# Flash Diffuser



## fotogenik (Jun 22, 2006)

Hello All,

I recently purchased an omni bounce flash diffuser for my SB600. I figured it would help me with a wedding I am shooting in the coming weeks. 

Outdoor, in the evening with ffading light, I figure I am gonna need flash most of the time.

Anyway. I am not seeing a lot of difference in my shots with and without the diffuser and am curious what others have seen from them. It is a Stofen Omni-Bounce Diffuser and everyone I have spoken to about them just raves. Maybe I am not looking for the right thing but it just seems very unmodified to me other than a change in color temperature.

Here are two shots taken from the exact same spot with the exact same settings with and without the diffuser on my flash. Am I doing something wrong? Do I need to adjust my exposure?

1) With Diffuser









2) Without Diffuser






Anyone take a stab and tell me a correction for what I am seeing?

EXIF Data is attached to these files in case anyone wants to check the settings. White Balance was set for flash, Aperture Priority with an Aperture of 5.6, Focal Length was zoomed all the way in on my small zoomer lens at 80mm. Interestingly the shutter time was not recorded in exif but it was 1/60th.

No edits in PS other than resizing for display on the forum and this is full frame no crop.  Flash was my SB600 and was not bounced, I aimed it directly forward.

Thanks,


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## mysteryscribe (Jun 22, 2006)

one thing always jumps out at me, you lose a stop of light with a defuser at least. Some of them even more. But you also do that with a white cloth or a piece of bond paper. Oh wait they do the same things never mind.

I personally don't see a lot of difference but most people swear by them. I also don't see a lot of difference in bounce light but it is supposed to be the same kind of light as defusion. Bounce light in my opinion, which isn't worth much, mostly changes the angle of the light and lowers the intensity. Im not all that fond of lowering the intesity but the angle is nice. You can also do that with a very long handled L bracket. But you keep the high intensity of the light. I know I'm hopelessly out of date.

The other thing that bounce light does is to spread the pattern of light. and defusers do the same. They widen the beam of the light giving you a wider more even coverage of light. So I guess they are okay. You got to compensate for the exposure and shoot it. If you have to shoot a wedding with it, you might have a coverage problem as it cuts the distance your light will carry a bit.

Let me see if I left out any negative thing. Oh yeah, when you need it, you most likely wont be able to find it. That is the most important one.

Oh what to do add a stop of exposure to the shot


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## fotogenik (Jun 22, 2006)

So maybe try a few shots without the diffuser and see how it goes?  I was thinking mostly that the diffuser might be needed for the actually posed shots and I would be fine with any other shots without it.


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## markc (Jun 22, 2006)

It's going to be really hard to see the difference in that image. It won't show in the lit areas, but at the edges of shadows, and I only find two that are in the background. Rather than being sharp and harsh, diffuse light will soften the edges. You can see a little of that at the upper right.

There are several factors that affect how direct or difuse light is. The smaller the source and the further away the source is, the more direct it is. Putting a diffuser on a flash can help, but if it's the same size as the head, the size of the source remains small, so it won't get very diffuse. You can only scatter the light, which weakens it. That's why umbrellas work so well. They become a relatively large light source. And while they do weaken the light, you don't have to scatter the light as much to get the same effect, since they are larger.

I was having a hard time finding good examples, but here's a couple from this page on the Blender site: http://www.blender.org/documentation/htmlI/x12593.html

The image under "point light" or "sun light" is a good example of direct, and the image under "area light" is a good example of diffuse.


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## fotogenik (Jun 22, 2006)

the thing that struck me the most with the two example photo's was the color shift.  Is there a shift or is this something I am simply seeing on a non calibrated monitor at work?

The diffuser seems to impart a brownish cast to the entire image.


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## markc (Jun 22, 2006)

With the diffuser on, you are getting more ambient light into the mix, which is warmer than the flash that the white balance is set for. You'll probably have to use a custom white balance based on the room you are in.


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## fotogenik (Jun 23, 2006)

interesting, thanks, Something else I need to learn how to do on my camera LOL.

Cheers,


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## mysteryscribe (Jun 23, 2006)

again I have given advice based on film... in film the color shift you see is called being muddy.. it is caused by the shot being underexposed which happens almost all the time with diffusers that aren't compensated for. 

The amount/intensity of light from the flash is less after it is diffused. In the case of film if you dont compensate, you get a thin negative which makes the colors dark and drab. Evidently in digital (which I didn't know, since I know very little about digital) the balance between strobe and daylight changes most likely for the sort of the same reason, the flash is not as powerful as in the first shot so doesn't override the ambient light.  

I would think you could use the strobe on auto and use the manual setting to dial in the exposure for the strobe /defused and not have to worry about custom white balance. I would expect that the ttl function is where you are getting the ambient light. Since the camera is trying to balance the two light sources.

I would think that if you set an auto strobe up as you would on a film manual camera and compensated the exposure for the defuser you would get exactly the same color in both shots.  I tried this when digital got to the 4mpx state and it worked that way for me.  But the cameras were much less automated that I tried it on.

Am I wrong on this, I am seriously curious now. By the way my son in law who is a very serious digital photographer says TTL is very dangerous to the subtle difference so you need to be careful using it. I think he does use it most of the time though. I know he bounces all his flash last wedding was interesting it was in a traditional catholic church. I think he had a little trouble with the 40 foot ceilings lol.


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## markc (Jun 23, 2006)

From my understanding, underexposure wouldn't cause a color shift like this. It is a bit muddier, but to me that only means darker, not more brown. You would see the same color shift in film if you used daylght balanced film. White balance isn't something new to digital, just the fact that you can change it on the fly and you can pick a custom one, whereas with film, you can only get what the manufacturers make (usually just daylight/strobe and incandescent).

If you boost the flash output to compensate for the diffuser, then the color balance will be the same, but that's because you will have the same balance of strobe vs. ambient in both images, just one will have diffuse light.

Im not sure what he means by "TTL is dangerous". TTL is Through The Lens. It means the light is being measured after it passes through the lens, and not just on some sensor on the flash. It's a much more accurate way to measure the light reaching the film/sensor.


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## Digital Matt (Jun 23, 2006)

I made a simple diffuser for my flash from a 1 quart soup container (won ton soup).  I cut a hole in the lid that is the shape of my flash head, and when I use it, I point the flash straight up, as if to bounce from the ceiling.  The light bounces around the soup container and comes out all directions very soft.  You do lose several stops of light however, so the flash power is normally all the way up, and I bracket with my aperture.


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## mysteryscribe (Jun 23, 2006)

maybe its just me but the colors in the picture look muddy ie dark on my screen and muted.  Like I have always said I don't pretend to understand digital differences. but it looks underexposed to me.

my Sil I think, and im not sure, meant the ttl allows a more balanced approach than setting the strobe on auto and manuel exposure.  Therefore the color balance tends to change more often.  The way I shot strobe with the digital I tried out, was just like I always did with film and had no problems with white balance.  But it did look as though someone had used a stobe.  His ideal is to look as though he didn't use one.  Probably a differnce in thinking more than anything else.

The original cameras i tried out had set white balance programs not custom.  you could get daylight indoor florescent and maybe something else.  But being from a film background I just set it up daylight and used an auto strobe and manual settings.  It worked fine for me even with multiple studio lights in the studio.  Now I'm quite sure what My SIL does is much better than that, but it worked fine when I did it for what I wanted it to do.   I don't fault him for all the balancing act he does, he likes that kind of thing.

By the way I took the image one into my editor and did just the exposure compensation things to it.  When I finished the white were white more or less and there was a warmer tone to the color which I would expect from a thin color negative, but I do know that it isnt the same or maybe it is since the room light might invade in any under exposed shot.  The shot with the appropriate software change would be a usable shot, if not a perfect match.  With a one stop adjustment to the exposure when it was made It most likely would have exposed for the white light and been fine.  Again that is based on a totally different perspective and maybe all wrong.  If it was me, I would test it after I read all I could find on it.  I never trusted anyones opinion till I verified it.


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## Unimaxium (Jun 23, 2006)

MS: You are right that the first frame is underexposed. According to the exif data, the shot settings were identical in the two shots, except that with the first the flash had the diffuser on which caused it to be less powerful. But a slightly underexposed digital capture is not by itself going to cause a brown tone in the image. I believe mark is right in that when the diffuser was used, the flash was less powerful which meant that it did not overpower the ambient incandescent light as much, causing the incandescent light to be more visible in the frame with the diffuser. And that's what caused the redder tone in the image. It's kind of like mixing a recipe (or diluting photo chemicals if you want to think like that ;-) ). Instead of having something like 2 parts flash to 1 part incandescent light, it was 1 part flash to 1 part incandescent (or whatever it really was; I just made those numbers up).

But maybe that's what you were saying and I just misunderstood you.


As for advice for Rashadan: What you might want to do is to try taking the flash and diffuser outside and try it out as a fill flash rather than as the main light source. I think it will be easier to compare your results when all of your light sources are of the same color temperature (i.e. the sun and your flash, since flashes are calibrated to output the same color as the sun). Also, try taking some shots closer to your subject. I can see from the exif data that you used a long focal length for these shots (80mm, which is the 35mm equivalent of 120mm). This is probably why the shadows are about equally as harsh in both images. As you get closer, the relative size of your light source gets larger, which means that your shadows will be softer and you'll likely see more of a difference with the diffuser. These are just my guesses, anyway.


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## markc (Jun 23, 2006)

I found a how-to for making your own flash soft-box.
http://www.studiolighting.net/low-cost-flash-mounted-softbox/


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## markc (Jun 23, 2006)

I don't know if you care about the "why" behind using a larger light source, but I tried to show it with these diagrams.











Everything on the wall above point "A" gets light from the full light source. As you head down towards point "B", less and less of the light source is exposed to the wall, beyond which it is completely blocked by the object.

With a larger light source at the same distance, you have a wider area over which the light drops off, so you get a softer shadow. You can move a smaller source closer (blue outline) to get the same effect. Of course you can run into other issues if you get a light too close to your subject.

A diffuser works by scattering the light. Less light reaches the object directly. Some of the scattered light bounces off nearby objects, which then act as additional light sources and soften the shadow in the same way as using two or more lights does. It's an inefficient way to do it and doesn't work as well as a larger source does, but can help soften the shadows if you don't have other options.


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## mysteryscribe (Jun 23, 2006)

I think probably everyone knew what was happening but we all see it from a different point of view... Mine i know is less analytical and more antidotal. probably not a word.

Mine is based more on intuitive knowledge based on my experiences such as they are.  And they are with film.  In some ways digital is backward and others note.  I know from having talked to my SIL and from having dealt with it a little in the ebay shots that over exposure is death in digital when under esposure is death in film.  Exact opposites, but in other things it is very similiar in effect.

That is why I always say others with more digital knowledge will come along but it really doesn't hurt people to get a feel for it all.  Then work out their own answers that is how you truly learn.  To hear or read a fact is not nearly as good a teacher as to prove it to yourself.  Everyone should take the basic kernal and then either prove, disprove  or improve it.

At least that's how I always treated photography.


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## castrol (Jun 23, 2006)

Try the same experiment, only with a human subject. You'll see a huge difference.

Try with the flash straight on for both photos, then do a 45 degree shot with
both photos. It makes for some pretty nice light when working with faces and skin.


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## fotogenik (Jun 23, 2006)

Thanks, I wil try that this evening.


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## castrol (Jun 25, 2006)

Well, did you get a chance to try it out?


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## fotogenik (Jun 25, 2006)

not yet, been a busy weekend.


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## Flash Harry (Jun 26, 2006)

These Stofen diffusers are meant to be used at a 45 degree angle to the subject and not straight on, your output is cut down by the diffuser though so compensation is required, its best to take several test shots to get it right before setting out on a job with it.


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## W.Smith (Oct 17, 2006)

mysteryscribe said:
			
		

> [...] Mine i know is less analytical and more antidotal. probably not a word. [...]



I think you mean 'anecdotal'.


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## W.Smith (Oct 17, 2006)

markc said:
			
		

> I found a how-to for making your own flash soft-box.
> http://www.studiolighting.net/low-cost-flash-mounted-softbox/



Excellent find, mark.
Looking at the backgrounds in the demo pix at the bottom it seems to suggest that diffuser costs between 1/2 and 1 stop of light.

A [ame="http://www.youtube.com/watch?v=RNCmuExlHvM"]D-I-Y bounce card[/ame] (< click!) is of course even simpler . . .


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## fmw (Oct 17, 2006)

Mark has the right idea.  Diffusers don't really provide soft lighting.  What provides that is the difference in size between the light source and the subject.  The larger the light source relative to the subject, the softer the light.  Bouncing the flash from a ceiling does that, as an example.  You can't really to it outdoors, however.

The best thing you can buy for your flash unit is an extension cord.  That will allow you to get the flash gun away from the camera where you will get more modeling and more pleasing images.  When I shoot an outdoor event like that, I just keep the flash gun in a pocket of my vest with the cord connecting it to the camera body.  When I want a flash shot, I just extend my arm holding the flash unit to get it away from the camera and make the exposure with the other had that holds the camera.  I've always done it that way.  It's a big improvement from on-camera flash.


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## W.Smith (Oct 17, 2006)

fmw said:
			
		

> [...] The best thing you can buy for your flash unit is an extension cord. [...]


An even better thing you can buy for your flash is if you go wireless!

fmw is right. Using off-camera flash improves modelling variables ginormously.

For mobility, I have a 'portable studio' that basically consists of 3 wireless 5600D flashguns on tripods, a 38" and a 48" silver/white reflector. Gives me plenty 'oomph' and endlessly variable possibilities, including faking a 'softbox' and balancing shadows. Easily fits a medium-sized suitcase.
I mostly use the camera unsupported. Flash freezes motion anyway, and it keeps me much 'free-er' to move around, direct the scene, try different viewpoints and angles, or adjust the light.

Next on my wishlist is a 20" MacBookPro immediately displaying every shot fullscreen. That'll need to be wireless too, somehow. And not just wireless, but superwide broadband wireless, to accomodate my 15MB exposures (and growing). That may be a while!


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## Big Mike (Oct 17, 2006)

I made one of these





for about $4....works great.

Got the idea here


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## W.Smith (Oct 17, 2006)

Big Mike said:
			
		

> I made one of these  for about $4....works great.[/QUOTE]
> Absolutely. I'm a fan of those too, Mike. But they're primarily used with [U]on[/U]-camera flash.


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## Big Mike (Oct 17, 2006)

Well sure, that's what I made mine for.  Although, I could certainly use it on a remote flash unit as well.  Actually, I use this on camera for fill (to control the darkness of the shadow) and use my Alien Bee as the main light.

I even took a spare piece of the black foam and made a snoot for another small flash unit that I'll use as a hair or background light with an optical trigger.  I'm thinking I could make another diffuser like this one (but bent more forward...to use for the background light.


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## loves_guitar (Oct 18, 2006)

I just read today that a coffee filter works as a diffuser!! I haven't tried it. Has anybody?


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## Big Mike (Oct 18, 2006)

A coffee filter should work...but it would block a fair amount of light.  I've used tissue before with good results.


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## W.Smith (Oct 18, 2006)

loves_guitar said:
			
		

> I just read today that a coffee filter works as a diffuser!! I haven't tried it. Has anybody?


Why don't _you_? So you can _see_ for yourself _if_ and _how_ it works. Then _you_ can tell _us_!
The proof of the pudding is in the eating, after all.
Of course a coffee filter is an expensive purchase....


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## loves_guitar (Oct 18, 2006)

W.Smith said:
			
		

> Why don't _you_? So you can _see_ for yourself _if_ and _how_ it works. Then _you_ can tell _us_!
> The proof of the pudding is in the eating, after all.
> Of course a coffee filter is an expensive purchase....


 
Hey, sorry Fresh Prince. I literally was sitting in the doctors office at 5pm, read it in an article, and then was reading about flash diffusers on here at 9pm! I just thought I'd throw in my two cents and see if anyone had heard of it before.
I don't have a flash aside from my on-camera flash (D70s), but I will try in the coming days.

Say hi to Uncle Phil for me.

/j


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## W.Smith (Oct 19, 2006)

loves_guitar said:
			
		

> Hey, sorry Fresh Prince. I literally was sitting in the doctors office at 5pm, read it in an article, and then was reading about flash diffusers on here at 9pm! I just thought I'd throw in my two cents and see if anyone had heard of it before.
> I don't have a flash aside from my on-camera flash (D70s), but I will try in the coming days.


An on-camera flash through a coffee filter? We can't wait of course.


> Say hi to Uncle Phil for me.


Phil is now on his island in the Caribean. I'm handling the garbage and the numbers businesses now.
Oh, BTW, Vinnie and Baby Face are coming to see you about business this week. Be nice.
:greenpbl:


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## loves_guitar (Oct 20, 2006)

Well, after much demand, here are the examples of using a coffee filter as a diffuser.

Regular flash:






Flash with both layers of the coffee filter:





Flash through just one side of the coffee filter:






So, after trying, I think that magazine was full of coffee grinds! 
Unless someone thinks I didn't do it probably.

Let me know.

/j


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## markc (Oct 20, 2006)

Well, like I was saying, it's not going to do much more than just reduce light output. You need to enlarge the light source. Mike's attachment will do this somewhat, because the area the light is bouncing off is larger than the face of the flash. You can do that with shoot-through material also, but it can't be right up against the face of the flash. You need space so that the light can spread out and light up the whole diffuser, which then becomes a larger, if dimmer, light source. I'm guessing the filter was pretty close to the flash. Try it with a single filter closer to the subject and see if there is a difference. There may not be. I'm not sure how a coffee filter will behave.


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## W.Smith (Oct 20, 2006)

loves_guitar said:
			
		

> Well, after much demand, here are the examples of using a coffee filter as a diffuser.
> 
> Regular flash:
> Flash with both layers of the coffee filter: [IMG]
> ...


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## fmw (Oct 20, 2006)

Again, Marc is right.  Diffusion doesn't create soft lighting.  Making the light source larger relative to the subject is what does that.  If you could have bounced it off the filter, you would have had some results.  It wouldn't have been very efficient.  There are better things to bounce it from.

That's why portrait photographers use umbrellas and soft boxes.  They enlarge the light source and soften shadows.


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## W.Smith (Oct 20, 2006)

fmw said:
			
		

> Again, Marc is right.  Diffusion doesn't create soft lighting.  Making the light source larger relative to the subject is what does that.  If you could have bounced it off the filter, you would have had some results.  It wouldn't have been very efficient.  There are better things to bounce it from.
> 
> That's why portrait photographers use umbrellas and soft boxes.  They enlarge the light source and soften shadows.



Home-made reflectors do an excellent job as diffusers for a main light.

Just wrinkle alu foil (wrinkle it good! You want thousands of itsy-bitsy 'mirrors'), then stretch carefully and spray-glue (the matt side!) flat onto a piece of foam board. The shiny side of the alu foil must of course be visible, because that is the most reflective side. Iron it (if the foam can handle the heat; you can use other materials for that board too of course) to make extra flat. And hey presto! you got a reflector you can use to diffuse a main (flash) light, or to open up shadows (place opposite the main light just outside the FoV).

OR you can spend a hundred bucks on one of those snazzy collapsible reflectors, of course.


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