>> If you simply want to boost on camera flash the 400 may be adequate.
>> If you want the ability to use "commander" off camera flash the 600 is
[quoted text clipped - 15 lines]
> there compelling reasons why I should be considering getting 2xSB800s
> instead of 2xSB600s?
> Here's something I ran across which sounds useful:
> Page 6 of this Nikon pdf:
> http://www.nikonusa.com/pdf/SB800_techniques.pdf
> "Auto FP High-Speed Sync
> Automatic high-speed flash synchronization at
> shutter speeds exceeding the cameras flash sync
> speed is possible. When shooting with flash
> outdoors, faster shutter speeds allow you to use a
> wider aperture to blur the background and/or
> freeze fast-moving subjects"
Yeah, but you lose a lot of power doing this.
> I (think?) this is what Rockwell calls "Idiotic repeating strobe
> mode": http://www.kenrockwell.com/nikon/sb600vs800.htm
Maybe. I think he's referring to what Nikon call Repeating (RPT)
flash operation.
> I've not used flash hardly at all but recently experimented with my
> on-camera flash on a hummingbird & found it awfully frustrating to be
> limited to 1/250 sec when using flash.
The best way to fix something like that is to use a powerful flash,
say 500 Joules or more, at 1/64 power to get an extrememly short
pulse. Add a neutral density filter if required. Auto FP High-Speed
Sync wouldn't help: you'd still get blur. The point of this mode is
fill-flash in daylight.
Andrew.
Paul Furman - 20 Jun 2007 17:39 GMT
>>Here's something I ran across which sounds useful:
>
[quoted text clipped - 27 lines]
> Sync wouldn't help: you'd still get blur. The point of this mode is
> fill-flash in daylight.
Thanks for trying to clarify but I'm still not clear. Auto FP High-Speed
Sync would seem to have allowed me to use fast shutter speeds like
1/3000 and get some flash in there, even if it's not super powerful and
not enough to freeze the wings. I was shooting in the shade of a tree
with a partly sunlit background at about 10 feet away. As soon as I
flipped up the flash I was forced down to 1/250 second so I had to stop
down to prevent overexposure & lost the ability to isolate the subject
with shallow DOF (ND filter would be another option I guess). Plus I was
shooting at 300mm & 1/250 is marginal for hand held on a 1.5 cropped sensor.

Signature
Paul Furman Photography
http://www.edgehill.net/1
Bay Natives Nursery
http://www.baynatives.com
Rita Ä Berkowitz - 20 Jun 2007 22:43 GMT
> Thanks for trying to clarify but I'm still not clear. Auto FP
> High-Speed Sync would seem to have allowed me to use fast shutter
[quoted text clipped - 6 lines]
> another option I guess). Plus I was shooting at 300mm & 1/250 is
> marginal for hand held on a 1.5 cropped sensor.
In reality the supposed loss of power in the flash using Auto FP real is a
none-issue. An SB800 doesn't have any trouble filling a scene at a distance
of 12' at 1/8000. And for close in macro work it really is fantastic. I
keep Auto FP enabled most of the time and have no complaints.
Rita
Andrew Haley - 21 Jun 2007 12:27 GMT
>>>I've not used flash hardly at all but recently experimented with my
>>>on-camera flash on a hummingbird & found it awfully frustrating to be
[quoted text clipped - 5 lines]
>> Sync wouldn't help: you'd still get blur. The point of this mode is
>> fill-flash in daylight.
> Thanks for trying to clarify but I'm still not clear. Auto FP High-Speed
> Sync would seem to have allowed me to use fast shutter speeds like
> 1/3000 and get some flash in there, even if it's not super powerful and
> not enough to freeze the wings.
Ah, OK. I was assuming that freezing the wings was the goal.
> I was shooting in the shade of a tree with a partly sunlit
> background at about 10 feet away. As soon as I flipped up the flash
> I was forced down to 1/250 second so I had to stop down to prevent
> overexposure & lost the ability to isolate the subject with shallow
> DOF (ND filter would be another option I guess). Plus I was shooting
> at 300mm & 1/250 is marginal for hand held on a 1.5 cropped sensor.
I would have thought that shallow depth of field was inevitable,
really, with such a long lens.
Andrew.