How to compare diffusers

It would be nice if we could "measure" diffuser quality somehow to criteria:

• No hard shadows (soft light) anywhere
• Is the light evenly distributed over the subject
• Is the underside of a subject at least somewhat lighted
• Specular highlight control
• Does the light fill the diffuser surface completely evenly
• Is the subject not rendered too flat (for example too much light from straight ahead, or with all shadows completely eliminated)
• How well does the light reveal texture in surfaces

I think most problems are with specular highlights. Consider the following pictures, they are completely unedited. Dark shiny reflective material, like beetles, with curves. The curves are where the speculars show up.

First is AK diffuser, second is Popeshield, third is mini octabox shining 30 degrees angle down/forward. The flashcap left on for all. TTL metering. Let's call specular highlight SHL. With the same light level for all, the popeshield, with no reflector at all, has the lowest intensity SHL. The softbox, with silver reflector inside, makes light strongly directional, and causes the most intense SHL. The AK diffuser sits in between (white reflective material in stead of silver inside). Reproduction ratio = 1:2.







This is just one aspect, but I which there was a standard test.

--

Bas
https://www.flickr.com/photos/bahazzie/

What you want is a large light source as close as you can get to your subject and the farthest off axis it can be, the better.

Think studio lighting for people. There are reasons why the light never comes from the same direction as the camera, why huge light modifiers like giant umbrellas are used, and why the lighting is positioned so close to the model.


Light illuminates, shadow defines. So to get the best contrast for high detail, a light source positioned from a frontal side angle will give you the kind of illumination / definition ratio that really pops. A straight on, frontal direction cannot do this. The farther you can get your light source off the camera, the less flat it will be.


Hard light comes from not just a straight on direction, but a point source far from your subject. It may seem counterintuitive but the closer you place your light to the subject, the softer the quality of the light becomes. Small and distant = hard, large and close = soft.

Some examples:

Bas Hamstra said:

I think most problems are with specular highlights.

Click to expand...

Without a doubt, specular highlights are the problem child. But it's usually an issue where the light that the subject sees has a hot spot in it, so it's not even and therefore not really diffused. That specular light will erase detail, and even though I don't focus stack I think that everyone shooting in this discipline has a "detail threshold" that they're trying to achieve. No point in doing a triple digit focus stack if the light is going to erase detail because specular surfaces are returning the color of the light source, and not the color of the surface itself, because the light is specular.

Just to be clear: It's OK to have a specular highlight, since they really can't be avoided. But I want to see color and texture in the specular areas and not the color of the flash.

Getting detail in black, glossy surfaces is my kryptonite. This first shot is with my old diffusers. There's detail in the specular areas of the compound eye, but it could be better. There's also a glossy stripe down the bee's abdomen which is a sign that the light isn't diffused well enough. Either a slight hot spot, or the diffusers aren't large enough. Or maybe the dimples in the Puffer Plus plastic are creating a specular lighting effect.


Tech Specs: Canon 90D (F11, 1/125, ISO 200) + a Canon MP-E 65mm macro lens (set to over 2x) + a diffused MT-26EX-RT, E-TTL metering, -1 FEC. This is a single, uncropped, frame taken hand held. In post I used Topaz Photo AI and Clarity in that order.

Contrast the shot above with this one, taken at the same mag. Not the same angle, but the eyes are rendered better due to the larger diffusers, and I think that the light is even.


Tech Specs: Canon 90D (F11, 1/125, ISO 200) + a Canon MP-E 65mm macro lens (set to 2x) + a diffused MT-26EX-RT, manual mode, key (A) on a Kaiser Adjustable Flash Shoe set to 1/16 and the fill (B) set to 1/32. This is a single frame taken hand held. In post I used Topaz Photo AI and Clarity in that order.

Since the light gets further away as the magnification decreases I've had a tough time getting good light at 1x mag. But the new diffuser set is holding up pretty well, and I'm going the shoot more between 1x and 2x.


Tech Specs: Canon 90D (F11, 1/125, ISO 200) + a Canon MP-E 65mm macro lens (set to 1x) + a diffused MT-26EX-RT, manual mode, key (A) on a Kaiser Adjustable Flash Shoe set to 1/16 -1/3 and the fill (B) set to 1/32 -1/3. This is a single frame taken hand held. In post I used Topaz Photo AI and Clarity in that order.

We could also get into a discussion about mixing natural light and flash. In the photo above the honeybee and the flower its feeding from is lit with the flash (no natural light) but the background is harsh sunlight that doesn't look harsh because it's out of focus and a little under exposed. I was using one of the diffusers to cast a shadow over the bee.

--
Also known as Dalantech
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Thanks for responding Kevin. I agree with everything you say, and maybe one day I will take my radio triggger on a trip, and plant a diffused speedlite aside. In the meantime there are also many beautiful images created with on camera diffusers, commercial or not, it's not like it can't be done. And the closer we get the more off angle the lightsource is going to be, beit from above.

But yeah off angle gives the best definition that's true.

Bas

kmhwildlife said:

What you want is a large light source as close as you can get to your subject and the farthest off axis it can be, the better.

Think studio lighting for people. There are reasons why the light never comes from the same direction as the camera, why huge light modifiers like giant umbrellas are used, and why the lighting is positioned so close to the model.

Light illuminates, shadow defines. So to get the best contrast for high detail, a light source positioned from a frontal side angle will give you the kind of illumination / definition ratio that really pops. A straight on, frontal direction cannot do this. The farther you can get your light source off the camera, the less flat it will be.

Hard light comes from not just a straight on direction, but a point source far from your subject. It may seem counterintuitive but the closer you place your light to the subject, the softer the quality of the light becomes. Small and distant = hard, large and close = soft.

Some examples:

Click to expand...

--
Bas

John K said:

Bas Hamstra said:

I think most problems are with specular highlights.

Click to expand...

Without a doubt, specular highlights are the problem child. But it's usually an issue where the light that the subject sees has a hot spot in it, so it's not even and therefore not really diffused. That specular light will erase detail, and even though I don't focus stack I think that everyone shooting in this discipline has a "detail threshold" that they're trying to achieve. No point in doing a triple digit focus stack if the light is going to erase detail because specular surfaces are returning the color of the light source, and not the color of the surface itself, because the light is specular.

Click to expand...

My little test was done at 1:2 and later I re-did it a bit closer at 1.3:1 and the results were shocking. For the AK diffuser the reflection was just as bright white as the reference flashed-on white. Popeshield did much better.

There was in interesting article on the web, where they had to product-photograph a shiny kettle, starting with a softbox. The shape of the SB was clearly reflected. Then they placed a silk diffusion screen in between. After that there still was a reflection/specular HL, but extremely soft and spread out, so soft that it became beautiful.

John K said:

Since the light gets further away as the magnification decreases I've had a tough time getting good light at 1x mag. But the new diffuser set is holding up pretty well, and I'm going the shoot more between 1x and 2x.

Tech Specs: Canon 90D (F11, 1/125, ISO 200) + a Canon MP-E 65mm macro lens (set to 1x) + a diffused MT-26EX-RT, manual mode, key (A) on a Kaiser Adjustable Flash Shoe set to 1/16 -1/3 and the fill (B) set to 1/32 -1/3. This is a single frame taken hand held. In post I used Topaz Photo AI and Clarity in that order.

Click to expand...

Beautiful shot above, but it would have been ALMOST just as good with a flappy 10$ diffuser IMO. Some people just clone out speculars For me the shot is mainly about a sharp bee, beautiful contrasting colors and bokeh.

--
Bas

Bas Hamstra said:

Bas Hamstra said:

Tech Specs: Canon 90D (F11, 1/125, ISO 200) + a Canon MP-E 65mm macro lens (set to 1x) + a diffused MT-26EX-RT, manual mode, key (A) on a Kaiser Adjustable Flash Shoe set to 1/16 -1/3 and the fill (B) set to 1/32 -1/3. This is a single frame taken hand held. In post I used Topaz Photo AI and Clarity in that order.

Click to expand...

Beautiful shot above, but it would have been ALMOST just as good with a flappy 10$ diffuser IMO. Some people just clone out speculars For me the shot is mainly about a sharp bee, beautiful contrasting colors and bokeh.

Click to expand...

Agreed about the diffuser, it all boils down to what allows you to take the photos that you want to take.

--
Also known as Dalantech
My New Book: https://www.blurb.com/b/11015692-extreme-macro-the-art-of-patience-volume-ii
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Managed to get this shot today, while the critter was more hungry than afraid.


Tech Specs: Canon 90D (F11, 1/125, ISO 200) + a Canon MP-E 65mm macro lens (set to 2x) + a diffused MT-26EX-RT, manual mode, key (A) on a Kaiser Adjustable Flash Shoe set to 1/16 -1/3 and the fill (B) set to 1/32 -1/3. This is a single frame taken hand held. In post I used Topaz Photo AI and Clarity in that order.

Pretty much resolved every pore on the critter's forehead.

--
Also known as Dalantech
My New Book: https://www.blurb.com/b/11015692-extreme-macro-the-art-of-patience-volume-ii
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Tech Specs: Canon 90D (F11, 1/125, ISO 200) + a Canon MP-E 65mm macro lens (set to 2x) + a diffused MT-26EX-RT, manual mode, key (A) on a Kaiser Adjustable Flash Shoe set to 1/16 -1/3 and the fill (B) set to 1/32 -1/3. This is a single frame taken hand held. In post I used Topaz Photo AI and Clarity in that order.

That's the kind of performance that I've been trying to get out of a macro twin flash for the past 15 years. Funny thing is that I might switch to a Canon EL 100 just so I don't have to deal with two specular highlights.

--
Also known as Dalantech
My New Book: https://www.blurb.com/b/11015692-extreme-macro-the-art-of-patience-volume-ii
My Blog: http://www.extrememacro.com
My gallery: http://www.johnkimbler.com
Instagram: https://www.instagram.com/extrememacro
Macro Tutorials: http://dalantech.deviantart.com/gallery/4122501/Tutorials

Beautiful macroshot, strong contrasting colors, bokeh, yep classical macro. Ambient light nicely mixed in. Actually bees are not so hard for specular highlights, never had any problems with them. These reflective beetles are a better test, yes. Looks good. When mixing ambient light in, you also have to take care that ambient isn't reflecting. As long as ambient is 2 stops under probably not a problem.

Yesterday I had a specular HL festival with a highly reflective dragonfly, these are tough too. I will probably post a few of them. Shot the same kind of dragonfly a year ago and had the same problems too.

John K said:

Tech Specs: Canon 90D (F11, 1/125, ISO 200) + a Canon MP-E 65mm macro lens (set to 2x) + a diffused MT-26EX-RT, manual mode, key (A) on a Kaiser Adjustable Flash Shoe set to 1/16 -1/3 and the fill (B) set to 1/32 -1/3. This is a single frame taken hand held. In post I used Topaz Photo AI and Clarity in that order.

That's the kind of performance that I've been trying to get out of a macro twin flash for the past 15 years. Funny thing is that I might switch to a Canon EL 100 just so I don't have to deal with two specular highlights.

Click to expand...

--
Bas
https://www.flickr.com/photos/bahazzie/

Bas Hamstra said:

Beautiful macroshot, strong contrasting colors, bokeh, yep classical macro. Ambient light nicely mixed in.

Click to expand...

Thanks!

Actually bees are not so hard for specular highlights said:

https://imgur.com/NLf9REj

Bas Hamstra said:

These reflective beetles are a better test, yes. Looks good. When mixing ambient light in, you also have to take care that ambient isn't reflecting. As long as ambient is 2 stops under probably not a problem.

Click to expand...

I'm normally just shading the subject with the diffusers so I don't have to worry about natural light on the subject. For the lady beetle the only light on it is the flash.

Bas Hamstra said:

Yesterday I had a specular HL festival with a highly reflective dragonfly, these are tough too. I will probably post a few of them. Shot the same kind of dragonfly a year ago and had the same problems too.

Click to expand...

I'd be curious to see them!

Bas Hamstra said:

John K, post: 67727314, member: 321630"]

Tech Specs: Canon 90D (F11, 1/125, ISO 200) + a Canon MP-E 65mm macro lens (set to 2x) + a diffused MT-26EX-RT, manual mode, key (A) on a Kaiser Adjustable Flash Shoe set to 1/16 -1/3 and the fill (B) set to 1/32 -1/3. This is a single frame taken hand held. In post I used Topaz Photo AI and Clarity in that order.

That's the kind of performance that I've been trying to get out of a macro twin flash for the past 15 years. Funny thing is that I might switch to a Canon EL 100 just so I don't have to deal with two specular highlights.

Click to expand...

Click to expand...

--
Also known as Dalantech
My New Book: https://www.blurb.com/b/11015692-extreme-macro-the-art-of-patience-volume-ii
My Blog: http://www.extrememacro.com
My gallery: http://www.johnkimbler.com
Instagram: https://www.instagram.com/extrememacro
Macro Tutorials: http://dalantech.deviantart.com/gallery/4122501/Tutorials

Click to expand...

Bas Hamstra said:

It would be nice if we could "measure" diffuser quality somehow to criteria:

• No hard shadows (soft light) anywhere
• Is the light evenly distributed over the subject
• Is the underside of a subject at least somewhat lighted
• Specular highlight control
• Does the light fill the diffuser surface completely evenly
• Is the subject not rendered too flat (for example too much light from straight ahead, or with all shadows completely eliminated)
• How well does the light reveal texture in surfaces

Click to expand...

I agree it would be nice, but to get decent "measurements" one would have to make a standardized test (as you mentioned at the end). The issue I see with a standardized test for something like diffusion is that the properties of a diffuser can change pretty rapidly as variables of the test change even a little, as it sounds like you saw when varying the magnification from 0.5 to 1.3.

That said, I do certainly agree it would be nice if we could have an effective standardized test for diffusers

Bas Hamstra said:

I think most problems are with specular highlights. Consider the following pictures, they are completely unedited. Dark shiny reflective material, like beetles, with curves. The curves are where the speculars show up.

Click to expand...

Reflections, and especially specular highlights, are certainly my biggest issue with many diffusers, though I think my stance on the topic is a bit uncommon (I think that since reflections are sometimes unavoidable, round, "sun-like," reflections are important).

Bas Hamstra said:

First is AK diffuser, second is Popeshield, third is mini octabox shining 30 degrees angle down/forward. The flashcap left on for all. TTL metering. Let's call specular highlight SHL. With the same light level for all, the popeshield, with no reflector at all, has the lowest intensity SHL. The softbox, with silver reflector inside, makes light strongly directional, and causes the most intense SHL. The AK diffuser sits in between (white reflective material in stead of silver inside). Reproduction ratio = 1:2.







This is just one aspect, but I which there was a standard test.

Click to expand...

It would definitely be nice if someone could figure something out. Thanks for posting, this was fun to think about.

--
Lily Ayres (she/her)
Macro, wildlife, landscape, and occasionally sports. I'm a gearhead who thinks gear is often overrated. I don't use generative AI or Adobe.