indoor strobing

[redrocket]

noob question.. I have read the threads and listened to podcasts about stopping action with flash by under exposing the ambient light... people write and talk about "2 to 3 stops" below ambient exposure.. is that f-stops?? or ISO?? or the flash has to be 2 to 3 stops above ambient.. ???



so i take a shot with no flash and get a good exposure @ max sync speed (1/250)

i then underexpose by moving f stops?? or with ISO???

turn on flash.. if still under i need more flash power.... and if it is too bright??? iso??

[Zivnuska]

noob question.. I have read the threads and listened to podcasts about stopping action with flash by under exposing the ambient light... people write and talk about "2 to 3 stops" below ambient exposure.. is that f-stops?? or ISO?? or the flash has to be 2 to 3 stops above ambient.. ???



so i take a shot with no flash and get a good exposure @ max sync speed (1/250)

i then underexpose by moving f stops?? or with ISO???

turn on flash.. if still under i need more flash power.... and if it is too bright??? iso??


Redrocket,

People taking sports photographs with flash will want the light from the flash to be at least 2 and preferably 3 stops brighter than ambient. As you indicated, this is usually done at the max sync speed (often 1/250 sec.). You can check this by taking an ambient shot at 1/250, at a large aperture like f/2.8 and then seeing what ISO will produce a properly exposed ambient image. Then take a flash shot at 1/250, same aperture and see what ISO is required to get a proper exposure. If the ambient is good at ISO 3200 and the flashed is good at ISO 400, then the flash is 3 stops above ambient (3200-1600-800-400). In this example, I kept the SS and aperture constant to have the one variable (ISO) change to make the calculation easier. You could vary aperture or or both aperture and ISO and do the calculations. It just might get a little more complicated.

If the flash is 3 stops above ambient, then the flash will stop the action and the background ambient light will be too weak to cause any 'blurring' or 'ghosting.' This is what the podcast is trying to show/teach. You have to have enough flash power to get those 2 and preferably 3 stops brighter than ambient. Keep upping the flash power until you do!

Does that help explain things?

Phil

[Big K]

To add to Phil's excellent summary, the 2-3 stops is the minimum you need. I am a sharpness freak to the point of being OCD about it and am normally not happy unless I am 4-5 stops over ambient but it is very, very difficult to get this unless you have extremely powerful lights and/or really poor gym lighting. Knowing how far over ambient you are is good to know mainly so you can anticipate if you are going to have lots of ghosting problems or not.

Unless you are using speedlights, I suggest shooting a full power to minimize your flash duration. Again, this is because of my obsession with sharpness. It also makes the process of figuring out the stuff you asked irrelevant because you will either have enough light to make it work or you won't, no calculations required.

[redrocket]

Kevin and Phil... Thank you very much..

so dropping SS below max sync (1/200 for my T1I) is to be avoided??
im thinking of using a 50 1.4 with a speedlight bounced off a wall..
and some day I will get a pair of strobes.. and if they are powerful enough will my 70-200 f4 be of any use.??

p.s. I am trying to shoot indoor soccer with flourescent tube lighting...( f4 @ 1/30 ISO 1600 look like crap..) now armed with a speedlight and more knowledge I am going to try again..

[Zivnuska]

Kevin and Phil... Thank you very much..

so dropping SS below max sync (1/200 for my T1I) is to be avoided??
im thinking of using a 50 1.4 with a speedlight bounced off a wall..
and some day I will get a pair of strobes.. and if they are powerful enough will my 70-200 f4 be of any use.??

p.s. I am trying to shoot indoor soccer with flourescent tube lighting...( f4 @ 1/30 ISO 1600 look like crap..) now armed with a speedlight and more knowledge I am going to try again..

I agree with what Kevin said.

Stay at the max sync speed for your camera. Slower will only add ambient light which is the opposite of what you want. Faster shutter speeds will require HSS (high speed sync) which will reduce flash output and is also undesirable.

Speedlights can be used but it will be difficult to get enough light if they are bounced off the wall (indirect flash). You might have to use the speedlights aimed directly at your subject. When you get some strobes with power, your 70-200 f/4.0 will be a good lens to use.


Kevin, was it you who had the pics of a direct flash speedlight set up for basketball?

Phil

[Big K]

Kevin, was it you who had the pics of a direct flash speedlight set up for basketball?

That was not me. I did comment in this thread about speedlighting basketball and there was some other good info in it as well.

http://photography-on-the.net/forum/showthread.php?t=781023

[bjoynes]

Great explanation of setting the lights. Zivnuska, you answered a question about this for me a couple of months ago but I was too slow to get the answer, but this time you nailed it for me. Roll on Volleyball next fall, by which time I might have some AB's to play with.

Bryn

[davethejnz]

Thank you Phil

For the fist time ever I have been able to understand an explanation of how to use flash.

I am sure this is not all there is to flash photography but it is a great kick off point for someone whose main interest lies in shooting sport.

I take it the same scenario applies to shooting outdoors in poor light ( either dull grey overcast or dusk)?

One other basic question I would like to ask (if the OP doesn't mind) is how do you calculate the range that your flash will be effective at.

Thanks again

[Zivnuska]

Bryn,

When you realize that the key to flashed sports images is to get flashes that are far above ambient (I'm going to say 3+ stops. YMMV), then you can understand why darker gyms are actually better for the sports photographer using supplemental lighting. The darker the ambient, the easier to get 3+ stops above it (brighter).

When I shoot at a new venue, an important task is to measure the ambient light and ask if it is sufficient in quantity and quality to shoot without flash or will you be able to strobe the venue to get the light levels 3 stops higher. Either approach can work but if you can't have one or the other, you're screwed.

Here are two volleyball shots to illustrate.

The first shot is at my home gym. The ambient is f/2.8, 1/400, ISO 6400. I strobe this gym. Here is a strobed shot:

f/3.2, 1/320, ISO 400, 70mm, strobe - 4 stops above ambient - 70-200 f/2.8 IS
.http://i137.photobucket.com/albums/q225/zivnuska/GoddardGBendatValley215of215-Edit-2.jpg

The next venue was a large arena that had extra lighting with a 48 ft. high ceiling and ambient light of f/2.8, 1/1000, ISO 3200. It was an easy choice to shoot ambient in this case. Fortunately, I had confidence in the ability of the 1D III to give good images at ISO 3200 so I could keep a fast SS to reduce motion blur.

f/2.8, 1/1000, ISO 3200, 300mmhttp://i137.photobucket.com/albums/q225/zivnuska/_ZIV6444-Edit.jpg

Both approaches worked in the appropriate situation. However, I could not have gotten a good ambient image in the first venue and it was not possible for me to get strobed flashes 3+ stops above ambient in the second venue.

Sometimes, people will ask what settings or what lens a person should use for basketball or volleyball etc. A definitive answer cannot be made because the lighting conditions are varied, different camera bodies have different ISO capabilities, and those factors play a huge part in the answer.

Phil

[wyofizz]

BigK and Ziv brought up excellent points about strobe power. 3 stops above ambient might stop the action but you can still be underexposed if your lights aren't powerful enough.

[40Dude6aedyk]

...
Sometimes, people will ask what settings or what lens a person should use for basketball or volleyball etc. A definitive answer cannot be made because the lighting conditions are varied, different camera bodies have different ISO capabilities, and those factors play a huge part in the answer.

Phil
But you can always answer:
I use a focal length to get me close to the action.
I use an aperture to have the action in focus and the background out-of-focus.
I use an ISO so I don't have too much noise.
I use a shutter-speed consistent with stopping the action.
I use a flash if I am allowed consistent with all of the above.

My experience is that one can zero in on settings in about 30 seconds. I can take someone else's kit and set it so they are getting great exposures in about 30 seconds. They are left to their own creativity and skill in following the action and pressing the shutter button.

Also if your equipment won't get you that 3-stops that the other folks are talking about, so what? You can still get some great photographs with flash. You might have a bit of ghosting on the ball or fingertips, but wouldn't you rather have that than nothing?

[geoff5093]

Lots of good info here, but now I have a question. I read a post that said:

"Stay at the max sync speed for your camera. Slower will only add ambient light which is the opposite of what you want. Faster shutter speeds will require HSS (high speed sync) which will reduce flash output and is also undesirable."

So it sounds like you should be shooting at 1/250? I see lots of people shooting with flash at 1/320-1/500 or more to freeze the action.

[J.Napier]

Phil,Kevin,
Great job explaining this. I still sometimes strugle with settings but manage to get it right or close eventually.
I have a light meter but never use it, I suppose it is nearly the same as using the meter in the camera which always seems to get you there.
davethejnz,
I have found in photography, that sometimes you can read the same info explained by others 4 times and not get it then someone comes along and puts in terms that click for you.
Again great job explaining this and it should posibly be stickied or included there somehow.

[Sibil]

Very educational thread and I did learn new stuff although I had read about the subject dozens of times. The explanations did put things in terms that I understood. Thank you all for taking the time to explain things.

I do have one question.
So when the gym is really dark to shoot ambient and therefore lends itself to strobing, what does one do if the ceiling is black and the walls are nothing close to light color? Use multiple direct flash? Or .....?

[wyofizz]

So it sounds like you should be shooting at 1/250? I see lots of people shooting with flash at 1/320-1/500 or more to freeze the action.

You will want to read your camera and flash manuals to determine what you can do. Cameras have different sync speeds.