Interesting Test in Lighting

[scootermcq]

More for my own information than anything else, I played with some lights today and thought I would share the results

I was seeing how much light I get out of different systems

All tests were at ISO 100 measured at 10' out

On my bare lights no modifiers I got:

180w/s Strobe: f10
My Double 180 setup: f14

SB900 zoom 24mm: f8
SB900 zoom 85-105mm: f13
SB900 zoom 200mm: f14

SB600 zoom 24mm: f8
SB600 zoom 50mm: f10
SB600 zoom 85mm: f11

So zoomed in, my SB900 = 2 x 180w/s strobes... interesting

Then I put the lights in my rear facing softbox (like a westcott apollo)

Double Strobe setup: f9
SB900 24mm zoom: f3.6
Any other zoom: f3.2
SB600 24mm zoom: f2.8

What I really found from this experiment is that when using a modifier my speedlights are pretty much useless unless they are right on top of the subject. On a bright day, my odds of firing at f3.6 are pretty slim.

My double setup will be quite useful in a modifier, but will need to be a little closer than 10' if I am shooting f11 in direct sunlight.

Interestingly enough, the modifier only steals about 1 stop from the strobes (f14 to f9), but steals a little more than 2 stops from a speedlight (f8 to f3.6) at 10'

Here is an image of the modifier & double setup in case someone does not really "get" what I am referring to:

[zona5101]

Huh. Putting the double strobes in the box loses 1 1/3 stops (f14 to f9) But putting the Sb900 in the box loses a full stop more at 2 1/3 stops (f8 to f3.6 @24mm). I am not sure why that would be...

[scootermcq]

Originally Posted by zona5101

Huh. Putting the double strobes in the box loses 1 1/3 stops (f14 to f9) But putting the Sb900 in the box loses a full stop more at 2 1/3 stops (f8 to f3.6 @24mm). I am not sure why that would be...

I was confused as well. The only thing I can think of is the shape of a speedlight causes it to not fill the box or something. I have put everything away now, but I am wondering the effects of putting the wide angle diffuser down. I would imagine more even lighting, but would steal even more light with another diffuser down.

[zona5101]

noodling it a bit, perhaps the double set hits a more efficient part of the box (both sides) where the single sb is hitting the apex of the corners. dunno. just guessing that the light is not getting out of the box as efficiently...

[OsmosisStudios]

What about a forward-facing softbox? The one I use has the speedlight on the back of the softbox with just the head poking in, facing the white face of the softbox. I've never had issues.

[ccting]

Hmm, wht is the core reason for using softbox? I think it is to enlarge the light source to get more transmit diffuse lighting. I think transmit diffuse lighting via softbox is a waste of power.. Why we don't just use the reflected diffuse lighting using umbrella, perhaps with silver and within family of angles to maximize the lighting? Any difference...they are just about the size of light source and angles, are they?

I am a noob.

[scootermcq]

Originally Posted by OsmosisStudios

What about a forward-facing softbox? The one I use has the speedlight on the back of the softbox with just the head poking in, facing the white face of the softbox. I've never had issues.

Just for you Adam... SB900 1/1 24mm zoom f6.3 @ 10' or f9 @ 5' shot into a 24" speedlight softbox

So, pretty good, but not enough for a wedding photographer stuck in direct sunlight at 3pm in the middle of July. I might get away with f/9 for a single shot or a couple depending on the background, but you can't light a group shot from 5'

To continue to answer the forward facing question, one of my 180w/s strobes shot into a 36" softbox (same size as the rear facing) is f9 at 10' or f18 @ 5'

I also forgot to mention the rear facing softbox for a single strobe @10' was f7.1

Originally Posted by ccting

Hmm, wht is the core reason for using softbox? I think it is to enlarge the light source to get more transmit diffuse lighting. I think transmit diffuse lighting via softbox is a waste of power.. Why we don't just use the reflected diffuse lighting using umbrella, perhaps with silver and within family of angles to maximize the lighting? Any difference...they are just about the size of light source and angles, are they?

I am a noob.

Yes, to enlarge the light source & soften shadows. Actually a softbox wastes less light than an umbrella & does not blow over as easily in the wind breaking $500 to $5000 in lighting equipment. I would never use an umbrella outdoors.

[ccting]

I virtualize the shot...

What if i use 3 speedlights (1 lightstand) with maximum zoom and power for side lighting for group lighting, which may cause hard shadow on the other side that increase the tone variation, then use another speedlight that is near the camera with 18mm zoom to reduce the hard shadow or flatten it so that hard shadow disappears (thus reducing tone variation)?

Now i have 2 different source of lighting that are 90 degree to each other, should provide wide angle of lighting source. Then, i think the I can get the same diffuse light on the group subjects?

For me, if i have lighting equipments, i will never bring softbox outdoor. It is so troublesome, heavy, risky, and the worst everyone is looking at me like allien...What i will bring only lightstands and speedlights ;D

I just virtualize the shot without any experience or equipment..;D

[zona5101]

Originally Posted by scootermcq

Yes, to enlarge the light source & soften shadows. Actually a softbox wastes less light than an umbrella & does not blow over as easily in the wind breaking $500 to $5000 in lighting equipment. I would never use an umbrella outdoors.

plus a softbox is much more controllable as far as direction, feathering, ability to take a grid or mask...

[ccting]

Originally Posted by zona5101

plus a softbox is much more controllable as far as direction, feathering, ability to take a grid or mask...

I have seen some grid and mask for softbox, but what is the main purpose of having them? for putting Gobo?