[Dave]

Hopefully I'm not alone in finding the whole flash photography game a bit of a dark art Have a look here at a test I ran :- Lambency Flash Diffuser - Comparision vs standard Nikon SB800

Now problem is, I expected softer shadows behind the subject with the Nikon Dome & especially the Lambency Diffuser, yet I find the shot taken with the naked flash bouncing off the ceiling to have less shadows vs the diffusers in same mode

Can I assume it's the iTTL auto mode that is compensating & possibly throwing the results ? Any advice welcome & if anyone else is experiencing similar problems, please shout

[silkstone]

If you bounce the flash straight up with no diffuser, there is no light going directly from the flashgun to the subject - hence no shadow.

With a diffuser fitted, some light will go straight from the gun to the subject through the sides of the diffuser, so you'll still get a shadow.

The diffuser doesn't really solve the 'point light source' problem completely. It spreads the light around more, but you're still getting some direct light on the subject.

[orangepeel]

Indeed. i thought the point of a diffuser was to slightly lessen shadows (not eliminate them) and kill off most of the shiny face problem u get with some portraits.

Plus by the looks of your shots you've got your subjects close to the background. This, I thought, was a no-no.

[Dave]

Yep fully understand that Silky, but the 1st shot taken with no flash had an exposure time of 3.6 secs ....... the one with flash fired straight up , only of course 0.6 secs ...... so the flash obviously has hit the object.

I believe I'm possibly working in to small a room & being 7-8 feet away from subject, too close for a sensible comparison test ?

[Dave]

Originally Posted by orangepeel

Plus by the looks of your shots you've got your subjects close to the background. This, I thought, was a no-no.

In practice you are right, but I wanted to force the shadows to allow a comparison for the test (about 1 foot from wall)

Off to run another test from 12 feet away in main living room

[silkstone]

Originally Posted by Dave

Yep fully understand that Silky, but the 1st shot taken with no flash had an exposure time of 3.6 secs ....... the one with flash fired straight up , only of course 0.6 secs ...... so the flash obviously has hit the object.

I believe I'm possibly working in to small a room & being 7-8 feet away from subject, too close for a sensible comparison test ?

Yes, without a diffuser the flash hits the subject, but only after bouncing off and around the ceiling, walls, etc which scatters the light so it hits from all sides. The diffuser lets some of the light hit the subject direct.

Even at 60 deg, the flash beam (no diffuser) is quite narrow so little or none will be directed at the subject.

[JMitchell]

Like what silkstone said, the reason the naked flash is creating less of a shadow (or none), is because there is absolutely no (or a negligible amount) of light going directly to the subject, but with the diffuser, some will come out of the sides (diffuse....) and go straight forward. If I were you, try doing that exact setup, and turn the flash to face slightly up and a bit more slightly to the left, and if that fails, switch to manual

[Les Meehan]

Dave

The bottom line is this: The 'quality' of the light (i.e. how soft or hard the edges of the shadows are) is determined by the ratio of the size of the light source and the subject. Simply put, the bigger the light source in relation to the subject the softer the edges of the shadows will be. This is why many pros use very large light boxes placed close to the subject when requiring soft lighting.

In your experiment (which is something everyone should do to actually learn first hand) the actual size of the light source varies only slightly compared to the size of your subjects (nice mates!). This is why in your first three shots the edges of the shadows are actually virtually the same, the 'quality' of the light hasn't changed much! When you bounce the bare flash into the ceiling (or a wall for more interesting lighting) you have dramatically changed the 'size' of the light source compared to the subject (the light source is now the area of the ceiling lit by the flash) hence the shadow edges go very soft. You have dramatically changed the 'quality' of the lighting.

Bouncing the diffused flash into the ceiling has produced shadows from the flash's direct light as others have explained (even your bare flash into the ceiling has also produced a faint shadow since you obviously did not flag the flash head to prevent this stray light reaching the subject. Note that this faint shadow has hard edges too!)

I have purposely used the term 'quality' to describe the 'edges of the shadows'; this has nothing to do with 'contrast'! Note how the depth of tone in the first three shots does vary but this is because the diffused flash is bouncing light around the room which is 'filling in' the shadows and lightening them. However, since the edges are similar the light quality is similar. The use of the terms 'light contrast and 'light quality are often incorrectly interchanged (rather like depth of field and depth of focus). They should be considered two separate things when lighting a subject. A very common use of soft boxes is to produced soft-edged shadows but retain high contrast by keeping the fill-light low (or none at all) to produce that wonderfully strong but 'full' lighting seen in celebrity portraiture (check out the work of Snowdon or Lichfield for examples).

My advice would be to make a large tracing paper screen, about 3'x2', using a wooden frame (2x1 is good) covered with white tracing paper (rolls from art shops always great to have). Prop the screen where you want the light and fire flash thru screen for a great professional light (and cheap!!). On my lighting workshops I use cardboard frames of varying sizes covered with trace to get the point across that you don't need to spend money to do expert lighting, knowledge is the key! Tip: by varying the distance of the flash to the trace screen (not the distance of the screen to subject) you can fine-tune the shadow edges because you will be changing the 'size' of the light source since more or less of the screen will be lit by the flash.

Hope this helps. Lets see some renewed tests using the ideas given by folks here.

Regards

Les Meehan
Workshops in spain, come on down!

[Dave]

Originally Posted by silkstone

Yes, without a diffuser the flash hits the subject, but only after bouncing off and around the ceiling, walls, etc which scatters the light so it hits from all sides. The diffuser lets some of the light hit the subject direct.

Yep, which why I was saying the small room was giving a false impression ....just about to upload versions from 21ft x 13ft room

[Dave]

Right 2nd set of results. Taken with same settings on camera / flash as in link form 1st post. This time in 21ft x 13 ft room, with camera about 12 ft from subject this time.

Lambency Flash Diffuser - Comparision vs standard Nikon SB800

[Dave]

Now I'm not sure whether this is a Lambency problem, or something I am doing, but at 12 feet away the upright mode does not give enough light. I tried upping EV to +1 & then +2 on SB800, but results are not much better (original at 0, then +1, then +2) :-



Surely at f/8 at this kind of distance the Lambency diffuser is supposed to work ?

[silkstone]

Because you are diffusing the light around the whole room, rather then concentrating it as a focused beam, the flash guide number goes way, way down.

You'll probably have to use a higher ISO - say, 400 - for the (diffused) light from the flash to be sufficient.

[Dave]

Cheers Silky..... for some reason I had just given up , thinking it should easily cope with f/8 at that distance. So I opened up to f/5.6 & was pleasantly surpirsed to get this result from upright Lambency Diffuser :-



& if I opened it up to f/2.8 I managed to be 18 feet away no problems :-



At last & still being IS0100 I know I have quite a bit more to play with before introducing noise

Goes to show though, how you need to run through tests like this with new kit (eg. Lambency ) to get the best out of it. If I had gone straight to an event with it I would have been lost

Well I'm going to keep playing with different distances & f/stops with this Diffuser until I get a gut feel what it can achieve. Of course it will compeltely change when I get a room with a tall ceiling , but hey

[silkstone]

One thing you could try is to put some aluminium foil around the rear of the diffuser (when t