Pentax-110 Zoom 20-40mm f/2.8

Zoom

Yes

Focus

Manual

Macro

No

Mount

Pentax 110

Format

110 (13 x 17 mm)

Groups

8

Elements

8

Weight

174g

Autofocus

No

Filter Thread

49mm

Spec Notes

NO DIAPHRAGM. Auto 110 super manual, verbatim: 'There are no aperture settings on Pentax-110 lenses. The aperture is set automatically by the diaphragm mechanism of the camera's programmed shutter system.' f/2.8 is this optic's fixed maximum and only aperture, which is why every lens in the system is f/2.8. `aperture Min` is therefore ABSENT, not zero and not a number. REJECTED: lensreview.xyz prints 最小絞り F16 for the 24mm and 50mm - inconsistent with both body programme limits (f/13.5 and f/18) and with the lens having no iris; the same site prints 最小絞り F2.8 for the zoom, which is the field being filled mechanically. NOT A MINIATURE K-MOUNT LENS - it cannot meter or expose without an Auto 110 body. ENGRAVING is 'Pentax-110', hyphenated, with no 'smc': zero instances of 'smc PENTAX-110' were found in maker print, museum catalogues, dealer transcriptions or databases. APERTURE CONSTANCY UNVERIFIED: every maker designation writes it flatly as 20-40mm f/2.8 with no variable notation, and the Auto 110 super manual lists the zoom with NO f-number at all. One PentaxForums user reports roughly a stop of falloff at the long end - a forum observation, which corroborates but does not establish. Minimum focus NOT SOURCED.

Max Aperture

f/2.8

Introduced

1981

Focal Length (Max)

40mm

Focal Length (Min)

20mm