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)
M42	1959–1960	Petri Penta
Petri FT	1960–1969	Petri 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)	1969–1977	Petri FT EE Petri FA-1
M42	1977–1978	Petri FT 500 Petri FT 1000 Petri MF-1 Petri SLR 35 Petri SLR 35 Compact Petri MF-2 * Petri TTL-2
Pentax K	1978–1980	Petri 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 *

Petri FT vs. Petri FT (EE)

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 length	Max aperture	FT type
28	f/3.5	FT (auto)
28	f/3.5	FT EE
35	f/2.8	FT (auto)
35	f/2.8	FT EE
55	f/1.4	FT EE
55	f/1.7	FT EE
55	f/1.8	FT EE
100	f/4.5	FT (preset)
135	f/3.5	FT (auto)
135	f/3.8	FT EE
200	f/4.0	FT (auto)
200	f/4.0	FT EE
300	f/5	FT (auto)
300	f/5.5	FT (preset)
400	f/6.3	FT (preset)
500	f/5.6	FT (preset)
1000	f/8	FT (manual)
1000	f/8	FT (preset)
80-200	f/4.5	FT (auto)
85-210	f/4.8	FT (preset)
85-210	f/4.5	FT EE

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.