The shutters of old mechanical cameras are affected in their function and accuracy by a common defect: the gumming of the lubricants used during their production. Decades later, these lubricants are usually so much solidified that the shutter speeds run considerably longer than set or the shutters even get stuck after being released. Last but not least, the leaf shutters of folding cameras from the 1950s are affected. In addition to the resinous oils, abrasion during operation and dirt that has penetrated into the system are other causes that impair function.

An initial test can be done by ear by setting a shutter speed of one second. If gumming occurs, the shutter remains open for up to several seconds. The same applies to a mechanical self-timer, which sometimes even gets stuck in the event of heavy gumming up. At this point at the latest, a service in the form of disassembly, cleaning, lubrication and adjustment is due.

In addition to the aperture, the shutter speed is a crucial parameter for dosing the exposure of film according to the given lighting situation. A considerable and uncontrolled extension of the exposure time leads to overexposure and blown-out highlights. To avoid this, it is advisable to have the shutters of old cameras checked and cleaned by a specialist before use.

Lukas Fritz (https://www.filmomat.eu/photoplug) has been offering an app (called Shutter Speed) for some time now to check shutter speeds, which can be used with a smartphone. The longer times are checked acoustically via the smartphone’s microphone and the shorter times under 1/30 second are checked optically with the help of a photocell (called PhotoPlug) that is plugged into the smartphone’s headset socket. The PhotoPlug can be purchased directly from the manufacturer or from various online stores.

After installing the Shutter Speed App and purchasing the PhotoPlug, I first checked the shutter speeds of two Zeiss Ikon Super Ikonta III (531/16) cameras: a Super Ikonta III with a Prontor SV shutter that had been serviced by a professional camara service in Germany and a privately purchased Super Ikonta III with a Synchro-Compur shutter. The latter may not have been serviced.

The result was that both cameras showed a more or less significant increase in shutter speed. In particular, the shortest times (1/300 and 1/500 second) are actually more than twice as long as set, which corresponds to an overexposure of more than one exposure value. Testing the shortest exposure time (1/250 second) of a pre-war Ikonta C (521/2) with Compur shutter resulted in a mere 1/100 second, the only exposure time left for hand-held shooting.

Super Ikonta III with Novar set in Prontor SVS shutter – CLAd

target	actual (acoustic)	actual (optical)
1	0.9
1/10	1/9
1/50	1/40	1/40
1/100		1/65
1/300		1/125

Super Ikonta III with Tessar set in Synchro-Compur shutter

target	actual (acoustic)	actual (optical)
1/10	1/5
1/50	1/30	1/30
1/100		1/55
1/250		1/130
1/500		1/200

For all cameras the critical maximum exposure time of about 1/100 second for handheld shots is actually significantly longer than set, which greatly increases the risk of camera shake. Therefore, if you want to avoid camera shake, you should always set the shortest shutter speed possible when taking handheld pictures using these cameras. Only the 1/250 second of the Super Ikonta III with Synchro-Compur shutter with a real 1/130 second comes also into question.

The results confirm two of my experiences with these cameras: (1) Hand-held shots with the Super Ikonta III cameras, taken with exposure times shorter than 1/100 of a second, are generally significantly sharper than those that were exposed at a setting of 1/100 of a second. (2) Photographs taken with the 6 x 9 Ikonta C at 1/250 second are sometimes a bit blurry because the exposure is actually longer than 1/100 second. The longer focal length of 105 mm, the somewhat stiff shutter mechanism and the poor grip may further compound the problem significantly.

The question arises as to how accurately the Shutter Speed App measures the shutter speeds. A comprehensive German website on analog photography reports on a test of the shutter speeds of the Nikon FE2 and an old folding camera (Welta Weltax). In the case of the Nikon FE2, the actual shutter speeds largely match the set shutter speeds. Only the times shorter than 1/1000 second deviate by half a light value towards overexposure. In the case of the folding camera, however, the shortest exposure time of 1/250 second was actually 1/122 second and thus within the range of deviations of the shortest speeds of my cameras (Analoge-Fotografie.net: https://analoge-fotografie.net/blog/belichtungszeiten-testen/).

Two other sources of information confirm the measurement of extended exposure times, particularly in the case of the shorter shutter speeds: In his homepage, Jurgen Kreckel (Certo6: https://certo6.com/shutters/ ), an internationally recognized expert for folding cameras, describes his experiences with the built-in shutters: ”Now , having said that, let me also add that most Compur-Rapids and Synchro-Compurs even on a “ good day ” or factory fresh, never reach 1/500 of a second … maybe 1/350 or so (that’s Prontor territory!), but no way have I ever electronically been able to see one of these shutters hit the 1/400 or 1/500 speed ”.

In the camera review of his Ikonta 523/16 with Prontor SV shutter Kurt Munger (Photo Jottings: https://photojottings.com/zeiss-ikon-ikonta-review/) reports: “Note: This review has been heavily updated from the original to include shots after a professional clean, lube and adjustment of the shutter mechanism and lens group by Jurgen of Certo6. I think it really helped out a lot! The shutter speeds are pretty close to indicated except at 1/300, which clocks in at 1/200 sec, and I’d guess that’s about what it did from the factory based on the other two dozen folders that I have”.

Further interesting information about old shutters can be found at Petrakla Classic Cameras (https://www.petrakla.com/pages/how-to-use-a-compur-shutter).

Posted: May 3, 2024