# Confused about Flash Sync speed?



## Nikon_Josh (May 22, 2012)

A question for you guys, just got my SB700 and am still learning it and enjoying every second.

The thing I don't understand is the max flash sync speed, I assumed as my D90 has a max sync speed of 1/250th of a second. That if I tried to take a photo with flash at say 1/1000th of a second I would get a partial black out of my exposures? But I am not getting this.. is there something I am missing here? I guess there must be.


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## Robin Usagani (May 22, 2012)




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## Overread (May 22, 2012)

This might help:


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## o hey tyler (May 22, 2012)

Are you saying you're not getting a partial black band at 1/1000s? Or that you're not getting _why_ there would be a black band at 1/1000s? 

If you're able to shoot at 1/1000s with flash, you must have Auto-FP enabled, which is Nikon's equivalent for Canon's HSS (High Speed Sync). Not sure what Auto-FP stands for... Possibly flash priority?


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## Mach0 (May 22, 2012)

Auto fp is on. It won't give you a partially black frame. It enables you to sync your flash above 1/200s.


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## table1349 (May 22, 2012)

Auto FP High Speed  Sync is a flash mode used for fill-flash photography under brightly lit  conditions. It will fill in and open up shadowed areas in order to  portray the greatest detail in subjects. It's also ideal when using wide  aperture lenses, and because it allows fast shutter speedsup to  fastest shutter speeds on compatible Nikon D-SLRsit is often used for  action-stopping sports photography. And for portraits, you can open up  your lenses to their full aperture in order to isolate your subject  against a blurred background without overexposing the image.
    When  Auto FP High Speed Sync is selected, the flash will fire for the  duration of the shutter curtain's travel, thus syncing with the camera's  shutter speed when that speed is set higher than the camera's normal  sync speed.

Auto FP High-speed Sync from Nikon


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## fokker (May 22, 2012)

gryphonslair99 said:


> Auto FP High Speed  Sync is a flash mode used for fill-flash photography under brightly lit  conditions. It will fill in and open up shadowed areas in order to  portray the greatest detail in subjects. It's also ideal when using wide  aperture lenses, and because it allows fast shutter speeds&#8212;up to  fastest shutter speeds on compatible Nikon D-SLRs&#8212;it is often used for  action-stopping sports photography. And for portraits, you can open up  your lenses to their full aperture in order to isolate your subject  against a blurred background without overexposing the image.
> When  Auto FP High Speed Sync is selected, the flash will fire for the  duration of the shutter curtain's travel, thus syncing with the camera's  shutter speed when that speed is set higher than the camera's normal  sync speed.
> 
> Auto FP High-speed Sync from Nikon



I have to correct you on your statement about stopping action with high-speed-sync (or whatever the nikon equivalent is) flash. This is not true. When you use HSS, you are effectively lighting the scene over the maximum sync speed, usually 1/250s. I'm about to leave for softball now so I can't type out the full explanation why, but hopefully someone else will.


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## table1349 (May 22, 2012)

fokker said:


> gryphonslair99 said:
> 
> 
> > Auto FP High Speed  Sync is a flash mode used for fill-flash photography under brightly lit  conditions. It will fill in and open up shadowed areas in order to  portray the greatest detail in subjects. It's also ideal when using wide  aperture lenses, and because it allows fast shutter speeds&#8212;up to  fastest shutter speeds on compatible Nikon D-SLRs&#8212;it is often used for  action-stopping sports photography. And for portraits, you can open up  your lenses to their full aperture in order to isolate your subject  against a blurred background without overexposing the image.
> ...



Don't correct me, correct Nikon if you like.  They wrote it.


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## fokker (May 23, 2012)

Well then Nikon are guilty of giving out misleading information....

Quote from a website that can do a better job of explaining this than I can:
"The problem with "high speed sync" for action photos is that it works by making the flash slow down. Since the camera's shutter can't open fully in less time than its max normal sync speed, the film can't be exposed all at once at high shutter speeds. Exposure must be controlled by the shutter's slit travelling across the film, exposing different parts of the film successively. Instead of giving one almost-instantaneous burst of light, the flash gives a sequence of many pulses of light, approximating a continuous light source during the time the shutter is open. So instead of freezing motion with the fast electronics of the flash, motion is stopped by the much slower and less effective mechanics of the moving shutter curtains. The maximum shutter speed is in the neighborhood of 1/4000 or 1/8000, but the fastest flash duration at ordinary sync is much faster. When using high speed sync, fast shutter speeds are only available at wide apertures and close ranges, precisely the conditions where ordinary auto flash produces its shortest durations."

High Speed Shutter vs. Ordinary Flash Sync


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## Village Idiot (May 23, 2012)

fokker said:


> Well then Nikon are guilty of giving out misleading information....
> 
> Quote from a website that can do a better job of explaining this than I can:
> "The problem with "high speed sync" for action photos is that it works by making the flash slow down. Since the camera's shutter can't open fully in less time than its max normal sync speed, the film can't be exposed all at once at high shutter speeds. Exposure must be controlled by the shutter's slit travelling across the film, exposing different parts of the film successively. Instead of giving one almost-instantaneous burst of light, the flash gives a sequence of many pulses of light, approximating a continuous light source during the time the shutter is open. So instead of freezing motion with the fast electronics of the flash, motion is stopped by the much slower and less effective mechanics of the moving shutter curtains. The maximum shutter speed is in the neighborhood of 1/4000 or 1/8000, but the fastest flash duration at ordinary sync is much faster. When using high speed sync, fast shutter speeds are only available at wide apertures and close ranges, precisely the conditions where ordinary auto flash produces its shortest durations."
> ...



But generally you'll get action stopping shots at the higher shutter speeds.

Not all strobes will have a flash duration under 1/4000 and 1/8000. When you start using higher powered strobes, the flash duration starts dropping...generally. This isn't the case with certain brands as those of us with some experience know.


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## Nikon_Josh (May 23, 2012)

Thanks very much to all you guys for the explanation! I was completely thrown by it to begin with, I read that if you shot over the flash sync max speed you would get blackouts. I didn't know about this neat feature called Auto FP.

Just to say, since I have got my SB700, I have found it hard to believe I didn't buy one sooner. It's an amazing purchase. I did debate going all manual with a cheaper third party flash but I am glad I bit the bullet and got the SB700, it has so many features and I find the TTL very effective and user friendly!


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