p.2 #1 · High School Gym Mercury Vapor Lights - Focus problems
I shoot winterguard also. This year I went to a gym in Austin Texas and really got to experience that color shift that you are talking about. I use manual exposure and you can literally see the color shift from 1 second to another. I have have even had half a picture get caught between changes.
Now I do notice that my focus does seem less sharp when the lights change and the picture starts to become underexposed. I shoot with a Mark III and in those situations I am already shooting at iso 64k and what I think I am noticing is the 'more noise' in the picture due to the slight underexposure. When I take a picture at the light's brightest moment it is perfect but when they start shifting to a lower light spectrum I notice a significant noise increase.
As far as bouncing strobes goes I have tried that. We have a couple of issues though. Unlike basketball where the focus is usually on just two areas of the court we have to take pictures all over the entire gym floor. That means a bunch of strobes to make sure the entire floor is lit evenly.
The other big hurdle i have is convincing the circuit directors to let me even run strobes to begin with. I went to a rehearsal and ran them one time and the kids did not even notice at all. I think it is much more of a mental thing we are going to have to work on with colorguard people. Until Winter Guard International lets photogs at their events run strobes I don't see the local circuits letting us run them.
Right now I do not own any strobes and they can be pretty pricey because I would have to get at least 4 strobes, stands, extension cords..... it can add up pretty quick... I am fortunate in that 90% of my gyms do not have lights that cycle really bad and until I can get a guarantee that I can even run strobes I am not going to invest in them ... at least for this sport
p.2 #2 · High School Gym Mercury Vapor Lights - Focus problems
dmwierz wrote:
Charles,
I know you said you can't use flash, but would they still be averse to strobes bounced indirectly off the ceiling?
Regarding the AF locking onto sabres, flags, rifles, etc., I have faced the same thing while covering band/color guards/flag teams and have found that if I focus lock on the subject (via the back button focus) and providing the subject isn't moving towards or away from me, I can concentrate on timing the shot when the rifle isn't blocking the face (or take a burst). However, even if the AF does lock onto the shiny weapon, is your DOF that small that this throws the subject OOF? If so, an alternative is to shoot a longer lens from farther away which will open up your DOF somewhat (though if you're already at f/2.0, I presume you're shooting a 200mm lens already, and if you need f/2.0 in order to get your exposure values correct, 200 may be as long as you can go)....Show more →
Winterguard and colorguard during band contests are quite different. Shooting colorguard at band contests, no problem whatsoever, except if a band has 300 members and you are trying to zoom your way back to the other performers. The colorguard routines at band contests are pretty fluid, and in line formations, etc... Winterguard shows are much more challenging and stop-n-go'ish. If they are standing and just twirling, I can usually pin-point the focus no problem. The focal plane is that narrow. Therefore, I try and shoot on a 45-60 degree angle. That way, if the focus locks on the rifle on that angle, it is most likely in the same focal plane as the face. Shooting straight on, if the focus locks on the rifle, the face will be soft and OOF. Like I said before, I really shoot tight and I want that. That of course means little or no room for minimum focus errors. I accept that, especially when i get some really nice shots. I shoot close because I want that hand-eye-coordination kind of shots. I also like the look of the 45-60 degree angle shots. there is more of a 3D look to them and the weapon and body have a better separation.
p.2 #3 · High School Gym Mercury Vapor Lights - Focus problems
wiens51 wrote:
I have never really noticed focus problems - but color shifts in a fast sequence can be quite different. When I do my white balance, I drop my shutter speed to 1/20 of a second and the white balance gets both ends of the color shift in the same frame and all images have the same white balance ( an average between the all the color shifts).
Gerald
gerald,
I set my color balance the same. That way I try and minimize the color shift and average it the best. I do a color balance at 1/60 sec with my expodisc. I also use a Gretag color checker and take a few shots at different ISOs, mostly to get a nice color profile so I can set a make a nice noise profilefor ISO's I might use at that venue. It also provides another nice reference.
p.2 #4 · High School Gym Mercury Vapor Lights - Focus problems
Yeah, I have tried unsuccessfully to convince circuit directors that strobes would work fine and not distract the performers. I told them the flash duration would be somewhere around 1/1000-1/1200 sec, so fast that our human eye wouldn't have time to notice it. I try and tell them by referencing to basketball games. I said you watch the games on TV and asked them, ever really notice the storbes firing away? Anyways, one of these days, maybe.
I think gymnastics doesn't allow strobes also. Am I correct?
p.2 #6 · High School Gym Mercury Vapor Lights - Focus problems
crfrey71 wrote:
I set my color balance the same. That way I try and minimize the color shift and average it the best. I do a color balance at 1/60 sec with my expodisc. I also use a Gretag color checker and take a few shots at different ISOs, mostly to get a nice color profile so I can set a make a nice noise profilefor ISO's I might use at that venue. It also provides another nice reference.
If you don't have the 1D, the trick is to shoot a neutral grey card or color chart at 8 fps or so with proper shutter speed so that the color shift is in phase/sync with the light cycle and then use those grey card or color chart images as references during post-processing with the hope that your images color casts fall into one of these references. The key is to use proper shutter speed so that the images are in phase/sync with the light cycle. If they are not in phase/sync, you will see gradient (such as half or multi-color cast or as what satxbiker called "half a picture get caught between changes") instead of a constant color cast throughout an image. If you get the multi-color cast, it is almost impossible to do WBing or color correction in post-processing. You will see gradient or multi-color cast if it is not in phase/sync with the light cycle because of the CMOS mechanical shutter (the leafs movement) as Hammy pointed out.
In 1D (CCD camera), you won't see gradient or multi-color cast, but instead an uniform color cast because of its electronic shutter (CCD turns on and off) when the shutter leafs are fully opened (the whole CCD is exposed), which makes post-processing in WBing or color correction easier. CMOS needs mechanical shutter because CMOS can't turn on and off as fast as CCD. The mechanical vs. electronic shutter is also why 1D Mark II and newer models have slower x-sync speed compared with the 1D, which a lot of sports photogs cried about when Canon first introduced the 1D Mark II. The slower x-sync is really not a problem is you use arena strobes that overpower the ambient by two stops or more since it's the flash duration that stops the action.
In other words, for CMOS cameras, using proper shutter speed so that images are in phase/sync with the light cycle (i.e., uniform color cast instead of multi-color cast); hence, makes color correction easier during post-processing, even if you don't shoot grey card or color chart references. Images with multi-color cast, even with grey card or color chart references, are almost impossible to do color correction.
