Imaging coins with great luster - tips?

keoj

I don't have images to share (my bad) but have a question. Is there a s to reduce the luster on coin images? I use Reveal lights for macro shots. Luster on comes coins is great but when trays to print the images in B&W, the luster tends to devolve into a lot of speckles. If I use diffuse lights, the plastic of the slab tends to "glow" and the sharpness of the image tends to degrade. Any ideas? Thanks.

cmerlo1

I've had good luck with axial lighting.

It's very difficult to do with slabbed coins, but for raw ones, it works great:

messydesk

To decrease contrast, increase diffusion on your lights.

BillJones

I find that having the light source higher above the coin works better than having it close to the piece. Therefore I use a table lamp instead of a spot light when I'm really going for the luster. The more diffuse the light source the better. That one of the reasons why the pros use the cones for coin pictures. The trouble is I would not have a spot to store use the thing in my house. The wife is after me for having too much junk already.

Also shooting at an angle helps, but then you get into distortion issues.

nwcoast

I've found that moving the lights further away works better most of the time while keepin them close to axial.
When the light is closer, it's less a point source of light and more diffuse (softer). Further away it becomes harder and captures the luster better in my experience.... Tent lighting (which is very soft) will accentuate color while almost completely eliminating luster.
Just got to play around with light positions and watch what happens.
I think others here will offer some better ideas.

I can't quite figure out the axial lighting set-up you've got there.

rmpsrpms

Luster comes from high local contrast caused by your lights reflecting off the high points of the metal flow lines, and being scattered by the lower points. If luster is overpowering your photo, here are a few things you can do:

1) Add another light. This makes the overall image brighter and de-emphasizes the luster. Sometimes these are called "fill-in" lights.
2) Similar to above, add a reflector to shine some of the existing light onto the coin at a different angle
3) Raise the angle of your existing lights. cmerlo1's suggestion of axial lighting is the extreme, with lights at 90-deg to the coin surface. I find that anything at 75-deg or higher starts to seriously reduce luster.
4) Make the lights appear "bigger". This is really the same principle as #1 and #2 above, because the bigger light simply makes the light hit the coin at a range of angles instead of all at one angle. This can be done by moving the lights closer to the coin, or by adding diffusion as messydesk suggests.
5) Change the "clock position" of your lights. Luster presentation is maximized with a single light or with two lights at 90-deg to each other, ie at 10:30 and 1:30, at 12 and 3, etc. This makes the "luster bars" form an X on the surface of the coin. But if you make the lights more opposite each other, for instance at 9 and 3, the local contrast is reduced and the luster bars merge from two well-defined bars into one that is much less defined.