{"id":5502,"date":"2012-04-11T08:00:39","date_gmt":"2012-04-11T15:00:39","guid":{"rendered":"http:\/\/wkoopmans.ca\/notebook\/?p=5502"},"modified":"2012-04-10T22:00:16","modified_gmt":"2012-04-11T05:00:16","slug":"olympus-om-1-metering","status":"publish","type":"post","link":"http:\/\/wkoopmans.ca\/notebook\/?p=5502","title":{"rendered":"Olympus OM-1 metering"},"content":{"rendered":"

\"Olympus<\/a><\/span><\/span><\/span><\/span><\/span><\/p>\n

There is plenty of good information about the Olympus OM-1 and the other cameras in this series on the Internet so I don’t feel that I need to cover that ground.\u00a0 I will however take a moment to discus the metering and how it is measured and presented to the user.\u00a0\u00a0<\/p>\n

The OM-1 has TTL metering (Through the lens) that is provided by two Cds cells placed internally around the eyepiece.\u00a0 A certain portion of the light passing through the viewfinder prism falls on these cells causing their internal resistance to drop.\u00a0 This effects the circuit causing the meter needle to move.\u00a0 Other parts of this circuit are the ASA dial, on off switch and of course the shutter speed and aperture linkage.\u00a0All these variables contribute to the position of the meter needle. This meter requires batteries to operate but the camera it self is entirely mechanical allowing you to shoot without the meter.\u00a0<\/p>\n

The meter itself is located on the left hand side of the viewfinder and gives an indication of proper exposure for an average scene.\u00a0 As you make changes to the aperture and shutter the needle moves correspondingly.\u00a0\u00a0 As the lens remains at it’s maximum aperature\u00a0 prior to actually taking a picture these changes are transferred from the lens to the camera via a mechanical linkage.\u00a0 In addition to centering the needle you can determine +-1 EV of adjustment in half stops by comparing\u00a0 the needle to the markings in the viewfinder.\u00a0 I’ve created this animation to show these.<\/p>\n

\u00a0\"Olympus<\/a><\/span><\/span><\/span><\/span><\/span><\/p>\n

My camera has an interesting focus screen that does not have the standard central focus micro-prisms or split image\u00a0but is essentially a matte screen with a finer circular\u00a0matte at the center\u00a0and frame lines that are well within the image.\u00a0 I believe this was the all matte type that someone has\u00a0customized with frame lines for either astrophotography or as Ted Samzadeh of Omnilargess<\/a>\u00a0has suggested for medical imaging.\u00a0 In any case the fine matte screen provides an exceptionally clear\u00a0and unobstructed view.\u00a0<\/p>\n

\"Olympus<\/a><\/span><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

Here are some of my ubiquitous sample images from my OM-1 taken with the Zuiko 35-70 F3.6 or the 28mm F 3.5 Zuiko as these are the only two lenses I currently own.\u00a0 Duncan Turner of\u00a0 DLT Photographic<\/a>\u00a0has now lent me a Vivitar 55mm macro in OM mount so that should be an interesting lens to try out with this camera.<\/p>\n\n\t\t