Last image, maybe some progress. Question for photo folks: why does this happen?

pharmer · January 31, 2006 4:49AM

I like to take raw images prior to submitting, and I just center 1 reveal bulb's "corona" on the coin, holding camera and coin in hand. My question is, why does this direct light reflection wash out the luster like this? Seems counter-intuitive that the bright luster that this coin exhibits would be diminished, rather than enhanced?

I realized how much it suppresses luster when I took this image with the corona offset, next to, not on, the coin. Now some luster shows, but the light is now indirect instead of going directly from the bulb, to the coin, and then to the camera. Why does direct light on the coin suppress luster? Thanks.

kryptonitecomics · January 31, 2006 4:53AM

Why don't you send me the coin and I will experiment and come up with ananswer for you in a couple of months?

pharmer · January 31, 2006 5:09AM

This old thing, Shane? I'll take it under advisement. Just took this image, same thing, has great spotlight luster, but you wouldn't know it.

pharmer · January 31, 2006 1:20PM

Same with the reverse on the last one. Maybe I need to buy a second light bulb?

ldhair · January 31, 2006 1:36PM

Don't think you need a second bulb for that great looking eagle.

mozeppa · January 31, 2006 1:41PM

pharmer...got a question for ya...

are you using a "SLR" camera?....one you can see the shot thru the lens or ...a camera with one of those 1" x 2" view screens

MikeInFL · January 31, 2006 1:44PM

What do you mean by your use of the term "corona"?

mgoodm3 · January 31, 2006 1:45PM

Think of it this way: With lower angled light you get very narrow bands of luster with wide intervening darker areas. As the angle of lighting is increased the width of the luster bands gets wider and wider. As the angle approaches the same angle as the camera (reflecting the light directly off of the coin), the luster bands widen until there are no gaps between them. At that point, all you see are luster bands, there is no dark between them anymore. So you see a white sparkly coin and you see all of the color.

coppercoins · January 31, 2006 2:13PM

The way I tend to explain it is that the surface of a coin is a myriad of tiny mountains called "flow lines" - if you look at a coin under 100 power, that's all you see...ridges, peaks, and valleys. There's nothing "flat" about a coin unless it is either very early die state or a proof. When you have light off at an angle, it reflects off of the sides of the mountains pointing toward it. That and the shadows on the other side of the mountains cause luster. If you shine light straight down on a mountain, all sides are lit, thus you have no shadows, thus no luster.

pharmer · January 31, 2006 2:17PM

Thanks for trying to help me, guys. I need to solve this, as I'm catching a lot of flack that my images aren't accurate, but they are as accurate as possible. Light, coin, camera, images are as is. I thought it would bring the true colors out, and it does, but without the luster that's there they look wrong.

Just basic Nikon 4200. By corona, I mean the round white reflection spot off of the 2x2 mylar. I look into the 2" screen until the spot is covering the coin and shoot. Nice color, no luster is the result. Is the camera make an adjustment? I didn't think so. Off of plastic, of course, and without a filter I have to angle my lights at about 45 degrees when imaging a slab. But I want to image raw

Mark, I'm not quite getting that, but I wish I could. I do understand the physics of visible light transmission, so you can get technical. This coin has both untoned and toned areas, and the corona is offset to the south east, just a sliver was over the coin. Now some luster makes it to the camera. How come? The angle of incoming light is only slightly off of directly above, and with the offset much less light is hitting the coin, but luster has appeared. With less incoming light. That's what I'm not getting.

pharmer · January 31, 2006 2:22PM

Chuck, I was still composing when you posted. I understand what you are saying, I guess I just didn't understand what luster is. I've been thinking it's reflection, but it's not. Since the offset, angled light, like Mark said also, does produce luster, now I get it. Thanks everyone for the help.

mgoodm3 · January 31, 2006 2:48PM

low angle lighting - narrow band of luster from 8 to 2 o'clock

Medium angle - luster band gets wider

high angle - even wider band of luster.

Now extrapolate out to ultimate high angle lighting - reflecting the light directly off of the coin like a mirror - the width of the luster bands go infinite and they cover the entire coin. All you see is luster, no dark intervening areas to show the luster for what it is.

CoinResource · January 31, 2006 2:49PM

Read about 'specular highlights' on a photo site. cm

pharmer · January 31, 2006 3:30PM

OK Mark, I get it now. I will check that out, coinresource. I'm glad I asked, and I'll alter my imaging to fix the problem. Thanks all.

Coindexter · January 31, 2006 4:55PM

Pharmer, the biggest question here is where do you get all of these awesome Washingtoners?

MikeInFL · January 31, 2006 5:12PM

<< <i> By corona, I mean the round white reflection spot off of the 2x2 mylar. I look into the 2" screen until the spot is covering the coin and shoot. Nice color, no luster is the result. Is the camera make an adjustment? I didn't think so. Off of plastic, of course, and without a filter I have to angle my lights at about 45 degrees when imaging a slab. But I want to image raw

Mark, I'm not quite getting that, but I wish I could. I do understand the physics of visible light transmission, so you can get technical. This coin has both untoned and toned areas, and the corona is offset to the south east, just a sliver was over the coin. Now some luster makes it to the camera. How come? The angle of incoming light is only slightly off of directly above, and with the offset much less light is hitting the coin, but luster has appeared. With less incoming light. That's what I'm not getting. >>

I think what you are seeing is the often-discussed tradeoff between showing luster and showing color. If you reflect the light directly off the coin and into your lens, as I believe you are Pharmer, you will show the color of the coin best. If you instead reflect the light off the coin and past the lens, as Mgoodm3's photos show, you will show the luster the best. It is a tradeoff.

I've found that toned MS coins show the best color when shot with the light at the point just before reflecting off the mirrors. This way some luster is preserved in the shot. For proof coins, direct shots off mirrors look the best as they reflect the colors the best. Add a slab to the equation and I've yet to figure out a way to show a toned proof coin in its true glory.

Also, I think you might have a white balance problem as well. Shoot a pure white piece of paper (or a grey card) and post the results.

Hope this helps...Mike

pharmer · February 1, 2006 4:25AM

Thanks, Mike, I will do that. You are right, some of the color is lost, but the coin is brighter, more like it actually looks.

shylock · February 1, 2006 4:45AM

To me the answer is simple: Reveal bulbs are not very good for capturing luster.

MikeInFL · February 1, 2006 7:29AM

<< <i>To me the answer is simple: Reveal bulbs are not very good for capturing luster. >>

I disagree. Technique is more important than bulb type...Mike

pharmer · February 1, 2006 12:45PM

I think the direct, on the coin light, has been the problem. Now when I have that spot of light on the 2x2, next to and not on the coin, it looks better. I'll do one more image, and see if it's worth posting.

pharmer · February 2, 2006 12:10PM

I think the offset light spot is going to help, giving up some color but gaining some luster. And I realized as I was doing this image that I'm shooting under our fluorescents in the store

as well as the one reveal bulb, so I turned them off. Thanks again for all the advice.

Last image, maybe some progress. Question for photo folks: why does this happen?

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