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finnbay

Practice with strobes....

18 posts in this topic

I've gotten some new equipment, primarily to try some strobes in the gym for some of the sports I shoot. Had to set it up to see if it works as advertised, and used a captive audience to accomplish this - birds at my feeder. Though I've done a lot of "bird on a stick" type shots, I'm more concerned about what you think of the lighting in this series of shots. C&C welcome, and I realize it's a work in progress.

The set up: Two strobes set at about a 60 degree angle from each other at my back deck feeder. They are triggered remotely by Pocket Wizards. I placed them about 10 feet from the feeder, had them set to Manual and at 1/4 power and high speed sync. The camera was my 40D with the 100-400L, from about 25 feet. Had the camera working on manual mode, ISO 400, f7.1 and at 1/500th second.

NL2.jpg

NL3.jpg

NL4.jpg

NL5.jpg

Everything seemed to trigger as it was supposed to, need to fine tune technique. Monday I'll get a chance to set them up in a gym and see how that will work.

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Here is what is going on Ken. You don't have HSS available when off camera and using PW's. You only have that when teathered to the camera via ETTL cord or on your hotshoe.

Did you notice multiple flashes? I'm guessing you didn't, that is how HSS works it is multiple flashes of light to give you even exposure from opening of shutter to close of shutter.

Notice the darker lower half of your shots almost as if you feathered the flash up? That is because you are shooting above the max sync speed of your camera. The bottom of your birds have no shadow, up by the head there is a shadow.

I am actually surprised you got any exposures at that shutter speed, good information to put in your back pocket.

If you are still set up fire a shot with your current settings. No multiple flashes of light, no HSS. I am guessing you will see one flash, powered at your manual power setting on the flash. Another one of the limitations of off camera flash. You are stuck with 1/250s or whatever your sync speed is. This becomes a bit problematic when shooting outdoors with bright light. You have to lower your ISO as low as you can and stop down your aperture until you get your shutter speed to its max sync speed. Now you have lost control of your backgrounds because of your high DOF. Its a vicious cycle!

The only way around that presently are Radio Poppers, they retain ETTL and I think (I may be wrong on that)HSS as well with off camera flash. You don't have the range that PW's do but they are a bit cheaper.

I believe Alien Bees has a new transmitter that will work in ETTL but haven't researched it yet.

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Mike,

Focal plane shutters which most DSLR's have don't move fast enough to open all the way before allowing the exposure from the light from the flash, hence the darker banding in the photo. The flash is faster than the shutter.

Leaf shutters move much faster allowing for faster sync speeds. Cost and complexity, failure rate dictate what most manufacturers use for shutters. Thats why we usually see focal plane shutters.

Some cameras are going to electronic shutters which will hopefully allow for considerably higher sync speeds. Even with the advent of all these cool new features in cameras we are basically stuck with decades old flash, camera combinations.

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Ken and anyone else interested, another point you really don't want to use HSS for most sports applications. HSS is designed as a fill flash for outdoors where ambient lighting is too bright to control your DOF. Here is why;

1. It really reduces your flash distance, by a large amount! You can look at the back of your LCD on your flash and see the distance on the bar on the bottom. Put it in HSS and watch the bar drop waaay down.

2. It increases your flash duration, this is bad because the longer your flash duration the less effective the flash is at stopping action. Lower power settings shorten flash duration, stopping faster action. Remember stopping action with flash is controlled by the power off the flash(flash duration) and the aperture and ISO. Your shutter speed ONLY controls the ambient exposure, shutter speed has no effect on flash exposure of the subject!

Do you remember my water drop shots a while back? I shot those at 1/64 power to give me a quicker pulse of light, stopping a fast moving water drop. If you shoot at say 1/4 power your flash duration increases which will likely introduce ghosting in your image. Because the light is longer, exposing the movement of the object longer. Shooting with flash to close to ambient also causes ghosting you want at least two stops difference from ambient, more if you can swing it. Whew!

3. Last using HSS will greatly increase your power consumption of both your flash and camera. My experience has shown as few as 150 flashes with fresh charged batteries in the flash. The flash is going off multiple times with every shot, there goes your batteries.

Flash can be a head scratcher for many it just doesn't quite click especially when flash is moved off camera in manual. You get the concept but it doesn't all fall into place until one day, boom you get it and it is not nearly as hard as you thought. Ken you are doing the best thing possible, getting out and shooting different combinations of settings, see what happens when you change SS or aperture or ISO. When you see how these interrelate the light, so to speak will really go off.

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Wow! Learning curve, here we go again! I didn't get a chance to shoot for very long, and only changed SS once, to 250, and that blew everything out, so figured 1/500th was the way to go. Yes, just one flash. Thanks, Dan. I'm going to print this all out.

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Dan,

Question for clarification - flash intensity is controlled by length (in time) of flash firing, not a change in the intensity of the light emitted? If this isn't clear, I mean controlling the settings of the flash manually doesn't actually increase/decrease the intensity of the light emitted, just the duration of the light (which emits at a constant intensity). An analogy, it's light taking a 60W light bulb in a lamp and flipping it on for one second vs. 1/4 of a second. The longer it's on the more overall light emitted - hence higher intensity. Am I in the ballpark here?

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For anyone who is interested, since Ken started this experiment in using your flash manually I will give you some of my thoughts on manual flash. Just remember SS controls ambient exposure. The best thing to do with manual flash is to first take a picture to determine your overall exposure of the scene. Starting with proper exposure of the scene will simplify the rest of this exercise.

Start with your shutter speed at say 1/125s or a stop or two less than what your max sync speed is in this case I believe the 40D is 1/250s. I like to have a stop or two to play with and you will see why in a minute.

Use an aperture that you want to control your depth of field. Now adjust your ISO to make that all work out to a properly exposed scene. So lets use Ken's settings, I would have started with 1/125s which would make the f-stop at F9 or maybe F10 at ISO 400 with his lighting.

What if I didn't want that much DOF, I now have to lower my aperture lets say back to the F7.1 that Ken used, it looks nice because the background is so far from the subject. I must then lower my ISO from 400 to maybe 200. This puts me in the same exposure that Ken was at just slightly different numbers to get a better effect.

We take a shot and look at the histogram. If the histogram looks good we have our camera set for our ambient exposure. Now its time to introduce our manual flash into the picture. I don't use guide numbers but I do like the bar on the back of the flash to determine my flash effective distance. I am using a 580EX similar to Nikons SB-800 in power. A lower power flash will require a bit more juice to get the same results I will be covering.

I happen to know through experimentation that at 8' my flash will give me a good exposure of the subject at 1/4 power on manual. If my subject distance is 12' I will need approximately 1/2 power. At 15' maybe around 3/4 power and so on. This changes slightly based on the color the subject is (light or dark) but it gives you a great starting point to get close in the camera.

Ken mentioned he was at 25' at 1/4 power to me that is about right when lighting for FILL light. That is different than say lighting a portrait at 25' With fill we are just trying to bring out the shadows and add a nice catch light in the eyes of the subject so it will take a lot less power to do this.

Take a shot and look at your photo and histogram for any "blinkies" if your highlight warning is turned on in your camera, it should be if it isn't. Lets say the subject is overexposed slightly we can do a few things to fix that. Stop down the aperture a stop and try again, reduce the flash power slightly, or move the flash further from the subject. In this case the easiest thing to do is change our aperture from F7.1 to F8 or F9 and shoot again.

If all looks good you are ready to capture a photo. If the subject is underexposed again we can do a few things, open up your aperture, increase flash power or move the flash closer. Again we will do the easy thing and change our aperture from F7.1 to F6.3. Take a shot and see how it looks.

With in a few test shots you should have a properly exposed shot with some nice fill flash. Good fill flash shouldn't really look like it has a flash look at all.

Remember I started with 1/125s shutter speed? What if I want to darken my background just a bit for a more dramatic look. Now that the subject is properly exposed its easy to change my shutter speed to 1/250s, this will underexpose my background ambient light. If I want to lighten the background up a bit I will decrease my shutter speed to say 1/80s or 1/60s to lighten up my background.

This has no effect on my exposure of the subject at all!!!!!! Shutter speed controls ambient, aperture controls subject exposure. This is the hard one to convince yourself of. Go out and try and convince yourself. You will not learn this by reading my rambling writing. Once you try this a few times it will be easy to get very close to the settings you want with just a few shots.

The big problem here is birds usually don't stay in one place. Manual flash only works when the subject distance is not changing. That is when you want ETTL flash and if it is bright enough HSS for fill.

I hope this is a help to folks willing to experiment with getting your flash off camera. In many cases you will get some very nice lighting effects when your flash can be positioned where it will give you the nicest effects.

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Dan,

Question for clarification - flash intensity is controlled by length (in time) of flash firing, not a change in the intensity of the light emitted? If this isn't clear, I mean controlling the settings of the flash manually doesn't actually increase/decrease the intensity of the light emitted, just the duration of the light (which emits at a constant intensity). An analogy, it's light taking a 60W light bulb in a lamp and flipping it on for one second vs. 1/4 of a second. The longer it's on the more overall light emitted - hence higher intensity. Am I in the ballpark here?

Mike that is the way I understand it. A “thyristor” circuit, which is what we use in our modern flashes abruptly shuts off the flash at the right moment as indicated by the desired power level. Reductions of flash power result in shorter and shorter flash durations. But my understanding is that you don't change the intensity of the light, only the duration of the light. I'm no expert here so if I'm not right someone could set me straight, but that is the way I comprehend it.

Studio strobes work on a completely different principle light output is changed with power changes but I don't think anyone here cares.

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I do apologize for throwing this out on Ken's nice pictures but I think the information is worth having. Its a rainy day and I am tired of processing photos and this seems to be a subject that has come up on occasion and could prove beneficial to folks.

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Dan and Mike you both must be correct because when using ttl flash, your camera will shut the flash off when it gets the signal that the subject has been properly exposed. If it would change the intensity, there would be no way to change it until after the flash had cycled, which would then be too late.

At least I understand it and have read that it works like that.

Dan, Thanks very much for "enlightening" us with your flash expertise. wink This has been very educational. Perhaps you can take some parts out and add them to the thread on photography basics.

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Mike thanks for the compliment, if its useful information I could put it up in the basics section after a few days.

What you are correctly describing is as you mention ETTL which sends the signal to shut off the flash at the correct exposure. In manual flash the thyristor will shut off the flash at the desired power setting. Two subtle but important differences in flash operation which can give you two very different results. But we are all on the same page I believe, intensity is not changed just power or time.

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Quote:
I do apologize for throwing this out on Ken's nice pictures but I think the information is worth having.

That's why I started this thread, and I've found exactly what I was looking for! Thanks Dan!

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Dan, that's a dynamite tutorial, and when this thread eventually calms down it's definitely worth tightening up and adding to the basics thread.

Great job! You taught me a couple things there. Thanks for that. gringrin

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Thanks all, I hope there is maybe some new info for everyone. This might be OK to throw in the basics at the top in a day or two. Manual is a different beast than ETTL, but I love the control it gives you and the consistent results. And getting the flash off camera can give you some great looks! This really touched on the basics, so many other things can come into play, how much you zoom the flash head, angle of light, feather of light. This will get you started and off to discovering new ways to control your light.

Here are a few from last week that put into play the same things I talked about above. All shots were camera and flash in manual. If I hadn't gotten the light off camera I would not have gotten the look I was after. The sun acted as a rim light behind the players, I was shooting right into it, you can see it in the hair and around the legs. The strobe was at about 7' high and opposite the sun to camera right. Because of the distance to the closest player I actually aimed the strobe at the player to the far left. This feathers the light giving you more even lighting across all the subjects, you don't nuke out the close player and darken the far player. The strobe was at about 12' from the players.

The background was underexposed by two stops if I recall, about 1/2 power on a Alien Bee 800 strobe. More power than I could put out with a flash because of the sun, but the way you set up the camera does not change just gives you more power.

#1 ISO 50, 1/250s, f5.0, 17-40 lens at 17mm. I had to use that low of an ISO to get allow me to get a two stop difference from the ambient of the background, another words normal exposure at these settings was 1/80s at f5.0 and ISO 50. Darkens the background sky, I was lucky the clouds moved in to give me some dramatic sky.

371946309_sEzUg-L.jpg

#2 Same settings as I recall.

371946413_abbmt-L.jpg

#3 This one had some small additional darkening in Photoshop on the background, but same basic settings. The clouds moved in and darkened things up as well. I didn't have to change a thing in camera even though the light changed! I could have used a slower shutter speed to lighten up the background but the subjects light settings don't change, just the balance between the players and the background. Let mother nature do all the work!

371946578_U6Cqj-XL-2.jpg

#4 The last is from the winter shooting basketball with a single 580EX flash on a stand bounced off the ceiling at about 1/4 power. You can see how high the ceiling is and still one flash needed very little output to give good light. If I recall the camera settings they were ISO 640 (about 3 1/2 stops under ambient), f4.0 and 1/250s shutter speed. The short duration of the flash freezes the action at a slow shutter speed. This gym has horrible cycling lights leading to color shifts in every shot and normal lighting is ISO 3200, f2.8, and 1/250s way to slow a speed to stop action with no flash.

371966415_LDQPq-L.jpg

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That is amazing! I played a little today while the Vikes were on (should have spent my time playing more) set up my shot and played just with shutter speed. Used manual settings on the flash, and also on the camera. I'm impressed with your explanation. Subject dialed in, and correctly exposed in every shot, background changes. That last shot of the basketball player really excites me. It doesn't look like the ceiling in my gym is any higher than that, so should get some good results.

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I was watching the Twins and Vikes at the same time, wow, I should have been finding something else to do for sure!

Hard to comprehend this stuff until you get out and try it for yourself! But it works! That is why I posted the last shot Ken, I didn't figure your gym ceiling would be any higher than that shot!

There is no PP on the last shot either. That is right out of the camera in JPEG. Flash can do wonders for making your subject pop and give you good colors! Remember what we talked about though in the gym, make sure in your ambient set up shot the players are dark with background very dim. This will give you the stops necessary to prevent ghosting.

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