Canon RF-S3.9mm F3.5 STM DUAL FISHEYE — Canon RF mount and filter size

Canon RF-S3.9mm F3.5 STM DUAL FISHEYE is listed for Canon RF with APS-C coverage. 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 RF
Image format	APS-C
Front filter thread	Not specified in checked source
Model ID	canon-rf-s3-9mm-f3-5-stm-dual-fisheye-canon-rf
Focal length	3.9 mm
Maximum aperture	f/3.5
Filter attachment type	rear
Weight	10.2 oz (approx.; 290 g maker value)
Length	3.30 in (approx.; 83.7 mm maker value)
Maximum barrel diameter	112 mm
Closest focus	0.66 ft (approx.; 0.2 m maker value)
Maximum magnification	0.03×; see maker conditions below
Lens AF hardware	Maker states yes

The reported maximum magnification is conditional: 0.03x. 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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Choosing a camera

Look for the Canon RF designation on the camera specification, then verify the exact model code and mount variant against its support page. The maker lists a 3.9 mm focal range and f/3.5 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.

Hoods, caps and other maker-listed parts

“Supplied” describes the maker’s package statement for this exact lens record. A merely related part may be sold separately, and neither label establishes cross-generation interchangeability.

Part code	Maker label	Relationship
Lens Dust Cap RF	Lens Dust Cap RF	Maker lists as related; inclusion not established
Not Supported	Not Supported	Maker lists as related; inclusion not established
Canon Lens Cap 3.9	Canon Lens Cap 3.9	Maker lists as related; inclusion not established
LS1014	LS1014	Maker lists as related; inclusion not established

Keep exploring

Check filter fitChoose exact lens and filter diameter

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.