HD PENTAX-D FA645 35mmF3.5AL[IF] is listed for Pentax 645 with 645 medium format coverage. Its verified front filter size is Ø82 mm. Ricoh lists this exact lens under its 645-mount catalog. Camera-specific electronic functions remain unassessed.
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Verified specifications
| Field | Value |
|---|---|
| Mount | Pentax 645 |
| Image format | 645 medium format |
| Front filter thread | Ø82 mm |
| Model ID | pentax-645-hdpentax-dfa645-35 |
| Optical construction | 10 elements / 7 groups |
| Closest focus | 0.3 m |
| Maximum magnification | 0.25x |
| Minimum aperture | F32 |
| Aperture blades | 9 |
The maker also lists 10 elements / 7 groups for the optical design and a closest-focus specification of 0.3 m. These are lens specifications, not a guarantee of performance on every body or in every shooting mode.
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Look for the Pentax 645 designation on the camera specification, then verify the exact model code and mount variant against its support page. 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.
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Checked for this reference on October 30, 2026. Product firmware and support lists can change; inspect the current maker page for your exact revision.