Internal mirrors in Speedlight flash modifier unit

[TheLostVertex]

I have gone a head and did a couple fast macro scale shots to see how my mentioned diffuser stacks up verse some other common things. All images were taking at the same exposure, WB, and flash settings. I felt the subject should be ok since it has shiny and flat surfaces. (mp3 player )


Left: Homemade diffuser with reflective inside, Middle: bare flash, right: Tissue paper diffuser

I can see a slight change in color balance between the images. I think the home made diffuser does quite well as well at keeping the light levels close to the undiffussed flash. Tissue paper diffusion seems to have a large amount of light lose with not change in highlights, though a slight change in the shadows it appears.

Craig, the images look quite nicely lit. Are these with or without the dome panel you mentioned to had ordered?

Chris, I had not actually thought about the complications of adding polarizing film in such an arrangement. Good to know before I attempt something of that nature in the future

[rjlittlefield]

Tissue paper diffusion seems to have a large amount of light lose with not change in highlights

Hhmm... This result is very different from my own uses of tissue paper. I use Kleenex-type tissue very often as a wrap-around diffuser and find that it does an excellent job of creating a uniformly illuminated "light tent". See the example HERE and the discussion HERE and below.

The result that you're showing suggests that the paper you're using is very thin (almost transparent) or that it was placed very close to the flash (wrapped tight around the head, perhaps).

Can you clarify what kind of paper you're using and how you're using it?

--Rik

[TheLostVertex]

Can you clarify what kind of paper you're using and how you're using it?

--Rik

It is a generic branded paper towel. While not wrapped tightly around the head, it is only an inch or so of space. The areas was larger than that of the flash head even though the highlight does not appear to be much different. My only guess would be that any difference might be lost in a difference in exposure?

Im sure it being further away with a larger area would increase its diffusion more. I do admit to being rather quick and dirty with the creation of that as a diffuser, as I had not planned on making it to last for much longer than the shot.

[Craig Gerard]

Are these with or without the dome panel you mentioned to had ordered?

They were taken with the 'flat' panel. I'm waiting on the 'dome' panel to arrive.

Could imagine the dome being helpful for certain indoor event photography situations, in which the convex surface might divert some light to walls or ceiling, a portion of which might bounce to the subject and give a some "bare bulb" effect. But outdoors--much of the time, wouldn't there be little for this diverted light to bounce off of?

Some very minor internal tweaks to the dome may return a desirable outcome. The aim would be to broaden the catchlight; the flat panel is a more direct form of illumination but sufficiently diffuse in most situations.

I neglected to mention some details pertaining to the previously uploaded images: 1) the Metering Mode was set to 'Spot', probably not the best option given the range of subjects: 2) I set my flash unit to full telephoto when working with macro and diffusers, even at such close range the telephoto setting does have an impact on overall light modifying output.



Craig

[Chris S.]

I wonder if the material marketed as "Darice Foamies sheets," in the white-colored version, would be translucent?

Update: Today I stopped by a craft store that carries this material, and found that it is not translucent, but in fact is nearly opaque. So it's not a candidate for use as a diffusing material--but I did buy a sheet to try out as a reflector.

[DQE]

The interesting demo using the test object with a red center and a shiny dark frame reminds me how sensitive these tests are to exactly how one equalizes the "Photoshop" (or other) image processing steps.

Perhaps one should include a small diffuse white or gray patch in the scene to set the basic "exposure" level and white balance for each photograph.

[Craig Gerard]

Additional images taken with the Graslon Insight diffuser.....looking mainly at the catchlights....

Side approach:
Canon 50D, 100/2.8 L, single frame @ f/5.6, ISO 100


Overhead approach:
Canon 50D, 100/2.8 L, single frame @ f/5.6, ISO 100



Craig

[defante]

Nice. Here's some examples with just the flat diffuser and no additional diffusion.

#1


#2

[DQE]

Can anyone figure out if this flash unit would work on Canon's MT-24 dual macro flash unit?

One major limit of this flash unit is that the flash heads (including any add-on diffusers) must not project too far in front of the lens. Otherwise, one will too frequently bump into the surface on which a bug is crawling, especially if one is using the MPE-65 lens. Even just adding some fairly thin Fong Puffer diffusers causes problems sometimes.

Now if they'd only make an MPE-100 lens, with a 100mm focal length!!

[Craig Gerard]

David,

The catchlight in your images is similar to what I'm seeing with some insects and other smooth, spherical objects; this is not an uncommon challenge.

I attempted a number of different 'tweaks' today but the catchlight outcome was always the same. The dome diffuser panel may provide some benefit...but this is yet to be determined; failing that, for challenging scenarios, positioning a cloud of some description (as previously suggested) between the subject and diffuser may be an option.

Most subjects react well to the Graslon diffuser and I can see myself using it for many situations.


Some images from today....I have many more.
The second one looks like an emergence? The ants reside under a pot plant; the pot is lifted and I fire off as many shots as I can before the ants disperse....then I carefully put back the pot...until the next time

Any colour balance issues can be attributed to me, not the Graslon. These images were taken handheld and focus is not as sharp as I would have liked.

Canon 50D, 100/2.8 L @ f/11, single frame, cropped.


Canon 50D, 100/2.8 L @ f/11, single frame, cropped.



Craig

[Craig Gerard]

Phil,

I cannot see any of the current Graslon products being applicable to the MT-24EX...I haven't attempted to tackle that beast yet, but others have achieved good results; personally, I do not like distinct, twin catchlights appearing in shot, but there is a way to avoid this....I'm short of time at the moment but will send through some information when able.


Craig

[johan]

The shots in this thread are very much in line with what I was saying earlier in the thread, that with a beauty dish you need the centre blocking reflector to actually be quite large before it makes a noticable difference to the hotspot. I found it could be better by the shape being a hemispherical parabola design rather than planar, and with the inside of the parabola a reflective white rather than metal. White reflects less than pure silver metal, but actually that's quite nice because the light is softer.

[Craig Gerard]

Johan,

Could you elaborate further? I believe I understand the concept you are suggesting and if I am correct in my assumption, I may have suitable materials on hand to explore the concept further.


Craig

[johan]

I went through a big diffuser making phase last year, one of which was several tries at a beauty dish variant. They were not quite right in the end for the particular purpose I wanted them for, but it did allow me to observe a few things as I evolved it. I made them using silver foil 'cook lasagna from frozen in oven' type dish, which are boxy, rectangular, with black card reversed on clear laminating paper to act as the block. Worked ok, but I still had hotspots.

After a number of trial and error evolutions the best light I got out of it was when I coated the inside white rather than the highly reflective metal it initially was, when I beat up the aluminium boxy food dish into more of a 'part of a hemisphere' parabola shape, when I changed the first flat blocker to a hemisphere shaped blocker about 10cm diameter (total diameter was by now about 17cm), and when the blocker was shiny kitchen foil. I stopped at this point but it's something I'm sure I'll come back to as it's got legs but required some different shaped materials for me to move on with it... on the todo list

[Craig Gerard]

The Graslon Dome Diffuser Panel has arrived; but I'm not seeing any notable advantages or disadvantages in comparison to the Flat Panel when used for macro application.

Looking at the flash output (reflected in a dark screen) it would seem the shiny, internal chrome finish is creating a somewhat overly intense output, particularly around the perimeter of the diffuser when using either the Flat Panel or Dome Panel; this is not the most desirable distribution of light at close range. I am tempted to 'dull' the chrome with 'flat' white; but because I'm currently working on an alternate diffuser I'll leave the Graslon as/is for the moment.

After a number of trial and error evolutions the best light I got out of it was when I coated the inside white rather than the highly reflective metal it initially was, when I beat up the aluminium boxy food dish into more of a 'part of a hemisphere' parabola shape, when I changed the first flat blocker to a hemisphere shaped blocker about 10cm diameter (total diameter was by now about 17cm), and when the blocker was shiny kitchen foil. I stopped at this point but it's something I'm sure I'll come back to as it's got legs but required some different shaped materials for me to move on with it... on the todo list

I've been busy putting together an alternate diffuser which consists of a series of hemispheres of various dimensions nested or stacked inside oneanother. I'll go into more detail in a separate thread.

I purchased a number of these items (see image below) in a range of sizes after noticing Charlie using them for various diffusion tasks. They are spherical, however, by design can be easily separated into hemispheres.

eBay search criteria: clear plastic balls. A range of sizes are available.




Craig