Without TTL, how to use a flash to light up an entire room with correct exposure?

Discussion in 'Exposure Discussion' started by ted_smith, Nov 2, 2013.

  1. ted_smith

    ted_smith Member

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    Hi all

    My friend has asked me to take a few large B&W group photos at the Christening of her child this weekend (tomorrow).

    She says she expects about 50 people to be in the shot which is going to be in a very small Church.

    I am going to try and use my Hasselblad 501CM (no TTL metering possible) with 80mm lens (the widest I have) with my Metz 45CL-4 flash. To get the maximum DOF I need to set my lens to the smallest aperature possible but obviously if it's in a Church and the light is low, that is going to give a really slow shutter speed.

    Now, usually, for portraiture, I use my Sekonic Flashmate L-308S light meter to meter the scene, then set the flash to one or two stops below that to provide soft fill in flash. e.g if the meter say f8 1\60th sec I set the flash to f4 or f5.6. But in this scenario I expect I am going to rely on my flash to light up the entire room. But I'm worried that in the Church the light will be low anyway and using a small DOF might result in a metered reading of, for example, 1 second or something and so setting the flash as I usually do won't help the matter because it won't be making the exposure any faster. What I don't know how to do is use my flash to override that reading?

    So my question is - how do I meter the scene to get a good overall light effect but use my flash with more power, given that I don't have TTL metering?
     
  2. AgX

    AgX Member

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    No flash will make the exposure shorter if there is continuous light next to the flash and the level of continuous light sufficient enough to expose the film with the chosen aperture/time combination, which of course will be the case with fill-in flash.
     
  3. baachitraka

    baachitraka Subscriber

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    A flash meter might help. Other then that try shooting with a digital camera to see how it goes and open 2/3rd of a stop in HB.
     
  4. R.Gould

    R.Gould Member

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    Use the flash on full power, and take meter readings from the middle and ends of the group and average out the reading, and try to bracket, remember that it is the flash that sets the exposure so use the fastest speed possible, it will make no difference to the final exposure,with the flash mentioned, 40cl4 you really should not have any problems, and you could depend on the flash meter built into the flash unit, If you have a wide angle diffuser then fire the flash using that until the flash itself gives you a good exposure reading and use that.
    Richard
     
  5. Ed Bray

    Ed Bray Member

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    First thing is to use a 400asa film, this will maximise the amount of light captured from the flash. Is there anyone close to where you live that can lend you a Studio type flash? I have a 300w battery powered you could borrow if you are close to Plymouth.

    You do not need to use your smallest aperture to cover off the depth of field, with an 80mm lens on 6x6cm format from a distance of about 15ft at f8 you should get a depth of field from about 11.5ft to 21.4ft, although ideally you would have a wide angle lens such as a 50mm where at 12 ft at f5.6 you would have a depth of field covering from 8.5ft to 21ft which should easily cover your group.

    You then need to bounce the flash into an umbrella or large white or silver board to provide more average lighting across the group (you could get someone to hold this above the flash at a 45 degree angle) and to cover the AOV of your lens. If you do have a 50mm lens (or wide angle), you should easily be able to cover the distance with your 45CL-4 on manual and bounced into a large reflector of some sort, with the 80mm you may need to do a couple of tests prior to the event.

    During my time as a Professional Photographer I used to capture many large groups on my Hasselblad with a 50mm lens including groups well in excess of 200 and I rarely needed to use greater than f8 to cover the group with more than acceptable sharpness.

    Good luck.
     
  6. markbarendt

    markbarendt Subscriber

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    Not familiar with the Metz but many flash guns have an "auto" mode.

    If your Metz is capable of this it will have a built in sensor that controls the light based on what bounces back off the subject.

    In the auto mode the flash and the camera don't talk to each other, so you need to manually match the settings on camera and flash for ISO and aperture.

    For bounce flash this works nicely and is very reliable.
     
  7. ted_smith

    ted_smith Member

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    Hi guys.

    I have been asked rather "last minute" and I only have ISO100 film in stock, so I can't get faster film now unfortunately.

    And I only have the 80mm and the 150mm and that's that at the moment.

    What I'm more unsure about is how to use the flash under these kind of conditions, which I've not done before.

    For example, with the Metz 45 CL-4, how do you set it to "full power"? It has a series of auto modes for f2.8 - f16, a TTL mode (that I use with my Nikon F5) and a series of manual settings - M, M1\2 and M1\4.

    I understand that if I set the dial to f8 on the flash that should emit enough power to light up from 7 to 15feet or thereabouts, but if my handheld Sekonic light meter reports the natural light scene to be, say, 1 second at f8 at ISO100, I don't understand how I manage\adjust the flash to make it f8 at 1\125 sec, which will ensure better sharpness?
     
  8. R.Gould

    R.Gould Member

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    Ted,
    M will set to full power, m1/2 and m1/4 is half and quarter power, forget about the naturel light, the flash used as main light source will negate that, if you use full power the use the sekonic as flash meter, or use the auto mode, and get the group as tight as possible, check the distance and set the flash for the distance and use as if it was the only light source, you should be ok with that
    Richard
     
  9. markbarendt

    markbarendt Subscriber

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    With the flashgun in auto mode the time is not relevant on camera for the flash as long as it is in the sync-able range.

    Time only effects how much ambient light gets to the film.
     
  10. baachitraka

    baachitraka Subscriber

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    Lot to consider.
    - If bounce in auto mode, flash may fire at full power.
    - If so the recycle time may be slow.
    - If a group of 50 people sitting in rows, one flash may not be adequate.
     
  11. Sim2

    Sim2 Member

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    Hi there,
    Assuming that the church is like most churches i.e. rather dark inside, the flash will be your main (only) illumination.
    Use your flashmeter to read the light reaching your subject from the flashgun (this could be averaged from the middle and edge of the group, as suggested) - this is the aperture to set on the lens.
    Take an ambient light reading from the same spot - this is for your shutter speed, using the aperture previously established. How much slower the shutter speed is compared to your lowest comfortable setting will, in general, be how underexposed the surroundings outside of the flash pool of light will be. Unless you light the background seperately with additional lights or balance the ambient with the flash, the background/surrounds will always be darker than the main subject.
    Tricky area but hope all goes well.
     
  12. ted_smith

    ted_smith Member

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    OK, I think I get it.

    So for example, lets say my crowd of 50 people starts 10 feet away from me, and ends at 15 feet, for arguments sake. What I think you're saying is I can do one of two things:

    1) Put flash into Auto mode, set it to f8 (f8 covers the range 10-15 feet according to the dial). It doesn't then matter what settings I have on my camera lens (unless it was really really bright) - I can set it as f5.6 or f8 or f11. The flash will then throw as much light as is needed. Or

    2) Set it Manual mode for full flash power and then set the camera lens according to the ranges on the flash dial. Using the example above, again, f8 if the crow is 10-15 feet away.

    Is that right?
     
  13. markbarendt

    markbarendt Subscriber

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    You got it Ted.
     
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  15. ted_smith

    ted_smith Member

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    Thanks Mark. It sounds almost too easy! Fingers crossed then.
     
  16. baachitraka

    baachitraka Subscriber

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    Metz 45 CL-4

    GN: 45 meters. @ISO 100 @35mm
    @f/8, Distance = 45/8 = 5.62 meters = 18.454 feet.

    If you use it has bounce flash, you can calculate the distance roughly and see whether you get the coverage.
     
    Last edited by a moderator: Nov 2, 2013
  17. markbarendt

    markbarendt Subscriber

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    It isn't to tough.

    Bounce is the easiest and most forgiving. For a group it is the best choice.

    One of the big things that makes flash seem tough to do right is the size of the flash, bounce is more forgiving and looks more normal because you are turning the ceiling/walls/whatever into the light source for your subjects rather than just the lens of your strobe.
     
  18. bdial

    bdial Subscriber

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    +1 on the bouncing, but the calculator on the flash won't do you much good, as you will lose at least a couple of stops, I would think.
    If you can meter the flash with your Sekonic that would be best, or else tilt the flash head and try auto mode on the flash. If you can keep the people together long enough, I'd use every method presented in here.

    No matter what, your flash is going o have a hard time lighting that room on it's own, and if the interior is dark wood you probably need to forget about bouncing and use the flash direct.

    Hate to say it, but, you may also want to consider multiple shots the could possibly be stitched together using that "numbers" method.
    Because, depending on what the group and the room are like, you'll be hard pressed to get good light everywhere, especially since the Metz's rectangular head doesn't match your Hasselblad's format very well, though with the 80 that problem will be minimized.
     
  19. Ed Bray

    Ed Bray Member

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    As I said earlier, bounce the flash into a sheet of white or silver card or a reflector, someone could hold this behind the camera position tilted at 45 degrees towards the group. Straight flash will not work well with large groups, it will lead to a large fall off at the extremes (inverse square law) and hot spots in the middle.
     
  20. ParkerSmithPhoto

    ParkerSmithPhoto Member

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    Bounce it off the ceiling. Even if it is dark wood and soaks up some light you will be much better off than with direct flash.

    Go ahead and plan on pushing at least a stop as well to maximise the strobe. I would stage the group evenly across the room shoot one half for.six frames then the other half allowing for some overlap. Print the best pic of each half then mount them together on one board like a Hockney. If you have the baby's family in the middle and they are in both frames so much the better. They will love it.

    So just Max out the flash bounce it and take a meter reading. You'll be good to go.
     
  21. ParkerSmithPhoto

    ParkerSmithPhoto Member

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    Also at f5.6 or f8 use a shutter speed around 1/30 and you'll pick up some glow from any lights in the room.
     
  22. wiltw

    wiltw Subscriber

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    Assuming ambient is sufficient to register on the ISO100 film, and to use your Metz as fill...

    1. Set Auto (flash photosensor) mode, aim Metz flash head up to ceiling...photosensor takes care of compensating for light loss due to bounce
    2. but set ISO on the 45CL4 to FASTER than actual film speed (e.g. set ISO 400 on flash will result in -2EV fill)

    Easy!

    If ambient is too low to register 'proper' exposure, ...
    1. if possible use an aperture+shutter combination which will register ambient light about a -1EV below 'proper', and use the flash as primary illumination.
    2. Set Metz to actual film ISO100, use Auto mode and flash head aimed up to ceiling to bounce
     
  23. MattKing

    MattKing Subscriber

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    According to the manual for your flash, if you use the flash in "Auto" mode, the distance opposite your f/stop on the setting dial is the maximum distance that the flash will illuminate, and the minimum distance is about 10% of that.

    So the f/8 auto range is between 1.85 feet and 18.5 feet.

    A couple of hints:

    1) Get up a bit higher (on a chair?), and shoot down at the group;
    2) Have the flash start even higher;
    3) Bounce the light off something reflective, and a bit larger than the flash head;
    4) Make sure the sensor is pointing at the people at the centre - same for the smaller, secondary flash;
    5) If you can, have the people in rows - on risers if possible.

    With regard to #1 - watch out for low-cut dresses:whistling:.
     
  24. markbarendt

    markbarendt Subscriber

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    And focus carefully there. :D
     
  25. ted_smith

    ted_smith Member

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    Guys

    I think I've screwed it up :-(

    I got to the Church today and to my surprise it was better lit than I expected and the sun was shining outside and conveniently the stain glass windows diffused the light quite well. In addition, there were windows on only one side and one end of the church - the opposite walls were solid other than a door. Also in my favour was the ceilings and walls were not bright white but more like a bright cream - better than brown! There was no wooden beams either. In addition, the Church was unusual - narrow and quite long with a large stain glass windows at one end. So I used that as a backdrop and asked all the guests to squeeze in beneath it, wall to wall.

    However, despite quite impressive "crowd control" if I do say so myself, and squeezing them together like sardines in order to get them all in using my 80mm lens, I was still a long way off. I'd estimate about 20 feet! I did manage to get myself up on a chair, and the camera was mounted on my tripod that I also raised as advised. The light sensor of the flash was directed to the middle of the group.

    I bounced the flash at 45 deg up and also left of the crowd (as the windows I mentioned were to the right of them) to bounce the flash across the darker side of the room.

    However, in my panic, I had the flash set only to f8 - likewise with the lens which was set to f8 @ 1\125th (EV13). According to the dial, the maximum range is about 15 feet and I assume that's head on - I suspect it is more like 10 when bounced (though WillTW above says the flash compensates for that?)?

    So I am expecting a set of prints with a well lit empty middle space and the figures beyond it in total darkness at the back :-(

    I have sent the two films (Fuji Acros 100) off to Ilford for development. I guess I'll see what I get. I am not optimistic though.
     
    Last edited by a moderator: Nov 3, 2013
  26. markbarendt

    markbarendt Subscriber

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    Be prepared for success. :wink:

    WillTW is right in that in auto the flash will try to adjust; it will give it everything possible until it either sees enough or runs the capacitors out of power, if as you say, the ambient was good then the flash just tries to "fill" so you may have plenty.

    Did the flash max out? My Nikons give an audible beep when the flash didn't have enough juice.