Olympus OM1n

I already have an Olympus OM camera – the OM10. The OM10 is an amateur camera – aperture priority exposure meter and very clumsy manual mode. This OM1 is a professional camera. It is entirely manual and entirely mechanical. That means it will work with no battery and will even work if the meter dies. The full name of the camera is the OM1N MD. The MD signifies that the camera is ready to accept a motor drive. The original OM1 needed the base plate to be replaced before the motor drive could be fitted. The N signifies that this is the second verion of the OM1. As far as I can ascertain, this second version was an entirely cosmetic upgrade.

lens:  G. Zuiko Auto-S 
focal length:  50 mm
apertures:  f/1.4 to f/16
focus range:  0.45 m to infinity
lens fitting:  OM bayonet
shutter:  cloth focal plane
speeds:  1 second to 1/1000 seconds
flash:  PC socket and contcts for optional hot shoe
film size:  35mm

Olympus cameras are easy to date. Open the back and carefully remove the film pressure plate (it is loosely held in place and is easy to remove). On the back of the pressure plate are four characters. The first is the code for the manufacturing factory (this might be in Kanji). The second is the year and the third is the month. The fourth character is the revision of the back plate. With my camera, the code is S9Y5. So, factory S (I have no idea which factory this is!), year is 9 (so 1979) and month is 11 (months are 1 to 9 and X,Y and Z giving twelve months) so November. Pressure plate revision is #5. We do not need more for the year as production started in 1972 and ended in 1987 so only one year 19×9. Don’t forget to put the pressure plate back! So, my camera was made in November 1979.

The layout of controls are idiosyncratic. With most focal plane equiped cameras, the shutter speed selector is on the top plate above the appropriate gummings in the shutter crate. Not here. The shutter speed selector harks back to leaf shutter layout and is a ring at the base of the lens barrel. This means that it is easier to change shutter speed with the camera at your eye. With the speed selector on the top plate, it is necessary to remove the camera from your eye to adjust speed. Where you might expect to find the shutter speed selector is a large knob with numbers, but this is the film speed selector.

As always, I shall give a description before describing using the camera. The camera weighs 505g without the lens but with a film inside. It measures 135 mm wide by 85 mm high and 50 mm deep (this is with no lens attached). The top plate looks normal (but see comments above) and is made from stainless steel. At the extreme right is the window to the frame counter. This resets to ‘S’ when the back is opened. ‘S’ is actually ‘-3’ as you need to wind three frames to get to ‘1’. Frames 12, 20, 24 and 36 are printed ingold (the rest are in white). These were the standard lengths of film that were available in the 1970s – just 24 and 36 frame films are available now. Frame 38 (should your film be that long) is a gold ‘E’ – the frame counter will not go beyond this but the film winder still works.

Next to the frame counter window is the film advance lever. This is metal with a black plastic tip. The lever has two positions when at rest. It has a park position flush with the edge of the top plate. In this position the lever cannot get in the wat but is more awkward to use. The lever’s natural position after advancing the film is to sit proud of the top plate. This makes it easier to use but leaves the lever rather close to your eye if you are right-eyed and possibly sticking in your right eye if you are left-eyed.  The lever works on a ratchet so the film can be advanced by repeated small strokes for those with limited mobility in their hands. If the film is advanced in one go, the lever will move through about 180°.

Forward, and slightly to the left, of the film advance lever is the shutter release button. This is within a fairly large collar. The button is threaded for a standard cable release. The collar around the button has a recessed mark which is an index mark for the film speed selector.

This film speed selector is the largest control on the top plate. It has film speeds (all in ASA – essentially the same as the modern ISO) from 25 ASA to 1600 ASA. With most of my cameras, it is necessary to lift the film speed selector to turn it. Not here. There is a small and hard to reach button nestling between the film advance lever, the shutter release button and film speed selector. Once depressed, the film speed selector turns easily. The standard film speeds are printed in gold but between them are two speeds printed in white. These white speeds are 1/3 of a stop apart.

 Dominating the top plate, as is usual with SLR  cameras, is the pentaprism hump. There is no accessory shoe as standard but one was available as an optional extra. There are three contacts on the top of the pentaprism hump to connect the hot shoe contacts.

To the left of the pentaprism hump is the on/off switch for the light meter. On my camera, this switch ‘leaks’ What I mean is the light meter still works when the switch is in the off position but givs a reading that is about 4 stops greater than it does when in the on position. The reading when in the on position is roughly what I would expect if using the Sunny 16 rule.

On the far left of the top plate is the film rewind crank. This is the standard fold-out crank and doubles as the catch for the back – you pull up the crank to release the back.

In the centre of the front is the lens mount. This is Olympus’s bayonet mount. This mount has two mechanical linkages – one tells the light meter which aperture has been set. This allows the meediately before the shutter is released. At this date (1979), there are no electrical contacts.

Around the lens mount bayonet is the shutter speed selector. This has speeds from 1 second to 1/1000 seconds and B. There are two milled lugs on either side of the ring to aid both finding the ring by touch and also to aid turning it. Contrary to to usual usage, the lens release button is on the lens rather than on the body.

On the left side of the lens mount is a PC (ProntorCompur) socket for a flash gun.Around the PC socket is a selector for flash bulbs (FP) or electronic flash (X).

On the right side of the lens mount is a switch. There is no indication on the switch as to its purpose and it took me a while to work it out (I have no manual). When turned, the mirror is raised up against the focus screen, thus rendering the viewfinder useless. This is for use with a tripod, raising the mirror once the shot has been composed to prevent the slight vibration caused as the mirror snaps out of the way as the photograph is taken. This is important for critical use such as macros and copying. A nice feature to have even if I will never use it.

On the front of the camera to the right of the lens mount is a switch with a position marked ‘R’. Turning this to ‘R’ allows you to rewind the film.Below the rewind switch is the self delay lever. Turning this winds up the clockwork delay timer – turn the lever 170° anti-clockwise. This reveals a second small lever which you press sideways to start the timer.  This gives a delay of 12 seconds before the shutter is fired.

The only other item on the front is a strap lug on either front corner.

The rear of the camera only has the viewfinder eye-piece. The viewfinder image is large and bright – brightness will depend on the maximum aperture of the lens. In the centre is a ring of microprisms and a split-image centre – these two are aids to focussing – more later. On the lower left of the focus screen is the meter needle. When the exposure has been properly set, the needle is central. If the needle is across the corner of the middle part of the display, the exposure is either 1 stop over (by the +) or 1 stop under (by the -).

The base plate is ready for a motor drive (see my opening comments). This consists of a pair of electrical contacts, a locating hole and access to the film advance mechanism. This last is via a largish hole that is covered with a blanking plate when not in use. There is also a second similar blanking plate which gives access to the battery compartment. The battery should be a 1.35 v mercury battery but these are no longer available – see my later comments on using the camera. By the lens mount is a standard tripod boss – 1/4 inch UNC.

The Lens:

The lens I have is a G. Zuiko Auto-S lens. The G tells us that the lens has 7 glass elements (A=1, B=2, … F=6, G=7). The focal length is 50 mm wich is a normal lens for 35 mm photography (‘normal’ means it produces images close to that which the human eye produces) and its maximum aperture is f/1.4. Most ‘kit’ lenses that Olympus provided were f/1.8 so this is a fast lens for its day (and quite fast for the present day!).

Close to the bayonet mount on the lens is a silver ring. This has depth of field marking on it – standard fare at the time and very useful. On the top left of this ring is a button which releases the lens from the body. On the opposite side of the lens (i.e. lower right) is a similar button but this is a depth of field preview button.

The camera in use:

I found this camera  joy to use. Some aspects require learning – the shutter speed selector, for instance. There are two fairly large lugs which can be found by touch but I kept finding the lens relese button by mistake. I am sure practise will make this easier (I have only used the one film so far).

I kept forgetting the light meter switch. Leaving it on all the time will run thebattery down. Leaving it off will give me false readings (see my comments above re the switch leaking). The first 13 frames I shot at the box speed of 200 ASA/ISO and from frame 14 onwards, I shot at 400 ASA/ISO. This is essentially to test using the meter with the wrong battery (1.5 v instead of 1.35 v). I can look at the negatives to get a first idea of accuracy by looking at image desity. If the meter uses a bridge type circuit (such as the early Spotmatic cameras did), the change in voltage will have no effect. It is possible that the extra 0.15 v will affect the meter and give an over-exposure so the shots at 400 ASA/ISO might be better exposed. As the meter works by having the needle centred I am not expecting a difference. If the meter worked by the needle pointing at a shutter speed, rather than being centred, I would very much expect a difference. We shall see.

Test film results:

I have looked at the negatives very carefully and I can see no difference between the 200 ASA/ISO shots and the 400 ASA/ISO shots. My conclusion is that the meter is fine with the 1.5 v battery.

The shutter is working fine. One problem with old focal plane shutters is that the blinds no longer move smoothly giving uneven exposure. Also, there are no visible pinpricks of light which would indicate that the shutter blinds were no longer fully light proof.

The camera back closes against a foam plastic seal to keep light out. In cameras of this age, this is usually (always?) deteriorated. There are no signs of light leaks around the back.

The negatives are well exposed telling me that the meter is working fine

The lens is good. I have most of the shots at infinity but some deliberately closer – the kids bike for instance. Someone else can tell me about the bokeh as this is something I just cannot care about.

Click on the individual images to see them larger.

See here for details of the OM range.