rmpsrpms Loc: Santa Clara, CA

Been a while since I posted here. I've been doing a lot of stacking and 3D/perspective rendering, mostly detail shots of coins. Recently I upgraded my system to have an automated XY stage, and can now do stack and stitch technique on full-coin shots. This is allowing me to fulfill a goal that I've had for the last decade of presenting a single image of a Cent that can be zoomed-in to show the details of die varieties and their markers. This would replace the usual method of zooming-in on each marker and shooting it at 3x-5x magnifications. What I have been doing is shooting a panorama of 6 images, each shot at 2x magnification, then stitched together to form a complete image of the coin. This results in typically a 9600x9600 (92.2MP) final image. That size image is difficult to share, but I have been using the EasyZoom hosting site, which has a simple and effective interface for viewing large files.

Take a look here for an example of my recent work:

https://easyzoom.com/image/125112

alx Loc: NJ

Beautiful depth and detail. Really shows the age and wearing on the coin incredibly. Congratulations.

jak86094

This is fascinating. When you mention die varieties and their markers, are you talking about variations in the dies used to make the coins? For example in the example attached to your message I note the following: 1. The stamping of “In God we trust” on the front of the coin, it looks like the die did not completely form the final “...ust” as if the die did not hit the coin evenly; 2. The mint code “D” under the date appears to have been struck twice (making a “DD”); and finally, in the left hand stem of grain, there appears to be a scrap of some metal embedded in the coin. Are these the kinds of items you are trying to capture? If not, maybe you can explain better for us novices. If so, then I would assume coins struck with another die would have different “markers.” I’ll be watching for your answer.

napabob Loc: Napa CA

I'm impressed .............nice job

rmpsrpms Loc: Santa Clara, CA

You have it about right:

1) The weakness in IGWT is due to insufficient force during striking that did not bring up the metal all the way. This can change from coin to coin,so is not a die variety. It is very common so is also not considered an error, just a variation in the minting process.

2) Mintmarks in US coins from early days up until 1992 were punched into the die by hand. It often took 2 or more punches to sink the mintmark punch deep enough, and if there was misalignment between punches, a "Re-Punched Mintmark" (RPM) was created. This is a true die variety since every coin struck with this die would show the RPM. This creates a subset of coins struck at that mint for that year, and the number of coins struck varies due to the life of the die.

3) The blob of metal in the left wheat grains is due to a missing piece of die metal allowing the planchet metal to push up and form what is called a "die chip". Coins that were struck early in the life of the reverse die do not show this characterstic, so it is not a die variety, but is known as a die error or sometimes a mint error. The importance of this die chip is it is a marker to help identify the "Stage" of the RPM die variety. Early Stages of the RPM do not have the die chip, but later stages do. This allows the specialist to determine when in the life of the dies the coin was struck. Sometimes these markers are more prominent than the die variety itself (not in this case, the RPM is very prominent) and the markers can be used to verify particular varieties and stages.

jak86094

Thanks so much for the additional information...all makes sense. Can you share some of the additional information that might be available from your example...kind of show how you would use the stacked image and why you do it?

rmpsrpms Loc: Santa Clara, CA

Sure...here is the online reference for this particular RPM:

http://www.varietyvista.com/02a%20LC%20RPMs%20Vol%201/1956DRPM001.htm

By looking through the images of the various stages, you can determine this coin is from Stage F.

I am actively searching for a Stage H of this RPM. Stage H has a "BIE", which is a die chip/break between the B and E of LIBERTY which looks like an "I". These are common from the 1940's through the 1950's.

Here is an example of a BIE from 1955-S taken with the same Stack and Stitch technique:

https://easyzoom.com/image/125304

Mark Sturtevant Loc: Grand Blanc, MI

Very interesting and exacting stuff. I had no idea that this was something that people follow. But of course it would be, just like any genre of antiques with different but traceable designers and manufacturers.

rmpsrpms Loc: Santa Clara, CA

This coin collecting specialty started in 1955 when the mint released a small number of 1955 Doubled Die Cents. They were publicized widely and their value skyrocketed, creating a new sub-genre to the hobby.

When a coin die is manufactured, it goes through two "hubbings", where the coin "hub" (which has raised features like a coin) is impressed into a blank die twice, with annealing between the hubbings. This gives rise to the possibility of misalignment, or in some cases a different hub (with slightly different features or design) is used for the second hubbing. The result is a Doubled Die, and since every coin struck from the die has the doubled characteristics, it is a type of die variety.

jak86094

Once again, thanks for all the wonderful information. I assume then, that some collectors are trying to find all of the version of a coin from a particular year: mint, hub, die, etc. Then are there additional rarities in a coin "set"? Here's one more question you can probably answer...are the front and back of coins always aligned correctly or is that another feature that can vary from coin to coin or batch to batch? Just curious, and you seem to have the knowledge to be able to answer such questions. Have a great day.

sippyjug104 Loc: Missouri

I am quite impressed. Fabulous work and I really like the view of your work on the easyzoom website.

rmpsrpms Loc: Santa Clara, CA

It would be quite a task to find all varieties from any given year. Certain rare issues, such as 1909-S and 1909-SVDB have been fully analyzed and collected, mostly by the certification services in order to ensure they can identify counterfeit and modified coins. But for later issues, with a large number of dies used, it would be a near impossible task to do this. What folks have done is to identify all the unusual die varieties, which is a (theoretically) collectible set of coins. For the Lincoln Cent series until 1958, there are perhaps a few thousand unusual, die varieties, ie with unique and identifiable RPMs or Doubled Dies. So far no one has completed such a collection, but indeed there are quite a few specialists working on it.

Regarding die alignment, they are almost always aligned 180-deg, but there are many cases where the die has come loose and does odd things like rotating, shifting (causing an off-center strike), etc. These are not common, but are not rare enough to command a high premium.

jak86094

Once again you have provided a cogent and enlightening explanation. Thanks and best of luck with your projects.

fjwallace

Nice work! What are you using for an automated XY stage and are you using PS for stack and stitch or other programs. Thanks!

rmpsrpms Loc: Santa Clara, CA

I built my own XY stage using a pair of THK KR15 linear rails with NEMA-11 stepper motors. The Z-stage is my original THK KR20 with a NEMA-14 stepper motor. They are controlled with the SnS hardware/software controller solution offered by mjkzz.com, who also offer a rail solution, but I chose to build my own.

For stacking, I use Helicon Focus, and for stitching I use ICE. It is not supported any more, but it works very well for this type of panorama, and it's free!