Vintage Stuff Part 1: SEI Exposure Photometer

December 17, 2009 § 20 Comments

The SEI Exposure Photometer with leather bag. Click to enlarge. Photo by Øystein Horgmo © All rights reserved.

The cupboards and shelves at the Photographic & Video Services, my new job,  are filled with old photo equipment, collected throughout the department’s history. In this new post series I’m going to pull some of the more interesting items into the strobe light. The first item is the SEI Exposure Photometer, a truly remarkable vintage gadget.

When I found this heavy metal rod thing, I couldn’t figure out what it was. The label suggested it was some kind of light meter, but it looked nothing like any other meter I’ve ever seen. A quick web search revealed that not only was it a light meter, but it is one of the most accurate reflected-light meters ever produced.

Produced by Salford Electrical Instruments (SEI) in the UK from about 1948 to the 1960s, it used to compare the brightness of a subject with the brightness of a lamp inside the meter. As the lamp’s brightness is predetermined, the brightness of the subject can be assessed and translated into correct exposure.

Left to right: Too bright spot, correct measure, too dark spot. Photo by Øystein Horgmo © All rights reserved.

The comparing is done by looking through the 1,3x telescope. In it you see a spot in the center (actually smaller than the mock-up above). The spot is placed on the subject area you want to measure. You press a button to turn on the lamp, and then rotate the base of the meter to adjust the brightness of the spot. The correct measure is found when the spot disappears (above center).

Exposure settings can be read from the tables on the meter’s barrel. You can choose a shutter speed and find the correct aperture, or vise versa.

The barrel with shutter speeds to the left and f-stops in the middle. For 1/200 the correct aperture would be ƒ/5.6. The numbers to the right are used to set the film speed (in British Standard Log speeds). Click to enlarge. Photo by Øystein Horgmo © All rights reserved.

For the sake of illustration I used “measured” a part of the barrel in the example above. But to determine exposure you must measure the darkest part of the scene that you want to have detail (negative film), or the brightest part that you don’t want to clip (slides, movies, digital photography).

Although they stopped making it a long time ago, it’s still used by some Hollywood cinematographers for its extreme accuracy.

So the next time I’m heading over to the OR, I’ll bring this along, have it sterilized and measure those deep crevasses of the abdomen. Or maybe not.

Sources:

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§ 20 Responses to Vintage Stuff Part 1: SEI Exposure Photometer

  • Ansel Adams used one of these meters and wrote about it in his basic photo series. In 40 years of photography I have never actually seen one.

  • Peter Kristoffersen says:

    What wonderful shelves, what a wonderful place. My personal Jerusalem is currently Photographica in Copenhagen, or just browsing the net… wonderful places like Cameraquest.com. Anyways, there seems to be more photographic… Meccas :)

  • William Sacco says:

    I have one and am about to put it up for auction on eBay.

  • thomi wroblewski says:

    Hello
    this an open letter to SEI meter enthusiasts … I have an SEI with the original manual that has recently stopped working. NOW i am not going to fix it SO
    anyone who is willing to pay the price of the postage can have it ( and hopefully be able to fix it

    regards
    thomi wroblewski
    london uk

  • Anne says:

    Thanks, for the information. Someone just gave me one with the case, but it didn’t come with a manual, hopefully it works.

  • Jeff Clegg says:

    I worked at SEI for 9 years from 1963 during my time there I spent 2 years repairing SEI Photometers, sadly manufacture & repaired stopped when Charlie who I trained retired. I think Zoomar in the US bought all the remaining parts & tools which would be either late 60s or early 70s.

    • Vincent Price says:

      Just as a bit of added history,…..
      I worked at SEI in Heywood from 1975 till it eventually closed down in 1993, and I knew Charlie very well, and visited him on many occasions in his repair ‘darkroom’, to see him work on the Photometers.
      He actually trained another person for several months just before he retired, (about the early 1980’s) as although SEI had long since stopped making new ones, there was a reasonable amount of repairs coming in to warrant someone working on them on a part time basis, and I think this continued till around the mid/late 1980’s.
      As it was such a prestige instrument, there was always talk of a new ‘up to date’ model being made, but it was deemed uneconomical to so.

  • Urs Meyer says:

    Hello there! If anyone else showing up reading this page and have a SEI photometer… I am *very* interested in getting one!

  • 168petri-ebay-name says:

    Hello, I have also a SEI photometer, I would like to sell the unit on Ebay. but unfortunately no suitable battery to see if the device still works. What battery do I need??

  • Leonard Fashoway says:

    I have been using standard American D-cells, and never had to “remove the paper cover” from the cell, they always seemed to fit and still be removable. Be VERY careful to not drop an SEI, the meter will need replacement! Good luck.

  • John Williams says:

    I have one for sale. If anyone is interested let me know before I ebay it next week. It is fully functional, but out of calibration. I have the original 1.5v bulb, but its calibration is so far out so at the moment it has a 3v bulb and a lithium battery. Use with the original D cell would entail changing the resistor in line with the photocell. It would then need to be calibrated against a known good light meter and a grey card.
    john5247 at myway dot com

    • I am on my second replacement bulb, I first used a standard 1.5 V round clear glass flashlight bulb long ago, and it worked perfectly. It only did not have the frosted glass of the original lamp, but I do not think this has much effect on the light calibration, as the rheostat and photocell is there to standardize the brightness of the spot.

      My recent replacement (an emergency purchase out west) has the lens type bulb, and I simply adjusted the SEI rheostat until the calibration was correct, based on a good meter (my favorite Weston, and a Pentax Spot Meter were used). No need to rewire anything!

      The bulb did not fit tightly into the SEI brass lamp adapter, so I made a tiny brass shim to stuff in, and it works well. Therefore…

      My most sincere apologies to our former repair expert.

      Does anyone know where an SEI repair manual is hiding?? I would like to clean the optics some day.

  • I know it’s an old thread, but does anyone still have an SEI Photometer for which they are looking for a loving home? I am super interested in obtaining one. Cheers! :)

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