Shooting over 1/250 // D90 // SB900

DropDead

DropDead

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Jake Lewis
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Hey guys,

I've been doing some BMX shoots recently and i'm using my SB900 in FP mode to shoot at like 1/1250 or near there but after seeing others EXIF data I see that they shoot at 1/250 I understand that 1/250 is the cut off point for the FP mode...

BUT

My question is... How come their shots don't blur? My ones still blur at 1/1250?! :bang:
 
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Flash duration is the answer, on minimum power some flash's fire around 1/20,000sec

Flash on manual and minimum power, rear curtain sync to stop ghosting, works for me (y)
 
PaulJC said:
Flash duration is the answer, on minimum power some flash's fire around 1/20,000sec

Flash on manual and minimum power, rear curtain sync to stop ghosting, works for me (y)
Click to expand...

Care to expand? Or show me where to read up on this? I'm rather confused in all fairness as I was always under the impression of faster shutter speed, the better it is at stopping the action
 
DropDead said:
Care to expand? Or show me where to read up on this? I'm rather confused in all fairness as I was always under the impression of faster shutter speed, the better it is at stopping the action
Click to expand...

I'd suggest getting ahold of a copy of the Lightenupandshoot v-book ($20 download) and reading that and the Strobist 101 ocf basics, that should give you a better understanding of the relationship between the flash and shutter speed/aperture. (y)
 
DropDead said:
Care to expand? Or show me where to read up on this? I'm rather confused in all fairness as I was always under the impression of faster shutter speed, the better it is at stopping the action
Click to expand...

Google how focal plane shutters work, and x-sync. In a nutshell, the max x-sync speed is the fastest the shutter can run while the whole of the sensor is completely uncovered. You can run slower, but any faster and you get a dark band at the bottom which is a shadow of the second curtain on its way to closing.

With flash, the effective shutter speed is the flash duration, and as stated above, that is always very brief, like 1/1000sec to perhaps 1/40,000sec at lowest power.

Then there is also the ambient light exposure, that is affected by the actual shutter speed. If it's bright, you get two exposures going on - the very brief flash exposure and the much longer ambient exposure that can cause blurring and ghosting around the frozen flash image.

PaulJC said:
Flash duration is the answer, on minimum power some flash's fire around 1/20,000sec

Flash on manual and minimum power, rear curtain sync to stop ghosting, works for me (y)
Click to expand...

Rear (second) curtain sync doesn't stop ghosting, it just puts the ghost behind the direction of movement instead of in front of it. Also, rear curtain sync doesn't work at all above about 1/30sec (unless you have a PW Flex/Mini) even when it's set.
 
HoppyUK said:
Rear (second) curtain sync doesn't stop ghosting, it just puts the ghost behind the direction of movement instead of in front of it. Also, rear curtain sync doesn't work at all above about 1/30sec (unless you have a PW Flex/Mini) even when it's set.
Click to expand...

While i agree it doesn't stop ghosting, unless you have a long shutter and light source their wont be any ghosting from ambient but could potentially be some from light drop off caused by the flash's if you have had to up the power increasing the duration...

I've just tested the rear curtain sync using a Nikon D90 firing the flash via CLS with an SB700 it'll happily capture shots on rear sync all the way up to it's maximum shutter speed of 1/4000, i've also optically fired flash's on rear sync at 1/200 as i was doing it in a skatepark yesterday evening.
 
PaulJC said:
While i agree it doesn't stop ghosting, unless you have a long shutter and light source their wont be any ghosting from ambient but could potentially be some from light drop off caused by the flash's if you have had to up the power increasing the duration...

I've just tested the rear curtain sync using a Nikon D90 firing the flash via CLS with an SB700 it'll happily capture shots on rear sync all the way up to it's maximum shutter speed of 1/4000, i've also optically fired flash's on rear sync at 1/200 as i was doing it in a skatepark yesterday evening.
Click to expand...

Rear curtain sync normally fires quite a bit ahead of the rear curtain, and looks something like this http://www.pocketwizard.com/inspirations/technology/rear_curtain_sync/ If you try it, you'll find it doesn't engage at all until above 1/30sec or higher, though some cameras are a bit faster than others.

Try this. Wide angle lens (to improve your hit rate) and shoot a bright light like a desk lamp against a darker background. Swing the camera fast from side to side, in a violent panning motion, to create speed blur. Set rear curtain sync and start at say 1/125sec.

You'll find that the ambient blur appears in front of the frozen flash image, as with normal front curtain sync. Then slow the shutter speed down and at around 1/30sec you'll see ambient blur both in front and behind the light as the camera switches over to rear curtain sync proper. It's more like middle curtain sync, if you follow. As the shutter speed gets longer, the small amount of blur in front appears to get less as it becomes a relatively smaller part of the overall exposure time.

If you want 'real' rear curtain sync, and at faster shutter speeds, then PW's optimised rear curtain sync mode is the only way I know you can get it.

Edit: you cannot get rear curtain sync above the max x-sync speed, by definition. Whatever you were getting at 1/4000sec, it wasn't rear curtain sync. Probably normal FP-sync, or high speed sync in Canon-speak.
 
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Not disagreeing with you at all about the light trails, i did say "unless you have a long shutter and light source their wont be any ghosting from ambient" i'm talking about potential ghosting from the flash burst which can and does happen.

TBH i have no idea how Nikon CLS manages it's application of rear sync and what speeds it can maintain.

I think we've gone a little off topic here, bottom line, the flash freezes the motion :D
 
Right i've been practicing what you guys have been saying.. And literally just blown my mind... SOOO MANY possibilities! I just want to go out and shoot now!

Literally just blew my mind haha!


I've read everything you guys have told me before and what i've read on strobists but I have no idea why I thought shooting at higher speeds was a good idea!

And yeah i've come to realize how it all works now!

The shutter speed is for the ambient light and the flash is set to freeze the action!

Eureka! :D
 
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You got it. shutter Controls ambient, apeture controls flash. Lower the flash power the faster the flash, so might need to bonk your iso up to increase the flash power if its too low. Your right though.......so many possibilities
 
HoppyUK said:
- In a nutshell, the max x-sync speed is the fastest the shutter can run while the whole of the sensor is completely uncovered. You can run slower, but any faster and you get a dark band at the bottom which is a shadow of the second curtain on its way to closing.


Note to Canon users: Most Nikon flashguns can sync with most Nikon cameras at 1/8000sec. This is because the flashgun can be set to pulse the flash as the FP shutter travels across. Downside is the power output is lower. Not sure Canon flash has this feature
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PDM said:
Note to Canon users: Most Nikon flashguns can sync with most Nikon cameras at 1/8000sec. This is because the flashgun can be set to pulse the flash as the FP shutter travels across. Downside is the power output is lower. Not sure Canon flash has this feature
Click to expand...

Canon flashes utilise HSS (high speed sync)
 
PDM said:
HoppyUK said:
- In a nutshell, the max x-sync speed is the fastest the shutter can run while the whole of the sensor is completely uncovered. You can run slower, but any faster and you get a dark band at the bottom which is a shadow of the second curtain on its way to closing.


Note to Canon users: Most Nikon flashguns can sync with most Nikon cameras at 1/8000sec. This is because the flashgun can be set to pulse the flash as the FP shutter travels across. Downside is the power output is lower. Not sure Canon flash has this feature.
Click to expand...

All current Canon guns can do this. As said above, Canon calls it High Speed Sync mode, Nikon calls it FP-sync - same thing. Some higher end third party guns can do it too.

Yes, downside is substantially reduced power, because of the inherant way it works, so range is reduced. The higher the shutter speed, the greater the power loss.
Click to expand...
 
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