High Speed Sync - Any Downside?

<p>I use Canon 5D MkII with 580 EX II and 430 EX II speedlights. Over the last year or so I have been delving into artificial lighting and am trying to learn more about the otpimum use of this equipment.<br>

So far it appears to me that the best may to use the speedlights in automatic mode is to put the camera in manual mode dial in a moderate setting (e.g. f11 1/125) and let the flash light the scene to give the ocrrect exposure.<br>

So two questions:<br>

#1 While I grasp that the "purist" way to use the flash is to set meter the subject with an exposure meter and adjust the flash output manually, can anyone tell me any disadvantage to putting the camera in manula mode and letting the flash set itself automaticaly as compared to using the camera in some other mode (program, or aperture)?<br>

#2 Is there any disadvantage to leaving the flash always set in the high speed sync mode all the time and setting camera manual ? Doing so would seem to give the best of all worlds - providing you's got enought flash energy on tap (I have 4 speedlights to work with) and the scene is not huge, it would seem that you could get almost any range from f11 / 125 out to f2 / 800? </p>

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<p>#1 The downside may or may not be when the camera/flash doesn't meter properly. Either something is reflective in the scene or some other issue. You may also notice slight differences in exposure from shot to shot. Nothing major, but each exposure is metered independently from the previous. I find putting the camera in M and the flash in eTTL is pretty reliable though.</p>

<p>#2 You lose effectiveness by crossing over your X-sync, which is 1/200th of a second. The flash will not go into HSS until it actually reaches 1/200th of a second or faster, so there's no downside to just leaving that on. But for every stop in shutter speed that you exceed the sync speed, you lose a stop of light from your flashes.</p>

<p>In weddings I use the automatic mode (never the "TTL") setting a f number in the flash (usually bettween f:4 and f:8) and use the camera in manual mode. So I get the flash provide a known amount of light while I decide the exposure with the real f number in the camera.</p>

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<p>So I get the flash provide a known amount of light while I decide the exposure with the real f number in the camera.</p>

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<p>Hopefully you are using a flash set to a fixed beam pattern and it isn't zooming automatically as you change lens focal lengths. Tta will very effectively change the guide number of your light.<br>

Approximately 90% of the time I shoot with my camera set to Aperture Priority and the Speedlites in e-TTL mode. The other 10% I sett he camera to manual and leave the flash in e-TTL mode. In either Manual or Aperture Priority mode unless I put the flash into HSS mode the x-Sync of a Canon body I am limited to the X-Sync shutter speed as a shoirtest duration. If I leave the flash in HSS mode I have the full range of shutter speeds to play with, So I agree with Dan Ferrel's the second sentence in Dan Ferrel's second point: <em>"The flash will not go into HSS until it actually reaches 1/200th of a second or faster, so there's no downside to just leaving that on."</em> </p>

<p>However I don't think he is right about losing a ful lstop of flash output for every full shutterspeed over the camera's X-Sync speed. However Canon's HSS system is known to be very lossy when it comes to energy management so I use PocketWizard ControlTL radio sync system which makes much more efficient use of a Speedlite's available energy when you are at shutter speeds over the camera's X-Sync speed. The only downside with the ControlTL system comes from how electronically noisy the Canon 580 EX II. They produce so much electronic noise right around the frencies PocketWizard uses that they sell both a soft and a hard Shield for the 580 EX II Speedlites, I use the AC7 hard shield. The Canon 430 EXII does not need to be shielded in my experience.<br>

It is rare that I have a Canon Speedlite or MiniTT! + Speedlite or FlexTT5 + Speedlite mounted in a camera's hotshoe so I cannot from personal experience comment about that. </p>

<p>1. If you haven't already, got to photonotes.org/eosflash to read about how ETTL reacts in the various camera modes. In camera manual modes, there is no downside except that ETTL is still an automatic mode and you'll get varying responses. If you get good at predicting responses, it is a workable way to go.</p>

<p>2. There should be no downside to leaving the flash in HSS. I don't know about the 5D II, but with the 5D, I recall that at 1/200th (the borderline), if your flash was set to HSS, the camera did not revert back to non-HSS, like it is supposed to. Might want to do some research. I have a 5D, and I consequently leave the flash to non-HSS, and change it if I need to.</p>

<p>"ETTL is still an automatic mode and you'll get varying responses.", and there's your downside.</p>

<p>What's the downside to using manual, on both camera and flash? Especially if you are working with / fine tuning a concept in a controllable situation (ie: co-operating subjects and a fixed location and POV)?... t</p>

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<p>Nadine Ohara wrote:<br /><em>If you haven't already, got to <a href="http://photonotes.org/articles/eos-flash/">photonotes.org/eosflash</a></em></p>

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<p>I haven't, but it looks like a great resource, so cheers for that, Nadine!<br />Also Canon's <a href="http://cpn.canon-europe.com/content/education/technical/getting_the_most_from_speedlites_IV.do"><em>Getting the most from Speedlites</em></a> series of articles may be of interest / some help.</p>