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Subject: "What exactly is sync speed?" Previous topic | Next topic
jaymor Basic MemberSat 18-Aug-01 12:44 PM
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"What exactly is sync speed?"



          

in flash photography, does a camera only have one sync speed or is it a range 'up to' it's advertised sync speed? for example, my n80 has a sync speed of 1/125. does that mean the shutter speed 'always' stays at 1/125 whenever the built-in flash is activated as well as when a flash is attached to the hot shoe? or does the camera choose the fastest shutter speed (ie. in aperture or program mode) but only up to 1/125? actually the n80 manual says that the sync speed is 1/60 to 1/125. which makes it more confusing.

if it is variable, can i control it by changing aperture if i place the camera in manual mode (i vaguely understand that aperture is related to the flash power as well as distance)? are the rules the same as in non-flash photography except my shutter speed only goes from bulb to 1/125? the questions in my mind go like this:

' will the shot be blurred if lens focal length
is greater than 1/125
. what about action shots needing faster speeds
above 1/125
. if i make aperture smaller to gain dof will the
shutter speed stay at 1/125 or will it go down
making the shot vulnerable to camera shake

thanks for this site! my pictures have greatly improved from using what i have learned from everybody here.

  

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Replies to this topic
Subject Author Message Date ID
Reply message RE: What exactly is sync speed?
jjussi
18th Aug 2001
1
Reply message RE: What exactly is sync speed?
jaymor
18th Aug 2001
3
     Reply message RE: What exactly is sync speed?
Ed
18th Aug 2001
4
Reply message RE: What exactly is sync speed?
Ed
18th Aug 2001
2
Reply message RE: What exactly is sync speed?
jaymor
19th Aug 2001
5
Reply message RE: What exactly is sync speed?
Johnny
24th Aug 2001
6

jjussi Basic MemberSat 18-Aug-01 01:09 PM
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#1. "RE: What exactly is sync speed?"
In response to Reply # 0


KLAUKKALA, FI
          

>in flash photography, does a camera
>only have one sync speed
>or is it a range
>'up to' it's advertised
>sync speed?

It means higest speed what can be used with flash! It's highest speed where shutter is wide open for very short time!

> for example,
>my n80 has a
>sync speed of 1/125.
>does that mean the shutter
>speed 'always' stays at 1/125
>whenever the built-in flash is
>activated as well as when
>a flash is attached to
>the hot shoe?

Yes and no... Depens on light.

> or does
>the camera choose the fastest
>shutter speed (ie. in aperture
>or program mode) but only
>up to 1/125?

Yes!

> actually the
>n80 manual says that the
>sync speed is 1/60 to
>1/125. which makes it more
>confusing.

If there is not much ambient light camera chooses 1/60. But if you say to camera/flash to go "SLOW SYNC" or Rear curtain sync it can choose up to 30 second times, depending on ambient light!

>if it is variable, can i
>control it by changing aperture

Only if there is enought ambient light!

>if i place the camera
>in manual mode (i vaguely
>understand that aperture is related
>to the flash power as
>well as distance)?

Then you can choose aperture and speed up to 1/125 and flash is TRY TO give enought light to get picture.

> are the
>rules the same as in
>non-flash photography except my shutter
>speed only goes from bulb
>to 1/125?

Yes and no! With flash you can take pictures in total darknes.

>will the shot be blurred
>if lens focal length
> is greater than 1/125

No and Yes!
Yes if you have so much ambient light that camera choose max flash speed.
No, if there is not enought light (f.ex. without flash camera choose 1/10) then flash "stops" everything what moves. Flash speed is 1/5000 sec. - 1/8000 sec.

>what about action shots needing
>faster speeds
> above 1/125

Some camera models with some flash models can go up to 1/4000 shutter speed. But those who take action shots usually use cameras what have 1/250 (1/300) flash sync speed.

>if i make aperture smaller
>to gain dof will the
> shutter speed stay at
>1/125 or will it go
>down
> making the shot vulnerable
>to camera shake

Sometimes yes. Depent on ambient light!


--
© Jussi Jaaskelainen


© Jussi Jääskeläinen from Finland
All photos posted to nikonians

  

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jaymor Basic MemberSat 18-Aug-01 06:04 PM
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#3. "RE: What exactly is sync speed?"
In response to Reply # 1



          

jussi, thanks for replying.

from your answers, i get the impression that the camera WILL CHANGE shutter speeds up to a max of 1/125 depending on the amount of light present. also, on manual mode i can go above 1/125 and the flash will do as much as it can but only up to it's maximum capability. if it's max is not enough i will get an underexposed shot. please confirm if my understanding is correct.

i dont get the slow sync speed. why cant the sync speed be able to go down to 1/30 all the time instead of having to ask for it by switching to 'slow sync'?


  

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Ed Basic MemberSat 18-Aug-01 09:59 PM
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#4. "RE: What exactly is sync speed?"
In response to Reply # 3


US
          

> i get the impression that the camera WILL CHANGE shutter
> speeds up to a max of 1/125 depending on the amount of light
> present.


Exactly. If ambient light calls for above 1/125, you get "HI" reading and overexposure. That's why a faster top sync speed found on top-of-the-line cameras is a nicer feature.


> on manual mode i can go above 1/125 and the flash will do
> as much as it can but only up to it's maximum capability.


If you go above your top sync speed, you'll get the "slit". Part of your picture will be completely black.


> if it's max is not enough i will get an underexposed shot.

Flash underexposure is not dependent on shutter speed, only on aperture and flash power. In flash work, aperture governs flash exposure and, shutter speed AND aperture governs ambient exposure.


> why cant the sync speed be able to go down to 1/30 all
> the time instead of having to ask for it by switching to
> 'slow sync'?


On my fully manual camera FM2, I can go down to 1 sec and use flash without problem. On modern electronic cameras, the auto-exposure modes governs your low limit speed. Nikon seems to think that 1/60 is the lowest hand-holdable limit and they've programmed this into P and A modes. The simple override is switch to "slow-sync" or use M (full manual exposure mode).

Ed

Visit my Nikonians gallery.

  

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Ed Basic MemberSat 18-Aug-01 05:35 PM
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#2. "RE: What exactly is sync speed?"
In response to Reply # 0


US
          

Warning: back to basics!

Before you understand sync speed, you must understand flash duration as well. Flash duration is the amount of time the flash stays on. There's 2 methods of measuring flash duration but suffice it to say that the flash duration is anywhere from 1/800 to 1/20000 sec, much higher than any camera shutter speed.

Now imagine the shutter mechanism of the camera. There are 2 curtains. Think of this in slow-motion. As you trip the shutter, the first curtain goes first across the frame, exposing part of the frame until it reaches the other side. For slow shutter speeds, the first curtain reaches the other side BEFORE the second curtain starts its travel across the frame, i.e. the whole frame is open for an amount of time. At high shutter speeds, the second curtain starts to move before the first curtain has travelled across. This makes for a slit moving across the entire frame. Since flash duration is much faster than the camera's shutter speed, using flash at these settings will expose only a slit of the frame.

This brings us to sync speed. It's the camera's fastest shutter speed at which the first curtain has travelled all the way across before the second curtain starts to move. In other words, this is the faster shutter speed at which the shutter mechanism remains wide-open. Normal-sync is a settting that tells the flash to "fire" when the first curtain has reached the other side, whereas rear-sync tells the flash to "fire" just before the second curtain starts its travel.

So, you may use flash anytime the whole frame is exposed, i.e. use any shutter speed up to and including the top sync speed. Nikon's modern cameras limit the shutter speed between 1/60 and the top sync speed in auto-exposure modes, like P and A, unless you employ slow-sync (then it goes down below 1/60 if necessary). In very bright conditions, using A and flash will sometimes get you a reading of "HI". It's because the flash limits you to the top sync speed and paired to your chosen aperture, over-exposure is imminent. In this case, either remove the flash or stop down until you're well within the sync speed.

Using a slow shutter speed with flash may or may not give you a blurry image. With flash as the "only" light (like a completely dark room), the flash duration will become your effective shutter speed. That is why you can take pictures of a light bulb shattering or a balloon bursting. Motion can be frozen by the 1/20,000 sec flash duration. It is the ambient light that causes blur. Ambient light has no duration. It is always "on". With flash and ambient light, you may get ghosting of images depending on the level of ambient.

Hope this helps.
Ed

Visit my Nikonians gallery.

  

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jaymor Basic MemberSun 19-Aug-01 03:11 AM
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#5. "RE: What exactly is sync speed?"
In response to Reply # 2



          

Ed, thanks for your explanation. have you ever thought of teaching? i really appreciate the time and effort you gave for the two long explanations you gave and also jussi's. your saying that aperture controls flash exposure while shutter speed and aperture handles surrounding light did the trick. it also makes me understand more why my fireworks shots last july 4 was a disaster.

  

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Johnny Basic MemberFri 24-Aug-01 05:05 PM
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#6. "RE: What exactly is sync speed?"
In response to Reply # 2


Westampton, US
          

LAST EDITED ON Aug-24-01 AT 07:06 PM (GMT)

Great exaplanation Ed!

>In very
>bright conditions, using A and
>flash will sometimes get you
>a reading of "HI".
>It's because the flash limits
>you to the top sync
>speed and paired to your
>chosen aperture, over-exposure is imminent.
> In this case, either
>remove the flash or stop
>down until you're well within
>the sync speed.
>

You can also put the camera in shutter priority and if you have a newer style Nikon Speedlight, set it to FP High Speed Sync. This will allow you to have fill flash in 'brighter than flash sync speed' situations.


Johnny

Johnny

---
"I hear and I forget. I see and I remember. I do and I understand." -Confucius

  

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