One of the most wonderful creations from God is light. Light plays an important part in our life, without light, the world might not exist, humans might not survive. Without light, we wouldn't know what is photography, we wouldn't have the luxury to enjoy nicely detailed cars. However, in order to judge your detailing work accurately, you have to know how to spot paint defects with proper lighting.
To make it basic and simple, there are generally two types of light: hard and soft light. Hard light is produced by a small light source (in relative to the subject size) and produces harsh shadows on those areas which the light source can't illuminate directly. Imagine your room is only lit with a small incandescent light bulb hanging high on the ceiling (more distance), what will you see around you? Yes! The darkside of you! Just kidding, I was referring to your shadow. A huge light source which is so far away from the subject, such as the sun, will also produce harsh shadow, HIGH contrast.
On the other hand, a soft light is produced by a large light source (again, in relative to the subject size) and produces very soft or even no shadow on areas which are not illuminated directly. An overcast day with the sun behind a thick blanket of clouds will make the light source huge, hence we get soft light, LOW contrast. Even if there're shadows, the transition between the highlight and shadow is smooth.
OK, enough of the introduction. Now apply it on car detailing. If you observe the paintwork under hard light source such as a halogen worklamp mounted on a tall lightstand, you will be able to observe swirls/scratches easily. Same goes to observing the paintwork under the harsh sun light (without clouds covering the direct sunlight). The HIGH contrast caused by the hard light source shows up more difference between the highlights and shadows. Since the scratched paint is uneven, hence it's not able to reflect light perfectly. The deeper the scratch, the easier we can spot it.
Now, observe the paintwork under an overcast sky. Most probably you won't be seeing much of scratches/swirls as compared to the previous scenario. But you didn't do anything to the paintwork! Where have most of the scratches gone? By knowing that overcast sky will produce soft light, hence LOW contrast. The light is coming in every direction, illuminating every corner, and in this case, the scratches/swirls. The difference between the highlight and shadow level isn't great. Got what I mean?
What if you're observing the paintwork in a car detailing shop with dozens of fluorescent lights? The light does not only come from all over the ceiling, but also the side walls (light bounces and diffused!). Yeah, at that moment you'll think that your car is almost swirl-free, but the moment you switch off all the fluorecent lights and start illuminating your paintwork with just ONE halogen worklamp which is positioned far away, you might be frustrated again. But if you're using a small LED torch light, you can go much nearer as the light source is much smaller compared to the halogen worklamp.
Think about it, it might help you to see/avoid defects better. I'll add-in some photos if I'm able to shoot some good samples. Also, I'll cover more on spotting paint defects on different types of paintwork and colour.
Labels: lighting scratches swirls defects detailing
