Imaging Coin Surfaces

[Ray Parkhurst]

I'm trying out a new (for me) imaging technique that is giving promising results for showing strong detail on coin surfaces. I finally got it set up right to give just the right magnification to show Lincoln Cent date and MM in the full image field. Here's what the technique gives for my heavily-toned 57D that I use for most of my image comparisons:

[wavysteps]

Very nice picture. Can you give us any insight to what that new technique is?

BJ Neff

[Ray Parkhurst]

Very nice picture. Can you give us any insight to what that new technique is?

BJ Neff

Certainly...

I'm using a Nikon 5X CF Plan infinity-corrected objective mounted on a Nikon 150mm EL-Nikkor which is in turn mounted on a bellows. The 150mm acts to re-focus light from the objective onto the sensor. The combination gives a nice, clear image at around 3.75x magnification.

The image is a composite of 5 individual images at varying focus planes "image stacked" to create a single image in focus in all areas. I use CombineZP to stack the images.

For lighting, I used a single LED at approximately 11:00 and coming in from a very low angle to give shadowing of the surface features. The LED is a Jansjo gooseneck desk lamp from IKEA. Getting the right position to highlight the features without too much shadowing or highlighting, and the right angle to bring out the surface textures, takes a little trial and error.

[wavysteps]

Thank you for the explanation. Your photo is excellent.

BJ Neff

[Tuebits]

request

Ray, are you taking request. Is so, i'm requesting a 1956 cent date photo.

Nice Picture.

Tuebits

[Ray Parkhurst]

Ray, are you taking request. Is so, i'm requesting a 1956 cent date photo.

Nice Picture.

Tuebits

Here's a 1956-D RPM#1. This coin has almost no toning and is very lustrous, so contrast is a lot higher on it. I am working on getting the lighting set up to reduce the shadows but am not sure how I will deal with the very bright highlights using this method. Anyway, here it is:

[Tuebits]

Thanks, looks GREAT!!!

[wavysteps]

Ray - Try using an opaque piece of white plastic over your light source. This will help to diffuse the light and eliminate the "hot spots". Just make sure that you do not have a heat build up with the plastic over the light source.

BJ Neff

[Ray Parkhurst]

Ray - Try using an opaque piece of white plastic over your light source. This will help to diffuse the light and eliminate the "hot spots". Just make sure that you do not have a heat build up with the plastic over the light source.

BJ Neff

BJ...this had a little diffusion already using translucent paper. With the "strafing run" sort of lighting technique I used on these to get the surface details, you can't make the light look too "big" with diffusion or you lose the shadows and thus the details. But your idea is good, and I'll try a bit more diffusion to see if it helps and post the results...Ray

[Ray Parkhurst]

Ray - Try using an opaque piece of white plastic over your light source. This will help to diffuse the light and eliminate the "hot spots". Just make sure that you do not have a heat build up with the plastic over the light source.

BJ Neff

BJ...Looks like your suggestion worked well. I changed three things:

1) I doubled the amount of diffusion
2) I adjusted the light a bit closer
3) I changed over to a B&L MonoZoom7

The more diffused and closer light significantly reduced the contrast.

The MZ7 has less chromatic abberation so improves the color definition, and ultimately the resolution.

Looks like the heavy diffusion didn't reduce the detail much if at all, and allowed me to get an overall better image. The hot spots are still there, but are not as noticeable with the rest of the photo being brighter and with fewer shadows. Here is the result:

[wavysteps]

Great Ray and you also lost some of the deep shadows as well that were present on your first pictures.

BJ Neff

[coin-crazy]

Very nice indeed!!!