Is there a trick to photographing overstruck coins to make the original more visible?

[messydesk]

A few general answers:

Regarding revealing undertypes in general with conventional photography, what you need is contrast between the surface of the coin and the edges of the design elements of the undertype so that you can see them. If the coin has surface dirt on it, you will have a harder time achieving this than if it doesn't. Soft, axial lighting would be the best way to light a coin.

Regarding measuring relief, this information is typically more interesting than it is useful. In the case of undertypes, I don't think there's enough of a difference in relief signal to overcome the "noise" signal of the surface of a circulated coin from wear, damage, and dirt.

Regarding spending one's money on photo gadgetry, always start small and get advice from someone who understands your goals.

Regarding how else to reveal undertypes, I don't know if anyone has experimented with electron backscatter diffraction, but this might be able to reveal history of the deformation of the metal struck into a coin much as Nic-a-date does destructively. The smooshed undertype should pop out. Mind you, this is national lab or major research university technology, so not practical unless you have connections who you could convince that they could publish a paper on using EBSD to show undertypes on overstruck coins and that it would be worthwhile for them to do it.

Regarding undertypes on Morgan and Peace dollars, I'll refer you to my previous answer.

[vampicker]

Here's a solid example of a piece that's clearly been overstruck. Not a great deal of the host coin is still visible, but there's enough to ID the undertype. I don't think his images required anything more that his usual level of skill.

https://www.civilwartokens.com/Listing/ ... -War-Token

[fogie]

I have a lot I'd love to send to you, vampicker, can't afford the shipping with enough insurance to feel safe. Certainly can't afford the expensive equipment mentioned here, or even to rent, but knowing what equipment could be used is a start, maybe I'll find a person/company/university lab/museum that will grant me access.

... What part of the country do you live in?

[RogerB]

This short section about axial lighting is from a book on numismatic photography I wrote about 25 years ago. If you have questions just ask.

It's very simple and effective, but one has to be precise. The plastic pipe is a baffle to prevent stray light from hitting the coin, and the light must be a small as possible -- as close to a point as you can get.

Axial lighting_Page_1.jpg (130.38 KiB) Viewed 468 times

Baffle ---

baffle.jpg (93.55 KiB) Viewed 468 times

Really simple beam splitter ---

beam split.jpg (110.91 KiB) Viewed 468 times

[UNCLE BINGO]

Roger does this technique have any effect against glare produced from the light reflecting off a TPG holder ?

[messydesk]

Roger does this technique have any effect against glare produced from the light reflecting off a TPG holder ?

You can't use it for coins in slabs.

[UNCLE BINGO]

That's what I thought .but asked just the same. Thanks

[RogerB]

Roger does this technique have any effect against glare produced from the light reflecting off a TPG holder ?

Most of the best lighting techniques are useless with slabbed coins and clear plastic holders, as messydesk noted. The primary difficulty is reflection off the slab's front and secondary surfaces of plastic. A second problem is internal reflection the interferes with lighting the coin. Third come defects and irregular refraction within the piece of plastic. This causes false images and distortion. Fourth, partial polarization which produces color fringes and bands related to internal stress of plastic. Mounting and sealing of holders creates nonuniform stress.

Messydesk can tell you about lighting slabbed coins.

[coinnoob7]

I'm in North Texas.

My other question about measuring relief isn't related to my question about overstrikes.

Here is my photography setup and an example.

mycollect_0550ee73f396fcf40c7de7d8eda9d6388815a6bfe97a53e4a3e9d422f73758e9.jpg (74.78 KiB) Viewed 428 times

Since I started doing coin photography I've wondered if there might be some solution to doing axial lighting of slabbed coins (though the solution might be the TPGs changing slab design, which is unlikely). For example they could make the slabs thicker and mount the coin at an angle. I'd love to see that as it would let us see the coins edge better, but since they're in the business of selling photography services too I doubt they'll ever do this. There might be some trick involving polarization and anti glare films but I haven't figured it out yet.

The thing that isn't standardized is the distance of the light bulb or rather the angular size of the light source. If you use a single small LED, almost a point source of light, you'll notice you can see more die polishing lines and fine scratches. If you use a large diffuser close to the setup, the coin looks very flat but you have the benefit that the areas usually shrouded in darkness around design elements are now visible.

I had purchased one of those circle drawing tools on amazon for $20 to put over my light source so I could control the size, but noticed its mechanism was grinding itself and making dust I feared could pose a problem.

The other tools I've found useful are a labjack to move the platform up and down, and a microscope stage for moving it up/down/left/right. This is useful for not having to slide the coin once its set down, and it helps for making super high resolution images by stitching together many closeups using a tool called Microsoft Image Composite Editor. I've found though this method can introduce some false doubling and other distortion if photos don't overlap enough.

The mirror allows me to make sure the camera is perfectly perpendicular to the surface by moving the focus to the lens itself and centering it.

After some experimenting I don't think focus stacking software is going to work for measuring relief. The result is much too noise and it sortof works on larger design elements but text and rays are a total mess. I also think my lens stepper motor isn't actually adjusting the focus sometimes when I click the button on my PC, which completely ruins the concept of counting steps between different parts being in focus. Someday I'll scrape together the $ to rent a scanner or find someone who will let me use theirs and report back. Thanks for the help.

[coinnoob7]

I might end up doing something like this if I can acquire the software.

https://www.reddit.com/r/coins/comments ... _comments/

[RogerB]

coinnoob7 --- Good info post !

Axial lighting uses a small light source which improves clarity of fine detail. Using a larger light (or reflector) works contrary to the purpose.

RE: "After some experimenting I don't think focus stacking software is going to work for measuring relief."
Correct. Measuring relief can be done with a calibrated vertical micrometer on a microscope. No common photo technique is suitable.

(One of the major TPGs learned this the hard way a couple of years ago when they convinced themselves a coin was "high relief" when it was proven to be imaginary due to false measurements using image stacking. They still refuse to admit their mistake, but have not done this again for any coin or medal.)

[coinnoob7]

https://youtu.be/y6n852Im9zU

[coinnoob7]

Screenshot 2023-10-12 111442.jpg (170.18 KiB) Viewed 327 times

[coinnoob7]

https://youtu.be/y6n852Im9zU

really, no comments on this?? does anyone see it?

[coinnoob7]

this version is higher quality with blended frames to make the animation smoother

https://youtu.be/3idgNKmK1pA

[coinnoob7]

Screenshot 2023-10-12 111442.jpg

there is so much going on with this coin. I've searched every coin 25-29g, 35-39mm, from every country for 500 years, and exonumia, and patterns, and I can't figure out what the overstrike is. Beginning to think its two or more smaller coins. Has such an overstike ever been found?

Untitled.jpg (171.81 KiB) Viewed 267 times

Screenshot 2023-10-24 021652.jpeg (35.68 KiB) Viewed 267 times

[keilg1]

I say this as a neuroscientist as well as a VAMmer of some time: your arrow clearly points to something - but something likely insignificant (as far as VAMming goes). The brain is incredible at both recognizing patterns as well as creating them where they don't necessarily exist: we all fall into this trap by the design of the nervous sytem so don't take this personally.

I don't see anything of note at the end of the arrow - if anything it looks normal, nothing to do with an overstrike. Could be PMD, could be slight variation in the metal flow during the strike, a planchet defect, the residue of some long gone liquid droplet that evaporated but left a trace, etc. Way too many potential variables that are more easily explained than an overstrike.

We all need to play the odds here, and what is least likely is some ultrarare overstrike where the working obverse die was consciously struck over another working die - from another Morgan die or some other die - or was with a different die.

Sorry to sound rather negative (or harsh) as this is not my intention. My hope is to help us all learn how easily it is to head down a certain train of thought that ultimately doen't bring resolution.

Looking forward to hearing more from the (other) experts!

[RogerB]

Really good post !

[coinnoob7]

I say this as a neuroscientist as well as a VAMmer of some time: your arrow clearly points to something - but something likely insignificant (as far as VAMming goes). The brain is incredible at both recognizing patterns as well as creating them where they don't necessarily exist: we all fall into this trap by the design of the nervous sytem so don't take this personally.

I don't see anything of note at the end of the arrow - if anything it looks normal, nothing to do with an overstrike. Could be PMD, could be slight variation in the metal flow during the strike, a planchet defect, the residue of some long gone liquid droplet that evaporated but left a trace, etc. Way too many potential variables that are more easily explained than an overstrike.

We all need to play the odds here, and what is least likely is some ultrarare overstrike where the working obverse die was consciously struck over another working die - from another Morgan die or some other die - or was with a different die.

Sorry to sound rather negative (or harsh) as this is not my intention. My hope is to help us all learn how easily it is to head down a certain train of thought that ultimately doen't bring resolution.

Looking forward to hearing more from the (other) experts!

did you watch the youtube link I posted?

The arrow isn't pointing to something. It is the something. Look at the original pic I posted zoomed in on her eye. There's an arrow clearly above and to the right of it.

There is a banner with some text in front of her face.

On the reverse you can see text below the word AMERICA.

There is clear evidence of an overstrike all over this coin. I don't know what the coin was originally, I've spent lots of time in photoshop playing with overlays and every possible coin and pattern I could find that features arrows, stars, and text in roughly the right place.

Look closer, this is not pareidolia or hallucination.

[UNCLE BINGO]

I have no axe to grind here , but I am curious about what year and MM the coin being photographed is ?