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Art Deco Cameras

Purma Special

Specification

Purma Special
Purma Special
Manufacturer: Purma
Produced: 1937
Type:Extending Body
Film Size:127
Image Size:1¼ x 1¼
Lens Type:Beck Anastigmat
Focal Length:57mm
Focus Type:fixed
Focal Range:10ft - Inf.
Aperture Type :Fixed
Apertures :f/6.3
Shutter Type:Variable Speed
Shutter Speeds:1/25s, 1/150s, 1/450s
Size Open (w x h x d):153 x 72 x 70 mm
Size Closed (w x h x d):153 x 72 x 56 mm

Art Deco Credentials

star star star star star Iconic: Famous, well-known and celebrated

Description

The design of this camera has been attributed to the London office of Raymond Loewy who was a Franco-American industrial design consultant for more than 200 companies, creating product designs for everything from cigarette packs and refrigerators, to cars, railway engines and spacecrafts. It surely shows the American Streamline Moderne influence.

It features fine ribbing on Bakelite and a tapering form, with a lens cap that conceals a telescoping lens. The shutter cannot be released until the cap is taken off and the lens extended.

Adjustable Shutter Slit
Adjustable Shutter Slit

The most unusual feature of this camera is the shutter, whose speed is controlled by gravity. As the photographs produced are square, the orientation of the camera does not matter. In the horizontal position, the camera has a medium shutter speed (1/150s). If the camera is turned clockwise to a vertical position, the slow speed is selected (1/50s). Turning it counterclockwise to a vertical position, the fast speed is selected (1/450s). The focal plane shutter is comprised of two metal plates that slide together across the curved film plane. As the camera is turned, the speed is varied by the position of brass cam/weight which changes the slit width. The mechanism acts with a spring, which in one vertical orientation acts against the weight to slow up the shutter and in the other vertical orientation acts with the weight to speed up the shutter. Ingenious!

Two film windows
Two Film Windows

Film advance indicated by two windows and is not coupled to shutter. Cameras were supplied with both red and green film advance windows. The green plastic windows were for panchromatic film and the red for orthochromatic. These could be interchanged by the user. The film is advanced until the image number is seen in the first red window, and for the next frame, the film is advanced until the same image number appears in the second window.

How to Use

This camera takes 127 film which is still available from select outlets - search for 'Rera Pan 100-127' which is a black & white film. For those photographers in the UK, try Nick & Trick photographic services. If you want to use a particular type of film which is not available commercially, then you can cut your own 127 film from any 120 film. See my page on 'How to cut 127 film from 120 film'.

I have had three of these cameras and one problem seems to be that the back film door doesn't always close properly. Also, there is often damage to the Bakelite seals. So, you may need some black electricians tape handy. At least put black tape over the red/green windows and only remove briefly to wind on the film - modern film is sensitive to red/green light!

If you don't want to bother with an exposure meter, follow the guide shown. It is based on the 'Sunny 16' rule. Film is so forgiving and will produce acceptable results even when over-exposed by 2 or 3 stops or under-exposed by 1 stop.

The table assumes that the sun is at least 30 degrees above the horizon - that's 10am - 5pm on a summers day in the UK.

Remember that the exposure guide in the manual may not be helpful as it is based on the use of old film with a low ISO value.

So, on a nice sunny day, it's simplicity itself. Just load film, choose the correct speed and snap away.

Using ISO 100 film - Aperture f/6.3

Weather ConditionsShadow DetailShutter Speed(s)Exposure
Sunny
Snow/Sand
Dark
with sharp edges
1/450+1½ Stops
Overexposed
Acceptable
SunnyDistinct1/450½ Stop
Overexposed
Good
Slight OvercastSoft around edges1/150+1 Stop
Overexposed
Acceptable
OvercastBarely visible1/150Good
Heavy OvercastNone1/50½ Stop
Overexposed
Good
Open Shade
/Sunset
None1/50-½ Stop
Underexposed
Acceptable