 spellings, so it covers four Tamron F/2.8 lenses and five from Rokinon and Sigma. Tamron's 28-200mm, at F/2.8-5.6, has a choice of its own.
Are these lenses sharp, and is the autofocus fast?
Sharpness and autofocus speed aren't compared on this page. What does differ on paper is the aperture blade count, given for 15 lenses: 7 on the Rokinon 18mm and Sigma 45mm, and 11 on five, including the Sigma 85mm F1.4 DG DN. Among the zooms, that Tamron superzoom covers the most range at the aperture given above, while Sigma's 24-70mm and 28-70mm are F2.8 zooms.
