Scanning Elongated Coins 101

Last edited January 12, 2017

I am offering my experience with scanning elongated coins.

I scan EC's mostly for trading purposes and to see which ones I already have in my collection.
I have scanned EC's and later re-scanned them because of a better technique, appearance or equipment.
If you have a lot to scan in your collection start off right by getting the proper scanner.
It's hard to determine what coin you have if the scan is .

Basically there are two types of scanners.  The first type is CIS and the second is CCD.

I have an HP All-In-One with a CIS type scanner.  I also have an Epson CCD type scanner (with LED lights).
Both were used in this review.

CIS - Contact Image Device
    Pros: Cheap to build, found in most All-In-One Printer/FAX/Copier/Scan
             Uses LED lighting
             Runs on battery power or USB 
powered
             Great for scanning text
             Built thin
             
Eliminates the housing unit
    Cons: 
Will not clearly focus on curved objects not in contact with the glass scanner bed
             On occasion it will not scan colors correctly, especially pink

CCD - Charged Coupled Device
    Pros: Great for scanning elongated coins because of it's depth of field focus and close to true colors.
    Cons: Costs to build are higher than CIS type because:
                It requires a housing unit
                Uses mirrors and lens to focus the image
                Uses fluorescent lighting (newer models use LED lights)

CIS type scanner will focus only on the portion that is in contact with the scanner glass.  If the elongated coin is curved the raised portion will be out of focus.

CCD type scanner will focus on the entire elongated coin even if curved.


Test Examples


Curved Coin Example

Elongated coins are flattened using extremely high pressure and generates a lot of heat.  During this process the heat bends the coin causing the coin to remain curved after it cools.  I picked a well curved elongated coin for this scanning test.

The left coin was scanned using a CIS scanner.

On the right the same coin was scanned with a CCD scanner.

Only the top and bottom portions of the 
CIS scan are in focus while the middle, raised portion is .
On the right the entire 
CCD scan is in focus, even the curved, raised portion.
The bottom picture shows the curve in the coin from a side view.


Wavy Test Example
I can only describe this coin as "wavy".  The below picture shows the wave.  The dot border is visible on the bottom of the coin where the design is.  This "Side View" scan was done on the CCD scanner.
Wavy example EC

Here are scans of this wavy coin with the 
CIS and CCD scanners:
The CIS scan is in focus only where the coin was touching the glass bed of the scanner.

Inside a 2x2 holder Example
If the coin is curved (and most elongated coins are curved) the portion of the coin not in contact with the scanner glass will be out of focus in a CIS scanner.  Here are examples of a vertical design and a horizontal design inside 2x2 elongated coin holders:

Horizontal

On the Maui Tropical Plantation coin in the CIS scan the words, the fruits under the words and catch notch are .


Vertical

In the CIS scan the middle portion of the Bucket of Blood Saloon coin is  where the coin is curved.


Elevated Scan Example

I picked a 2X2 holder containing an elongated coin that was fairly flat for this test.
The coin is almost entirely focused in the CIS scan with slight fuzziness on both ends.


I then placed the 2X2 holder atop two pennies on each end.
It's clear to see how distorted the CIS scan gets just from elevating an object slightly.
The CCD scan remained focused.


How to Check for a CIS versus a CCD scanner

When shopping for a scanner check the "Specifications" of a particular model to see if it is a CIS or CCD type.

Here are two examples of Epson Perfection scanners.
One is an Epson Perfection V370 and the other is an Epson Perfection V19.
Different devices are used for scanning.
The Perfection V19 has a CIS device while the Perfection V370 has a CCD device:

Epson Perfection


Conclusion: I'm not bashing the CIS type scanner; it has it's place. If you're scanning elongated coins use a CCD type scanner to get depth of field focus. Also, newer CCD scanners use LED lights and the costs have dropped.


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