First Attempt At Axial Lighting

The ideal glass for axial lighting - "beamsplitter" glass - is the stuff they use with teleprompters. Its' best capability is to reflect on the order of 75% of applied light. And it's not cheap - a 12"x12" pane of 75% reflective will run you on the order of $400. A "regular" pane of glass will not approximate that transmission level, both a good and a bad thing. Good, because it limits the possibility of washing out details via excessive illumination; bad because it seriously compromises the "sweet spot" of your settings. You'll need to jack ISO up and exposure down. I'm in the neighborhood of ISO800 and 1/8sec for axial work (at f/8, of course ) although that will probably improve a bit with a more-lustrous coin like your 1884. You might be able to reach 1/25 or even better (consider ISO1600) with it.

The key to axial lighting is the only light reaching the coin is that reflected. One must be very picky about eliminating any chance of light from other sources, direct or reflected from the environment. In addition, you'll find broader sources of light such as regular incandescent bulbs - as opposed to more point-oriented sources like Jansjos - to be the better tool. A point source will supply a point illumination, perhaps not fully covering the coin and leading to "hot spots" of color which fail to cover the whole coin. Slabs will be particularly difficult, and you may end up needing to adjust the glass positioning by a degree or two along both axes - tilt and angle - to effectively illuminate the subject.

Pro tip: Once you've got the technique down, point it at a nice Cameo Proof, and giggle at the results.

I didn't do this brain dump for your first image because - frankly - it's a great image and IMO quite faithful to what the coin looks like in the real world. It's only a little bit of increased contrast from being world-class.

I also wonder if instead of using beamsplitter glass (the best, I know) if a glass platen from an old broken scanner would be close? It should be optically pretty good, and broken scanners can be had for cheap or next to nothing! Haven't tried it, but just may look for one to tear the glass platen out of. Could be better than hardware store glass I'm betting.

You can get beam splitter glass much cheaper than $400.00 Here one example:

http://www.ebay.co.uk/itm/Telepromp...em3ca72bae36

For accurately Mounting the glass( rather than cardboard) I discovered a School geometry set that included a large triangular Protractor, as opposed to semi circular. I purchased 2 sets at the great expense of about US$12.00 in total I then used silicon sealer to attach the Beam Splitter to the two large protractors ....the result is the glass sits at exactly 45 degrees. Finding the protractors was a fluke I had been looking at sheet perspex (plexiglass) which I was going to cut but that was closer to US$30.00 a sheet and with the protractors there was no cutting involved.

That listing is for 30% reflective, approximately equivalent to uncoated glass. Take that 70/30 relationship in the other direction as I mentioned in my post, and you're looking at some expense. The *only* advantage to beamsplitter is superior reflection due to the coating, similar to "one-way" mirror coatings which are beamsplitter with the highly-reflective side toward the interviewee and the transmittal side (with the observers) in a darkened room.




That's a testament to the fundamental effectiveness of axial lighting at illustrating color on a coin. The only thing the excess light did was diffuse the color somewhat. I was thinking more contrast, not less, as a result.

As I mentioned in another thread, it's important to factor in the lighting conditions under which you look at a coin in-hand when evaluating images. We're always extremely careful about lighting setup for imaging, but far less-so when using the loupe and then we wonder why the photo doesn't match the in-hand look. If you look at your 1884 under sharp, bright direct lighting, you might find it rather brighter-hued than you think.

You've got all of that right, austrokiwi. A 50-50 is head and shoulders above regular glass, which doesn't do better than 20% or so. The only reason for beamsplitter stuff - and each photographer has to rationalize the cost based on their own needs - is the increased zone of usable settings as one increases in total reflected content.

We nitpick here, austrokiwi. That's what we do.

"Most folks who are successful with axial lighting are actually not doing axial lighting! They have axial setups, but use large or multiple lights to create a variable lighting system that includes axial content to bring out the color presentation only axial can produce as a part of the overall image."

Interesting because being relatively new at this I was contemplating this very idea. After realizing my axial attempt was not really a true axial procedure I at first tried to contemplate ways to render a truer axial image(which I will most likely still do). Then after re-visualizing this particular coin per Dave's suggestion I still feel the photo I accidentally got during this attempt is to date the best rendition I have been able to get. It truly resembles the coins actual color. I have been rethinking my procedure and was wondering how a combination of axial & additional lighting (which would have to be tweaked) would work on some of my other coins with DMPL, PL & cameo proff surfaces. Lots of experimenting seems to be in the future.

Ray you and Dave did this to me :)
Can't say that I'm not having fun though.
Bob