Bertram Chrolon Cased by br1078phot, on Flickr
Manufactured by Ernst & Wilhem Bertram in Munich, Germany (makers of the BEWI line of meters) during the early 1950's. Some references say '54-'56, but I've seen a Willoughbys advert from '53, priced at $19.95.
Bertram Chrolon Case Open by br1078phot, on Flickr
The case is in good shape, but the hinge has broken, and the only thing holding the two halves together is the zipper pull. The zipper is also separating from the lower half.
Bertram Chrolon Mount by br1078phot, on Flickr
The meter is retained in the case by a post and pin arrangement. The model number is on the back (355).
Bertram Chrolon Cell Doors by br1078phot, on Flickr
The selenium cell is covered by flip-out doors that open automatically when you hit the cover release button.
Bertram Chrolon Open by br1078phot, on Flickr
Just above the clasp you can see the release button for the meter cover. On the clasp, there is a button-hole tab so you can wear this on you shirt or jacket. As with most meters back then, there are also scales for cine application. At either end of the EV needle scale are the actuating pins that open and close the cell doors.
Bertram Chrolon Profile by br1078phot, on Flickr
Showing how the cell doors open. You can also see the actuating pins better.
Bertram Chrolon Dial Detail by br1078phot, on Flickr
This is Model 355 for the US market, so it has the DIN, Scheiner, and ASA scales for film speed setting. The European f stops are also represented above the modern stop scale. The serrated dial below the film speed dial controls the EV number displayed, and moves the shutter speed scale to align with the proper aperture. There are two nub pins on the film speed dial to change that setting with your fingernails.
PF
