How to photograph glossy surfaces to show defects more clearly?

Question

I want to take a photo of an Apple Watch to show the scuff marks and the scratches on the watch face. However if I take a short cut and use an mobile phone to take a shot, because of the reflectiveness of the watch face surface, the watch face appears to be smooth.

I have read this SO answer which seems to be related: How do I photograph coins with a glossy surface?

However I find it hard to understand part of the answer:

The first thing to do is move the light to the side and put a dark object where it used to be. The dark object is now reflected in the coin, but that's not noticeable

I just find it incomprehensible to me. Maybe because I can't actually visualise the arrangement.

Therefore I want to ask this question specifically for an Apple watch. I as a hobbyist have access to a mirrorless camera (which is hopefully more capable than a mobile phone camera) but I don't have any sophisticated studio lighting equipment or light diffuser.

How can take a photo of the watch face that can shows the defects?

The SO answer appears to show how to reduce reflections and possibly hide defects. — xiota, Sep 25 '19 at 17:51
@xiota You're probably right. I actually have a poor understanding of the root cause of the smooth appearance of the watch face in the photo in the first place. — Anthony Kong, Sep 25 '19 at 22:27

xiota · Accepted Answer · 2019-09-25T23:03:16.783

How can take a photo of the watch face that can shows the defects?

To see defects, it's helpful to use Live View and change the angle of the object until scratches "light up" (they will appear brighter than the rest of the surface). A hard (vs diffuse) light source might work better.

If manual focus is available, focusing precisely on the scratches with sufficient depth of field will make them more visible. Here is a photo that was taken of the LCD screen of a camera resting on a table. The lamp is positioned up high with the taking camera at an angle using auto exposure at 32mm f/5.3.

Another answer advises, "the light should be low... almost parallel to the glass... so the bottom of the scratches doesn't see the light and appears as a shadow". That will hide the scratches because you will have dark scratches against a dark background.

score 2 · Answer 2 · answered Sep 24 '19 at 14:45

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If you want to show the scratches the light should be low (light rays almost parallel to the glass) so that the bottom of the scratches doesn't see the light and appears as a shadow. IIRC when I had to do this the best camera position was with the light in the back, slightly on the side to not cast a shadow.

answered Sep 24 '19 at 14:45

xenoid

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This will hide the scratches. When the light is "almost parallel to the glass... so the bottom of the scratches doesn't see the light and appears as a shadow", the scratches will not be clearly visible because you will have dark scratches against a dark background. Here is an image to demonstrate. – xiota Sep 25 '19 at 22:52

score 1 · Answer 3 · answered Sep 25 '19 at 19:42

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With some materials, a polarizing filter can help - or even cross-polarized lighting (you put polarizing filters on both your camera and your light(s)). Especially so if the uppermost surface of the reflective material is translucent: Most translucent plastic materials shift polarization. When they are damaged or stressed, they shift polarization differently.

answered Sep 25 '19 at 19:42

rackandboneman

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Is this conjecture, or have you done it? Do you have a photo to demonstrate the effect? – xiota Sep 26 '19 at 04:32
Done it in microscopy (where it is a well known technique to see defects in plastic items), not photography. – rackandboneman Sep 26 '19 at 08:26
A photo to demonstrate would improve this answer. – xiota Sep 26 '19 at 12:41

score 0 · Answer 4 · answered Sep 30 '19 at 09:18

About the sentence that you can't comprehend:

It means that you should put your light source at the very right or very left of the object. To do it you can put you watch on a surface like a table and put a lamp directly on a table too. In a way that your light source touches the surface of the table. But not too close to the watch (12 inches).

Now put a dark cloth on your head (yes, that's right!)and try to cover every other light source that being reflected on the surface of the watch.

Much easier solution:

just turn your camera flash on and take a picture like the one you uploaded here but get a little closer to the watch. If it didn't work tilt the watch a little and try again.

How to photograph glossy surfaces to show defects more clearly?

4 Answers4