elliott_gordon Posted November 19, 2003 Share Posted November 19, 2003 I have the camera (700si) and the flash slaves (2)... How do I set the camera to the correct Flash Sync setting as described in the Flash Instructions. I have checked the 700si manual and all it talks about is Slow Sync and HSS... I want to fire the strobes via the pc terminal, I can manually set the apature from my meter, but what about the shutter speed? Thanks in advance, Elliott Link to comment Share on other sites More sharing options...
sean_bolden Posted November 19, 2003 Share Posted November 19, 2003 Are you going to use the slaves only or also with the built in flash or accessory flash? To get the sync speed with studio strobes fired via a pc cord, I use a flash meter. Link to comment Share on other sites More sharing options...
danny_spence Posted November 19, 2003 Share Posted November 19, 2003 You didn't mention if you have the grip on the 700si. The 700si doesn't have a PC terminal unless you have attached a VC-700 grip to the camera. The flash synchronization speed on the camera for the PC terminal is 1/200 or slower. Setting the shutter speed on the meter is irrelevant, (unless ambient light is high) as exposure is determined by measuring the strobes and adjusting the flash position/power or the lens aperture. The meter will give the exact same reading for the flash regardless of the shutter speed selected. Link to comment Share on other sites More sharing options...
elliott_gordon Posted November 19, 2003 Author Share Posted November 19, 2003 More info - I do have the grip. Ok.. I plug the strobes into the pc terminal on the grip - then check the light with the meter.. get a reading - then what??? I know I sound dumb, but I just don't have a clue how to make this work.. Sorry for being dumb. Link to comment Share on other sites More sharing options...
sean_bolden Posted November 19, 2003 Share Posted November 19, 2003 Your meter should give you a aperture and shutter speed setting. You need to go into manual mode and set the camera to match the flash meters settings and then shoot away. Don't feel dumb. Everyone has to go thru the same learning process. Link to comment Share on other sites More sharing options...
danny_spence Posted November 20, 2003 Share Posted November 20, 2003 Elliot, as Sean suggested all you need to do is put your camera in manual mode and enter the handheld meter reading into the camera. It would probably be best to just set the shutter at 1/125 or 1/200 on the camera (ignore the shutter speed suggested by the handheld meter, enter the aperture vaule only or adjust the flash position/power) and leave it set at that speed for working in the studio. For studio flash the shutter speed for the camera does not matter much. The reason for this is the duration of the flash burst. On portable flash units the flash burst lasts somewhere about 1/10,000 of a second or faster. Few, - if any - focal plane shutters can operate at these speeds! Those that can do so by creating an extremely fast moving slit that scans across the surface of the film. Here's how: For these very high shutter speeds, say 1/1000, the shutter in the camera cannot physically fully open and close to expose the surface of the film evenly at one time. If you look in the back of your camera where the shutter is you can see that it appears to be made of several small blades. Basically when the shutter is opened these blades move out of the way to allow light to strike the film. Think of a window with a curtain that is split down the middle and retracts to both sides. As you open the curtain, The gap between the fabric appears first in the center and eventually widens to expose the entire window. Then as you close it, the gap where the curtain first opened is the last to be closed. Say you only wanted to open the curtains for five seconds. As you opened the curtains, light would first appear in the center, then finally at the far sides. If it took you two seconds to open the curtain, then another two seconds to close them fully, you might have had the center open for five seconds, but the left and right corners would have only been open for one. Now say you want to leave the curtains open for a five minutes. You could easily open and close them in that amount of time and only lose a few seconds in the process of opening and closing. If you wanted to open the camera's shutter very quickly, it would have to be opened in segments. Did you see how the shutter seems to be made of several blades? For very high speeds, each one can be opened and closed in such a way that it creates a moving slit. If the window and curtains I described above had a slit for an opening in the curtains and you still wanted to have them open so that they provide an even amount of light for five seconds, you could move the slit across the window frame at a rate so that the entire window would be exposed five seconds from one corner to the other. Why can't this be used for flash? Imagine a thunderstorm with lightning outside. If you had the slit for curtains and wanted to see the lightning, you would only see a brief sliver of it through the slit as curtain was moving. If you opened the curtains fully for two minutes and there was a flash of lightning within the two minutes the curtains were open, you would see the entire lighting flash. As the burst from your flash units is so quick, the only way to expose the entire frame of film evenly is when the entire frame is fully exposed through the open shutter. The fastest rate at which the camera's shutter can be opened and closed to expose the film all at once is also your flash synchronization speed. This is why you have a flash synchronization speed that is slower than the fastest the camera's shutter can provide. This is also why you cannot control flash exposure by adjusting the shutter speed, and why any shutter speed shown by the meter when metering flash is really not needed. Thus for indoor studio photography with strobes for lighting, the only way to control the amount of light that strikes the film is to physically move the flash units around, reduce their power or the amount of light they put out, or alter the amount of light going through the lens by changing the aperture. Whew! Link to comment Share on other sites More sharing options...
elliott_gordon Posted November 21, 2003 Author Share Posted November 21, 2003 That answer is AWESOME!!!! And I now fully understand - set the camera to 1/200 and then set the f/ stop from the meter... I think I got it..! Link to comment Share on other sites More sharing options...
eastonphotography Posted November 26, 2003 Share Posted November 26, 2003 Hi Elliott Don't Totally Ignore the shutter speed... If you are using a hand held flash meter, you NEED to set the shutter speed setting on meter to match what you are using on your camera (1/200 s), so it will give you the proper aperture reading. If you can't set the shutter speed on your meter, then you have to do the calculation yourself... e.g. if you meter tells you f5.6 at 1/250, and your sync speed of you camera is 1/200, then you have to adjust the reading from the meter. You can set you camera at f8 at 1/125. This will give you the same exposure, but WITHIN your sync speed. The only thing that will change is your Depth of Field. Link to comment Share on other sites More sharing options...
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