Petri Flex 7

Petri were a prolific maker of cameras in the 1950s, 60s and 70s — for themselves and for own-label resellers. I already have a Petri 7s rangefinder camera and a 2MTL made for Wirgin and sold as an Edixa 2MTL. It is possible that I have other Petri camera that I am not aware of.

lens: Petri anastigmatic
focal length: 55mm
apertures: ƒ/1.8 to ƒ/16
focus range: 0.6 m to infinity
lens fitting: Petri breech-lock bayonet
shutter: cloth focal plane
speeds: 1s to 1/1000s plus B
flash: PC connector
film size: 35 mm 

This Petri Flex 7 was introduced in 1964 and superficially looks like a Zeiss Ikon Contarex in its first incarnation. It is a sturdily made camera and quite heavy. It measures 151 by 98 by 91 mm and weighs 970 g which is heavier than most of my SLR cameras. Visually, the outstanding feature is the round exposure meter window above the lens — it is this feature that creates the similarity with the Zeiss Ikon Contarex.

In many ways, this is a ‘standard’ SLR camera. The layout of the top plate is much as you would expect with the film advance lever on the right. This is metal — anodised aluminium — and fairly straight. It has two rest positions, one flush with the edge of the top plate and the other standing proud about 5 mm which makes it easier to use.

In front of the film advance lever and slightly to the left is the window onto the frame counter. This is reset to ‘S’ when the back of the camera is opened — ‘S’ equates to ‘-3’. Next along is the shutter speed dial. This runs from one second to 1/100 seconds plus B. Speeds of 1 s to 1/60 s are marked by a red arc and the letter X. These are the shutter speeds suitable for electronic flash — this indicates that at these speeds the shutter is completely open as the flash fires. Faster shutter speeds can be used with flash bulbs as these give their maximum brightness for long enough for the shutter slit to move across the film gate.

Centrally on the top of plate is the pentaprism hump. This is bigger than you might expect as it holds the light meter as well as the pentaprism and focus screen. On top of the pentaprism hump is a Barnack accessory shoe. This has no electrical contacts so is a ‘cold shoe’.

On the rear of the pentaprism hump is the viewfinder eyepiece. This is large enough to be comfortable to use while wearing glasses. Inside the viewfinder is the focus screen. Most of this is a Fresnel lens which gives even illumination over the field of view. In the centre of the field of view is a circle of ground glass which the manual says is there to allow you to see the depth of field when the lens is stopped down. Fresnel lenses give nice even illumination but at the cost of fine detail. Mostly this does not matter but for critical focus (an judging depth of field) they are no good. Inside this circle is a rectangle of micro-prisms to aid accurate focus.

On the lower right of the focus screen is the light meter readout. This consists of a black rectangle with a gap on the left hand edge. To achieve a good exposure, you centre the needle in this gap by altering the lens aperture and shutter speed. It is intended to be used as a shutter priority system.

On the front of the pentaprism hump is the light meter sensor window. This is a CdS sensor and so requires a battery to work. The sensor window is circular and slightly recessed. Around the meter sensor window is a collar which rotates to set the film speed. This is in both DIN (red) and ASA (black). It is unusual for Japanese cameras to have film speeds in DIN but perhaps Petri were hoping for significant sales in Europe. Film speeds are from 11 DIN to 30 DIN or 10 ASA to 800 ASA. With modern digital photography, this range can seem a bit strange but, in 1964, films as slow as 10 ASA were available and films faster than 800 ASA were rare and niche. Just below the light meter sensor, to one side, is the camera serial number.

Left of the pentaprism is a signal to indicate whether the meter is switched on or not. When the flag is red, the meter is off — the meter is switched on by advancing the film so to conserve the battery you need to advance the film only when you are ready for the next shot. On the far left of the top plate is the rewind crank — this is the usual folding crank. Less usual, this crank only rewinds the film; it does not double up as a catch for the back and there is no memo function or any of the other functions that frequently appear here.

Now the front of the camera. At this point I usually mention that the front is dominated by the lens — and there is certainly a nice large lens sticking out of the front — but the eye is definitely drawn to the light meter sensor. It might not be as large as the lens but it is visually dominant.

The lens mount is Petri’s own three flange bayonet mount. This works much like any lens bayonet mount but instead of turning the lens to lock it you turn a locking ring — the lens itself remains stationary. This mount has an auto-indexing facility. The most prominent SLR camera at the time that this camera was produced was the Nikon F which had a curious requirement — on fitting a lens you had to turn the aperture ring from maximum to minimum to tell the light meter the aperture range of the lens. Petri have obviated the need for this by having a nodger which connects to a socket on a ring around the lens mount which is very similar to the AIS system introduced by Nikon in 1976. There is a small window at the top right of the lens mount which shows the set aperture. At first glance, this seems pointless as the aperture scale is clearly printed on the aperture ring of the lens. Unfortunately, the presence of the large bull’s eye light meter sensor means that you cannot read the set aperture off the aperture ring — hence this aperture window. If you remove the lens and move this indexing ring on on its own, it is apparent that this camera can only manage lenses with an aperture range of ƒ/1.8 to ƒ/16.

Inside the lens mount, my camera has a disaster. Just inside the mount there is a black steel plate with a negative sized rectangular hole. Someone has attacked this plate and bent and twisted it quite severely.This is obviously an attempt to repair the camera — the camera is quite jammed: the shutter will not fire and the advance lever will not move. The worry is what other damage has this person done in the futile attempts to repair this camera?

The locking ring for the breech lock is attached to the camera. In Canon’s FD mount, which is also a breech lock mount, the locking ring is attached to each lens. I find Petri’s version easier to use.

The lens is Petri’s own design and make (as far as I can ascertain). I am told that it is a seven element lens.It has a focal length of 55 mm and a maximum aperture of ƒ/1.8 which is quite wide for an amateur lens in 1964. Minimum aperture is ƒ/16 which is not as impressive.Focus is from 0.6 m (2 feet) to infinity. ƒ/11 is marked in red – with many cameras, this represents a Happy Snapper setting in conjunction with a red mark on the distance scale, but not here. I do not know the reason for ƒ/11 being in red. There is a switch on the lens for automatic diaphragm of manual diaphragm. If set to Auto, the diaphragm closes just before the shutter fires. If set to manual, the diaphragm is always closed to the set aperture. This aids in seeing the depth of field but gives a darker image which makes focusing harder.

Right of the lens mount, at the top right of the body, is the battery holder. This is intended to hold a PX625 cell which is a mercury cell and banned everywhere. However, I easily managed to find an alkaline alternative with the slight drawback that it gives 1.5 v instead of the 1.3 v intended.

Right of the lens mount, at the bottom of the body, is a PC connector for attaching a flash gun. The flash gun can be fitted to the accessory shoe for casual photography or mounted away from the camera for studio work.

On the left of the lens mount is the angled shutter release button. This was quite common on Praktica cameras from Germany and a similar system was used by Voigtländer and Zeiss Ikon in the 1960s but I have never been comfortable with it. The shutter release button, which is chromed metal, is not threaded for a shutter release cable. If you want to use a cable release, you need to unscrew a metal collar from around the button and screw a non-standard cable release onto those threads. A number of cameras have used a similar system but I fail to see the advantage of not using the more usual Gauthier tapered thread system.

Below the shutter release button is the self timer lever. To set this, you turn the lever anti-clockwise to wind the clockwork mechanism and then press a small chrome button that is revealed by moving the lever. Winding the lever through 180º gives a delay of eight seconds. Winding the lever through 90º gives a delay of two seconds — and between those two, a pro rata delay. Wind the lever less than 90º and the shutter will not be fired.

The base plate of the camera has little on it. In line with the lens is a standard tripod socket. This is the usual 1/4 inch socket and probably a Whitworth thread but the camera is recent enough that petri could have been early adopters of the modern UNC thread. Also on the base plate is the button to enable the film to be rewound.

The back of the camera is opened by a sliding catch on the left hand edge of the body. The inside of the back has a reasonably large pressure plate but none of the springs or rollers that are frequently found on the inside of 35 mm camera backs. However, there is a very small stud near to the catch which is intended to hold the film cassette steady.

On the left side of the inside is the film chamber which holds the 35 mm film cassette. The film gate surround is quite large which will help to keep the film flat over the film gate. To the right of the film gate is the sprocket shaft – this is there to count the number of sprocket holes that pass this point: eight holes equals one frame. Right of the sprocket shaft is the take-up spool. This has a single slot for the attaching the film leader.

The shutter is a cloth, horizontally moving, focal plane shutter. Shutter speeds are from one second to 1/1000 seconds plus the ubiquitous B. The flash synch speed for electronic flash is up to 1/60 seconds (which is the fastest shutter speed when the shutter is completely open) and the synch speed for flash bulbs is any shutter speed at all.

My camera does not work. Neither the film advance lever nor the shutter release button will mov e at all. As mentioned earlier, someone has viciously attacked the insides of the lens mount to the extent of seriously bending a steel baffle just inside the mount. What other repair attempts have they made? If someone has made such a crass attempt at a repair, I don’t think it worth my while attempting anything myself.


Author: John Margetts

I am a keen photographer who also collects cameras. I am retired with about 50 years photography experience.

4 thoughts on “Petri Flex 7”

  1. I have and still use my Petri FA_1. I Like it,s robustness ,55mm l.7 Mc standard lens,producing really good transparencies, I like its practicability because it can be used even without battery. The Petri 55 mm Mc lens is a good all rounder.


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