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Question about FP flash mode

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Uncle Frank

Uncle Frank

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I've set my d200 in FP mode, and apparently my sb800 can sync at any shutter speed. That's great for outdooor flash fill, as in this shot.



So why the complaints about the d200 having a 1/250 sync speed? Is FP somehow inferior to true sync?
--
Warm regards, Uncle Frank
FCAS Founder, Hummingbird Hunter, Egret Stalker
Dilettante Appassionato
Galleries at http://www.pbase.com/unclefrank
 
The flash actually does several low power burst thereby significantly reducing the guide number. So, reach is impacted big time.

--
Speed is significant and interesting but accuracy is downright fascinating
http://www.pbase.com/pradipta
 
And burning the flash prematurely is an issue (but let's not get paranoid, the flashes are really bullet-proof and lose in value before they wear out)
 
Ken Rockwell has the best explanation. It basically burns your batteries out prematurely and recharge time is A LOT slower.
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Nathan A. Luna

Freelance Photojournalist for the Visalia Times-Delta and Tulare Advance Register. Photographer, LunaImages Photography. Currently attending the College of the Sequoias, a junior college in Visalia, CA. Learning, day by day. Equipment in Profile.

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Reduction of GN? If you are saying that it is not true then I would say, you are certainly incorrect.

--
Speed is significant and interesting but accuracy is downright fascinating
http://www.pbase.com/pradipta
 
Yes, it's inferior. The biggest thing is the reduced power output. Here's the reason why.

At speeds above the maximum sync speed, the shutter opening is actually a slit traveling across the sensor.

Second, flash power is determined by the duration of the flash. A longer duration means more power, a shorter duration is a weaker flash.

At sync speed, the flash can be of any duration, up to the full power of the flash.

At faster than sync speed (FP sync), the flash has to do multiple pulses, but now the power has to be limited by the duration of the slit over the sensor as well as how much total power will be consumed by all the pulses.

Obviously, the faster the shutter speed, the less power you're going to have in your flash, reducing your effective distance.

Anthony
Uncle Frank said:
I've set my d200 in FP mode, and apparently my sb800 can sync at
any shutter speed. That's great for outdooor flash fill, as in
this shot.



So why the complaints about the d200 having a 1/250 sync speed? Is
FP somehow inferior to true sync?
--
Warm regards, Uncle Frank
FCAS Founder, Hummingbird Hunter, Egret Stalker
Dilettante Appassionato
Galleries at http://www.pbase.com/unclefrank
Click to expand...
 
Besides the lower maximum flash power available, Thom Hogan mentions in his D2H guide that the repeated short flash bursts with auto-FP can have effects on moving subjects that are different from what is seen with a single flash burst (non-auto-FP, below the camera's fastest sync speed).

I haven't seen that myself, but my primary use of auto-FP has been like what UF showed -- to allow fill in outdoor portraits and candids when I want to use a larger aperture -- where there isn't any (or at least not very much) subject motion.
--
Jim Kaye

'I believe that the electronic image will be the next major advance. Such systems will have their own inherent and inescapable structural characteristics, and the artist and functional practitioner will again strive to comprehend and control them.' -- Ansel Adams, 1981
 
It is my understanding that the the Auto FP flash mode will sync with high shutter speed.

My question is at the maximum sync speed (1/250s) or slower, does the Auto FP flash mode revert the flash to its normal sync mode? If so, then I cannot see any reason why I cannot leave my setting permanently as Auto FP.
 
There's no reason why you couldn't do that; however, if you leave it on and do daylight fill flash, you could run into a situation where your camera would be in FP mode and the flash wouldn't have the range it would have at a shutter speed of 1/250. Having to manually access FP mode makes you more aware of what you're doing and why you're doing it.

Anthony
Ant Yeung said:
It is my understanding that the the Auto FP flash mode will sync
with high shutter speed.

My question is at the maximum sync speed (1/250s) or slower, does
the Auto FP flash mode revert the flash to its normal sync mode? If
so, then I cannot see any reason why I cannot leave my setting
permanently as Auto FP.
Click to expand...
 
Anthony said:
There's no reason why you couldn't do that; however, if you leave
it on and do daylight fill flash, you could run into a situation
where your camera would be in FP mode and the flash wouldn't have
the range it would have at a shutter speed of 1/250. Having to
manually access FP mode makes you more aware of what you're doing
and why you're doing it.
Click to expand...
That's never a problem because:

1) if you're outside and need the camera goes in FP mode, this means it's a helluva sunny day, whch in return means no shot is missed by underexposure. Maybe the fill won't be as effective but that's it... But even this is not a problem as I have yet to see someone doing portraits 20-30 feet away.

2) simply dial the aperture until you reach 250 or slower, thus killing the FP mode right away.
Anthony32599 said:
Anthony
Ant Yeung said:
It is my understanding that the the Auto FP flash mode will sync
with high shutter speed.

My question is at the maximum sync speed (1/250s) or slower, does
the Auto FP flash mode revert the flash to its normal sync mode? If
so, then I cannot see any reason why I cannot leave my setting
permanently as Auto FP.
Click to expand...
Click to expand...
--
Je ne suis ni pour ni contre, bien au contraire!

Isn't this sentence partially incomplete? LOL
 
main issue here is that X-synch is for any strobe, Metz potato mashers, studio powerpacks, monolites, etc. the FP high speed synch is only going to work with Nikon's shoe-mount units, less than 1/4 the power of the Metz 60 flashes i need to use for large groups, especially in sunlight, needing a good fill flash at 40ft. away.
 
Ant Yeung said:
My question is at the maximum sync speed (1/250s) or slower, does
the Auto FP flash mode revert the flash to its normal sync mode?
Click to expand...
No. It does not. The flash continues to be in the mode of series of smaller power burst thereby continuing with reduced GN.

--
Speed is significant and interesting but accuracy is downright fascinating
http://www.pbase.com/pradipta
 
So then how do I set the shutter speed to faster than 1/250 in FP mode? The manual is unclear.

DC Steve
 
Pradipta Dutta said:
Pradipta Dutta said:
My question is at the maximum sync speed (1/250s) or slower, does
the Auto FP flash mode revert the flash to its normal sync mode?
Click to expand...
No. It does not. The flash continues to be in the mode of series of
smaller power burst thereby continuing with reduced GN.
Click to expand...
Where did you get that information? I have always thought that it would revert to normal sync at shutter speeds of 1/250 or slower.
--
Jim Kaye

'I believe that the electronic image will be the next major advance. Such systems will have their own inherent and inescapable structural characteristics, and the artist and functional practitioner will again strive to comprehend and control them.' -- Ansel Adams, 1981
 
»Just confirmed this with camera and flash in hand: just having the shutter speed move from 1/250th to 1/320th, the flash panel indicates a drop of more than 100% of maximum reach (60feet down to 25 ft with my actual settings) . Then it proceeds more slowly: 1/400th=22ft 1/500th=20ft 1/1000th=14ft

I elected to let the camera go seemlessly from normal 1/250 sync to faster FP shutter speeds. Just watch your shutter speed in A, and check your max reach. The SB-800 coverage relates to FF cameras, BTW, so in fact it over-covers all of your lenses. You can set the zoomhead to 50mm and use a 35mm on the camera, and be covered, and gain a little more reach.

--
Jean Bernier

All photographs are only more or less credible illusions
 
Actually, the light loss is much more than the 100% I had carelessly thrown in.

Due to the inverse square law, the light loss going from 1/250th to 1/320th is a radical 2½ stops, wich is around 500% !!!

In other words, if f:8 1/250th gives a max reach of 60 ft, as soon as FP kicks in, at 1/320th, you have to adjust aperture to between f:2,8/f:4 in order to have the same 60 ft reach. Then, as I stated, it's more gradual.

Bottom line, FP is for near subjects. Flash will have to work much more, so careful with batteries and possible overheating.
--
Jean Bernier

All photographs are only more or less credible illusions
 
When shutterspeed drops to 1/250 sec or slower. What is surprising is that the flash panel continues to indicate "FP" regardless of the actual shutterspeed on the camera. I had never looked at the coverage before. I am still wondering why does the flash then continues to say "FP"?

--
Speed is significant and interesting but accuracy is downright fascinating
http://www.pbase.com/pradipta
 
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