High Speed Sync...help me understand

rockcanyonphotos

Ok. I have recently noticed several posts where people are using HSS (canon term, don't know what Nikon calls it) with some very nice results, even in cases where they appear to be shooting below ambient and at high SS (ie., 1/1000).

Can someone educate me on the limitations of HSS with night-time football??

1) Can it be used to shoot below ambient and still get sufficient lighting for the shot while being able to use a faster shutter-speed than ambient will allow?

2) If I am shooting at a high ISO to get a high shutterspeed (say ISO6400, f2.8, 1/500) can I use the HSS feature to improve picture quality and fill under the helmet.

or is all of this just a pipe dream and I have to keep using the 2nd curtain shutter, underexpose and make the flash do all the work for me?? Just dreaming here. Would love to have the benefits of 1/1000 SS for stopping action and the quality of a flash photo... oh, and a faster recycle time would be lovely :-)


regards, Kevin

johng

the limitation is that the flash output is dramatically limited - instead of a single burst of light, the flash uses multiple bursts. If you're only using a 200mm lens and you have a powerful flash you can still get results.

mercphoto

If you don't care if you have proper exposure of your background then try this instead. Turn OFF the HSS feature and set the shutter to your fastest sync speed, which is probably 1/200 or 1/250. Set an aperture so that your background is about 2-stops under-exposed, or more. Your flash is now the primary source of light, and since HSS is not enabled that light source will be extremely brief. It will be like a strobe in a disco, and you will get an image that appears to have been shot with a much faster shutter speed as a result.

RedFish71`

to answer your second question, yes. just remember that as your shutter speed increases the less effective your flash is. also, the distance of your subject will be another factor. i'd have to say that anything over 1/1600s the flash will be useless, but below that you will get some of the flash. the best way to know is to fool around with it and see for yourself!!

rockcanyonphotos

JOHNG,
since my 300mm just went back to canon for servicing I am stuck using my 200mm this week anyway, so I may just give this a shot. The lower flash output doesn't bother me if i can get a 1/1000 SS and maybe get just enough flash to aid in illuminating a slightly underexposed shot at that shutterspeed. Might also help reduce some of the noise at the higher ISO required for me to get close to ambient.

MERC,
the method you describe is what I have been using for the last several years. I like the results, however, I would love to find a way to get close to the quality of shots I get with underexposing but reducing my flash cycle time so I can get more shots off in a sequence.

REDFISH,
good to know. I only need 1/500 - 1/1000 so maybe...

regards, Kevin

RedFish71`

kevin, one other thing i do when i am using a ss higher than the sync speed is take the flash to manual and set it to 1:1. that will give you max power output from the flash. to help with the recycle time of the flash you will need the battery pack. helps a ton!!!!

rockcanyonphotos

REDFISH,
Already use the canon battery pack. I will play with manual and see what happens. I am trying to reduce my current cycle time of 2-3 secs. I usually run in ETTL with +2/3 to boost flash output... is this 1:1 going to require even more juice?? If I can get the 1/1000 shutterspeed that will solve my stop action issue. Then I am just looking for enough flash output to help with WB and to better illuminate under the helmet (I mount the flash low on my monopod).

kevin

ziggy53

If you consistently use 200mm - 300mm then you might consider a BetterBeamer to extend your flash beam at potentially lower power and faster recycling.

ziggy53

rockcanyonphotos wrote: »

... If I can get the 1/1000 shutterspeed that will solve my stop action issue. ...

HSS/FP mode does not necessarily stop action any better than normal flash sync.

A focal plane shutter travels at the same rate regardless of the shutter speed rating. At faster shutter speeds the leading and trailing edges of the shutter form a slit which travels across the image plane. Since the slit takes the same amount of time to cross the image plane regardless of the width of the slit, any subject motion that occurs during the exposure will record as subject distortion. There is a good description of the cause and effect here:

http://en.wikipedia.org/wiki/Focal-plane_shutter

http://webs.lanset.com/rcochran/flash/hss.html

Notice the image distortion that can occur, even with HSS/FP flash.

http://upload.wikimedia.org/wikipedia/commons/6/6f/Bundesarchiv_Bild_183-1991-1209-503,_Autorennen_im_Grunewald,_Berlin.jpg

Stationary target:

http://webs.lanset.com/rcochran/flash/medres/turnedoff.jpg

Spinning target with HSS/FP mode flash (1/4000th):

http://webs.lanset.com/rcochran/flash/medres/s4000.jpg

Spinning target with normal flash sync, but low power (1/250th):

http://webs.lanset.com/rcochran/flash/medres/flash.jpg

Conversely a speedlite used in a single pulse has a typical duration of 1/600th or so, effectively much better at stopping subject motion. At lower power output the flash duration is even shorter. Hummingbird photographers often use multiple, synchronized, low power flashes to produce sufficient light but with extremely short durations.

rockcanyonphotos

wow ziggy, way to hurt my brain :-). So after reading through this I think what I am seeing is that my best option for low-light night football is still to underexpose and use the flash to stop the action. Normally I do this with the following settings (ISO800, f/4.0, SS 1/300, Flash in 2nd curtain with +2/3). I have just been trying to find away to get more than 1-2 shots per play. I already use an external battery pack. Reach has not really been an issue as the 580EX will reach a good 50yds.

As to your previous comment. I did use a better beamer for a few years but it was a bit of a pain to maintain while running around the sidelines. Now I will admit I was using it in HSS mode vs my current set-up.

kevin

ziggy53

I have a BetterBeamer (BB) also and I agree, it's kind of flimsy and doesn't hold position or tolerate even a minor bump without losing position. I have been meaning to create a better mount for the BB lens that would make for easier mount/dismount and sturdier positioning. If I come up with something I'll share it.

If you can use it to allow lower flash power that will result in shorter duration flash (better subject stopping) and faster recycling.

pathfinder

How about going to ISO 1600 first? That gains you a full stop of light, that your speedlight does not have to send out, and hence, does not have to refill into your flash's capacitor.

Your cameras ( or the 1DMkIII at least ) should produce fine images at ISO 1600 if they are not under exposed. Might be pushing it for the 1DMkII.

I second Ziggy's suggestion of the Better Beamer also. It is kinda clumsy, and frail, but it does send the light out further for wildlife. In the cut and thrust of football shooting, it might not hold up as well.......

Or use a double hot shoe mount and two flashes for more light -

rockcanyonphotos

PATHFINDER, I did use the BB for several years and it was a bit flimsy even when I mounted it on the camera. With my flash being mounted only 6" off the ground it would just fall apart as I move up and down the sidelines (I need to do this to eliminate the "ghost eyes"). I have used ISO 1600 before and the issue is that the photo is often not underexposed enough for the flash to freeze the action so I tend to get "ghost" images.

The Double hot shoe idea is interesting. I have seen one person post a pic of such a set up but I really have no idea how to control the setup.... Have you used such a setup? If so, answering a few questions on this type of setup it would be very helpful.

1) Does the connection have to be done wirelessly? (currently I have my flash hardwired for reliability)

2) Can the you program this set-up so that the flash usage alternates from one to the other with each exposure? (ie., one is recharging while the other is working) or do I get the faster recycle time by just reducing the power output of each flash?

Thanks, Kevin