Flash Sync Speed

On my Nikon D3100, it has a max flash sync speed of 1/200th of a second. Why is it that if the flash speed is so incredibly short (much faster than 1/200th of a second), you run into problems if using shutter speeds faster than 1/200 (a shutter blind causing an area of the photo to be darker). In other words, why if the duration of the flash is so much shorter than 1/200th of a second, can't it be synced to flash when the shutter is fully opened at speeds faster than 1/200th of a second??

Another part to this question, the pocket wizards talk about being able to use faster shutter speeds in midday shooting with fill flash, does that function work on a D3100, or is the D3100 always limited to 1/200th?

Do I ever need faster than 1/200th (I was able to freeze a hummingbird wings with that speed).

I have read all sorts of Google posts on flash sync but I must be missing something.

It can sync faster but cost more i guess,the compure(spelling?) shutter would sync up to 1/500th but that was a different thing built into the lens

I think I might have found the answer to my own question. At shutter speeds faster than 1/200th of a second, the frame of view is never fully open between the first and second curtain (a slit is moving across your sensor at the rate of your shutter speed from start to finish) ; whereas, at speeds slower than 1/200th, the second curtain doesn't start closing until after the first is fully open. Does that sound right?

If that is the case, the pocket wizard would not help it unless it gives you a longer flash so that your subject stays illuminated for the entire travel of the slit created between the first and 2nd curtain. Does it do this?? or I'm I totally off base here?

Revet said:

I think I might have found the answer to my own question. At shutter speeds faster than 1/200th of a second, the frame of view is never fully open between the first and second curtain (a slit is moving across your sensor at the rate of your shutter speed from start to finish) ; whereas, at speeds slower than 1/200th, the second curtain doesn't start closing until after the first is fully open. Does that sound right?

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Right. There is an example of this at Four Flash Photography Basics we must know - Maximum Shutter Sync Speed

If that is the case, the pocket wizard would not help it unless it gives you a longer flash so that your subject stays illuminated for the entire travel of the slit created between the first and 2nd curtain. Does it do this?? or I'm I totally off base here?

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The "longer flash to stay illuminated during the shutter travel" describes Auto FP flash mode (on higher end camera and flash models). This can allow any fast shutter speed with this FP flash mode. See Four Flash Photography Basics we must know - Auto FP and HSS

Exactly..On my D7100 it has these options^^I love shooting at 1/8000 second with my flash..Cool effect

ShootRaw said:

Exactly..On my D7100 it has these options^^I love shooting at 1/8000 second with my flash..Cool effect

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I am not a fan myself. Using FP mode indoors would seem ridiculous. Unnecessary. But it can allow using flash at f/2.8 in bright sun, if it has enough range to reach.

FP mode becomes a continuous light (for the duration of shutter curtain travel). This is quite different than regular flash mode.

SB-700 manual page H-26 says FP mode has Guide Number 42 (DX, 24mm, full power). This GN is good for any FP shutter speed, since exposure is compensated by aperture for different shutter speeds (just like in sunlight, both are continuous, simply just "on").

But regular flash mode (SB-700 page H-24) says regular speedlight mode has Guide Number 92 (DX, 24mm, full power). And GN 46 at 1/4 power there.

Page H-17 says SB-700 speedlight mode duration is 1/2857 second duration at 1/4 power. But technically, FP maximum is closer to 20% than 25% power, so it will be a bit faster than this. And speedlight becomes faster yet at lower powers, possibly extremely fast (like 1/40000 second, for water drop splashes and hummingbird wings, at close distance). And the speedlight does not require f/2.8 to work. Speedlights are called Speedlights.

Ive only used that effect outside....^^^

Woops, In my original thread I had said why would I need a faster shutter speed than 1/200th if I could freeze a hummingbirds wings. Sorry, I had my flash on with that shot so it was the flash freezing the wings, not the shutter speed. Now, if that was a mid-day shot and I wanted to open up my aperture to put everything out of focus except the bird, then using a fast shutter speed to cut back on the ambient light, and then use a flash to freeze him plus light him a bit, that is when the max sync speed is an issue, Correct? You could, however, get the shot by using a longer shutter speed (1/200 or longer) with a higher f stop (whatever it takes to get your ambient correct). This would allow you to freeze the bird without FP mode during the mid-day sunlight correct (with an increased depth of field of course)??

Revet said:

Woops, In my original thread I had said why would I need a faster shutter speed than 1/200th if I could freeze a hummingbirds wings. Sorry, I had my flash on with that shot so it was the flash freezing the wings, not the shutter speed. Now, if that was a mid-day shot and I wanted to open up my aperture to put everything out of focus except the bird, then using a fast shutter speed to cut back on the ambient light, and then use a flash to freeze him plus light him a bit, that is when the max sync speed is an issue, Correct? You could, however, get the shot by using a longer shutter speed (1/200 or longer) with a higher f stop (whatever it takes to get your ambient correct). This would allow you to freeze the bird without FP mode during the mid-day sunlight correct (with an increased depth of field of course)??

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Yes, you can use Auto FP mode (if your camera and flash support it), and use any faster shutter speed with wider aperture in sunlight (FP range is limited, but probably sufficient).

Or using 1/200 second sync with regular flash can work. The flash is much faster than the shutter (shorter duration), esp true at closer range with reduced flash power (low power is very fast). This is standard high speed flash photography stuff.... Low speedlight power is extremely fast, in a dim environment.

Bright continuous ambient (from the sun) can still blur motion that the flash could stop. Then reduce the ambient exposure at least a couple of stops, to be a negligible ambient.. then the speedlight can stop it, and the ambient won't blur it. Getting the ambient "right" is not what you want. You want the ambient picture to be dark, and then let the flash illuminate it. Sunny 16 says ISO 100 is 1/200 at f/11, so to get ambient dark and not exceed sync speed means f/22 or smaller... so instead, try to work in the shade.

The Nikon flash manuals have a duration specified in the spec chart in the rear of the manual. That is about regular speedlight mode. But in FP mode, the flash becomes continuous (longer than the shutter travel), and cannot stop motion at all... All you have then is the shutter speed, same as in daylight.

I love the Four Flash Fundamentals We Must Know. Maybe I should be starting a new post but there is a statement in there that is confusing. In the converting guide number for iso section, the following statement is made, " Doubling ISO doubles distance range, or doubles f/stop number, which is two more stops". That [FONT=verdana, sans-serif]contradicts[/FONT] everything else I learned concerning exposure or flash. I agree that two stops is doubling the distance, but isn't that also two stops on the ISO (ie. 200 to 800)? Doubling the ISO to me means going from 200 to 400, which I thought is one stop which would not be the same as doubling the distance (which is two stops)? Where am I going wrong here??

Revet said:

I love the Four Flash Fundamentals We Must Know. Maybe I should be starting a new post but there is a statement in there that is confusing. In the converting guide number for iso section, the following statement is made, " Doubling ISO doubles distance range, or doubles f/stop number, which is two more stops". That contradicts everything else I learned concerning exposure or flash. I agree that two stops is doubling the distance, but isn't that also two stops on the ISO (ie. 200 to 800)? Doubling the ISO to me means going from 200 to 400, which I thought is one stop which would not be the same as doubling the distance (which is two stops)? Where am I going wrong here??

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Thank you Revert, I appreciate the comment, and am always pleased to imagine it is helpful.

Doubling ISO or shutter speed is linear (double is 2x and one stop), but doubling Guide Number or f/stop number is not linear. And it can get confusing.

Guide Number takes the inverse square law into account, it lets us easily compute exposure anyway (direct flash).

A sequence like f/4 ... f/5.6 ... f/8 ... f/11... f/16 - Doubling the f/stop number is obviously two stops (f/11 is actually f/11.3 rounded off) These numbers explained at http://www.scantips.com/lights/fstop.html

Doubling the distance is two stops (less obvious, but it is the inverse square law).

Guide Number is (fstop x distance). Doubling either number obviously doubles the GN number, and is still two stops. All three values are non-linear.

For confirmation, check any Guide Number table. Each row is 2x power of the row below (a one stop difference), but it takes two rows to double Guide Number.

I love that my D7000 has FP mode, its almost necessary for me when using the 70-200mm handheld indoors, the lens is so heavy and long, that if I wasn't able to increase it over the max 1/250 Id have slightly blurry shots. I already realized this when I first got it, and before I turned the FP on. Being able to put it up to 1/320 or 1/500 really helps. It might just be my inexperience that can't keep it steady at 1/250 but either way I think its a great thing.

Also the lens does not have VR or OS in this case im sure that would help if it did

thegaffney said:

I love that my D7000 has FP mode, its almost necessary for me when using the 70-200mm handheld indoors, the lens is so heavy and long, that if I wasn't able to increase it over the max 1/250 Id have slightly blurry shots. I already realized this when I first got it, and before I turned the FP on. Being able to put it up to 1/320 or 1/500 really helps. It might just be my inexperience that can't keep it steady at 1/250 but either way I think its a great thing.

Also the lens does not have VR or OS in this case im sure that would help if it did

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You said "indoors", so I have to point out more details of how it really works.

Indoors, generally we can assume the ambient is 2 to 4 stops down, and insignificant. We are using flash instead. (I am ruling out using very high ISO to boost the orange ambient).

If you use FP flash mode and 1/500 second, all you have to stop motion is the 1/500 second shutter.

If instead, you use regular flash mode and say 1/200 second (or even 1/60 second), the ambient is still insignificant (even at 1/60 second). It is too dim to blur the action. But you have the speed light, which is intensely fast. Since FP mode is no more than only about 20% of maximum power, any where FP could work, we can assume the speed light is operating at only 1/4 power (or less). See the spec chart in the rear of the flash manuals for flash duration, and at 1/4 power, the speedlight duration is only about 1/3000 second (fast).

1/3000 second is much faster than 1/500 second. Stops motion incredibly well. Indoors the ambient is too dim to matter. And at lower power levels, the speedlight becomes unimaginably even faster... up to maybe 1/40,000 second. The speedlight is the standard motion stopping high speed photography tool (but this needs to be in dim ambient, so the ambient does not blur the action).

See Four Flash Photography Basics we must know - Auto FP and HSS for a comparison at 1/8000 second

I get that f stops are not linear, but isn't it so that increasing your f value by one stop (ie. 5.6 to 8) is halving the light. So although the f scale is not linear, it is linear if you think of it in stops, Correct?

Maybe another way to put it. I had to read over the "Four Fundamentals We Must Know" to make the whole thing pretty simple. Here is what I got out of it; When you are talking in terms of stops, you are essentially either halving or doubling the light by by changing one stop in either ISO, shutter speed, aperture, or flash power. What is different is when you try to use distance. Then you have to take into consideration the inverse square rule in that if you double or half the distance, it is actually 2 stops (or use a guide number when using flash which makes the inverse square law easy).

If this is all correct which I think it is, the statement in the "Four Fundamentals" in the section on "Converting Guide Number for Iso" is Incorrect. It says, and I quote, "Doubling ISO doubles distance range, or doubles f/stop number, which is two more stops." To me, doubling ISO would be going from 200 to 400 and this is one stop, not two as it states.

What am I missing here or is that a typo or maybe I am not reading it correctly.
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Revet said:

I get that f stops are not linear, but isn't it so that increasing your f value by one stop (ie. 5.6 to 8) is halving the light. So although the f scale is not linear, it is linear if you think of it in stops, Correct?

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Yes, one stop is a 2x change. And ISO and shutter speed are linear (a 2x change makes a 2x difference, which is one stop).

If this is all correct which I think it is, the statement in the "Four Fundamentals" in the section on "Converting Guide Number for Iso" is Incorrect. It says, and I quote, "Doubling ISO doubles distance range, or doubles f/stop number, which is two more stops." To me, doubling ISO would be going from 200 to 400 and this is one stop, not two as it states.

What am I missing here or is that a typo or maybe I am not reading it correctly.
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Oops! You are right, and I see it now, it was misworded. Thanks much for pointing that out.

It should say Doubling Guide Number doubles ... I assumed it did say what I imagined it said, which was the point of the little chart there with it, but it didn't, and you made me understand that it was worded wrong. I hate it when than happens.

Thanks very much, I really appreciate the correction. It is corrected now.

Wow, you wrote that Wayne?? What a great presentation of flash photography. It is a real help in muddling through this stuff. When it comes to photography, I think the tech stuff turns me on more the the artistic side (since I have barely any right brain to speak of) but I will tell you this, the more I learn about how it all works, my photographs are getting better, much better!! Thanks for taking the time to generate that section on Flash Photography. I have been testing the examples you use at night with my camera and sure enough, its spot on (fun too)!!

Revet said:

When it comes to photography, I think the tech stuff turns me on more the the artistic side (since I have barely any right brain to speak of) but I will tell you this, the more I learn about how it all works, my photographs are getting better, much better!

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Thanks, and yes, I am the guilty party. It gets mixed reactions. Some people do like it, but most find it very easy to skip over it. Not everyone wants to know anything, or to think about anything. Anymore it seems that if Auto Everything won't do it, it can't be done.

I am guilty of obviously having no artistic talent, but I also find that understanding how stuff works really helps anyway. I enjoy the understanding, and knowing what to do to be able to get it right certainly does go a long way. So I would say Bravo to you, but it is not the trend today. This is my own sour grapes, but popular appeal seems to want easy stuff that doesn't actually say anything, and certainly should not require thinking about it.

Oh cool, read your article about flash freezing the subject, I knew flash did that, but never really put 2 and 2 together to try in for indoor pictures with a lower shutter speed.

I was playing around right now on my 70-200mm, got these results

The first one was at 1/10 a second, just to test it at a speed that I would obviously get camera shake
It did pretty good, i turned the flash off and did the same exposure, and it was black, so the only thing lighting it up was the flash.

This was ISO 400 f/11 and 1/10 second, I think the flash was like 1/16 power





Then I turned the shutter speed past the sync speed to 1/500 f/11 and ISO 1600 looks sharper than above and not too bad for ISO 1600




Then I put it down to the sync speed at 1/250 f/11 and ISO 800, looks about the same as above just less noise



My question I guess, on the first one, why was it not as sharp as the other 2? If the flash at 1/16 power went off at 1/11100 sec according to the manual, and that was the only thing lighting the room, the camera shake shouldnt of mattered right? All of these were bounced off the ceiling, would that of made a difference?

Either way its pretty neat how well it did at 1/10 sec, i did it at that speed without the flash, just increased other things, and I couldnt get it still to save my life.

thegaffney said:

My question I guess, on the first one, why was it not as sharp as the other 2? If the flash at 1/16 power went off at 1/11100 sec according to the manual, and that was the only thing lighting the room, the camera shake shouldnt of mattered right? All of these were bounced off the ceiling, would that of made a difference?

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I can't answer about the first one not being sharp. I really don't see much difference, but yes, a little. I can't see the full size original of course, that you saw.

If it was black without the flash, then it was not camera shake. The speedlight at 1/16 power should have been around 1/11,000 second, which will handle camera shake.

However, I cannot resolve the conflict (to me) that ISO 400 f/11 could bounce at 1/16 power. Even it was a lower 8 foot ceiling, f/11 ISO 400 would need closer to full power. And full power is not very fast. The manual says 1/900 second, but there is a quirk. That is measured t.5, which is half power points, the time it is above half power. There is a lot of flash left, so it is slower. A t.1 time would measure 90% of it, and is classically assumed 3x longer, which would only be 1/300 second. However, lower power levels are cut off truncated (no trailing tail), so its about the same number either way.