The date on an old coin.

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mgoodm3
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The date on an old coin.

Post by mgoodm3 »

Nothing fancy, likely a D200, 28mm reversed lens, f8. about 2:1 mag. The crud in the 8 is the remains of a 7 - an overdate. 1808/7 half dollar.

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rjlittlefield
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Post by rjlittlefield »

Nicely done. :smt023

Lots of people have trouble illuminating shiny metal subjects, but it's obvious that have a great method.

I'd be interested to see & hear what it is, if perhaps you have time to show us, over in the Technical forum.

BTW, what's the story on that "overdate"? Did they actually stamp the coin twice, or rework the die? I'm clueless about coins.

--Rik

Cyclops
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Post by Cyclops »

Yea nice shot! Its great revesring lenses huh! First did that with my old Zenith-cheap and cheerful macro (Tho not so cheap with a modern AF camera!)

So they made an error making it and the coin was re-minted from 07 to 08?
Canon 30D | Canon IXUS 265HS | Cosina 100mm f3.5 macro | EF 75-300 f4.5-5.6 USM III | EF 50 f1.8 II | Slik 88 tripod | Apex Practicioner monocular microscope

mgoodm3
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Location: Southern OR

Post by mgoodm3 »

For most coin closeups they tend to benefit from lighting at a high angle to the coin (almost axial), but keeping it directional.

For higher mag images you generall can't get lighting at a really high angle (unless you are using true axial lighting through the lens, but I haven't tried it yet). In this case I bring the light in from one side - I typically use a daylight fluorescent source so I can get it in close. The fluorescent tube makse a fairly diffuse light already, but you may need to back it off to soften it up a little. The highlights can be pretty viscious from a low angle.

Regarding the coin - There are two typical ways for an overdate in a coin this old. Most of the elements were placed on the dies individually back then. In more modern times they have master dies that are used to make working dies - this adds all new ways to mess things up. There were lots of overdates in the early 1800's.

1) Die steel is expensive and you have a peefectly good 1807 die. Grind the 7 off and sink an 8 into it.

2) You screw up with the date stamps and put a 7 first.

Graham Stabler
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Post by Graham Stabler »

Assuming the die is a negative how do you grind off the & and sink an eight into it?

lauriek
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Post by lauriek »

That is nicely done! The lighting is really excellent!

What are those radial lines of 'grain' I can see there, I just looked at a coin in my pocket (admittedly a modern UK coin) and I don't see that effect...

mgoodm3
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Post by mgoodm3 »

To grind the date out you also gotta grind a fair amount of the fields to get rid of the number.

the radial lines are called flow lines. The metal flows into the die during striking under high pressure and gradually grinds these lines into the die. As the dies wear, those lines will get much more prominent and elements on the die will also start getting distorted.

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