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Flash Diffusion

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  #1  
Old 18-12-05, 21:47
Don Hoey's Avatar
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Default Flash diffusion

Quote:
Raw flash should be considered as a bright pin point of light. You can liken it to the sun on a bright day, as that is also a very bright point source of light that gives harsh shadows. When partialy obscured by cloud it is not so bright and any shadows are far softer. Totally overcast gives no shadows as there is no longer a key light, and light on a subject is coming from all around.
The key to a soft flash is diffusion. A way of making the point source bigger. Just as in the examples of sunlight the more diffuse the flash the softer the light. You will however loose a bit of the flash units power. If the unit is a TTL one exposure will be automatic and of no concern.

Diffusing a flash can be done in a number of ways. If it is a seperate flashgun then diffusing attatchments such as the one shown in the attatched picture can be used. These are very effective for their size which is why you will see them being used by the press. The flash can be bounced of a larger surface to increase the size of the light, or fired though a white material from a short distance to achieve the same. Unfortunatly on compact cameras the proximity of the flash to the lens limits options to a bit of tissue held over the flash tube ( fingers out of the way of the flash ).

As the options are so large I attatch a link to the Warehouse Express site where there is a large range on show. When the diectory on the left side loads go to Photographic - Flashguns - Lumiquest and Stofen. http://www.warehouseexpress.com/index.cfm

Attatched picture shows Stofen type diffuser.
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File Type: jpg D100_Sb-80DX_resized.jpg (34.1 KB, 91 views)
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  #2  
Old 20-12-05, 12:30
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Default Flash diffusion 2

Posting this now as it may help Stephen as he is looking at possibly venturing into portrait photography.

To save scrolling back through past posts a reminder........

Quote:
Raw flash should be considered as a bright pin point of light. You can liken it to the sun on a bright day, as that is also a very bright point source of light that gives harsh shadows. When partialy obscured by cloud it is not so bright and any shadows are far softer. Totally overcast gives no shadows as there is no longer a key light, and light on a subject is coming from all around. All of this can be achieved with flash.
The primary consideration is trying to convert a point source of light into a far bigger light to simulate the above.

I am attatching another graphic to hopefully explain the affect on shadows.

The lower reference to studio flash and brollie is that this is something most will have seen and can relate to.
Studio flash units are used professionally as they have a number of advantages over small flash guns. ..... More power.......variable output...... faster recycling times.......modeling light facility to name a few things. Although a portable flash can be used with a brollie but because of lack of power the flash to subject distance is very limited. The downside of studio flash is that the camera cannot control exposure and it has to be done manually.

I found some good stuff by Steve Aves on the Warehouse Express site. A good read if you are interested.
Click the link and go - Photographic - Studio Lighting -
Lighting Glossary - Steve Aves article
Lighting Guides - Steve Aves article
Product Reviews - Steve Aves article
Bowens
Elinchrom
Interfit
Interfit Pro
Interfit Stellar
Lastolite

http://www.warehouseexpress.com/index.cfm

My graphic attatched

Don
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File Type: jpg Flash diffusion.jpg (121.2 KB, 71 views)
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  #3  
Old 24-12-05, 22:16
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Default Diffusion 3

I am going to post a series of pics to graphically show the effects as a continuation of Diffusion 2. Due to the limits of uploading pics this will be spread over several posts.

I am using this to post a picture of flash units to give some idea of the relative sizes of the square area from which the light starts its journey.

This is important in that large subjects will require light coming from a source of greater area, in order to diffuse shadows to the same extent, as a smaller subject and smaller light.

I will post a set of 4 to show effect tomorrow.

Don
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File Type: jpg Size comparison of flash units.jpg (63.9 KB, 70 views)
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  #4  
Old 25-12-05, 14:26
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Default Diffusion 4

Attatched are images that show the effect of flash.

Notice how the shadows start hard on direct flash though to soft on diffused.

The pictures were taken in overcast conditions in my lean to. This was to show the effect on shadows to the best without too much influence from natural sunlight.

Flash exposure was TTL to not introduce any complications at this stage.

In the behind the scenes image you can see the set up. This type of photography is often referred to as Table Top photography. Ideal for any still life.

If you only have a compact camera you can still do Table Top using a 'slave' and remote flash. The power of the remote flash can be controlled by moving it closer to, or further away, or adding sheets of kithen toweling over the flash as this absorbs light.

Any number of flash units can be used, but balancing the light becomes more complicated the more units you use.

Don
Attached Images
File Type: jpg Direct flash_ no diffusion.JPG (61.3 KB, 68 views)
File Type: jpg Direct flash_ with Stofen diffuser.JPG (59.8 KB, 61 views)
File Type: jpg Off camera with diffusion.JPG (70.3 KB, 73 views)
File Type: jpg 2 Ducks_Behind the scenes.jpg (91.6 KB, 82 views)
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  #5  
Old 08-01-06, 15:29
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Quote:
Originally Posted by Don Hoey
Thanks for that. It was the Omni Bounce bit that confused me, I refer to them as Stofen as this was when it came out their only product, and a killer one at that. I use one all the time. The best addition to your flash you can get, and only 15:95 from Warehouse Express.
Pic from post #4. http://www.worldphotographyforum.com...0&d=1134942009.

Don
I have been looking for local stofen supplier when I found this comparison between two Stofen, Lumiquest and direct flash.

http://www.toddwalker.net/e20/flashtest/
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  #6  
Old 08-01-06, 17:32
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Quote:
Originally Posted by Stephen Fox
I have been looking for local stofen supplier when I found this comparison between two Stofen, Lumiquest and direct flash.

http://www.toddwalker.net/e20/flashtest/
Handy link Stephen,

It does show how hard direct flash is.

My first system flash was the Vivitar 283 and I had a 45deg bracket that held a large card and gave a slightly softer light than ' Lumiquest, white insert, no diffuser '. Once I got my hands on a Stofen I gave up using this.

There used to be a flash head described as being ' bare bulb ' in which the whole tube was above the flash body and had no reflector. When triggered the light emitted went everywhere. A bit like a lightbulb with no shade. Great for interiors as light bounced everywhere so any shadows were soft. For me the Stofen is the nearest to that.

In this test the ' Lumiquest, no insert, no diffuser ' does well as some light comes from the Lumiquest and some from the ceiling so making the light source really diffused. Very similar to ' Stofen Omnibounce, 90 degree bounce '

So are you still going with Stofen ? I presume its for your SB600. Two guns both with these ....... that will be light everywhere.

Don
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  #7  
Old 21-10-06, 13:39
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Arrow Shoot through verses reflective brolly technique

I spoilt myself yesterday and splashed out on a light stand and brolly. I am no expert in the field of brollies but this one allowed dual use and came recommended. A white inner allows shoot through when the outer reflective element is removed. I decided to test both ways what follows below are my findings.

Traditional Brolly (images 1&2)

Two flashes attached to a light stand and fired using remote camera cord. Light is bounced around the brolly and comes out diffused in all directions. Lots of light is lost and both flashes ate set to i-TTL +1 EV. Shadow is fairly heavy with two shadows near the tail most likely one from each flash. Colours and contrast are rich and good. Reflectors used in to bring some light back and soften shadows more. This method was fairy difficult to get close to the subject.


Shoot through (images 3&4)

Two flashes attached to light stand fired by the camera using a remote flash cord. Much light is lost as it spreads out from the curved diffuser. Due to the way light is spreading out it is possible to use other reflectors to bring some back and illuminate other parts of the subject. This method is less directional and more diffused creating softer shadow. Contrast seems slightly flat compared with images 1&2. Upper wing surface seems better light due to large lastolite reflector claiming wasted light back. Shoot through was easier to get close to the subject.

Conclusion
These two lighting techniques allow good diffused lighting with fairly soft shadows no harsh highlights. Colours and contrast are better using traditional method but shoot through creates softer shadows and more even lighting also permits use of other reflectors to illuminate parts of the subject that may be in shadow. It is difficult to get a brolly over a subject like the test whereas shot through was much easier.
Attached Images
File Type: jpg traditionalbrolley.jpg (173.1 KB, 38 views)
File Type: jpg biplane50mmf20reflectorfinal.jpg (255.3 KB, 28 views)
File Type: jpg shootthroughbrolley.jpg (141.4 KB, 30 views)
File Type: jpg biplane50mmf20final.jpg (201.2 KB, 32 views)
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  #8  
Old 21-10-06, 21:39
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I can see we are looking forward towards the darker days Stephen.
Guess when you are on bread and water you can easily use the dining room as a studio.

Brollie used as in image 3 provides an economical softbox. I see you managed f20 at ISO 200 which is quite impressive.

If you see a decent s/h flash around guide no 45 or more, that can be remotely triggered at full bore, you can recover your SB800 for fill in.

For future reference it would be nice to see a pic of the flash mounting in use on the stand.

Don
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  #9  
Old 22-10-06, 14:05
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Quote:
Originally Posted by Don Hoey View Post
For future reference it would be nice to see a pic of the flash mounting in use on the stand.
The stand is terminated in a 3/8" thread (pic1) and the brolly/hot shoe adapter slides over and screws in to form a compression (pic2) by rotating the bottom tightener. A brolley is attached in a similar way by inserting through the hole at the top of pic2. Angle adjustment is made by the joint and released by the middle tightener. Pic 3 shows assembled with hot shoe flash foot. Flash shown assembled in pic 4 diffuser optional but I found provided softer light in both applications above. Additional flashes can be attached using the adapter in pic 5 when brolley shaft is placed through the hole and tightened. This is not perfect as the hole is too wide but it was packed with card to make in effect brolley shaft wider in diameter. SB-800 on remote cable was attached to adapter in pic 5 as has a 1/4" suitable for remote cord.
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File Type: jpg 1.jpg (45.0 KB, 14 views)
File Type: jpg 2.jpg (47.7 KB, 17 views)
File Type: jpg 3.jpg (47.6 KB, 18 views)
File Type: jpg 4.jpg (52.1 KB, 22 views)
File Type: jpg 5.jpg (61.6 KB, 20 views)
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  #10  
Old 28-10-06, 15:35
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For those of you still following this tread with interest, A free white reflector comes with the November issue of What digital Camera. I've just got mine (pretty nifty)
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