Just to add more info on the original #3 comment " A thick diffuser will make the flash duration longer and this makes the risk of glare higher."
Some shots below using styrofoam diffuser of increasing thickness. You will just see as the diffusion increases by adding more layers from none intially, the contrast decreases and bright spots spread giving a more even light. The light loss is approx 1 stop per 3 layers, so the flash duration in the last shot was approx 3 X longer than the first shot.
Brian the highlights in the 6 layer shot look brighter to me than the highlights in the 3 layer shot (most noticeable under the fly's wing at the joint). So either adding more material to the diffuser is adversely effecting the highlights (making them brighter) or the exposure, relative to the subject, isn't the same (more light hitting the critter in the 6 layer shot). I'd also be curious to see the histograms for the four images broken out by channel to see if one color is being effected more than the others.
Sorry folks: For #3 I should have said that increasing the flash duration increases the odds of blowing the red channel -for some odd reason the red light spectrum will shift more to the right of the histogram as the flash duration increases (might have to do with the color of the light changing as the flash duration increases -not sure). Although it can cause problems with the specular highlights the biggest problem is a loss of texture detail, especially since the red channel is often 50% or more of the total image data in a scene.
That red channel shift may also be the reason why the 6 layer shot looks brighter in some areas than the 3 layer shot in your test Brian -although it doesn't explain the reduction in the 9 layer diffuser image. But, IMHO, at the 6 layer point the material is doing a better job of blocking the light from the flash than diffusing it
I don't believe adding layers will give you better diffusion.
I'd like to see the difference between one layer and 3 layers if there's any Brian. As it is, I don't see any difference in the softness of the shadow or the highlight, just the level of brightness. To me it kinda shows that adding more layers doesn't do anything at all apart from blocking more light making the flash pump more power.
I figure once the light is scattered by a layer of material, it can't get any more diffuse if you add the same type of material. I think it'll only work if you add a finer type of material but then why not only use the finer material in the first place?
n0b0 wrote:
I don't believe adding layers will give you better diffusion.
[Snip] ...To me it kinda shows that adding more layers doesn't do anything at all apart from blocking more light making the flash pump more power.
I figure once the light is scattered by a layer of material, it can't get any more diffuse if you add the same type of material. I think it'll only work if you add a finer type of material but then why not only use the finer material in the first place?
Agreed -there's a big difference between diffusing the light and simply blocking it.
Dubble posting. This belongs here too. I have now realized how important the angle of the light is...
5DII + MP-E65 + MT24 EX. ISO 800 , f/11, 1/200.
I am working on the diffusers and I think the light gets better. The eyes are not as blown in the full size photo. Might have to adjust my edit for the web. I have been blessed with lower temperatures and shower so the bumble bees are slow. A lot of shooting last night and this morning. This was from yesterdays shoot.
ISO 800 and 1600 is fantastic with the 5DII in good light (like flash...)
Would be much easier to see if the photos were smaller (could add a link to the larger versions so the page doesn't get too wide).
Much better light with the new setup! Try under exposing by at least 1/3 of a stop (1/2 might be better) then raise the exposure in post.
At ISO 800 and 1600 you might have some metering problems with the ambient light in the scene -might want to drop back down to ISO 200 or so. I'd also be curious to see how the specular highlights change at lower ISOs...
When shooting a portrait of a critter it's important to get the leading edge of the "face" in focus -if you don't then the viewer's eyes will go right to the out of focus area and the composition won't work. Remember that the area of acceptable focus is parallel to the sensor and look for angles that will allow you to lay it as flat against the subject as possible (called a "magic angle"). You'll end up with images that look like they've been stacked because you won't be wasting the depth of a single frame
I'm sure the diffuser works but I question the effectiveness being so close to the actual flash heads. Take a look at the Puffer, Fong made a bit of an effort to put a distance between the popup flash and the diffusing material. Same deal with Lumiquest Softboxes. I think even the Stofen has a bit more distance than that.
I fail to see the benefit of underexposing and raising it again in post. In my own experience, underexposing always resulted in having very noisy photo, specially the chroma noise, after I increase the exposure in DPP.
n0b0 wrote:
I'm sure the diffuser works but I question the effectiveness being so close to the actual flash heads. Take a look at the Puffer, Fong made a bit of an effort to put a distance between the popup flash and the diffusing material. Same deal with Lumiquest Softboxes. I think even the Stofen has a bit more distance than that.
I fail to see the benefit of underexposing and raising it again in post. In my own experience, underexposing always resulted in having very noisy photo, specially the chroma noise, after I increase the exposure in DPP.
I will try to put them further away and see what happens. As for underexposing it is also a question on which camera you have.
Anden wrote:
As for underexposing it is also a question on which camera you have.
A
Fair enough, let's say I use a 5D series or 1D series body which has excellent noise performance, what would be the benefit of underexposing and raising it again in post processing?
n0b0 wrote:
Fair enough, let's say I use a 5D series or 1D series body which has excellent noise performance, what would be the benefit of underexposing and raising it again in post processing?
I think that John is trying to cut reflections this way. I have not tried it myself. My answer was just a general answer.
n0b0 wrote:
I fail to see the benefit of underexposing and raising it again in post. In my own experience, underexposing always resulted in having very noisy photo, specially the chroma noise, after I increase the exposure in DPP.
If you under expose by a stop or less then the increase in noise shouldn't be a problem at ISO 100. But you will see a big difference in texture detail because the red channel doesn't have to be all the way to the right of the histogram before you start to lose detail. Also under exposing a little will boost saturation in ways that the saturation slider in post can't. Last, but not least, you will get a break on the specular highlights -less likely to blow them out...
Anden wrote:
I will try to put them further away and see what happens. As for underexposing it is also a question on which camera you have.
A
I agree with n0b0 on this one -getting the flash heads close to the diffuser will give you a "hot spot" in your lighting. Putting some distance between the flash heads and the diffuser will give you a more even light on the subject, better diffusion, and reduce harsh specular highlights.
