Those Dreaded Stadium Lights

jump71 · October 26, 2008

http://jump71.smugmug.com/gallery/6364843_entVZ

I'm looking for solutions to lights that constantly change temperature. Does anyone have an answer? AWB is a joke. For this game, I shot manual and set my Kelvin temp to 4100. It really didn't matter, though, as the lights changed constantly. This translated to hours in post-processing.

Please help!

Dano · October 26, 2008

I shoot RAW at night with AWB and mess with later in post. This is from a few weeks ago.

I guess that is what they call light cycling. Two shots taken split second apart.

Cuong · October 26, 2008

Unless the light is a powered by a DC source, you will continue to run into this situation when you use high shutter speed to freeze your action. The frequency of an AC source here is about 60 Hz. That means the light pulses 60 times a second. Your shutter speed is only 1/400 of a second, which means the shutter is opened for a much shorter time than the time needed for the light to get a full pulse. This is similar to exceeding your flash synch speed.

I have the same problem shooting gymnastics indoor without being able to use flash. There's nothing we can really do other than deal with it in post processing.

Cuong

HDShooter · October 26, 2008

Here ya go,
http://www.sportsshooter.com/message_display.html?tid=20873

jonh68 · October 26, 2008

That's the nature of the beast when shooting under stadium lights. If there were another 5 sets of lights on the other side, consider yourself lucky in the lighting situation. Many stadiums will have two sets on both sides. I would rather have the same lights spread out than have them concentrated on a few areas.

KED · October 26, 2008

jump71 wrote:

http://jump71.smugmug.com/gallery/6364843_entVZ

I'm looking for solutions to lights that constantly change temperature. Does anyone have an answer? AWB is a joke. For this game, I shot manual and set my Kelvin temp to 4100. It really didn't matter, though, as the lights changed constantly. This translated to hours in post-processing.

Please help!

It is what it is -- you could shoot a burst at 10 FPS on AWB and every frame would look different. That's the physics of the lighting and therefore a "given". AWB + RAW + post-processing is the only answer that I'm aware of (plus Noiseware since you are presumably at high ISO to boot, but that solves a different problem).

cecilc · October 27, 2008

jump71 wrote:

It really didn't matter, though, as the lights changed constantly.

Yep, you're right - it doesn't really matter ! It's unfortunate, but true ....

And there's really no way around this if you're shooting entirely with ambient light ... You might try shooting with a flash to negate the effects of the cycling lights (that's what I do!).

Samples:

The above images were shot at 1/250; f3.2 (I think); ISO 800; 550EX flash with FEC set at +2/3 (in camera) in manual mode in RAW with AWB (I know there's a bit of red-eye in these - I had used these images in another thread dealing with red-eye so I left the red-eye in them for demonstration purposes. The red-eye was elimnated in post)

As has been mentioned, shooting in RAW gives you a bit more leeway in PP.

But using a flash is the only way that I've come up with that will negate the cycling lights and (ultimately!) save time in post processing ....

Good luck with that, though .... I know it's tricky !!

jump71 · October 27, 2008

Thanks Cecil!

cecilc wrote:

Yep, you're right - it doesn't really matter ! It's unfortunate, but true ....

And there's really no way around this if you're shooting entirely with ambient light ... You might try shooting with a flash to negate the effects of the cycling lights (that's what I do!).

Samples:

The above images were shot at 1/250; f3.2 (I think); ISO 800; 550EX flash with FEC set at +2/3 (in camera) in manual mode in RAW with AWB (I know there's a bit of red-eye in these - I had used these images in another thread dealing with red-eye so I left the red-eye in them for demonstration purposes. The red-eye was elimnated in post)

As has been mentioned, shooting in RAW gives you a bit more leeway in PP.

But using a flash is the only way that I've come up with that will negate the cycling lights and (ultimately!) save time in post processing ....

Good luck with that, though .... I know it's tricky !!

Thanks Cecil! I'm actually shocked you got enough strobe light out onto the field. Looking at the shadows it appears as though the main light continues to be the stadium lights? I assume due to the red eye you were banging these shots straight-on with no diffusion, correct? Thanks again. Scott

jump71 · October 27, 2008

Thanks HD Shooter!

HDShooter wrote:

Here ya go,
http://www.sportsshooter.com/message_display.html?tid=20873

Thanks for forwarding the explanation!

Scott

cecilc · October 27, 2008

jump71 wrote:

Thanks Cecil! I'm actually shocked you got enough strobe light out onto the field.

Hi Scott ....

You really shouldn't be "shocked", though ... the higher end flashes'll easily get enough light ouput to reach out to midfield and beyond - I rarely "out-shoot" my flash even using the 400 ....

jump71 wrote:

Looking at the shadows it appears as though the main light continues to be the stadium lights? I assume due to the red eye you were banging these shots straight-on with no diffusion, correct?

Well, look at the shadows in that first shot - the shadow right behind the player is from my flash, not from the stadium lights. And in the 2nd shot, the shadow from my flash is lost in the background (I think) because I was kneeling on the ground when I took it ... That field metered at 1/250 at ISO 1600 at f2.8 (ambient). I was shooting at 1/250 at ISO 800 at f3.2. So, if my math is correct, I was actually shooting at -1 1/3 under ambient .... and that was at the brightest part of the field. I'm sure that down around the end zone I was more like -2 1/3 stops under ambient (which is where I probably should have been everywhere on the field). The flash is on a bracket that gets the flash about 8"-10" above and about 6" to the right of the lens ....

KED · October 27, 2008

cecilc wrote:

Yep, you're right - it doesn't really matter ! It's unfortunate, but true ....

And there's really no way around this if you're shooting entirely with ambient light ... You might try shooting with a flash to negate the effects of the cycling lights (that's what I do!).

Samples:

The above images were shot at 1/250; f3.2 (I think); ISO 800; 550EX flash with FEC set at +2/3 (in camera) in manual mode in RAW with AWB (I know there's a bit of red-eye in these - I had used these images in another thread dealing with red-eye so I left the red-eye in them for demonstration purposes. The red-eye was elimnated in post)

As has been mentioned, shooting in RAW gives you a bit more leeway in PP.

But using a flash is the only way that I've come up with that will negate the cycling lights and (ultimately!) save time in post processing ....

Good luck with that, though .... I know it's tricky !!

Cecil, your images are gone, or at least not visible to me right now, but I have a question about the combination you describe. I tried flash at night for football a few weeks ago, expecting that at 250 (ordinarily too slow for sports) the flash would help to eliminate motion blur. Not so, as you can see in the example below:

My camera/flash combo maxes out at 300, which of course I have no setting for. I feel like I may have missed something, and have reverted to shooting at night at ISO 3200 and thanking god for Noiseware. I'm content with that, but am wondering what I may have missed that gave rise to my motion blur problem. (This particular shot was at f/4.0, ISO 1600; I've since cranked it up to f/3.5 and 3200)

Edit: Your images came up when my post hit. They're great captures, but the context wouldn't necessarily have presented a motion blur challenge. Do you have MB in other shots at 250 with flash? Also I should note that in my original image (even as seen on SM) BOTH feet are blurred so it's not a DOF issue.

johng · October 27, 2008

The closer you are to an ambient exposure the more blur you'll show. About 2 stops below ambient you can start to eliminate motion blur completely. However then it becomes a trade-off with using more flash power and getting only 1 properly exposed shot. Truth be told a little blur in feet/hands isn't terrible and worth it to get 2-3 shot bursts. But, if you drop your settings by another stop or so you'll see that motion disappear.

cecilc · October 27, 2008

johng wrote:

The closer you are to an ambient exposure the more blur you'll show. About 2 stops below ambient you can start to eliminate motion blur completely. However then it becomes a trade-off with using more flash power and getting only 1 properly exposed shot. Truth be told a little blur in feet/hands isn't terrible and worth it to get 2-3 shot bursts. But, if you drop your settings by another stop or so you'll see that motion disappear.

Yep .... John's nailed it !!

David Evertsen · October 28, 2008

johng wrote:

The closer you are to an ambient exposure the more blur you'll show. About 2 stops below ambient you can start to eliminate motion blur completely. However then it becomes a trade-off with using more flash power and getting only 1 properly exposed shot. Truth be told a little blur in feet/hands isn't terrible and worth it to get 2-3 shot bursts. But, if you drop your settings by another stop or so you'll see that motion disappear.

About 2 stops below ambient...

That would mean increasing the shutters speed 2 stops correct? (making it faster)

Thanks,
David

johng · October 28, 2008

David Evertsen wrote:

About 2 stops below ambient...

That would mean increasing the shutters speed 2 stops correct? (making it faster)

Thanks,
David

Usually it's a drop in ISO first and foremost. No reason to shoot at ISO 3200 with a flash. Then possibly a stop down in aperture (backgrounds aren't as much of a problem because of light fall-off). So, for instance if ambient on the field you shoot on is 3200 1/400 and 2.8, dropping your shutter to 1/250 (2/3 stops gain), aperture to 4.0 (1 stop loss), ISO down to 1000 (1 2/3 stop loss) puts you right at 2 stops below ambient.
I stopped down to f4 but it doesn't hurt MOST of my backgrounds because of the fall-off.

Even in these you can see a little motion blur. But I simply don't want to go further below ambient and restrict myself to single shot bursts.

Sadly, however it's a blessing/curse for the endzone. Endzones are usually the darkest part and benefit from flash. However there are often structures and fans - those structures show shadows.

KED · October 28, 2008

johng wrote:

That's a classic right there; and thanks for the adjustment recipe that I didn't quote, but I'm curious on two fronts -- (1) you seem to be referencing burst mode, but I thought the flash could never keep up so in my attempt at this I just went single shot or 3FPS burst (useless!) and (2) you mention "dropping" shutter speed to 250, but as I posted above, it's been my understanding that the flash can't keep up at >300 anyway.

I'll admit it: I'm just not getting my head around flash at the moment.

johng · October 28, 2008

KED wrote:

That's a classic right there; and thanks for the adjustment recipe that I didn't quote, but I'm curious on two fronts -- (1) you seem to be referencing burst mode, but I thought the flash could never keep up so in my attempt at this I just went single shot or 3FPS burst (useless!) and (2) you mention "dropping" shutter speed to 250, but as I posted above, it's been my understanding that the flash can't keep up at >300 anyway. I'll admit it: I'm just not getting my head around flash at the moment.

Hey no problem.
1) Realize what happens with a flash - a transister gets charged. If a flash only dissipates 1/4 of the charge you get 4 shots out of one charge (assuming the flash is charging fully which for the life of me I can't figure out why it doesn't do some times but i'm not an engineer). The problem comes when the flash has to re-charge. So if your flash has to fire at over 1/2 power then it's going to have to re-charge to get a 2nd shot off. What really happens though is it fires anyway ant that 2nd shot is underpowered. Truth is I use ETTL - some photogs use manual flash settings. I just wish I could tell what flash output was being used from the EXIF info. It would be an interesting piece of data.

2. When I said 'drop the shutter speed', what I was referring to was WITHOUT flash you might be using a 1/400 shutter speed (along with 2.8 and ISO 3200) to get properly exposed shots. WITH the flash, you drop down to the synch speed (high speed synch isn't advised - smarter people than I can explain WHY but the important thing is it reduces the reach so it doesn't work too well for distances in football).
So again, assume WITHOUT flash you have ISO 3200, f2.8 and 1/400 and your shots are exposed as good as can be (can't do a whole lot about shadows inside the helmet).
As soon as you introduce flash your shutter speed drops to 1/250 or 1/300 because of the synch speed. IF you left the ISO at 3200 and aperture at 2.8 your shots would now be grossly over exposed (you're 1/3 - 2/3 faster without the flash then you add the flash you'll get over-exposed, flash-burned images). Now, you want to get rid of that overexposure so to keep the SAME exposure you had without flash you have to reduce ISO or aperture by 1/3-2/3 stops just to stay the same as before. BUT, if you keep the exposure the same you've got a problem - motion blur will be very evident at 1/250. The way to get rid of that motion blur is to have the in-camera exposure set at least 2 stops below ambient (so, remember synch speed limits us to 1/250 for sake of argument - ambient exposure is now f2.8, 1/250 ISO 2000 - in this case I dropped the iso by 2/3 stops - could just as easily have said f3.5 1/250 ISO 3200). Now we want to drop our exposure by 2 stops. See, the burst of flash is very fast (something like 1/4000 but I'm probably wrong

) - The rest of the time the shutter is open, the frame is pretty dark - too dark to properly expose the moving subject so the motion blur is hidden. As the camera's exposure settings approach proper ambient exposure the more you start to see that motion blur. At some point the flash is providing ALL the light required for the exposure - at which time the shutter speed becomes irrelevant. I have NO idea how far below ambient you have to be for the shutter speed to be COMPLETELY irrelevant. But 2 stops is kind of a good benchmark.

Think of it this way - imagine yourself in a completely dark room with a car on a track racing around. Without a light source, you don't see the car moving. Now imagine a light source flashing for 1/4000 of a second. Even though your eyes are open for a minute you don't really register the movement of the car - there's only enough light for you to see for 1/4000 of a second - so to your eyes the car would appear frozen. That's what's going on here (as long as we're not in high speed synch which is another topic).

But that's the beauty of digital photography - it's easy to practice. Try reducing the exposure from full ambient to 1 stop below to 2 stops to 3 stops and see how the photos turn out and how many shots you get out of a flash.

NOW, here are 2 important things to remember:
1. You're going to be using 1/4, 1/3, 1/2 or full power from your flash - after X number of shots your flash MUST recharge or you'll get underexposed shots. The speed of that recharge depends on your flash, the batteries and HOW MANY batteries (this is where external battery packs really come into play).
2. You CAN burn out a flash. I would not recommend taking 1000 flash shots in a 2.5 hour HS game. Even if you're running your flash at 1/4 power if you keep taking 4 shot bursts the flash will eventually overheat and fry. You gotta let that sucker cool down.

David Evertsen · October 28, 2008

johng wrote:

But that's the beauty of digital photography - it's easy to practice.

Wow, that statement is so true!! Thanks for the help. I take Football pictures to practice my Dance and taking pictures over and over really just makes it better. I have very few Dance Competitions every year that I can afford to take bad pictures. I practice low light action by taking football. If they won't let you take Varsity take JV/Freshman take flag football during the day , take a ton and look at what your settings do. Try stuff out see what it looks better you will learn all of the settings.. Then grab a friends
camera and see what you can do with it.. So you can get out of your safe zone..

John your help is absolutely invaluable this year, my football pictures keep showing it and can't wait to take some dance. You are absoluetely correct about Competitions and people buying pictures they will buy no question. They are more emotionally invested than Football and Soccer etc..

Thanks,
David Evertsen

cecilc · October 29, 2008

KED wrote:

(1) you seem to be referencing burst mode, but I thought the flash could never keep up so in my attempt at this I just went single shot or 3FPS burst (useless!) and (2) you mention "dropping" shutter speed to 250, but as I posted above, it's been my understanding that the flash can't keep up at >300 anyway. I'll admit it: I'm just not getting my head around flash at the moment.

Your last statement there is not unusual .... But a lot of this is just "math" .....

John gave a very good explanation up above, so I'll try not to re-hash what he's said (because he said it so well!).

I, too, take my camera off of "burst" capability (and all of this is in "manual" mode, too, by the way) - I change it to one-shot mode just so that I don't take a burst of shots. As John said, you CAN burn out a flash and I just don't try burst shooting at all. I find that I'm much more selective in my shooting that way .....

As far as "dropping" your shutter speed to 1/250 - you just have to match your camera's flash synch speed. In most cameras, that's 1/250 (although I know some cameras synch at 1/300 or even 1/500 - if so, go with that synch speed as your shutter speed).

Now, the math .... let's say your field meters at ISO 1600; f2.8; 1/250 (ambient). Most schools that I shoot at actually do meter at these settings at the brightest spot on the field, so that's what I'm using here for an example. Now, if you want to be shooting at 2 stops below ambient (and you're going to shoot with flash), then you can change your ISO and your aperture but not your shutter speed of 1/250 (since that's your synch speed - and, actually, you could change your shutter speed, but we're looking for the fastest shutter speed we can wring out of the camera). So, 2 stops below your ambient reading would be (possibly) ISO 800; f4.0; 1/250. If you wanted to go 3 stops under: maybe ISO 500; f4.5; 1/250.

Much of what appears to be motion-blur on images shot with flash at close to ambient readings is probably some ghosting - due to the same image being exposed twice on the same frame. One image exposed at the speed of the flash and another image exposed at the shutter speed using ambient light (which is a slower duration) - leaving the two images "close" but not quite matching, giving the illusion of motion blur .... Basically, what you're trying to do by using flash and shooting a couple of stops under ambient is to prevent that "ghosting" from showing up by having the speed of the flash capture the image and not allowing the ambient exposure to even show up .... because your ambient settings would leave the image 2 stops underexposed, and therefore very dark (and John's images above are great examples).

Hope that's not too confusing ....

jrowphoto · October 29, 2008

Just wanted to say thanks to all of those that contributed terrific explanations on this subject! I've always "hated" flash shots of sports and football, but seeing some of the nice results here and elsewhere really makes me want to try it out! Just wish the season wasn't winding down, and I could! lol

Flash has always seemed like alchemy to me (I know it's "math", but math wasn't my strong suit, so even math is like alchemy! hehe). Sometimes I think I grasp it, and the light seems to go on, but then at some point I'm all confused again!

I appreciate all of the great advice on this! thanks!!

rockcanyonphotos · October 29, 2008

I love this thread and the other similar ones this season... you guys have helped out tremendously!! I am sold on using flash for HS Football.

My question is about your lens choices, range and actual flash settings. You guys have been referencing 1/4 to 1/3 flash power at 2 stops under.

What lens are you typically using and at what range do you find this setup effective?

My fields are actually underexposed at 1/250, ISO1600, f2.8k but shooting RAW + NR in PP, I can make them work. Actual field exposure is more like 1/300, ISO6400, f2.8 falling off in the endzones.

My last two games have been with the flash at +2/3, ISO3200, f4.0, 1/300 with a 300mm lens. With this I find I have pretty good reach (30 yards) with the flash but over expose up close (which I can live with because it is pretty easy to recover in PP). I tried dropping to ISO1600 but shots started coming out underexposed even at 20yds.

I am wondering if I need to drop down to a 200mm lens and limit myself to 20yds or less for range??

regards, Kevin

johng · October 29, 2008

Kevin - what flash gun are you using? a 430? If you're going to shoot next season upgrade to a 580 and get the external battery pack. The 580 can cover 40-50 yards.
This is critical, IMO. The MAJOR benefit of using flash is the ability to drop ISO. The drawback is a less natural look. Shooting flash at ISO 3200 kind of combines the worst of both methods - you get high noise and the 'flash look'. So I'd suggest a more powerful flash - that way you can drop the ISO down and get cleaner images.

Also a note on flash settings - what you describe is the very reason I use ETTL with FEC rather than manual flash settings. Cecil on the other hand uses manual flash settings. It's a trade-off. For me, I'll dial in the FEC according to what I think I'm going to shoot. If they're on the near hash I might tone it down, far hash I might add some more. Am I shooting the QB? or the wideout near me? But the combo I'm using is pretty good I'm usually within +2/3 to -2/3 FEC so maybe 1 or 2 images a game ruined because of my flash settings (plenty ruined for other reasons including the flash not being fully charged because I'm not using a manual setting so I don't know how many shots I can get out of a charge).

rockcanyonphotos · October 29, 2008

johng wrote:

Kevin - what flash gun are you using? a 430? If you're going to shoot next season upgrade to a 580 and get the external battery pack. The 580 can cover 40-50 yards.
This is critical, IMO. The MAJOR benefit of using flash is the ability to drop ISO. The drawback is a less natural look. Shooting flash at ISO 3200 kind of combines the worst of both methods - you get high noise and the 'flash look'. So I'd suggest a more powerful flash - that way you can drop the ISO down and get cleaner images.

Also a note on flash settings - what you describe is the very reason I use ETTL with FEC rather than manual flash settings. Cecil on the other hand uses manual flash settings. It's a trade-off. For me, I'll dial in the FEC according to what I think I'm going to shoot. If they're on the near hash I might tone it down, far hash I might add some more. Am I shooting the QB? or the wideout near me? But the combo I'm using is pretty good I'm usually within +2/3 to -2/3 FEC so maybe 1 or 2 images a game ruined because of my flash settings (plenty ruined for other reasons including the flash not being fully charged because I'm not using a manual setting so I don't know how many shots I can get out of a charge).

John,

I use the 580EX with a Quantum Turbo battery pack (and yes I have reached out as far as 40yds). I have tried going ETTL but wasn't happy with the results, generally underexposed at any kind of distance, but I have never used it in combination with in-camera FEC adjustment... honestly, I will have to look that up to see how to set that with my camera :-).

As for ISO3200 with flash. I have actually been very pleased with the noise levels. I put on in-camera NR and with the nice exposure from the, flash the noise level is reduced tremendously. That said, I know I am doing something wrong here... I just haven't been able to get my head around it. That is one reason I was thinking of dropping down to my 200 prime and shooting within 10yds of the LOS.

thanks, Kevin

cecilc · October 29, 2008

johng wrote:

Cecil on the other hand uses manual flash settings.

No .... actually, I shoot in manual mode for the camera ....

But I have the flash on ETTL .... and any FEC I have dialed in also in camera - rather than on the flash ....

I find that using ETTL gives more consistent results, because the camera/flash combo in ETTL adjusts the flash output as needed to cover the distance at which you're focused. So if I'm focused at 10-15 yards, that's the coverage I get in ETTL - and if I'm focused out to midfield (or beyond) at, say, 20 yards or so, then that's the coverage I get ....

I tried the manual flash settings route - shooting at 1/4 power or 1/2 power or whatever - but found myself either blowing out the close stuff or really underexposing the further stuff .... so now I'm all ETTL .....

rockcanyonphotos wrote:

That is one reason I was thinking of dropping down to my 200 prime and shooting within 10yds of the LOS.

Man, I'd really hate to lose the reach of that 300 .... but your flash combo will easily cover the range of that 300, though. I'd recommend keeping that 300 over dropping back to the 200.

johng · October 29, 2008

Kevin - sounds like something definitely isn't working properly in your setup. The 580 should have no problems covering the range of a 300mm lens (certainly doesn't have a problem with my 300mm lens). Do you by chance have a diffuser on the flash? If so, take it off. But either there's a problem with the flash or a problem with the metering the flash is doing. A simple test would be to put it in manual and set to 1/2 power. 1/2 power should cover 30 yards if you're at 2 stops below ambient. If it's not throwing enough light at 30 yards at half power I'd suggest something is wrong with the flash or batteries. If it IS throwing enough then the issue would seem to be with the flash not metering properly. But my first thought was theh diffuser. I know i have an omnibounce on all the time for my normal flash use but it comes off for situations like this.

tomauto · October 29, 2008

Thank you guys for all the advice. I think I have all the puzzle peices now! The piece that I was missing was to underexpose the ambient...Hopefully the next game will go well.

I just bought a Canon 1D Mark II upgrading from a 30D because I couldn't take the amount of photos I was throwing away because of autofocus issues. Are there any quirks to the camera that I need to know? I can't wait to get my hands on it and start shooting with all the knowledge I have gained from the strobist site and lets not forget this great little forum

Does anybody try and match their flash color with the ambient via gels?

cecilc · October 29, 2008

tomauto wrote:

Does anybody try and match their flash color with the ambient via gels?

Nope ... and no good reason to even try ... (and I should add, "in my opinion" ....)

First of all, stadium lights "cycle", which gives you a different color temperature for just about every shot you take out there depending on where in that "cycle" you fire the shutter. That's also the reason that custom white balances don't "balance" anything out there, either - the color temperatures just aren't consistent enough for that.

Secondly, flash is "daylight" - no gel necessary to match that ... (at least, I don't think so ....).

Thirdly, if you're underexposed to minimize the ambient influence anyway .... then the ambient light (and its "color") should not be impacting your images .....

Leave the gels at home .... (again, "in my opinion" ..... )

cecilc · October 29, 2008

rockcanyonphotos wrote:

What lens are you typically using and at what range do you find this setup effective?

My typical set-up for bodies and cameras is:

On one body, I'll shoot with a 400 2.8 with a 550EX on a bracket positioned as far away from the lens as I can get it; the flash powered by a 40-watt Digital Camera Battery and with an off-shoe cord. This set-up is effective (to my taste, anyway) to just past midfield from the sideline - or about 25 yards or so ....

A 2nd body has an 80-200 f2.8 with a Sigma flash on the camera. And I use that body for closer shots ... probably not more than about 15 yards in ....

I really try not to "overshoot" the flash ... the exposure suffers and usually the framing is not tight enough anyway.

rockcanyonphotos · October 29, 2008

johng wrote:

Kevin - sounds like something definitely isn't working properly in your setup. The 580 should have no problems covering the range of a 300mm lens (certainly doesn't have a problem with my 300mm lens). Do you by chance have a diffuser on the flash? If so, take it off. But either there's a problem with the flash or a problem with the metering the flash is doing. A simple test would be to put it in manual and set to 1/2 power. 1/2 power should cover 30 yards if you're at 2 stops below ambient. If it's not throwing enough light at 30 yards at half power I'd suggest something is wrong with the flash or batteries. If it IS throwing enough then the issue would seem to be with the flash not metering properly. But my first thought was theh diffuser. I know i have an omnibounce on all the time for my normal flash use but it comes off for situations like this.

Interesting!?! I don't use a diffuser, but I also have never set FEC in camera. I like your ideas for helping get to the root cause of the problem. I have a couple more games in this season to try and get this all worked out... hopefully, I can get some stability by the end of the season that I can lock in by the time Lacrosse rolls around.

Thanks again, Kevin

KED · October 29, 2008

johng wrote:

Hey no problem.
1) Realize what happens with a flash - a transister gets charged. If a flash only dissipates 1/4 of the charge you get 4 shots out of one charge (assuming the flash is charging fully which for the life of me I can't figure out why it doesn't do some times but i'm not an engineer). The problem comes when the flash has to re-charge. So if your flash has to fire at over 1/2 power then it's going to have to re-charge to get a 2nd shot off. What really happens though is it fires anyway ant that 2nd shot is underpowered. Truth is I use ETTL - some photogs use manual flash settings. I just wish I could tell what flash output was being used from the EXIF info. It would be an interesting piece of data.

2. When I said 'drop the shutter speed', what I was referring to was WITHOUT flash you might be using a 1/400 shutter speed (along with 2.8 and ISO 3200) to get properly exposed shots. WITH the flash, you drop down to the synch speed (high speed synch isn't advised - smarter people than I can explain WHY but the important thing is it reduces the reach so it doesn't work too well for distances in football).
So again, assume WITHOUT flash you have ISO 3200, f2.8 and 1/400 and your shots are exposed as good as can be (can't do a whole lot about shadows inside the helmet).
As soon as you introduce flash your shutter speed drops to 1/250 or 1/300 because of the synch speed. IF you left the ISO at 3200 and aperture at 2.8 your shots would now be grossly over exposed (you're 1/3 - 2/3 faster without the flash then you add the flash you'll get over-exposed, flash-burned images). Now, you want to get rid of that overexposure so to keep the SAME exposure you had without flash you have to reduce ISO or aperture by 1/3-2/3 stops just to stay the same as before. BUT, if you keep the exposure the same you've got a problem - motion blur will be very evident at 1/250. The way to get rid of that motion blur is to have the in-camera exposure set at least 2 stops below ambient (so, remember synch speed limits us to 1/250 for sake of argument - ambient exposure is now f2.8, 1/250 ISO 2000 - in this case I dropped the iso by 2/3 stops - could just as easily have said f3.5 1/250 ISO 3200). Now we want to drop our exposure by 2 stops. See, the burst of flash is very fast (something like 1/4000 but I'm probably wrong ) - The rest of the time the shutter is open, the frame is pretty dark - too dark to properly expose the moving subject so the motion blur is hidden. As the camera's exposure settings approach proper ambient exposure the more you start to see that motion blur. At some point the flash is providing ALL the light required for the exposure - at which time the shutter speed becomes irrelevant. I have NO idea how far below ambient you have to be for the shutter speed to be COMPLETELY irrelevant. But 2 stops is kind of a good benchmark.

Think of it this way - imagine yourself in a completely dark room with a car on a track racing around. Without a light source, you don't see the car moving. Now imagine a light source flashing for 1/4000 of a second. Even though your eyes are open for a minute you don't really register the movement of the car - there's only enough light for you to see for 1/4000 of a second - so to your eyes the car would appear frozen. That's what's going on here (as long as we're not in high speed synch which is another topic).

But that's the beauty of digital photography - it's easy to practice. Try reducing the exposure from full ambient to 1 stop below to 2 stops to 3 stops and see how the photos turn out and how many shots you get out of a flash.

NOW, here are 2 important things to remember:
1. You're going to be using 1/4, 1/3, 1/2 or full power from your flash - after X number of shots your flash MUST recharge or you'll get underexposed shots. The speed of that recharge depends on your flash, the batteries and HOW MANY batteries (this is where external battery packs really come into play).
2. You CAN burn out a flash. I would not recommend taking 1000 flash shots in a 2.5 hour HS game. Even if you're running your flash at 1/4 power if you keep taking 4 shot bursts the flash will eventually overheat and fry. You gotta let that sucker cool down.

Thank you for an awesome tutorial -- seriously. I don't shoot at night again until weekend after next (and then, ironically, I'm done for the season), but I'm gonna put all this into practice. You're very generous with your time and your expertise -- many thanks.

KED · October 30, 2008

cecilc wrote:

Your last statement there is not unusual .... But a lot of this is just "math" .....

John gave a very good explanation up above, so I'll try not to re-hash what he's said (because he said it so well!).

I, too, take my camera off of "burst" capability (and all of this is in "manual" mode, too, by the way) - I change it to one-shot mode just so that I don't take a burst of shots. As John said, you CAN burn out a flash and I just don't try burst shooting at all. I find that I'm much more selective in my shooting that way .....

As far as "dropping" your shutter speed to 1/250 - you just have to match your camera's flash synch speed. In most cameras, that's 1/250 (although I know some cameras synch at 1/300 or even 1/500 - if so, go with that synch speed as your shutter speed).

Now, the math .... let's say your field meters at ISO 1600; f2.8; 1/250 (ambient). Most schools that I shoot at actually do meter at these settings at the brightest spot on the field, so that's what I'm using here for an example. Now, if you want to be shooting at 2 stops below ambient (and you're going to shoot with flash), then you can change your ISO and your aperture but not your shutter speed of 1/250 (since that's your synch speed - and, actually, you could change your shutter speed, but we're looking for the fastest shutter speed we can wring out of the camera). So, 2 stops below your ambient reading would be (possibly) ISO 800; f4.0; 1/250. If you wanted to go 3 stops under: maybe ISO 500; f4.5; 1/250.

Much of what appears to be motion-blur on images shot with flash at close to ambient readings is probably some ghosting - due to the same image being exposed twice on the same frame. One image exposed at the speed of the flash and another image exposed at the shutter speed using ambient light (which is a slower duration) - leaving the two images "close" but not quite matching, giving the illusion of motion blur .... Basically, what you're trying to do by using flash and shooting a couple of stops under ambient is to prevent that "ghosting" from showing up by having the speed of the flash capture the image and not allowing the ambient exposure to even show up .... because your ambient settings would leave the image 2 stops underexposed, and therefore very dark (and John's images above are great examples).

Hope that's not too confusing ....

It's not too confusing and as my props to you and Johng, I will tell you that my youngest son's last HS football game EVER (and hence probably the last football game I may ever shoot) is at night the weekend after this. I'm bringing your techniques with me! Thanks guys.

Those Dreaded Stadium Lights

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