How do I photograph coins with a glossy surface?

Question

I am trying to photograph my coin sets. The coins are encased in a postcard-sized glossy paper that acts as mirror.

I need to position my camera exactly on top of the card coin set. Unfortunately, when I do this, my reflection is seen on the glossy paper and also get captured in the image. The reflection vanishes if I move the camera too close to the card, but then I need a lens with a closer focal point.

What is the suggested way to take pictures of a glossy surface, avoiding the reflection on the surface?

score 16 · Accepted Answer · answered Oct 14 '11 at 17:25

The coin reflects light. With a light shining straight on it, much of it may be reflected straight back at the camera:

enter image description here

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:

enter image description here

There are still many specular highlights on the relief and lettering, reflections of the light and of other bright objects in the vicinity. Minimize those by surrounding yourself with a flat, black environment. This last photo was taken from above with a black cloth draped over photographer and camera:

enter image description here

(All three images are of the same coin. Some noise reduction was applied, but no contrast enhancement was performed in any of them. The softness in this last image is because there was much less light to illuminate the coin: because these images were handheld, this required a high ISO and large aperture. For good work you will use a tripod, of course, allowing a smaller aperture and low ISO, because a long exposure is no problem.)

fantastic answer. thanks for posting the images. they really help to make the point. I have faved the question just because of your answer. :) — AJ Finch, Oct 26 '11 at 11:01
Exactly what I was thinking. You stole my answer. (Seriously) I would have just rephrased my answer, but since you already got the correct answer, I'll just refrain. Besides, if I rephrased my answer to mean the same thing, and that was exactly what you said, to some, it would appear just down right plagiarism. Anyway, Good answer. — J. Walker, Mar 28 '12 at 00:57

ElendilTheTall · Answer 2 · 2011-10-13T07:47:22.053

3

You might try using a circular polarising filter, which can eliminate reflections on glossy surfaces. They reduce the amount of light coming into the camera so if you're not already you should use a tripod to make sure you're getting sharp shots. They are relatively cheap, around $30.

edited Oct 13 '11 at 07:47

answered Oct 13 '11 at 07:32

ElendilTheTall

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If I'm not mistaken, for using a CPL he needs a lens with non-rotating front element. – fahad.hasan Oct 13 '11 at 07:55
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Not necessarily, it just means you have to adjust the CPL after focusing. Not too much of a problem considering he'll be on a tripod and the camera will be the same distance from the subject each time. – ElendilTheTall Oct 13 '11 at 08:00
Where do you buy $30 CPLs?! Please share! Things are stupid expensive! – dpollitt Oct 14 '11 at 18:44
http://www.amazon.com/HOYA-52MM-Circular-Polarizing-Filter/dp/B00006HOAN/ref=sr_1_1?ie=UTF8&qid=1318618499&sr=8-1 Granted this is 52mm – ElendilTheTall Oct 14 '11 at 18:55
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I thought polarizers didn't work on metal? http://en.wikipedia.org/wiki/Polarizer - "[Circular polarizers] are used as polarizing filters in photography to reduce oblique reflections from non-metallic surfaces..." – anon Oct 17 '11 at 16:08

score 2 · Answer 3 · edited Apr 13 '17 at 12:43

2

You don't actually have to position your camera on top of the card coin set, you only need to make sure the camera sensor is parallel to the card to prevent converging lines. This means you can move your camera off to the side to prevent reflections and simply crop the resulting images to the view you'd get if your camera were right on top.

If you want to avoid cropping then you can use a tilt-shift lens at maximum shift, but these lenses are incredibly expensive!

How do I photograph coins with a glossy surface?

3 Answers3

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