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FORVM`s Classical Numismatics Discussion Board  |  Numismatic and History Discussions  |  Coin Photography, Conservation and Storage  |  Topic: Choice of light source - halogen! 0 Members and 1 Guest are viewing this topic. « previous next »
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moonmoth
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« on: August 16, 2006, 01:19:15 pm »

Last weekend I bought a new light source for 15 GB pounds.  It's a desk lamp with a flexible goose neck, a 20 watt halogen bulb and a frosted glass shade.  This turns out to be brilliant:

The colour temperature is close to natural light and the bulb is brighter than other desk lamps.  This means that you stand a better chance of getting the correct colour in the photo (even using custom white balance), and the presence of some natural light as well (from a window) will not tint the coin blue on one side.  But I still recommend drawing the blinds.

The long goose neck allows the source to be placed quite precisely.  Its length and flexibility allows the source to be placed high up next to the lens, giving a better view of the coin and more of a 3-D effect.

The built-in diffusion provided by the shade is very handy.  What prompted me to look for this in the first place was that when I tried an overpowered incandescent bulb in my other lamp (60 watts in a 40-watt limit lamp) and put tissue over the end to diffuse it, there was an interesting smell of burning.

The only drawback is that it's a touch-sensitive lamp with 3 levels of light, so the light level flips as I adjust it!

This combination is working well for some tricky-to-photograph coins.  Here are 2 examples: a very shiny assarion of Septimius Severus from Markianopolis, and an almost as shiny Sep. Sev denarius.  Look how 3-D the denarius looks, and the colour response is  accurate enough to show its cabinet toning.  On the assarion, I'm happy to see any detail at all!  It's almost like a mirror with my other setup, though in the hand the detail is clear enough.

Any comments on the photos (as opposed to the coins) would be welcomed.  I'm sure the assarion can still be improved.
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slokind
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« Reply #1 on: August 17, 2006, 12:24:05 am »

Yes, I must look into these, especially for some silver.  This is one of those miniature reading lamps, right?  Pat L.
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peterpil19
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« Reply #2 on: August 17, 2006, 06:18:20 am »

Hi Moonmoth, those pictures are quite good and all detail shows as opposed to hiding flaws etc. Shiny coins definitely harder to photograph from my own experience (which doubles my original desire for the coin to be toned or patinated) and you've certainly done a good job.

Your post has prompted me to go search for a new light source. My current set up has a fluorescent white tube which causes colour-correction problems (even after setting white balance at times)...

Peter
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moonmoth
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« Reply #3 on: August 17, 2006, 10:36:33 am »

Thanks .. For those who want details, the lamp is a "Gerald touch lamp" from Focus DIY at GBP 14.99.  The bulb is a 40-watt G9 capsule, this one branded Osram Halogen.  (I should have called it a "halogen" lamp rather than a halide lamp and I'll edit the messages accordingly.) 

The bulb box says "370 lm", which I suppose is lumen.  This is more or less equivalent to a 35-watt incandescent bulb according to the tables on the Wikipedia, but in fact it is a lot brighter than my 40-watt desk lamp, and the exposure times I get are about the same as the 60-watt incandescent bulb I tried briefly.  This probably shows that cheap desk lamps with incandescent bulbs are very inefficient.  I probably lost half the light because of its inefficient reflector, whereas the translucent shade on this one lets me use the output much more effectively.

As Pat says, it is a small desk lamp.  Here is what it looks like:

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« Reply #4 on: August 17, 2006, 12:35:51 pm »

This will give a balanced view of the results I am getting.  It's a fairly ordinary LRB from my specialist area - a Constantius II hut coin, RIC VIII Thessalonica 117, mintmark TES(Epsilon), that arrived today.  This is a high quality JPEG using custom white balance, and has had no post-processing except to "paint bucket" out the background, and a slight levels adjustment, precisely the way Pat likes it.  I would normally sharpen this image a bit - the lens is fine, but the camera's sensor is an old model.  Perhaps a more modern camera would give an image that was sharper to start with.

In contradistinction to the claims often made on eBay, this looks better than the coin in hand.  The bright light has brought out the best of what richness of tone exists.  Some may prefer completely smooth coins, but I love the genuine texture of the patina on this one, and the photo makes the best of it.  The worn high points are visible, but haven't come out too shiny.  All the details that can be found have been made very clear - the texture of the small figure's clothing; the hand to his face; the texture of the tree trunk; and more.

Not every photo with this setup is an improvement on the black background RAW shots I was taking before.  But there is an overall clear improvement, sometimes very much so, and I will now be using this method as standard.  Thanks again to Doug Smith for much of the basic idea, and Pat Lawrence for the elaborations on it.  The cheapo use of plastic, kitchen foil and kleenex instead of Pat's enamelled ceramic and ground glass is all my own.
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« Reply #5 on: August 18, 2006, 01:05:41 pm »

And here's a decent coin with exactly the same minimum processing - and downsized for the upload, of course.  This coin has slightly scrappy surfaces here and there, but I don't care.  I bought it for the lovely Salus, and now I feel I can do her justice.  Looking at a good photo is like having a microscope.  It's like opening a magic box full of wonders.  How can you not love a coin like this?  Look how Salus' toes point at you out of the frame, as though she were standing on a log; look at the motion in her drapery, suggesting a slight breeze; and look at that lively snake.  Does anyone know the name of that jaunty cap?  (And what on earth did snakes get fed on, that looks like this on the coins of this period?)

My web site is called "What I like about ancient coins," and I am starting to think that I need to go back and make a better attempt at getting this sort of feeling across.  It's not easy - two or three paragraphs like this in a row would get a bit cloying.

Here is the photo, and also a small section at the original scale of the photo.

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slokind
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« Reply #6 on: August 18, 2006, 03:46:30 pm »

Concerning what photographs afford us, you and I are soul mates!  Pat
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