Newbie Question: What Are You Looking For When You Photograph A Coin?

I use axial lighting when I have the time to take serious coin photos. Very cool.

I worked for a coin dealer taking photos for his ebay sales. I tried axial lighting but thought it took the life, the luster out of the coins.
I built my own rig with one stationary light offset by 10 degrees and a second I can adjust to get just the right look.

Luster is important for many coin types. It is one of the primary factors for grading business strike coins, so having luster show in a coin photo is extremely important for those coins. Indeed some coin photographers shoot to emphasize luster above other concerns in order to make coins appear higher grade. For proofs, medals, ancient coins, etc luster is not so important. In those cases different aspects of lighting come into play, and often an axial approach is preferred.

Luster is created due to reflections of the light off fine surface finish of the coin. Its appearance relies on contrast between the bright reflections versus immediately adjacent area with minimal reflections. Axial light does not hit the surfaces in a way that shows this contrast. Ringlights and domes and other techniques with low directionality also produce minimal to no luster as they shine light on the shadows. They "seem" like a good idea because they provide a very even illumination, but without the contrast between shadows and highlights, you lose important aspects like luster and definition of fine features.

thanks, jbuck, fascinating community.

When I shoot axial, I place tracing paper between the light source and the angled glass plate--mitigates contrasty images very effectively, while still allowing for a decent show of luster. Perhaps 20% of the time I'll add a second light source to bring out the luster just a bit--if the coin even has luster to begin with.

hi ijn1944, thanks for your info. I do use that diffuser on that 50W LED panel in my 2nd post along with some other light (by accident). So the axial configuration produced more 3D effect than the dome light did (very first post). Look at the lettering, under axial light, those letters appear rounded and curved, under dome light (very first post), these letters appear flat, as if they were chiselled or machined.

I am new, so I still do not have a concept of what exactly luster is, I think it might be one of those terms that is very subjective, different person have different preference. For example, I shot this, I think it has "luster' because edge contrast is low, it is still very reflective and appear to be metal, yet it still has "axial look'

For example, here (Japanese 10 yen), all details (scratches, defects) are visible if zoomed in. Yet, in my eyes, it has "luster", unlike images produced with axial lights where edges have very high contrast and almost appear black.