Methodology & sources
Three rules: every spec is taken from a published source and recorded, every page is dated, and nothing is invented.
Sources
- Manufacturer product catalogs (Sony, Canon, Nikon, Fujifilm, Sigma, Tamron) — focal length, maximum aperture, mount and coverage are taken from official product names and spec sheets.
- Prices are never stored in our pages. Where a price appears next to a buy button, it comes live from Amazon's product API, refreshed at least every 24 hours and shown with the time it was fetched; if Amazon returns no current new-condition price, we show none. The price on Amazon at the time of purchase is the one that applies. Lens weights, where shown, are the maker's published figure (weight is fixed at manufacture): from the manufacturer's own spec page where we have it, otherwise from a published lens database or review quoting that figure. Every weight carries a per-lens source in the dataset, and each weight table says how many of its rows came from which. A lens without a verified weight is omitted from the table, never estimated.
- Our catalogues list every lens that mounts on a system, including models no longer in production. A fit reference is most useful when it also covers the lens you already own or found second-hand — so we do not track retail availability, and a listing here is not a claim that a lens is still sold new.
What we never do
- No invented "ratings" or review scores — groupings reflect focal length and aperture facts, not opinions.
- No sponsored placements.
- No stale data presented as fresh — every page carries a "last verified" date.
Corrections
Spotted an error? Contact us with a link to the manufacturer page; corrections ship within days.