Lens Mounts: Petri FT

Basic Information on the Petri FT mount:

Petri Camera K.K (Originally Kuribayashi Seisakusho(栗林製作所)) is in many ways the quintessential YAJCM (Yet Another Japanese Camera Manufacturer) and the company’s trajectory in many ways embodies that of a large part of the post-war Japanese camera industry (that part that dropped out of the camera business before the end of the Cold War). While a case study into Petri Camera would be interesting (and if anyone has a link to a good account, let me know), for now, we’ll focus on discussing the Petri FT mount.

Somewhat idiosyncratically, the Petri FT mount (sometimes also referred to as ‘Petriflex’ mount) is not named in accordance with the model name of the first of Petri’s SLR’s that utilised this proprietary mount (as is the case with the Minolta SR mount, the Nikon F mount, the Konica AR mount, etc.), as the Petri FT was not the first Petri SLR to use the Petri FT mount (incidentally, neither was the Petri Flex). Instead, the FT mount was introduced in tandem with the 1960 Petri Penta V / Petri Penta automatic (alike many Japanese camera manufacturers the same camera would be sold under different names in different markets).

To add insult to confusion, although the Petri FT mount is often referred to as a bayonet mount (even by Petri themselves) the lens mount is of the breech-lock type (with the friction ring on the camera side). Even more perplexing is that some sources mention two different proprietary Petri mounts, and mention that there is both a Petri breech-lock mount (this one) and a, different, Petri bayonet mount. On closer inspection, that Petri bayonet mount turns to be the Pentax K mount(!). At this stage, finding out that there were Petri SLR bodies that were manufactured with several mounts (as happened with some German SLR’s) would be the icing on the cake of confusion, and while I have not found any mentions of that, I would not discount the possibility.

In the hope of trying to clear up the confusion, see table below:

Lens mount used
by Petri Cameras
Years (roughly)Petri camera models
(incl. names in different markets)
M421959–1960Petri Penta
Petri FT1960–1969Petri Penta Automatic / Petri Penta V
Petri Penta V2 / Petri Flex V
Petri Penta Junior
Petri Flex 7
Petri Penta V3 / Petri Flex V3
Petri Penta V6
Petri Penta V6 II
Petri FT
Petri FTE
Petri FTX / Petri TTL (also rebadged as “Focal TTL”)
Petri FT II
Petri FT (EE)1969–1977Petri FT EE
Petri FA-1
M421977–1978Petri FT 500
Petri FT 1000
Petri MF-1
Petri SLR 35
Petri SLR 35 Compact
Petri MF-2 *
Petri TTL-2
Pentax K1978–1980Petri MF-3 *
Petri MF-4 *
Petri MF-101 *
Petri MF-101A *
Petri MF-102 *
Petri MF-103 *
Petri MF-104 *
Petri GX-1 *
Petri GX-1 Super *
Petri GX-2 *
Petri GX-3 *
Petri GX-4 *
Petri GX-5 *
Approximate table of Petri-branded SLR cameras and the mounts they used – pieced together from various sources. Cameras denoted with * were Cosina bodies rebranded as Petri in some markets.

Petri FT vs. Petri FT (EE)

Petri FT EE body and lens
Pictured Petri FT EE body and Petri C.C. EE Auto 55 mm f/1.8 lens
Image Credits: Joe Haupt, CC BY-SA 2.0 via Wikimedia Commons

The Petri FT mount was originally introduced in 1960, at a time when exposure automation was still a relatively distant dream. As a result, while the Petri FT mount was geared to enable automatic aperture (focusing and composing with fully open aperture; automatic closing down at triggering of shutter) it only supported stop-down metering.

This shortcoming was addressed in 1969 with the introduction of the Petri FT EE (in 1960’s camera nomenclature ‘EE’ typically was short for ‘Electronic Eye’) that (when using FT EE lenses) enabled both open-aperture metering and shutter-priority auto exposure. The change from FT to FT EE was accomplished by adding an EE setting to the aperture ring and a pin (called the aperture control pin) in the mount that would communicate (to a compatible body) that the EE setting was engaged.

Physically Petri FT and Petri FT (EE) lenses are fully compatible (you can mount an FT lens on an FT EE body and vice versa), but the functionality would always be defined by the lowest technology present. A rundown of Petri FT lenses is given below.

Focal lengthMax apertureFT type
28f/3.5FT (auto)
28f/3.5FT EE
35f/2.8FT (auto)
35f/2.8FT EE
55f/1.4FT EE
55f/1.7FT EE
55f/1.8FT EE
100f/4.5FT (preset)
135f/3.5FT (auto)
135f/3.8FT EE
200f/4.0FT (auto)
200f/4.0FT EE
300f/5FT (auto)
300f/5.5FT (preset)
400f/6.3FT (preset)
500f/5.6FT (preset)
1000f/8FT (manual)
1000f/8FT (preset)
80-200f/4.5FT (auto)
85-210f/4.8FT (preset)
85-210f/4.5FT EE
List of various Petri FT lenses – pieced together from various user manuals of various Petri FT-mount SLR’s (lenses not mentioned in any of the manuals – such as a 135/2.8 that seems to exist but is not mentioned in any Petri literature – have been omitted). There is (in the manual of the Petri FA-1) some indication of a 21 mm lens also being in the pipeline, but whether such a lens was ever mass-produced is unclear. Quite clearly, the lineup of Petri lenses was heavily weighed towards standard lenses and tele lenses.

Petri FT mount specifications

Mount type: Breech-lock (ring on camera)
Flange focal distance: 43,5 mm
Film format: 36mm x 24mm (‘Full frame’)
Mount communication (Petri FT): aperture stop-down (camera-to-lens);
Mount communication (Petri FT EE): aperture stop-down (camera-to-lens); aperture control pin (lens-to-camera)

Key characteristics of the mount of Petri FT-mount lenses
[1] Breech-lock mount with three lugs, with something resembling a locking notch at 6 o’clock
[2] Orientation pin at 6 o’clock (on a camera, this always goes up)
[3] Aperture stop-down lever
[4] Aperture control pin (only on FT EE lenses)

The Petri mount is a breech-lock mount, where the breech-lock’s friction ring is on the camera’s end, meaning that (when only looking at a lens) one might mistake it for a bayonet mount.

Adapting Petri FT lenses

First, as always, why would you want to adapt Petri FT lenses? Notwithstanding the situation wherein you’re already in possession of a wide spectrum of quality Petri FT lenses, there are relatively few reasons. Petri lenses are generally considered to not be anything special (with one exception, the Petri Orikkor 50/2, that was never offered in Petri FT mount).

Even at its height, Petri’s lineup of lenses for the Petri FT mount can only barely be seen as comprehensive, and the total lack of any traditional short tele/portrait lenses is conspicuous. Moreover, looking at completed eBay sales, one has to conclude that most of these lenses (except for the 28, 35, 55, 135 and 400 mm lenses) are very rare and only the f/1.7–f/1.8 versions of the 55 mm lens is commonly available.

However, should one be interested in adapting Petri FT lenses, there are adapters available (as of 2022). While none of the major adapter manufacturers (K&F, Novoflex, Kipon etc.) offer Petri FT adapters, at least one professional adapter manufacturer is offering a full range of Petri FT-to mirrorless adapters. As JAPB have not tried said adapters, we do not vouch for their quality, but if we were to try to acquire a Petri FT adapter, this would be our go-to place to source them.


  1. Thank you for all this information. Just a small correction for the mount table: Petri FT 500 and Petri FT 1000 are M42 mounts, although the name suggests otherwise.

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