[derekkite]

I'm fooling with a bunch of flashes and bodies triggering both with an input output board. From time to time I get half dark shots, the bottom dark, which is a synchronization issue where the shutter is half open when the flash illuminates. I was using 1/10 shutter speed and 1/16 flash power, so the flash is something like 1/6000. Which end of the curtain action am I hitting?

Does the curtain open from bottom to top?

[stevebrot]

Does the curtain open from bottom to top?

The curtains travel from top to bottom. Edit: See comment below. In your half dark frame, the trailing curtain had not yet started its travel and the leading curtain had traversed half the frame. Remember, the recorded image is inverted.


Steve

[stevebrot]

The curtains travel from top to bottom

IIRC, that is! I did a quick check with my film cameras and the direction of travel is evenly split with two of the Copal (CCS variants) shutters traveling bottom to top and the other Copal (original Square) top to bottom. The Seiko (MFC variant) in my Super Program travels top to bottom. I tried to see the direction on my K-3 but it is too quick for me. Pentax dSLRs use Copal shutters.


Steve

[derekkite]

The curtains travel from top to bottom. In your half dark frame, the trailing curtain had not yet started its travel and the leading curtain had traversed half the frame. Remember, the recorded image is inverted.


Steve

I am attempting to take a series of 10 shots with three bodies (two K3 one K5) and five flashes. About the 7th shot one of the K3 has a half dark frame. All the rest are fine. So for some reason the body is not as responsive in that instance. The flash is too early in the sequence.

Thanks

[stevebrot]

The flash is too early in the sequence.

Did you see my revision above? Translation is that I don't have a clue what direction it travels.

Steve

[derekkite]

The K3 has an odd characteristic when set to single shot; there is a sizeable delay before the next shot can be triggered. It has to finish writing to disk. The interval is too long for my taste, so I set the body to continuous low. and trigger by closing the output for a short time to trigger one exposure. So the half exposed shot is either the body responding slowly to the trigger because of some processing or something and catching the half open leading curtain, or the second exposure in continuous mode is being triggered throwing the flash synchronization off and catching the closing of the trailing curtain.

I have some options to sort things out, but I need to know what is going on.

Hence the question. I tried looking at it is too quick to discern.

[stevebrot]

I tried looking at it is too quick to discern.

I even tried cell phone video in 1/8 slo-mo, but still too fast.


Steve

[stevebrot]

I left a message for my local repair tech. He would likely know.


Steve

[narual]

I thought the shutter went back and forth? Up one shot, down the next.

[stevebrot]

I thought the shutter went back and forth? Up one shot, down the next.

Some do and the Copal shutters used by Pentax may.


Steve