The Olympus M-1 Information Page
M-1 Picture

Welcome to my M-1 information page. This page is a documentary about the Olympus M-1, what it is, and what makes it so special in the Olympus OM lineup. Much of the information being presented here has been gathered as part of my M-1 restoration project.

M-1 History
M-1 Brochure  (9MB)

The M-1 and M-SYSTEM components were introduced by Olympus in 1971 and produced until February 1973. The system consisted of a single body, the M-1, and a collection of lenses and accessories. It is known that the following lenses were available and actually sold as M-SYSTEM lenses: 28mm f3.5, 35mm f2.8, 50mm f1.4, 50mm f1.8, 55mm f1.2, 135mm f3.5, 100mm f2.8, 200mm f4.0, 75-150mm f4.0. In addition, the following accessories were also produced and sold as M-SYSTEM components: VST-1, Auto Bellows, and Varimagni Finder. The name M-1 and the M-SYSTEM designation was changed to OM-1 and OM-System due to a complaint from Leitz. Since 1959, Leitz had been using the M1 designation for its rangefinder camera and felt Olympus was infringing on a trademarked name. Olympus honoured Leitz's complaint and agreed to change the name. Unfortunately, by the time that decision was made, quite a number of M-1's and M-SYSTEM components had already been built and sold in the marketplace.


Since the M-1 was the first OM model to be produced, it contained a number of unique features which were either changed or completely dropped in later OM-1 production runs. These features can be used to identify an M-1 and to roughly estimate when an M-1 was produced. The information presented here has been gathered from disassembly of an M-1 and from discussions with former Olympus technicians.

External Differences
M-1 Battery Cover

There are a number of externally visible difference between an M-1 and a late-model OM-1. The most evident difference is the inability to accept a motor drive or winder. This can be seen by examining the bottom plate of the camera and looking for the missing MD cover plate. The only cover plate which should be present on an M-1 is the battery cover.

M-1 Film Canister Assembly

The M-1 also used a different back than later vintage OM-1's. The back can be identified by the smaller film pressure plate, closer spaced film pressure plate mounting studs, and the early style film canister retaining assembly. The M-1 pressure plate measured 51.5mm x 38mm whereas later vintage OM-1's used a larger 60.5mm x 38.5mm sized plate. To measure the spacing of the film pressure plate mounts, it is necessary to remove the film pressure plate. Once the plate is removed, the spacing between the two studs can easily be measured. The spacing on an M-1 back should be 45mm centre to centre, compared to the later 52mm spacing. With the back open, the film canister retaining assembly is easily visible and is shown in the accompanying photo. The retaining assembly was redesigned such that two "fingers" applied pressure to the film canister to hold it in place.

Film Pressure Plate Datemark

With the film pressure plate removed, it is very easy to identify the production date of the camera (as long as the back has not be switched from another body!). On the back of the film pressure plate you will find a production stamp located in the centre of the plate. It would look similar to the attached photograph. The first character (the Japanese symbol) represents the manufacturing plant which built the camera. The next two digits are a date code which represents the year and month in which the camera was built. In this particular case, the code "31" indicates this particular M-1 was manufactured in January, 1973. It is believed that this was the last production run of M-1's. Very early OM-1's contain a production date code of "32" which is February, 1973.

Door Latch

The M-1 also used a slightly different style door latch mechanism than what was used on later OM-1's. The M-1 mechanism used a flat style hook instead of the more common "bump" style. You'll notice in the attached photograph that the latch hook is completely flush with the body casting. Later variations of the latch raised the hook away from the body casting.

Lens Mount Screws

One final external difference exists between an M-1 and later vintage OM-1's, the M-1 used slotted style screws on the lens mount. In later OM-1 production runs, the slotted screws were dropped in favour of phillips (star) style screws.

Internal Differences

The most significant difference between an M-1 and the newest OM-1's lies in a number of internal changes that were made. There were dozens of changes made, some were design improvements, some addressed problems with the original design, while others merely improved the manufacturing ability of the OM-1. Presented here are only those changes which were made shortly after the M-1 production terminated.

M-1 Top View

Under the top cover of the M-1, there are a number of clearly visible items which were changed early on in the OM-1 production cycle. The above picture points out several of these items which will be discussed further.

Meter Resistor R4

The original M-1 meter circuit consisted of four resistors labelled R1 through R4. Resistors R1 through R3 are used to adjust the meter for mid, high and low light levels respectively. Resistor R4 was present in the circuit to allow the meter to be calibrated to within 1/16'th of a stop. All M-1's left the factory with resistor R4 present and calibrated. Early on in the OM-1 production, it was determined that resistor R4 added very little value to the final accuracy of the exposure meter, so it was decided that resistor R4 would be dropped from the circuit. However, the circuit board remained the same, only the resistor was dropped.

Meter Needle Deflector

All M-1's were built with a meter limit warning circuit surrounding the galvanometer (ie. the meter) which would fully deflect the meter needle whenever the meter hit its low-light limit. The sudden deflection of the meter needle was meant as a warning to the photographer that the meter had hit its low-light metering limits. Although the circuit worked, it proved troublesome in the field and occassionally caused the meter to be permanently deflected. The disadvantages far outweighed what little benefit it provided, and the circuit was dropped early on in the OM-1 production.

Red-Black-Green Wiring

The photocells used in the M-1 metering circuit are also different from the ones used in later vintage OM-1's. The newer photocells had better resistance characteristics which made it easier to calibrate the meter. All M-1's used the original type of photocell, which can be identified by the red-black-green colour wires coming from the photocell. Newer photocells used the red-black-pink colour scheme.

Missing Motor Drive Facilities

As we already know, all M-1's were originally produced without the ability to accept a motor drive or winder. More evidence of this can be found by examining the first (primary) wind gear. The first wind gear (the one on the left) is missing the spring loaded ejector pin which is found in the centre of an MD capable first wind gear. The M-1's first wind gear should have a slotted screw present in the centre of the gear. In addition, the location where the motor drive electrical contacts are attached will be slightly different depending on the vintage of the M-1. The more recent M-1's will have the mounting holes for the MD electrical contact pre-drilled, tapped and filled with a screw. The earliest M-1's have no mounting holes present. Here is a photo of what a late-model M-1 would look like. The two slotted screws are used to secure the MD electrical contact bracket to the body.

M-1 German Brochure  (8.4MB)
M-1 English Brochure  (9MB)
M-1 English Brochure  (6.5MB)
M-1 Manual  (6MB)
Instruction Manual (Japanese)
M-1 Japanese Advertisment
Japanese Advertisement
M-1 Japanese Advertisment
Japanese Advertisement

      (1) Thanks to John Foster, (2) Thanks to Lars Petersen

The M-System

All the M-system bodies and lenses were produced at the Olympus manufacturing plant located in Suwa, Japan. M-System items were sold across the world, but the majority of the items seem to have been originally sold in Asia (Japan and Hong Kong) and Europe (Germany). Over time the items have migrated across the world and today they can be found virtually anywhere. The M-System items were produced in varying quantities depending on the popularity and price of the item. For example, the 50mm f1.8 was produced in far larger numbers than the 55mm f1.2. By tracking the serial numbers of M-System items and comparing those serial numbers to early OM-System items, we can make an educated guess as to the approximate number of M-system pieces produced for each item. For the M-1 body we have the added advantage that we can also track the production date of each body and correlate the production sequence with the serial number. After collecting data for a number of years, we can now summarise the production data as follows:

Rarity Confidence of Data
M-1 Body
Common Very High
28mm f3.5
Less Common Low
35mm f2.8
Less Common Very High
50mm f1.4
Common Very High
50mm f1.8
Common High
55mm f1.2
Very Rare Good
100mm f2.8
Less Common Very High
135mm f3.5
Less Common Good
200mm f4
Less Common Very High
75-150mm f4
Rare Low
Varimagni Finder   Very Rare Low
VST-1 Macro Stand   Rare Low

The "rarity" score is graded on the following scale "Common - Less Common - Rare - Very Rare" and represents the probability of locating that item when searching for M-System items. Keep in mind that all M-system items are far less common than OM-System items, but some M-System items are particularly difficult to find. A grading of "Common" does not imply that the item is easily located, it just signifies that the item is easier to locate than a "Very Rare" item.

For each item a grade is given for the amount of confidence we have in the production number estimate. The scale used to measure the confidence is "Very High - High - Good - Low - Very Low" and represents the likelihood that the estimated production number is accurate. The grade is based on how much actual data has been collected and how close the largest M-System serial number is to the smallest OM-System serial number. The closer the two serial numbers are the more likely it is that we have a complete representation of the M-System data.

From the data collected we can also see that the M-1 body serial numbers were not assigned in strict sequential order. Although the serial numbers were mostly assigned in an increasing order, there were small batches of serial numbers which were assigned out of order. If we ignore those out of order batches we can see that Olympus was producing approximately 2,000 M-1 bodies per month in early 1972 with production ramping up to approximately 5,000 M-1 bodies per month by early 1973. The production figures match very closely with the estimate of approximately 52,000 M-1 bodies.

The table below provides the raw data used to compile the above summary.

Component Database

The following table lists all the known components of the M-System along with their serial number and production date (if available). The data in this table will be expanded as new information is discovered.

Item Serial
Owner Comments
M-1 Body 100401   Ken O'Brien red dot
  101982 Aug/72 Ken O'Brien eBay Jan/06 - red dot
  102248 Aug/72 Micheal O'Carrigan  red dot
  102677 May/72   eBay Apr/04 - red line
  102962 George Sears red line
  106686 May/72   red dot
  107270     eBay Nov/05
  107715 Sam Morales red line
  108726 May/72 John Foster red line
  108949     Photokina demo model (details)
  108950 Pratt Dean red dot
  109329   Japanese Magazine
  109473 Aug/72 Ken O'Brien red line, eBay May/06
  109818   eBay June/02
  110679 Sept/72 Mark Dapoz red dot, purchased Nov/72
  110936 July/72 Stephen Troy red line
  111676 Sept/72 Ken O'Brien red line, eBay July/06
  115616 Tomoko Yamamoto  
  116143 Sept/72 Ken O'Brien red dot
  118435   Meinhard Schmitt red line
  118361 Sept/72 Ken O'Brien red dot, eBay March/06
  119532 Oct/72 Ray Young  
  119544 Oct/72 Stephen Troy red dot
  119960 Jim Timpe red dot
  121696 Aug/72   red line, eBay Oct/06
  122039 Oct/72   red dot
  122214 Sept/72 Mirko De Filippo red dot
  123511 Oct/72 Andy Radcliffe red dot
  124936 Sept/72 Ken O'Brien red dot, eBay May/06
  125018 Oct/72 Stephen Troy red dot
  125574 Nov/72   ebay May/06
  128433 Oct/72 Ken O'Brien red dot
  129737   Massimiliano red dot
  129883     eBay Dec/05
  130247   Peter Gawan  
  130256 Sept/72 Dan Troy red line
  130921   Akihiko Yajima  
  132135 Dec/72   eBay Oct/06
  132908 Dec/72 Ken O'Brien  
  137422     red dot
  139272 Jan/73   eBay April/06
  140673   David Waldie Steven Pidcock
  143245 Jan/73   red dot, eBay June/06
  144185   Akihiko Yajima  
  144572 Sam Morales red dot
  145837   Meinhard Schmitt red dot
  147466 Feb/73   eBay March/03, cross pt screws
  147792 Jan/73   eBay Nov/06
  148059 Jan/73 Mark Dapoz red dot
  148730 Feb/73 Mirko De Filippo red dot, eBay Nov/05
  149627 Feb/73 Stephen Troy red dot
  149750 Greg McGrath  
  149902 Raul Varona Ruiz red dot
  155243 Feb/73 Stephen Troy red dot
  162023 Feb/73 Dinkar Jhalera  
  174027 Apr/73   eBay Apr/04 - red dot, cross pt.
  222116   eBay May/02
  366218 Jan/73 Mirko De Filippo eBay March/06, cross pt. screws
  412527   error?
28mm f3.5 101021   Daniel Troy  
  101311   John Foster  
  104186   Meinhard Schmitt  
  104354   Mark Dapoz  
  105061   Mark Dapoz  
  106282   Dinkar Jhalera eBay April/04
  106402   Michael O'Carrigan  
  107699   Akihiko Yajima  
  108127   Stephen Troy  
  108392     eBay June/06
  108329   Ken O'Brien eBay April/06
  108929     eBay Nov/06
35mm f2.8 100373      
  102057   Mirko De Filippo  
  102493   Mark Dapoz  
  103181   Steve Troy  
  103931   Mark Dapoz  
  103957   Ken O'Brien  
  104090     eBay Aug/05
  104487   John Foster  
  105321   Akihiko Yajima  

Ken O'Brien

  107466   Meinhard Schmitt eBay April/06
  108255   Mark Dapoz  
50mm f1.4 100103   Meinhard Schmitt  
  100117     eBay July/03
  101345   Sam Morales  
  101778   Mirko De Filippo  
  102517     eBay Apr/04
  102951   Mark Dapoz  
  103455   Ken O'Brien  
  103733     eBay June/06
  103893   John Foster  
  106034   Ken O'Brien  
  106698     eBay May/06
  108410   Akihiko Yajima  
  108610     eBay June/06
  109003   Dinkar Jhalera  
  109257   Mark Dapoz  
  109735   Dan Troy  
  110110     eBay May/01
  112862   Steve Troy  
  114853   Mark Dapoz  
50mm f1.8 100157     M-1 User Manual
  101778   George Sears  
  101872   John Foster  
  101917     Histoire de l'appareil photographique Olympus de 1936 a 1983
  102037     eBay June/06
  102307     eBay April/06
  102560   Steve Troy  
  102850   Ken O'Brien  
  104443     Japanese Magazine
  104907   Meinhard Schmitt  
  105607     eBay Dec/05
  106054     Shop in Nagoya, Japan
  107165   Mark Dapoz  
  107586   Ken O'Brien eBay Jan/06, prod Aug/72?
  108622   Mark Dapoz  
  109372   Pratt Dean  
  109824   Lars Peterson  
  111039     eBay Jan/04
  112902   Steve Troy  
  112956     eBay Oct/06
  113846   Jim Timpe  
  114234   Mark Dapoz  
  114313   Meinhard Schmitt  
  115913   Greg McGrath  
  116138     eBay March/04
  116907     eBay May/01
  117596   Ken O'Brien  
  119806   Akihiko Yajima  
  120378     Japanese Magazine
  121253   Mark Dapoz  
  124424   Meinhard Schmitt  
  124781     eBay June/06
  124869   Massimiliano  
  125038   Mirko De Filippo eBay March/06
  125441     Japanese Magazine
  125506   David Waldie Steven Pidcock
  127421   Stephen Troy  
  127369     eBay Nov/03
55mm f1.2 100177   Akihiko Yajima  
100373   Meinhard Schmitt ebay April/06
100584   Mark Dapoz  
101279   Ken O'Brien  
100mm f2.8 100217   Ken O'Brien  
  100496     eBay July/03
  101092   Meinhard Schmitt  
  101215   Paul Connet  
  101775   Mark Dapoz  
  102076   Steve Troy  
  102159   Mark Dapoz  
  102290   Akihiko Yajima  
  102332   Dinkar Jhalera eBay April/04
135mm f3.5 100287   Akihiko Yajima  
  102044   Meinhard Schmitt  
  103439     WA
  104365   Ken O'Brien With Box, eBay July/06
  104486     Trademe June/03
  104951     eBay July/03
  105310   John Foster  
  106105   Ken O'Brien  
200mm f4.0 101073   Greg McGrath  
  101839   Ken O'Brien  
  102097   Meinhard Schmitt  
  102792     eBay June/06
  103805   Mark Dapoz  
  104134   John Foster  
  105139   Dinkar Jhalera  
75-150mm f4.0 102529   Meinhard Schmitt  
  102569   Ken O'Brien  
M-1 Boxes     M Schmitt, K O'Brien  
Varimagni Finder     Mark Dapoz  
Varimagni Finder     Ken O'Brien  
Auto Bellows     Peter Oerlemans  
Auto Bellows     Ken O'Brien  
Auto Bellows Box     Jaap Korten  
38mm f3.5 Box 200599   Alan Wood purchased Jan/76
VST-1 Macro Stand     Mark Dapoz  
7mm Extension Tube     Ken O'Brien  
14mm Extension Tube     Ken O'Brien  
25mm Extension Tube     Ken O'Brien  
55mm Filter (1A)     Mark Dapoz  
55mm Filter (ND)     Ken O'Brien  
55mm Filter (Red)     Ken O'Brien  
Shoe 1        
Tie Clip     Jaap Korten  
Filter Instructions     Ken O'Brien  
Len Hood     Ken O'Brien  
M-1 Display Tag     Ken O'Brien  
Lens Group Manual     Ken O'Brien  

Early OM-SYSTEM Items

Item Serial
Owner Comments
OM-1 non-MD 124763 March/73 Steve Troy  
  134839   GMG  
  150577 Aug/73 Ken O'Brien black body
  154043   Marianne Schultz  
  154309 Jan/73 Ken O'Brien  
  154384 Feb/73 John Robinson  
  154471 Feb/73 Mark Dapoz  
  155178     eBay Jun/03
  163283 Feb/73 Ken O'Brien  
  179355 April/73 Bob Janes  
  184410 Mar/73 Ken O'Brien  
  194109 May/73    
  204608 Nov/73 Mark Dapoz black body
  205088 July/73 Alan Wayman  
  205190 July/73 Stephen Strangways  
  214407 Sept/73 Nikos Chatzoudis  
  216699 July/73 Stephen Troy  
  228053 Aug/73 Ken O'Brien black body
  231040 Sept/73 Mark Dapoz black body
  231113 Sept/73 Ken O'Brien chrome body
  240638 Sept/73 Ken O'Brien chrome body
  245017 Nov/73 Hans Vlems black body
  245780 Oct/73 Ken O'Brien chrome body
  247237 Nov/73 Ken O'Brien chrome body
  276398 Dec/73 Stephen Troy  
  277015 Jan/74 CR black body
  314978 Ray Young black body
  408846 Sept/74 Ken O'Brien black body
  411768   Dinkar Jhalera black body
  492828 Feb/75 Nikos Chatzoudis  
  800001 Dec/75 Ken O'Brien black body
  823275 Dec/75 Andy Radcliffe  
OM-1 MD 396902 Sept/74 Mark Dapoz black body
  421662 Dec/75 Ken O'Brien black body
16mm f3.5 100142     eBay July/03
  100720     eBay Jan/03
21mm f3.5 100182     eBay April/03
24mm f2 100168     eBay Mar/03
  100603     eBay June/03
24mm f2.8 100655     eBay Nov/03
  101565     eBay April/03
  101920   Massimiliano  
28mm f2 101539     eBay April/03
28mm f3.5 109858     eBay March/06
  112728     eBay Sept/04
  118029     eBay April/04
35mm f2 100478     eBay Feb/03
  100485     eBay Dec/05
35mm f2.8 109202     eBay July/04
  109224     eBay Feb/03
  109598     Mark Dapoz
50mm f1.4 116063     eBay Jan/05
  118622   Mark Dapoz  
50mm f1.8 133276   Marianne Schultz  
  133720   Steve Troy  
  135162     Die Welt des OM Systems
50mm f3.5 100537     eBay Jan/06
  107595     eBay Jan/03
55mm f1.2 102605     eBay Mar/03
  102664     eBay Mar/06
  103607     eBay Feb/03
85mm f2 100879     eBay Jun/03
100mm f2.8 103189      
  104943     eBay Jan/03
135mm f2.8 102513     eBay Jan/03
135mm f3.5 107557     eBay April/03
  107679     eBay Mar/05
  108943   Massimiliano  
180mm f2.8 100305     eBay Dec/02
200mm f4 105699     eBay Oct/04
  105732   Steve Troy  
  105978     eBay Nov/01
400mm f6.3 100078     eBay July/06
  100514     eBay Mar/03
75-150mm f4 101866     eBay April/05
  104092     eBay Jun/03


Many thanks go to Clint Rumbo from Photosphere and John Hermansen from Camtech for answering my numerous (and sometimes nagging :-) questions regarding the M-1.

All photographs for this web page were taken using Olympus OM equipment (80mm macro, 135mm macro, T-8, T-10).

Last update: August 10, 2008 Mark Dapoz

All the material on this web site is ©copyright 2002 by Mark Dapoz. This material is provided free for personal use only. Redistribution or resale, either in part or whole, is strictly prohibited.