Lighting Challenge #10: White on White

[sk66]

Just as the Black on Black challenge was really about controlling/using falloff, this challenge is really about negative lighting. Whenever I think of "lighting" I'm really thinking of reflections; if it's not black that's because it is reflecting light back to the camera. And I'm thinking about shadows, because without shadows/contrast there is no detail... So I'm really thinking about everything else other than lighting. Negative lighting is creating a dark reflection in order to create a shadow and reveal shape/detail.

For this challenge our first task is to record a white background without blowing out the white subject. You might read elsewhere that in order to do that the background needs to be two stops overexposed, and that is correct in essence. But white meters as two stops over middle grey; it is not overexposed. And you do not need/want to blow out the background in most cases; that just causes additional issues like bloom, loss of contrast, etc. However, if the background has a texture (shadows) that is showing you will need to expose those as white and drive the rest into clipping. And similarly, you would need more flash power to drive a grey background into recording as white.

So how to light the background? We have quite a few options:

1. We can use a lack of falloff, and a lack of separation; the exact opposite of the last challenge. If your subject and the background are at essentially the same distance relative to the light, then a white background will expose as white when your subject is properly exposed... This is a one light solution. The problem with this approach is that your light source would need to be massive in order to not be hard. And if it is hard, then it's going to leave a hard shadow on the background... that's not always a negative, but it's not suitable for this challenge.

2. You can place your subject on a platform a good distance in front of the background and then light the background from below... this will create a gradient and uneven illumination which means that the nearer parts will be over illuminated/blown out; that's why you need the distance. You also need separate lighting for the subject.
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3. You could place your subject on a platform a good distance in front of a softbox you are using as the background... this will typically have somewhat uneven illumination which means that the brighter parts will be over illuminated/blown out; that's why you need the distance. You also need separate lighting for the subject.

4. You can use two softboxes and feather them across the background from opposite sides. By pointing them at opposite sides the background nearer the softbox will be brightest and falloff across the background, and the opposing softbox fills it in creating even illumination at all points. Because this doesn't require excess power, it also doesn't require additional separation/distance from the subject. In my opinion this is probably the best option, especially for larger subjects. You also need separate lighting for the subject.


But I decided to get tricky and combine concepts in order to accomplish this with a single 3ft softbox. Here is my setup:
AD200 bare bulb boomed in close. The angle of the softbox is optimal for illuminating the background so that it reflects back to the camera. The angle to the coffee cup is such that much of the light from the softbox will be reflected away from the camera. And the angle to the surface is such that the light will primarily be reflected up into the front of the cup and into the background. So, all things combined, the background should reflect the most light back to the camera and record the brightest.



But because the background/surface is diffuse (textured) some light will be reflected in all directions. And because the softbox is a diffused source from close it will throw light at all angles. And because the softbox is so close to the cup, and with the cup being highly reflective, I knew this approach would likely cause overexposure of the cup. So in order to prevent that I placed diffusion paper in a strip across the lower 1/3 of the softbox in order to create a gradient. I didn't even try it without the paper in place. The fact that the two zones are both diffused prevents there being a hard dividing line in the result. There's just enough space for me to photograph under the softbox.

So to summarize, I'm using a relatively large softbox from very close to create soft lighting and fill in shadows; and I have created a gradient to counter falloff.



After playing with the power and placement I got this result. I ended up changing the angle of the softbox to be a little more vertical, and placement of the cup moved just a bit. I wound up at 1/2 power because I arbitrarily chose f/8, 1/60, ISO 64 in a rather dim room with no lighting on... but none of that really matters; it's not "a recipe" other than starting with a black image without the softbox enabled.



This is a perfectly good result as most things white don't actually measure or appear as pure white; but that's not the challenge.
Increasing the exposure gets this after correcting the white balance (it measured a touch blue):


It's there and visible, but just barely. If your monitor is set too bright/uncalibrated you might not be able to see it hardly at all. So now we need to add the negative lighting. I used two small black v-flats made from craft board.



If the cup were a cylinder that may have been enough, but because the cup is curved at the bottom it's not quite right. And the flat on the right is too far forward; it's shadow/reflection doesn't go to the edge of the cup, making that side appear soft/blurry.


So I added triangles of black card to fill in the shadow to the bottom. It would have been better if I had more diffuse craft paper to use, but apparently I'm out. So I spray painted the back of some extra gold foiled cardstock I had (I don't use gold often). I considered just drawing the shape onto the paper directly with black marker... but I'd likely end up scrapping a lot of the roll. And I also changed the position of the v-flats so that the shadows/reflections are a little denser and all the way to the edge... little changes can make a big difference in the results!


I do believe I have lost just a bit of the lip in the back. I might have been able to retain it if I moved the cup a little farther from the background, but probably not... the angles mean it is almost certainly reflecting the softbox; maybe if I had changed the angle a little more so that the gradient step fell in a little different location. I don't think I could accomplish it with negative lighting in a single image, but probably with compositing.
And notice the reflection of the handle in the cup; technically it's the handle blocking the reflection of the v-flat... convex reflective surfaces are VERY challenging. To prevent that issue I would have needed to rotate the handle well towards the back, or maybe made the v-flat much larger to extend forwards more...I don't really know; I didn't notice it until posting this.

Overall I'm happy with the result as a single unedited image.

And here's what image review showed; the background overexposed but everything else is good. But histograms/blinkies lie and typically show overexposure if any channel reaches 250, so shooting tethered can help. It also would probably have saved me a few trips up and down the two flights of stairs.



It just occurred to me that I could/should have taken an exposure of just the lighting at a reduced exposure, in order to see it's exact pattern/character and place it optimally. But I didn't; and my studio space is on the third floor...

And here's a quick edit in Photoshop.





So, that's my attempt. Negative lighting works with anything that reflects light; and if the surface isn't completely black, it reflects light. I'm not particularly recommending the single light solution I used; I just wanted to challenge myself with a new idea/approach to the problem (new to me anyway).

EDIT:
I went back and took a picture of just the light pattern; because honestly, I was curious. It's pretty much exactly what, and where, I wanted.

 

[Barney]

I need to learn this, thanks for showing and instructions!

 

[Paulie-W]

This is way much harder than the last one.... Struggling but will keep trying.

 

[Garry Edwards]

This is way much harder than the last one.... Struggling but will keep trying.

Well, it's challenge No.10, we have to expect them to get harder

Real-world, white on white is rarely a first choice - Amazon insist on white backgrounds, eBay don't insist but mark down listings that don't have the main shot on white, but higher contrast is the usual order of the day. But, if we can create a good shot of white on white, without blowing out any of the important detail, we have an important tool, so it's very worthwhile having a go. Nobody should worry if they struggle, it's the learning process that matters, not the end result.

 

[sk66]

This is way much harder than the last one.... Struggling but will keep trying.

That's why so many resort to cutting it out in PS instead. TBH, often I am lazy and rely on editing much more than I should (crap product pictures for my website). And it's often a false benefit; because it takes more time to edit a poor image, and the result is still worse.

If you post a setup shot and result we may be able to give some suggestions to help.

 

[Paulie-W]

I'll have another go at the weekend, and post something up. I'll have to reset my film SIM settings as it's too red at the moment, so soc will look terrible

 

[Paulie-W]

Well here is my attempt. Only resized, nothing else done.

XT-5 35mm f5.6 iso 400 1/60th. Godox 685 1/64+3

 

[sk66]

Well here is my attempt. Only resized, nothing else done.

At first glance it's a decent result; but I'm not sure how much of it is "intentional."

It has a stronger shadow, but that's not necessarily a bad thing; with no shadow it would look like a cutout floating in space. The shadow is mostly because you light is smaller relative to the subject. And as is typical, the white pot isn't actually pure white; so that's helping separate it from the background. Or maybe it's the BG that's not pure white; or both... it's a very common issue.

It's also slightly underexposed (approx .25); if I set the middle of the background to white it looks quite different.

First thing I see is that your subject is too large for the setup, and it is too far back because your negative lighting is actually the darker room. I'll go through some of the finer points:



The green lines are where the white surface stops and the room/negative lighting begins in the reflection. The blue arrows are all the environment/ambient showing (negative and positive). And the orange arrows are where the pot is too far behind the negative lighting and it doesn't go quite to the edge, making it indistinct... i.e. the edge is showing the background. The easy answer here is to choose a smaller subject; and a simpler shape would make it easier as well. And to start with a much darker ambient exposure before the lighting is added (i.e. eliminate/overpower the highlight reflections with the lighting). For comparison, I used f/8, 1/60, ISO 64, with a 200WS strobe at 1/16; whereas you used f5.6, 1/60, ISO 400, with Godox 685 (maybe 70WS) at 1/64+3... i.e. you used about 4 stops more ambient and about 4 stops less lighting.

Lighting wise, it seems you chose the hard route and went with a single light. Do you know what your lighting pattern looks like, or what you expect it looks like? If not, you can't really know how/where to place it; or what to do to modify it. What I would suggest is to start with camera settings that result in a (nearly) black image without the lighting added. And then take a picture with the first lighting added, but well underexposed so you can see the pattern. That's a good way to begin any lighting setup. (assuming you didn't ...)

If you want to stick with the one light choice I think I would start by leaving out the inner diffusion, and maybe zooming out the flash to adjust the size of the hotspot... you might wind up with one or the other. The point being to create a (stronger) gradient you can use like I did, but then you would be discarding (not using) a lot of the softbox/light. I believe there is already something of a gradient as the left side of the BG remained below white when corrected, that's typical of a speedlight (fresnel light) firing forward in a softbox; unless that is the edge of the pattern...

Or choose one of the multi light options; they are more complicated in terms of required equipment, but simpler in execution.

(P.S. I hope that all comes across as constructive critique, not criticism)

 

[Paulie-W]

Wow, thank you Steven.
All very positive critique, and so helpful. Especially the little arrows.
To be honest, I do tend to go the trial and error route (more error). But will definitely take in the start dark advice.
As for the teapot, I just thought it was a nice shape

I really do appreciate your critique. So thank you again for taking the time with such an in-depth reply

 

[cargo]

Hi

I have had a try at this, it was fun to try and frustrating at the same time. @sk66 wrote "Do you know what your lighting pattern looks like, or what you expect it looks like? If not, you can't really know how/where to place it; or what to do to modify it"
If I could get to that level of knowledge i'd be very happy.

Gaz

1

2

3



Set up for 1,2,

Set up for 3

 

[sk66]

I have had a try at this, it was fun to try and frustrating at the same time. @sk66 wrote "Do you know what your lighting pattern looks like, or what you expect it looks like? If not, you can't really know how/where to place it; or what to do to modify it"
If I could get to that level of knowledge i'd be very happy.

It's usually pretty easy either because it doesn't much matter (e.g. adding fill), or because you are adding a specific effect (hard light). But when working like this you need to know cause and effect. Knowing what you are working with is pretty easy; point your light at a wall from a distance equal to its size, then take an underexposed picture of the pattern.

I think one of the first three images is missing? I want to make sure so I don't say anything misguiding.

 

[cargo]

@sk66
You are correct. That said I'll just edit the thread. I'm out at the minute and not sure what the third image would add to the thread.

Thanks
Gaz