How to light a church

Precisionpro

Senior Member
I have to take a picture of a choir (about 60) in a church. I have a D7000 with 18 - 200 mm lens and I also have a SB 910 speed flash.
I have my flash held above me to take a test picture and although it seems to fully light the area I am worried that it will not be enough when the choir are in position. Can anybody advise me? Do you think I will need two extra flash units either side and if so what sort?
 

BackdoorArts

Senior Member
Holy Spirit and Tongues of Fire, dude - because one flash will probably not do it.

OK, it will, but you'll want to bounce or diffuse it somehow. But I'm really the wrong guy to answer this ... unless you need the Holy Spirit and Tongues of Fire thing. ;) I just felt lead to answer.

And please, know that I'm not mocking ... it's just late on a Friday.
 

Precisionpro

Senior Member
How to light a church?

I have to take a picture of a choir(about 60) in a church I have a D7000 with 18 - 200mm lensa and I also have a SB 910 speed flash.
I have my flash held above me to take test picture ad although it seems to fully light the area I am worried that it will not be enough when the choir are in position. Can anybody advise me? Do you think I will need tow extra flash units either side ad if so what sort?
 

hark

Administrator
Staff member
Super Mod
Contributor
@WayneF would probably be able to give you some excellent advice. Do you know about how many rows of people there will be? I'm guessing 5 or 6 rows perhaps? And how close can you stand?
 

WayneF

Senior Member
I have to take a picture of a choir (about 60) in a church. I have a D7000 with 18 - 200 mm lens and I also have a SB 910 speed flash.
I have my flash held above me to take a test picture and although it seems to fully light the area I am worried that it will not be enough when the choir are in position. Can anybody advise me? Do you think I will need two extra flash units either side and if so what sort?

Not sure of a solution, but you can be aware of the problem.

The issue with flash is the inverse square law... Flashes fall off with distance, and so only illuminates ONE distance properly. If the background or back row is 41% farther, the flash intensity falls off one full stop there. Two flashes at same distance will not change that rule (but will be 2x more light, allowing exposure to be stopped down one stop).

Bounce can help the range at home, but bounce is not likely possible in church auditorium (too high). Different lights to illuminate the front and also the back separately and ideally will certainly help larger spans, but is very difficult for a group or choir.

But the range can depend on the distance.

If near point is at ten feet, 41% more is 14 feet. Then if flash is adjusted for 12 feet, that is plus or minus 2 feet (and 1/2 stop either way ... which is still a pretty large difference).

If near point is at twenty feet, 41% more is 28 feet. Then if flash is adjusted for 24 feet, that is plus or minus 4 feet (and 1/2 stop either way, and 2x distance needs two stops more flash power or aperture or ISO, but is a 2x larger range than 10 feet). Zooming can make this feasible. A problem is that a group of 60, of say four rows of choir chairs, might need 12 feet of range?

36 feet plus 41% is 51 feet, or an eleven foot range (for a one stop variation, plus or minus 1/2 stop). Be aware of depth of field, aperture should be closer to f/8 than to f/4... which two stops needs 4x more flash power or ISO. And a 2x greater distance needs 4x more flash power or ISO too... so that's 16x more power.

You might be able to judge satisfactory exposure range in practice by judging the light on the empty chairs? Or better, take three friends or kids to sit on first and last and middle row for a practice test. Measuring the depth of the rows will give you useful information.

Groups of a few rows is very often best done with both the flash and the camera up high (on a step ladder), both peering down into the rows. This height and angle makes the rows be a bit closer to equal distance for both flash and focus. But set up working with the middle range.

If we knew the width of your group, then we could compute the necessary zoom focal length for any distance, and from SB-910 guide number, could compute aperture for its maximum power. Or a trial test could determine it. Not knowing, and ignoring all that, and wildly guessing 35mm zoom, SB-910 DX guide number for ISO 400 is GN 232, divided by 41 feet (halfway between 36 and 51) is f/6.3. Two equal flashes (at maximum power) would be one more stop, or f/9. (GN calculator at Understanding Guide Numbers, including GN Calculator ). It's an inaccurate guess of course, but maybe halfway ballpark?
 
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WayneF

Senior Member
15 seats per row, with 18 inches spacing, is 22.5 feet width.

18mm DX at 15 feet is 19.7 feet width, field of view.

Calling the width 20 feet, then at 41 feet distance (for some range depth), that computes 48 mm focal length.
( Lens Field of View Calculator (FOV) )

SB-910 DX Guide number for 50mm zoom is 147.6 ISO 100. At ISO 400, GN 295.

Plugging these numbers (GN 147.6, ISO 400, 41 feet) into GN calculator at
Understanding Guide Numbers, including GN Calculator

at 41 feet shows f/7.1 with one SB-910 flash, maximum power (for this GN, Standard DX mode). Two equal flashes is f/10.

41 feet at f/7.1 shows +/- 1/3 stop range is 36.90 to 46.49 feet, which is 9.6 feet range.
I suspect four rows of chairs and aisles may be deeper than that?
and assuming if centered at 41 feet, then +/- 1/3 stop means there is 2/3 stop difference, front to back.


Calculator shows that at 18mm 15 feet, you could use 1/4 power level for f/10

But the range of 15 feet f/10 is only 13.05 to 16.44 feet, +/- 1/3 stop. That is only 3.4 feet range (at +/- 1/3 stop exposure).
 
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Precisionpro

Senior Member
Many thanks WayneF.
A genius if ever there was on. I will process the information you have given me and try out a few test shots.
Don't go away!!!
Can I post you an early test shot I took some weeks ago?
 

LouCioccio

Senior Member
Re: How to light a church?

adding more textOkay here are two images one in a gym and the other in church. These are before I bought big strobes (AC/DC Flashpoints 620); I am using two umbrellas to spread the light and two Olympus FL50 in "manual power mode" probably ½ power each.
PB151941A.jpgPB191956.jpg Both are on 8 or 9 foot light stands so that shadows are low. With some of the glasses you can see two umbrellas. Sorry not done with a Nikon. Borrow a friend's extra SB900 you'll need at least two, highest ISO that you find acceptable.
Lou Cioccio
PS I hate RED it saturates!!! Have enough room on each side if using a wide angle so that person(s) do not look wide or spread out.
 

hark

Administrator
Staff member
Super Mod
Contributor
Many thanks WayneF.
A genius if ever there was on. I will process the information you have given me and try out a few test shots.
Don't go away!!!
Can I post you an early test shot I took some weeks ago?

Yes, Wayne is absolutely brilliant when it comes to knowledge about flash. :)

Wayne has given me something to think about will let you know what happens when I process it all!!!

Please let us know how it goes. Looking forward to seeing your results! :cool:
 

WayneF

Senior Member
Re: How to light a church?

Aw you guys... Never seen multiplication before? :) Thanks, but it's really no big deal. I have learned the inverse square law, but it's just details. No grand new theories. :)


View attachment 152817View attachment 152818

PS I hate RED it saturates!!! Have enough room on each side if using a wide angle so that person(s) do not look wide or spread out.

Red does tend to clip in Daylight or Flash white balance, but it's not so much the red here. The flash is too close in the first picture (too close for the large range needed). The one center red jacket is overexposed (maybe too much overlap of the two flashes?), but mostly, it is all the front row faces that are overexposed. The second picture is farther back, and did better, greater acceptable range.

So it is the front row DISTANCE that is overexposed. Direct flash can only be a proper exposure at one single distance. Anything closer is brighter, and anything farther is darker. But how much works on sort of an exaggerated percentage basis (inverse square law), and a greater distance simply has more middle ground range. Important parameters include the depth of the needed range, and the distance to the middle range considered. We adjust the flash power for the middle row, not the front row. We can stand back and zoom in, or we can place just the lights further back. This does require significantly greater flash power, perhaps multiple lights.

I put a Guide Number calculator at Understanding Guide Numbers, including GN Calculator
and one of its features is that it shows this depth range for various exposure tolerances, like plus and minus 1/4 or 1/3 stop (each side of middle distance). I had not seen that feature before, but it just falls out of the numbers. Seems important photographically.

Guide Number and Inverse Square law is computed about direct flash, but umbrellas and softboxes can be approximated (the path distance fall off, not the absolute GN intensity) by considering the path distance to the FLASH itself. That means distance to the flash tube in softboxes or shoot through umbrellas, or to the umbrella fabric and back to the flash tube in reflected umbrellas.
 
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Pelush

New member
To shoot at such choir you really need to understand some things first:
- The athmosphere into the church: is it a modern one, medieval, light, dark, what illumination is there (warm light, neon tubes etc...) try to respect the ambient of the church making the same sensation you feel on the spot to appear in your picture, so plan carefully the temperature and softness of the light. (sometimes a candle light scenario may work 1000 times better than a bright scenario)
- The presence of natural light
- The place where the choir will stay: is it a restricted place, is it wide? is there any place in front above, at sides where you can place your light sources?
- The quality you are expecting: do you really need shooting at ISO 100 ?

Then on these information you can plan your lighting
consider that lighting a wide subject you will require a wide source of light, begin looking at the church warehouse they will probably have the items to make you build a big orientable white board, use it to reflect your flashes.
Or, if you really need a more intimate feel, try hiring some tungsten movie spot light, they are really cheap.
 
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