Coin Photography by Budget and Skill

That's not always the case though. If you combine extension tubes with enlarger or line scanning lenses, for example, you can achieve fantastic results with flat fields and extremely well corrected images. It of course depends on the lens you choose but there are cheap options (<$100) that are excellent performers. Which is to say it's not the extension tubes that are the problem, it's the glass you combine them with.

 

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I now have a $30 USD pair of extension tubes (10 mm and 16 mm) with electronic contacts for my older Micro Four Thirds camera. I am about a meter away from a window with daylight coming through.

When using the extension tubes, the first thing I noticed is that I had to extend my kit lens (14-42 mm) all the way in order to see the coin in focus. Another thing I noticed is that with both extension tubes on the camera, the flash is unable to reach more than the top quarter of the coin's surface, meaning that I was unable to use it. And finally, despite using a tripod and a ten-second self timer, the images are nowhere near as sharp as I'd like them to be. These technical deficiencies on my part meant that I ended up trying to compensate by aiming for an artsy-fartsy creative black and white portrait type image instead of an ordinary coin photo:

My latest numismatic tributes to Julia Domna, underexposed on purpose, but even so, probably excessively:




Taken with: my older MF4/3 camera (Panasonic G3 with kit lens (14-42 mm); with Meike 16 mm and 10 mm extension tubes. Monochrome. Detail of the image below:



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And a less underexposed one below..



Below, (most of) the reverse. I see now that I should have moved the coin so that the left was not cut off.



The coin is sitting on a piece of velvet that, now matter how many times I take lint-remover to, still seems determined to hold on to bits of dust.

Today's mission: I must come up with something to raise the coin above the velvet. And I still want to figure out how to get a sharper image.

 

I hope you are not using both tubes. The 10mm alone is a lot on a 14mm lens but should get the whole coin at 42mm. The size tube you need is proportional to the focal length of the lens. I have never had a 4/3rds camera but I would suspect there would be a market for a shorter tube if anyone made one. If you have any longer lens (telephoto) the tubes would give more working distance and allow light to fall on the coin.

 

I just basically point and shoot with my SLR camera, using a +4 macro lens and a black background, not terribly sophisticated. In the past I used natural light, but now I am finding that flash adds for resolution and clarity, so I am trending in that direction. I am still learning the basics of lighting.

All of my images are processed through Photoshop. The results are generally acceptable, but really just that.

Here's a picture taken today.



Now, here's a nicely patinated abdication follis of Diocletian taken with a flash and in natural light.

With flash:



Natural light:



As can be seen, the coin in the second photo has a richer tone, with nice earthen highlighting. However, the flash photo picks up more of the turquoise color present in the coin. I guess if I could figure out how to adjust shadows and highlights properly in Photoshop the naturally lit photo would be the most accurate of the two.

Given my learning curve, moving from minus to zero is a quantum improvement, with my late entry into this field of numismatics in early March 2020.

 

What Doug said: Try using only the smallest tube and turn off the flash. This and shooting in AV mode at about f10 and ISO 200 or 400 should be a good start. I'd love to see the results here!

 

Well, unfortunately, I did not get around to trying to photograph any coins today during daylight hours. For the above shot, I followed the advice of @dougsmit and @Orielensis (thank you both!), in using only one extension tube for this shot--the 10 mm. There was no flash. I used a Coleman camping battery-powered lantern to provide some light, although there is some ordinary light from the kitchen (sort a yellowish light).

I also followed @TIF 's advice in getting a dowel, a stand for it, and some velvet (thanks also to others here, including @kirispupis for that suggestion). And this is what I was able to do.

Overall, I like the image. What bothers me is that I feel like it should be sharper. Any comments, advice, or suggestions will be most welcome!

As for the details, I used Aperture priority mode for this, with F10, and a shutterspeed of "8/5 sec." according to my camera. I'm assuming this is eight fifths of a second (meaning more than a second?), but I really don't know. I've never really understood the theory of aperture, shutterspeed, and so on. Focus was 23-area, and ISO was auto, which in this case was 800.
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Update: also, I think a bit of the wood slivers attached to the putty, and then, when I flipped the coin over, lodged itself in the jawline of the portrait. This putty stuff: "FUN-TAK" "poster putty" from Lepage. It says "non-toxic," but I'm much more worried about the health of the coin itself. I hope it won't damage my coins.

 

Looking good! Once you've got the setup working for you reliably, you can start playing around with the lighting to achieve different results.

Though one thing you might want to try first is increasing the shutter speed and for that you would likely need more light. A 8/5s shutter speed is quite slow and without a flash to "freeze" any movement, it is possible you're losing sharpness due to minor vibrations. I personally wouldn't go below 1/60s without a flash for macro, even when mounted to a tripod or copy stand. If you whack a 10x microscope objective on your camera, you'd be surprised how much movement there can be between camera and subject due to things like cars driving by, people walking in your house, the refrigerator on the other side of the wall, etc.

ISO of 800 should be fine, though depends on the camera - for a camera from the last few years it should be no problem at all. Ideally, you'll eventually be able to bring it down to ~100-200 and the shutter speed up to 1/160s, which of course means you need a fair amount of light!

I use "blu tack" like stuff as well and it's never been a problem for my coins, just be careful using it on any that have weak or delaminating surfaces. After you've pulled off the tack on one side (i.e. the side facing down), just dab it across the surface again and it should pick up all the loose pieces that initially remained stuck to the coin. You can also buy some "museum-grade" putty if you want to be extra safe. I find it's not as sticky as other types, which is ideal in this case where you don't want much to hold the coin in place.

 

I believe diffraction will start limiting sharpness on a small micro 4/3 camera but it is fine for a larger one like 'full frame'. Try shooting at f6.3 and see if it is better. Ordinary 'kit' zooms are not optimized for close work. You may need to invest in a dedicated macro lens if what you see is not to your liking. I consider the shot you posted as good as any I have seen on Coin Talk from cameras that small.

I see no reason to use putty. That is why I suggested the rubber pen grip for coin positioning. Put it on top of the dowel. Do be careful to center the coin properly and do not knock it off. That is why I have a soft pad under where the coin would fall just in case.

It is possible to add artificial sharpness in postprocessing (see below). I don't think it helped your image much. There is also the fact that there is a limit to the detail set by the coin itself but I suspect here the problem is diffraction. Using a wider aperture like f/6.3 will require more careful focusing. It might be better to use manual focusing. If your camera allows magnifying the image for focusing or has other focus assist tools, try them. Every camera is different. I have never touched a 4/3 camera so it is up to you.

 

That's a good point as the effective aperture of the lens is likely much higher than f/10 and probably well into diffraction territory.

It's probably easier to just test different aperture settings and see what gives you the best balance of sharpness vs depth of field but if needed, Nathan, you can calculate the effective aperture using the following:
N' = N*(m+1)
N' is the effective aperture
N is the actual aperture setting
m is the magnification

To get an estimate of the magnification, the easiest method is usually to take a photo of the ruler and divide the actual width of your camera sensor by the photographed width as measured on the ruler. So if the ruler measured 10mm across in the photo on a sensor 35mm wide, the magnification would be ~3.5x.

 

The image looks very good to me! A slightly lower aperture, daylight and higher shutter speed might get you a bit more sharpness. See Doug’s advice above.

 

https://www.cambridgeincolour.com/tutorials/diffraction-photography.htm
The above site will tell you a lot more about diffraction than you want to know but I don't think they included micro 4/3 cameras in the charts. You would need to enter the pixel size manually.