Mystery unfolds!!

I would classify this blog for people who are really keen on Manual photography.

Before I went digital on cameras, I had been using a Full Manual Film SLR (Ricoh KR5 Super2). On this camera I had no other option to manually adjust the parameters based on the light conditions. When I took some shots with an external flash and a comparitively faster shutter speed(1/500 or even faster), I got quite a few images with a prominent black band.

An example is attached below...



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Completely baffled with the results, I would convince myself, considering some fault in the way the film was developed. Until recent I believed that it was the film that was causing the issue. But then I noticed the same band appearing on the images taken with my digital camera. Well, now this needs investigation!!

For symptoms, it was evident that a fast shutter was a clear suspect. Then I took a look at all the digicam images, versus the affected digicam images. I realized that the external flash was a common factor in most of the affected images. Beyond the above 2 , I could not find more culprits. But eventually these 2 were enough to nail this one down. Let me explain...

Test1:
To reproduce the issue, I started shooting with external flash + slower shutters and then increasing the shutter speed by a step. The anamoly didnt reproduce. I reached 1/250 and still there was no sign of the crime. But then with 1/500, I hit it, and subsequently all the faster shutters came with the band. So Test1 concluded that only shutter speeds 1/500 and above are affected.

Test2:
Then I tried without the manual flash, but using the inbuilt flash of the camera. But the camera wouldn't allow me to exceed the shutter speed beyond 1/180... WTF.

Then in one of the ref mans, I found something called Flash Sync!

Definition: It stands for flash synchronization. It means the fastest shutter speed you can use with the flash.

Use:
At high shutter speeds, the shutter closes faster, and only the part of the sensor is exposed to the light coming in. This leaves behind an un-exposed part of the sensor, resulting in a dark area on the image.

Icing on the cake: The old generation cameras did not have the facility to hold on the shutter speed. But now a days the digital cameras have an electronic lock on the shutter speed based on the sync speed of the flash being used. The inbuilt flash in my camera has a sync speed of 1/180, so my shutter speed locked out on the same speed. And the lock didn;t happen on the external flash because it was just a manual flash which is not identified by the camera.

Phew ... all questions answered!! Mystery sorted out!

For more information:
Flash Sync