Canon EF400mm f/5.6L USM is listed for Canon EF with image coverage not yet established in this record. A front screw-in filter size is not established by the checked evidence, so no diameter is recommended. The supplied research links this exact mount variant to manufacturer evidence. Body-specific AF, crop and adapter behavior remain separate checks.
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Verified specifications
| Field | Value |
|---|---|
| Mount | Canon EF |
| Image format | Not verified |
| Front filter thread | Not specified in checked source |
| Model ID | canon-ef400mm-f-5-6l-usm-canon-ef |
| Focal length | 400 mm |
| Maximum aperture | f/5.6 |
| Weight | 44.1 oz (approx.; 1250 g maker value) |
| Length | 10.10 in (approx.; 256.5 mm maker value) |
| Maximum barrel diameter | 90 mm |
| Closest focus | 11.48 ft (approx.; 3.5 m maker value) |
| Maximum magnification | 0.11×; see maker conditions below |
| Lens AF hardware | Maker states yes |
The reported maximum magnification is conditional: 0.11. Do not substitute a 35 mm-equivalent figure or a teleconverter configuration for the bare-lens value.
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Compare the exact model code and rear mount in each listing. Amazon results may contain another mount or generation; the search is not a compatibility verdict.
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Search camera lenses on AmazonChoosing a camera
Look for the Canon EF designation on the camera specification, then verify the exact model code and mount variant against its support page. The maker lists a 400 mm focal range and f/5.6 maximum aperture. A physical mount match is a starting point; still AF, movie AF, crop behavior, stabilization and firmware need separate checks.
Choosing a filter
A circular screw-in filter with a matching documented thread size is only a mechanical candidate. Magnetic filters, wide frames and stacked rings need separate system and vignetting checks. When no front thread is specified, do not buy a size from the focal length or barrel diameter.
This model cannot enter the diameter calculator until a verified front thread or dedicated holder specification is available.
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Official sources and scope
Checked for this reference on October 30, 2026. Product firmware and support lists can change; inspect the current maker page for your exact revision.