continuous lighting

Discussion in 'Beyond the Basics' started by spyder, Oct 12, 2007.

  1. spyder

    spyder TPF Noob!

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    i have a project which i need some advice on. I am part of my school yearbook and came up with a cover idea that requires photography. the idea is to have a line of people about 30 feet long that are holding hands and jumping in the air.

    I have 5 d80's and radio remotes to fire them simultaneously. i am planning on lowering the tripods so the camera are near the floor and looking up toward the people a bit.

    I am planning on doing this in the school gym which would allow me to roll out a white backdrop along the wall. i want white so i can easily cut out the people, or blend it into the white background on the cover.

    my problem is with the lighting. the lighting in the gym is not very bright at all and it is a weird color. i took pictures of a volleyball game in there recently and half the pictures were orange and the other half were blue. the color wont be a huge issue because i can preset the white balance, or fix it in photoshop if worse comes to worse.

    I am going to use 50mm 1.8 lenses because they are fast. unfortunately they are not as fast as i need. when i was doing the volleyball shots with this lens, i couldn't get above 1/250, and this is not nearly fast enough to freeze motion, especially with people jumping in the air.

    I realized that i need some extra lighting, but i have virtually no experience in that area. i own one sb600 which i hardly ever use. i dont have the money to buy a bunch of flashes, so i was looking into continuous lighting. it seems like it is alot more accessible money wise.

    If any of you have any suggestions concerning lighting (or anything for that matter), or have any good resources, please let me know. I have ran across and heard about the strobist site, but i have never needed to use it. is this a good place to start even if i am not using strobes?

    oh, and this is under a bit of a time constraint because the cover needs to be submitted by the 30th. i am hoping to place my lighting order this weekend, and expedite the shipping. thank you all very much, and sorry that this got so long.
     
  2. Helen B

    Helen B TPF Noob!

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    First thoughts off the top of my head:

    If you are making a composite by stitching together five images and removing the background, why not do it as a composite with one camera and only a few people at a time to reduce the amount of lighting you will need? You might even manage it with your SB600 - and you can test that approach today.

    The amount of continuous light you need for freezing people in mid air with the sort of aperture that will give you enough DoF will be considerable. Tell us the likely distance from the light units to the line of people, and we could estimate the number of 500 W construction lights (or fluorescents, or similar) you will need. How much electrical power is available? What f-number did you have in mind for DoF? What ISO will you be able to get away with? What is your budget? Can you rent?

    Flash is probably the answer, but there will be synchronisation issues, the importance of which will depend on how important it is to you that all the photos are taken at the exact same moment.

    Best,
    Helen

    PS Are you using auto white balance for your volleyball shots? Have you tried it with custom white balance?
     
  3. Mike_E

    Mike_E No longer a newbie, moving up!

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    Helen's idea would work if you just change the idea to having everyone raise their hands in the air (or somewhere) so that you can paste them all together. You could then use the flash you have on the camera. (a diffuser would be nice and hey you're in luck. here is a DIY you can put together for under $5.. http://super.nova.org/DPR/DIY01/ )

    Otherwise you would need 6 or 8 500W halogen work lights lined up just behind the cameras. If you do this be sure to shoot a grey card or to at least do a custom white balance. You will also need to supply sunscreen. ;)

    hth

    mike
     
  4. Helen B

    Helen B TPF Noob!

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    It's not just an idea - it is based on successful past experience (experience comes in handy now and then). It will work if they jump in the air. No need to change the concept. Oh, and it isn't really 'my idea' - it is often used in the commercial world.

    What camera settings are you using for your estimation? The amount of light will depend a lot on how evenly-lit you want the line to be, and exactly how far the lights are from the line of people, but I do wonder whether that will be enough for a 30 ft line of people who need to be frozen in mid-jump, unless everything is timed to perfection (ie they are all close to the top of their jump at the moment the photo is taken). If some motion blur is possible it would reduce the amount of light required. A lot depends on how sharp you want everyone - ie your concept of how the image will look.

    Remember that if you used continuous lighting, and did the whole line of people simultaneously, you will still have to stitch the frames - and they will probably not have been taken at exactly the same time, so you could have major problems if rapidly-moving people, or parts of them, are overlapping. That is one of the reasons why doing it in a series of separate shots could be better. Spyder has the equipment right now to try the separate shot concept in a simple way - and hence find the lighting and post-production issues that could arise, and assess the viability of doing it that way.

    Best,
    Helen
     
  5. Mike_E

    Mike_E No longer a newbie, moving up!

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    LOL, in my experience getting that many hands and arms pasted together with no evidence of any difference of exposure, or the angle their forearms to their wrists, is a pain to do. Having them not holding hands would simply make Spyder's life a lot easier. Just a thought though, breaking the group up is the best idea by far.

    As to the number of work lights, from my experience about 4 people (5 smallish ones) shoulder to shoulder is about the max. Any more across and you start to get noticeable light drop off on the edges. This is from a max of 8 feet away (6 is better) and at the shutter speed at this distance will most likely be too slow because if you go much below f5.6 you are not going to have everyone in good focus anyway.
     
  6. Helen B

    Helen B TPF Noob!

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    My apologies, I had got the idea that you meant that they should just stand there and raise their hands. I agree entirely about the hand-holding thing, but assumed it would be obvious. One of the things I like about web forums is exactly this ability to clarify things. However, the synchronisation problem between frames still exists with the 'five [unmodified D80] cameras taking a picture of a line of jumping people holding hands' concept.

    If Spyder has the five cameras then the ease with which they can be synchronised at a sufficiently exact instant can be tested with a falling heavy object dropped from the top of a measuring tape - see if they all record the falling object at the same location, using continuous light.

    With flash it is no longer an issue - you just synchronise all the flashes together and trigger on the second curtain of one camera set to say 1/8 s, and shoot in a very dimly lit space. The other cameras are set to a longer shutter speed. The idea is that the flash is triggered by the master camera after all cameras are guaranteed to have their shutters open, and the slave cameras have their shutters open for long enough to guarantee that the flash will have fired before they close. Spyder's timing tests will show how closely the cameras can be synchronised.

    Good luck,
    Helen
     
  7. Mike_E

    Mike_E No longer a newbie, moving up!

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    :) No problems at all! I don't own a D80 but I think that he is talking about the wireless trigger that has been around since the D70. If this is the case then all of the cameras going off at the same time shouldn't be an issue.

    Spyder, having 5 cameras to work with is great, perhaps you should do the shot outside so that lighting won't be an issue- a painted wall somewhere?
    One thing though, just because you can use 5 cameras doesn't mean that you have to. (I realize that it would be fun so do play around with it)

    Now, having said that, you do realize that a flash goes off at between 1/2000th and 1/10000th of a second don't you? This means that as long as the flash is 2 or 3 stops more powerful than the ambient light then it's the same as using a shutter speed just as fast. I think that this is why Helen suggested splitting up the group- so that you could stop the motion and still use the one flash you have. (unless you just want to spend another $800-$1200 on more flashes ;))
     
  8. RyanLilly

    RyanLilly No longer a newbie, moving up!

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    Do you have a theatre? That could solve you lighting right there.
     
  9. Helen B

    Helen B TPF Noob!

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    Here is a rough estimation of distances.

    The D80 sensor is about 1 inch across, and a 50 mm lens is 2 in. Therefore for every foot of scene width the camera needs to be 2 ft from the scene. You need some overlap between frames, so as a bare minimum each camera will have a scene width of 7 ft. – ie 14 ft from the cameras to the line of people. However, the scene height would be inadequate (2/3 of that, equal to only 4 ft 8 in) so you would might have to move to at least 20 ft to get enough vertical coverage (the cameras could be in portrait orientation at this distance). The lights need not be that far away. Suppose that they are 14 ft away (that may not be necessary, it is just an example to illustrate the effect of distance). That is about twice the distance in Mike’s example, so you would need four times as many lights for the same exposure conditions (Thirty-two 500 W work lights, or 16 kW in total). It should be no problem renting that many and the gym could be large enough to make the heat from the lights not too much of a problem if they are used for short periods. You would need to make sure that the available circuit(s) could handle the current. However, as Mike mentions, that amount of light may not be enough to freeze the action.

    Wireless triggering at the 'same time'? To what accuracy? Do you know for sure that the timing variation between D80s following simultaneous wireless triggering is small enough not to be a problem with fast-moving objects? I don't. I suspect that it could be small enough, but I don't know. That is why I suggest testing. It may not be an issue, but the time to find out is not after the shoot when you are trying to stitch frames together. This may just be an example of my attitude towards preparation and the prevention of foreseeable problems, so that when shooting time comes you are unburdened by technical cares - as much as possible, anyway.



    Best,
    Helen
     
  10. Mike_E

    Mike_E No longer a newbie, moving up!

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    Yep, plan B- 1 camera, one flash, 3 or 4 people at a time. LOL

    My plan C would be to use a medium telephoto (Zoom) so I could do it in one shot. Stand back far enough and use a couple of borrowed studio strobes (and get the photog who owns them to come down and supervise so that I could pick up some pointers from him/her. (with the added benefit of not having to be responsible for them) You would be amazed at the number of Pro photogs that would help, especially the ones who would like to get into Senior portraits. ;) Who knows, you might even get a summer job out of the deal. :)
     
  11. Helen B

    Helen B TPF Noob!

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    Indeed, one camera, one shot would be ideal, and I wondered why that wasn't your first thought - I guessed that you must have a good reason to discard the obvious (it should have been Plan A). Resolution was my first guess. I don't see any need to use a medium telephoto though - just have the people in a slight arc of a circle (if necessary) and use a normal lens or moderate wide angle. A 50 mm lens would be 60 ft away. You could use a wider lens.

    Rough calculation, as an example: Suppose that you were using f/4 at ISO 100 at 60 ft. That is a GN of 240 ft. A Metz 60 has an optimistic ISO 100 GN of 200 ft indoors, but the flash duration is 1/200 s at full power. You could move the flashes in to get coverage with two units at reduced power, or open up a little, and hence have a shorter flash duration and adequate exposure - or you could switch to ISO 200.

    Best,
    Helen
     
  12. Mike_E

    Mike_E No longer a newbie, moving up!

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    Hi Helen, I suggested the tele for the depth of field and being able to use a wider aperture.

    Having 2 kids in highschool, I fully understand the need to push the boundaries (that and still remembering myself back then), and using 5 cameras would do it. (if the wireless shutter release works then having the trigger for the two strobes mounted on just one camera would be all you'd need to pull it off.)

    As to the Metz 60- it really will light to 200 ft (mine does anyway) Finding someone with a pair of strobes though would be the best way to go. Whomever owns them would surely have the triggers and other gear needed for Spyder's shoot to be a huge success. Plus the networking aspect should be of benefit as well.
     

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