Axial lighting coin photography tests part two

[pendragon1998]

I've been busy lately and just got around to playing with my axial lighting photography setup (as mentioned previously). A month ago I took a small block of oak and used a table saw to cut a 45 degree angle halfway through it, which I use to hold a 5x8" piece of plate glass from a photo frame. I've got my usual pair of 60 watt Phillips natural lamps in small aluminum reflectors for lighting.

 

I recently got to add a 2006 PCGS MS69 Silver Britannia to my collection, so for these tests, I'm using this coin. The 2006 MS britannia is a little tricky to photograph because of it's reverse proof-like finish (not to mention the slab plastic). I'm not sure I've captured the coin as well as it could be captured. The Queen's portrait is not quite lighted to my liking, but overall, the technique makes photographing the coin a much easier proposition.

 

Following are three images of the coin, followed by the same three images with Photoshop's auto-contrast tool used. Opinions welcomed!

 

 

[James_OldeTowne]

I love how the slab glare is eliminated - a huge plus. But there seems to be something lacking with the images. They seem strangely "lifeless", almost as if they were hand-drawn. May I suggest additional examples of a coin with colors?

[pendragon1998]

I see what you mean. One drawback about this technique is that it creates such a flat, even lighting across the entire coin's surface. This is how it avoids slab glare, but it can make coins appear somewhat flat and should really only be used on coins where the slab is presenting a photography problem. How does this image compare to the others? I played more with the lighting.

 

Another problem I'm having is that I'm using an inappropriate light source. I'm doing okay with the dual lamps in hoods, but what I should really use is a flat light box for even uni-directional lighting. Black velvet-covered sides would prevent reflected light from entering and minimize the minor glare I'm still getting.

 

I'll go see if I've got anything colorful to shoot in the meantime.

 

[pendragon1998]

Before I forget, here's a little combo:

 

[pendragon1998]

I looked, and I don't have anything really colorful to photograph with the axial setup. I'd invite anyone else who does to give it a shot and post a thread.

[pendragon1998]

Good grief - the Queen is a bear to shoot in reverse prooflike.

 

2008 Australian Kookaburra - NGC MS69

 

[James_OldeTowne]

Whatever you did to achieve this obverse shot below is a big step in the right direction. There is now some variance in tone from left to right, which is closer to how a coin would appear in hand - much more lively! I think you are on to something here, and encourage you to keep making progress. The reverse is unfortunately still somewhat "flat", but better than the previous attempt.

 

[pendragon1998]

Keep in mind that on the kookaburra and the 2006 britannia, a great deal of the coins' surfaces are a very smooth matte-finished silver, so the fields are bound to appear very uniform.

[IGWT]

Nice pictures, Mike. Thanks for demonstrating the results of axial lighting . . . something that I've been tempted to try, but haven't yet. BTW, the Queen reminds me of the T-1000 Terminator.

 

[RWB]

Axial lighting, as the name implies, means directing a beam of light to and from the coin along the same optical axis as the lens. A beam splitter (or piece of glass) at a 45-degree angle between lens and coin will help you do this. Aim one light at the glass, and baffle all other sides so you don’t get any stray light. Try making the light source smaller and note how that changes contrast of the image and reflections off the mirrored portions of the coin.

 

If your axial light setup is properly aligned, and the slab/holder front is flat and parallel to the camera, you should get very strong reflections from the front of the plastic. Your photos are actually a mixture of diffuse and semi-axial lighting – this can be very tough to reproduce consistently.

 

[rexcat]

Axial lighting, as the name implies, means directing a beam of light to and from the coin along the same optical axis as the lens. A beam splitter (or piece of glass) at a 45-degree angle between lens and coin will help you do this. Aim one light at the glass, and baffle all other sides so you don’t get any stray light. Try making the light source smaller and note how that changes contrast of the image and reflections off the mirrored portions of the coin.

 

If your axial light setup is properly aligned, and the slab/holder front is flat and parallel to the camera, you should get very strong reflections from the front of the plastic. Your photos are actually a mixture of diffuse and semi-axial lighting – this can be very tough to reproduce consistently.

 

RWB, good explanation of Michael's photos. (thumbs u

 

In these photos the devices show the bright edges from the multiple directions of the light sources mixed with the axial lighting.

 

 

When only axially directed light reflects of a coin the surfaces that are flat like the fields reflect the most light back to the camera, mirrored fields glow brightly and as the surfaces the the devices become more angled, less light is reflected so the steeper surfaces are darker. This is greatest at the edges of the designs ringing raised devices with what looks like a dark shadow. This is how you see the letters, date and design of the coin.

 

 

Like this photo:

 

 

 

What axial lighting works best for is bringing out the colors on a coin. Do to the light reflecting for the same glass the photo being taken through there always the need to adjust the contast to get what looks like a fog out of the picture.

 

The next photo is taken with axial lighting and a little direct light of a bulb to add some brighter highlights on the top edges of the devices. The second photo was taken with two bulbs on each side of the camera off axis about 25-30 degrees.

 

 

[MikeInFL]

Axial lighting for coins in slabs/holders is problematic at best. As you've found out, the slab reflects light too, and this leads to loss of contrast. You can correct in post processing to some extent, but the photos become unnatural to the trained eye as a result (particularly so if the coin has some color).

 

For raw coins, it works OK, but other less-elaborate techniques can produce even better phototraphs. Its best use is for proof coins such as those shown here, and other brilliant-type proofs.

 

Regardless, thanks for sharing your results...Mike

[pendragon1998]

I haven't seen a better solution for photographing a brilliant finished coin in a slab where the glare on the slab is such a major problem. The axial lighting technique does have it's problems, but if you're flexible with your lighting source and use a little judicious post-processing, it's pretty good at solving that particular problem. As for lighting 'real' proofs - by which I mean coins with a mirrored field and frosted devices - I think that's best done the traditional way, with properly angled lamps.