Explain me HIGH SPEED SYNC

Hi, All !

I have G1 and 420EX. Explain me, please, the termin High-speed synchronization. Where to use, what parameters are better and so on. The description in manual is not enough for me.

Thanks

Simply said it means to be able to use shutter speeds faster than 1/60 with a flash. 1/60 or 1/80 are normal flash sync speeds (where flash will fire in sync with shutter opening). G1, Pro90 and D30 can sync up to 1/250 with Canon EX flashes. It let's you freeze movement (water droplets, kids jumping, sports) better.
Experiment!

Some flashes has a HS switch to enable this feature.

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Andrei

Hi-speed Synch is the ability of a camera to synchronize the shutter opening with a flash above 1/60th of a second. Originally cameras didnt have shutters that moved, they all had an iris based shutter in the lens, except for pinholes Anyway, with the invention of the 35mm camera and through the lens viewing there had to be a way of using the iris based shutter to preview the depth of field and keep the film from being exposed while doing so. The way they did this was to use a sliding shutter just in front of the film plane, which slid out of the way when the button was pressed.

The problem with this and flash was that the shutter moved across the film as a slit instead of opening fully at higher speeds. Flash has a short duration so if the flash duration wasnt long enough then only a small portion of the film would see it, as the shutter was moving. Thats why manufacturers chose 1/60th of a second to make the shutter and the flash have a synchronous duration.

Now high speed synch came into being because there are a lot of times when you want to use a fill flash out of doors and this was well known to photographers using cameras that had iris based shutters, they had been doing it for a long time and the results are great. The problem was making the shutter opening and the flash duration synchronize. This was accomplished through changing the duration of the flash as well as changing the way that the shutters opened so the entire film area was exposed during the shutters opening. With this capability you can use a shutter speed of 1/1000 on some cameras (1/250 is the maximum on the G1 & Pro90 I believe) and this allows you to set the exposure for the general scene, maybe a shot of skiers on snow and use the flash to fill in their faces and prevent shadows there.

Hope this answers your question, and try fill flash you will love the results.

Rick

Does it mean that G1 automaticaly set speed 1/250 when I choose HS on 420EX ? Or I should manualy do it ?

Pekka wrote:
Simply said it means to be able to use shutter speeds faster than 1/60 with a flash. 1/60 or 1/80 are normal flash sync speeds (where flash will fire in sync with shutter opening). G1, Pro90 and D30 can sync up to 1/250 with Canon EX flashes. It let's you freeze movement (water droplets, kids jumping, sports) better.
Experiment!

Some flashes has a HS switch to enable this feature.

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Tank you, Rick. I was very helpful for me.

Rick wrote:
Andrei

Hi-speed Synch is the ability of a camera to synchronize the shutter opening with a flash above 1/60th of a second. Originally cameras didnt have shutters that moved, they all had an iris based shutter in the lens, except for pinholes Anyway, with the invention of the 35mm camera and through the lens viewing there had to be a way of using the iris based shutter to preview the depth of field and keep the film from being exposed while doing so. The way they did this was to use a sliding shutter just in front of the film plane, which slid out of the way when the button was pressed.

The problem with this and flash was that the shutter moved across the film as a slit instead of opening fully at higher speeds. Flash has a short duration so if the flash duration wasnt long enough then only a small portion of the film would see it, as the shutter was moving. Thats why manufacturers chose 1/60th of a second to make the shutter and the flash have a synchronous duration.

Now high speed synch came into being because there are a lot of times when you want to use a fill flash out of doors and this was well known to photographers using cameras that had iris based shutters, they had been doing it for a long time and the results are great. The problem was making the shutter opening and the flash duration synchronize. This was accomplished through changing the duration of the flash as well as changing the way that the shutters opened so the entire film area was exposed during the shutters opening. With this capability you can use a shutter speed of 1/1000 on some cameras (1/250 is the maximum on the G1 & Pro90 I believe) and this allows you to set the exposure for the general scene, maybe a shot of skiers on snow and use the flash to fill in their faces and prevent shadows there.

Hope this answers your question, and try fill flash you will love the results.

Rick

I don't have a 420, but I suppose you'll best bet is to use the Tv mode and set it to up to 1/250. When my 550 is powered, it reverts G1 automatically back to 1/250 (when I press shutter release button half way) if I try to set it higher speed like 1/320. EX 420 might need the HS switch, you can experiment if it is so.

Thank you, Pekka.
Have a good night.