Sekonic L-358 and High Speed Sync

[george_nowakowski]

<p>Hi,<br>

I just want confirmation that my understanding is correct. I tried to shoot some outdoor scenes with my speedlights (Camera = D90, Flashes - SB-900). I took out my light meter to get a reading. I set my shutter speed high on my camera 1/2000, and turned on AutoFP for High Speed Sync. I was quite frustrated to see that my light meter only goes up to 1/1000 when measuring flash! After many Google searches, I reasoned that anything after 1/1000 would not effect the photo since the ambient light would be 0, so Sekonic only goes to 1/1000.<br>

Is my understanding correct? What if I were to shoot directly into the sun, do shutter speeds above 1/1000 still have no effect on the scene? Why would Sekonic only go to 1/1000?</p>

<p>Thank you in advance</p>

[bob_sunley]

<p>Electronic flash meters were never designed for high speed sync, which is actually a rapid pulsed flash tube. Stick with your in camera metering, it knows what is going on with your "high speed sync". Even at 1/2,000 sec you need a flash burst of approx 1/200 sec to illuminate the frame as the shutter curtain slit passes over it.</p>

<p> </p>

[frank_skomial]

<p>For outdoors, leave your Sekonic at home. Why would you use light/flash meter that is not iTTL/CLS compatiblle, with flash/camera in the FP/CLS mode?<br>

Readings from the flash meter would be quite useless, unless you use camera and flashes in manual modes, but you would need to use regular sync speed, perhaps max at 1/200 or 1/250 sec.</p>

[pete_s.]

<p>Your understanding is incorrect. At 1/1000s you can still get lots of ambient light. The reason Sekonic meter only goes to 1/1000s are probably technical and related to the meter itself. There are several cameras that can shoot at higher shutter speeds without using high speed sync so it would be useful in some scenarios to have a faster light meter.</p>

<p>What the Sekonic can't do is meter when you use are using remote speedlights controlled by Nikon's CLS. That's because the camera will send out lots of preflashes to control the remote spedlights. These will trigger the light meter at the wrong time.</p>

<p>But if you have the <strong>flash on the camera</strong> or if you are using <strong>radio controlled TTL triggers</strong> like pocketwizards or radio poppers you should be able to use your light meter also in high speed sync mode with some special care. Of course using your light meter is only interesting when you are controlling the flash power manually. If you are using TTL but still want to meter the flash you need to use the FV lock button on the camera.</p>

<p><strong>HOW TO METER HIGH SPEED SYNC FLASH</strong><br /> High speed sync flash is actually a long flash pulse just as Bob mentioned above. So when you shoot at a higher shutter speed than you max sync speed (1/200 on the D90) you just set your meter to 1/200s and then compensate your higher shutter speed with the ISO setting on the flash meter.<br /> So if you shoot at 1/400s ISO 100, set you flash meter to 1/200s, ISO 50. Now the meter will show the correct aperture.<br /> At 1/800s ISO 100, flash meter is set to 1/200s, ISO25.<br /> At 1/1600s ISO100 => 1/200s, ISO 12<br /> At 1/3200s ISO100 => 1/200s, ISO 6<br /> etc.</p>

<p> </p>

[russ_britt3]

<p>You use your flash meter to get the f-stop for you flash exposure. They you put the flash meter on ambient light to get the shutter speed for that f-stop. That is how you meter both types of light for and outside exposure.<br>

The flash meter is to meter the flash<br>

The ambient meter is to meter the ambient light<br>

Then you balance them how you like, to reach the look you are after in the exposure.......<br>

example:<br>

if you want the flash to be the main light raise the shutter speed<br>

if you want the ambient light to be the main light use a slower shutter speed<br>

Its all pretty simple, and yes learn to use your hand held meter and you will be far smarter than most people that post here, or call themselves photographers these days.<br>

You will spend less time correcting and more time shooting, knowing in advance what results you will get in advance. Keep shooting and keep learning, you are very lucky to own a meter these days.</p>

[russ_britt3]

<p>One other thing you do need to know what is the maximum speed your shutter will sync with the flash. My Hasselblads sync at all speeds.<br>

If you go above that speed with a focal shutter you will get dark banding in your exposure.<br>

But you can also do as recommended and shoot in full auto, but I would not.<br>

I always like to control my exposure myself, I never use in camera meters on anything important.</p>

[wayne_f1]

<p>>> What if I were to shoot directly into the sun, do shutter speeds above 1/1000 still have no effect on the scene?</p>

<p>Result is correct, but the reason why is not precise.</p>

<p>Definition: FP flash mode is a series of rapid sequential flashes, for the purpose to mimic continuous light, like the sun or a desk lamp is continuous. FP flash mode no longer acts like "flash", instead it acts like continuous light, like sunlight (continuous for the duration of the focal plane shutter travel).</p>

<p>So... we know continuous light (like sun light) has "equivalent" exposures.</p>

<p>1/500 at f/11<br>

1/1000 at f/8<br>

1/2000 at f/5.6<br>

1/4000 at f/4</p>

<p>These are equivalent exposures. True of continuous light - so true of sun light, and true of FP flash mode.</p>

<p>Your SB-900 shows maximum flash range distance reported on its LCD (with level flash head). In FP mode, you will see that that maximum range distance is all the same, for any FP shutter speed (FP - faster than 1/250 second) - when and if the aperture is adjusted accordingly, to be equivalent exposures.</p>

<p> </p>

[jcuknz]

<p>What if I were to shoot directly into the sun, do shutter speeds above 1/1000 still have no effect on the scene? Why would Sekonic only go to 1/1000?<br>

Most definitely increase shutter speed would have some effect in reducing the light reaching the camera ... but in actual fact you would not notice any difference. The camera sensor can only record so much light as white and more is still just white.<br>

When I used a Wratten 87 infra red filter which cuts all visible light my camera still used 1/4000 at f/8 to record an eclipse with sunspot detail on the sun. I hate to think what shutter speed plus aperture would be needed to record the sun normally.<br>

If a measuring device cannot go as high as your equipment you take the reading it does give you and interpolate [?] for the camera settings you want to use? [As Wayne shows]</p>

[jcuknz]

<p>Wayne F. .... Thank you for answering a query I have as I venture into High Speed Flash [ Canon :-)] It appears from your statement that HSF breaks the rule that the shutter controls the ambient light and the aperture the flash ... when the focal plane shutter gets faster it also affects the flash strength ... complicated :-) <br>

Quite apart from a fast shutter speed may only use part of even a normal flash's duration. If it requires 1/800 to deliver its full power then a higher shutter speed can only use part of the output.</p>

[wayne_f1]

<p>>It appears from your statement that HSF breaks the rule that the shutter controls the ambient light and the aperture the flash ... when the focal plane shutter gets faster it also affects the flash strength ... complicated :-)</p>

<p>Yes. FP flash mode is extremely different than regular flash. Simply said, no FP shutter can sync flash faster than maximum shutter sync speed. Period. That is what maximum shutter sync speed is. So FP mode changes the flash instead, to become a continuous light (rapidly repeating flash pulses to mimic continuous, for the FP shutter travel time, but at much reduced power level in order to be continuous). Continuous light has no sync requirements (same as sunlight). Note that continuous light has no motion stopping ability like flash, so the FP mode is NO LONGER a Speedlite. FP mode is continuous.</p>

<p>Realize the difference - there is continuous light (sun, incandescent, fluorescent, etc) - always on with respect to period the shutter is open. And there is instantaneous light (regular flash), extremely brief, hopefully sync'd to happen sometime while the shutter is open.</p>

<p>Regular flash duration is near instantaneous, at least shorter (faster) than any sync-able shutter speed, therefore shutter speed does not affect regular flash exposure. It does not matter how long the shutter might stay open afterwards, the flash finishes nearly instantaneously, and nothing more can happen, exposure-wise. As you say, this difference with regular flash allows us to use shutter speed to control ambient background, while exposing flash properly with aperture (and flash power).</p>

<p>But FP flash mode is NOT regular flash, not even close. FP flash (HSS, faster shutter than a FP shutter speed can sync) is continuous light (for the brief duration of the focal plane shutter travel). It is no longer Flash at all, it is Continuous light. Continuous light has no sync requirement. Works same as a desk lamp, or a flashlght, or the sun, or other continuous lights. It is on both before and after the shutter duration activates.</p>

<p>Continuous means, if you double the shutter speed, the light sampled in that shorter duration is reduced to half. Exactly like sunlight.... continuous. So yes, unlike flash, shutter speed definitely affects continuous, including FP flash. However, in practice, like sunlight, we simply open the aperture correspondingly to produce an equal "equivalent exposure", so in that sense, it does not. Same as sunlight.</p>

<p>If your camera is set to an automatic metering mode (aperture or shutter priority), then in sunlight, we twist the dials with wild abandon, and as we change one of them (shutter or aperture), the other is automatically compensated, to be same equivalent exposure. FP flash works exactly the same, same continuous light. Regular flash does not, not continuous. Very different animals.</p>

<p>So in regard to seeking to meter 1/4000 with a 1/1000 meter, it really does not much matter. Just meter for 1/1000, then open aperture two stops for 1/4000 (equivalent exposure, FP flash is exactly like sunlight).</p>

<p>This is surely fill flash, where you must balance the ambient too. Because FP mode would seem a dumb choice if it were the only light (indoors for example). Because regular flash mode is at least 4x stronger, and the flash is also vastly faster to stop motion. The only possible advantage of FP flash mode would be to use fill flash with a wide aperture in bright sunshine.</p>

<p>FP flash is different than sun in one way... sun is many millions of miles distance and inverse square law does not affect it here on Earth. But the flash distance is only a few feet, so small distance changes will decimate the flash however.</p>

<p> </p>

[jcuknz]

<p>In this discussion it should be remembered that not all electronic flash is the same and some take a considerably longer time than others. Which is what I aluded to in my final paragraph since while any flash is much faster than shutter speeds of the DSLR [ apart from FP/HS ] there are compur type and electronic shutters which are faster than electronic flash. Your bridge camera has no difficulty in syncing flash at any shutter speed, except that some of the faster ones are only using part of the flash.</p>

<p>Since FP/HSS is a continuous source to be sampled at various points on the sensor as the two blinds expose each part of it to the light it seems to me logical than FP/HSS does not use 'X' sync* but an earlier point as the first blind starts to expose the sensor, perhaps even the old time 'M' sync? :-) [M sync was early to permit the flash bulb to build up its strength as the magnesium foil inside [ whathaveyou] ignited. A 'slow' process compared to electronic flash]</p>

<p>*The question I have been seeking confirmation off the past couple of days in the beginners forum without success as of yesterday.</p>

[wayne_f1]

<p>Yes, FP HSS Mode starts the continuous light from just before the shutter opens, and keeps it on continuously until the shutter closes. The goal is to mimic a continuous light. The only useful word is "continuous". Any exposure properties are exactly the same as other continuous sources, sunlight, tungsten bulbs, fluorescent bulbs, flashlights, campfires, etc.. </p>

<p>Speaking of X or M sync, FP flash is like the old FP sync bulbs, which were longer burning flashbulbs expressly for focal plane shutters, exactly the same thing for exactly the same purpose. Continuous duration while the shutter is working.</p>

<p>FP flash does appear to "flash" to humans, seen as a brief pulse, but interaction with shutter speed is very different than like shorter flash. Its duration is longer, lasting perhaps a 1/4 second duration, being "on" continuously all the time the FP shutter is in the process of being open in any way. So all of its properties regarding shutter speed are same as any continuous light, and not at all like flash.</p>

<p> </p>

[OPK]

<p>leave your flashmeter behind....it's completely unnecesary in that case.</p>

<p>Here's the tip:<br>

1. set the camera flashmode in FP<br>

2. set the flash in FP mode<br>

3. put in camera exposure compensation -1 or -2<br>

4. make the same with your flash but in + (exactly same amount as exposure)<br>

5. take pictures and have fun:)</p>