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Author Topic: Photographing scyphate (cupped) coins - Methods and setups  (Read 671 times)

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Offline Ron C2

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Photographing scyphate (cupped) coins - Methods and setups
« on: December 11, 2021, 08:22:05 pm »
There has been lots of discussion here on the Forum about typical coin photography, and most people's setups are geared towards getting the best possible images of more or less flat coins of Greek and Roman origin. 

The later scyphate coins of the byzantine era get much less photography technique discussion.  It's equally true that the setups for flat coins rarely give satisfying results for scyphates.  The concave side of the coin is often deep enough that even fully stopped down, some cameras cannot keep the entire coin in focus.  Most forum members also probably do not have a camera capable of focus stacking, though such cameras do now exist.

The convex sides of these coins often end up over-exposed ion the center, and under-exposed around the rim - especially if multi-directions flashes are used. 

I have my own technique that I'd be happy to share, but first I'd like to hear what others are doing to get the most out imaging these challenging coins.  What is your setup? What tricks do you use? Are you doing a lot of post-production?  Let's hear it!
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Offline Ron C2

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #1 on: December 12, 2021, 10:52:06 am »
Well perhaps I'll get the ball rolling then with some photographic theory to see where this thread can take us.

First, let's talk about aperture and depth of field

In your high quality camera lens (typically NOT a smart phone camera), there are helical blades (called aperture blades) and lens elements.

The lens elements are arranged to collect a lot of light from the image area, and to then focus that onto what we used to call a film plane. In the digital area, we call this the sensor surface.   The lenses, generally, are sharpest in the middle of the lens. As you get out towards the edge of the lens elements themselves, all lens element stacks start to see some level of distortion where the light entering the lens is refracted through the elements onto your camera sensor.  Usually the more expensive and high quality the lens, the more went into the design and manufacture of the glass elements to reduce this effect.  Cheaper digital cameras try to compensate for this with software correction that is never quite as good as capturing the image accurately to begin with.  If you shoot in RAW mode and compare it to internally processed jpeg images, you would see this difference manifesting usually around the edges of your photograph.

The aperture blades are designed to close to a given diameter when you take your photograph.  Each lens expresses these values as "f-stops".  The lower the number, the greater the diameter of the opening the light can pass through when you take a photo.  The higher the number, the smaller the diameter.  I'll explain more, but in simple terms - the higher the f-stop number, the longer the exposure, but more of the image will be in focus.

When you look through your viewfinder, these blades in your lens are wide open in default settings, letting the maximum amount of light through to reach the sensor.  This high volume of light fully exposes your image quickly, allowing for faster shots that are fully exposed.  Sports photographers and portrait photographers value "fast" lenses that have very low f-stop settings numbers for this reason.  This comes at the expense, however, of depth of field.  Depth of field is the distance in front and behind your exact point of focus - where your image is sharpest - where the rest of the image is acceptably in focus.  When photographing, for example, people or scenery, this is usually not a problem.  The focal plane is the distance between your camera lens and the perfect point of focus in an image. The longer to focal plane, the longer the depth of field will be.

In other words, if you take a given lens and photograph someone's face 2 meters away from you, and you focus on that person's eye - on basically every lens, their entire face will be in focus - from the tip of the nose to their ears - no matter what settings you use on your camera, assuming your subject is focused on correctly.  If you have your f-stop at the lowest setting, say anything under f2.0 on a full frame camera (or f4 on a micro four thirds camera), you will notice this person's face is still in complete focus, but the entire background is blurred in a pleasantly artistic way.  Photographers call this "bokeh" and people spend a lot on lenses to get this idyllic effect in some shots.  If you change nothing else, but take the same shot at f22, you will notice two things.  First, the camera shutter speed will be far lower because the camera has to let light in longer to get a proper exposure when there is only a tiny opening in the lens to let light through, and second, you will notice that the entire background and foreground of the photo (more or less) will be in sharp focus. 

So what does all this mean for coin photography?

Well it's not often that a coin photographer wants any part of the coin to be out of focus.  You are basically chasing an archival-quality reproduction of your coin, giving you a realistic interpretation of what the coin looks like in-hand.  So you might ask, does that mean I should just shoot everything at f22?  Much depends on the lens you are using, you lighting setup, how you mount your camera, etc. - but generally yes, you will usually shoot all coins at a high f-stop like f22.  There are some exceptions, like if you have a focus-stacking camera - but most of you likely don't have one of these.  The technology is new and still quite expensive.

Some more things to consider - almost no camera will shoot at f22 if you leave the camera in automatic or program mode.  Even in macro mode, it may not do this.  My advise to all coin photographers - shoot in aperture priority or manual modes only.  This gives you maximum control of depth of field, and therefore, how much of your coin will be in focus. 

This is sound advice for a typical flat coin, but what about a scyphate coin? 



Let me start with one of the reasons why scyphates are tougher than a regular coin.  It has to do with the focal plane I talked about above.  As you reduce the focal plane, your depth of field gets much narrower.  When we get to macrophotography, the depth of field is now reduced to a distances measured in millimeters.  This means that if the height of your coin when laying flat is more than 2 or 3 mm, some macro lenses have too short a focal length to take a photo of a scyphate coin where the whole flan is in focus.  In other words, now you need to worry about which macro lens to use to take pictures of these coins - not just any old macro lens will do. Your common 60mm or 70mm macro lens (full frame) may not give you the results you expect here.

I'm now going to switch to full frame equivalent numbers for focal lengths for this part of the explanation.  It's important to note that each camera system's focal length number on their lenses (for example, a zoom lens being marked 70-210mm f4-5.6) is only comparable to other camera lenses that are used on cameras with the same sensor size.  Full Frame measurements are equivalent to the old 35mm camera standard, so many people still relate to these numbers most.  If you shoot with micro four thirds, for example, you would divide these numbers by 2, and the equivalent lens to a full frame 70-210 f4-5.6 would be a 35-105mm f8-11.2. This gets trickier still because many micro four thirds manufacturers list focal lengths in actual values (i.e. 1/2 the full frame equivalent), but list absolute f-stop values, which tend to make the lens seem "faster" than it really is. In the above example, if Olympus or Panasonic sold a 70-210 f4-5.6 full frame equivalent, they would likely market it as a 35-105mm f4-5.6. It can be misleading if you are not careful, but for coin photography it doesn't really matter - you will only use the slower end of your lens' range anyhow.

The human eye sees about what a 50mm lens sees.  Anything more than that is a zoom lens, and anything less than that is a wide angle lens.  Macro lenses use the same conventions, but are designed to be in focus when the subject is much closer to the front element of the lens.  Now because we want scyphate coins to be in focus, we want a macro lens, but one that puts the coin farther away from the lens than we would minimally accept for a flat coin - basically a "macro zoom".  The farther away the coin is is, we have a longer focal plane distance with a correspondingly longer depth of field - meaning a taller coin can still be fully in focus. 

You would have to experiment with your setup here, but I find the minimum acceptable focal length on a lens for a typical scyphate is around 100mm full frame equivalent, shooting at f22.  After that, the most important variables tend to be about keeping the camera steady and the lighting setup you use.  If you use an even longer lens (more than 100mm), then there are some lighting advantages - assuming you either already have, or are OK with buying, another expensive macro lens!

Here is a photo of a scyphate Histamenon Nomisma taken with a (full frame equivalent) 100mm macro lens set at f44.  It's actually a micro-four thirds 50mm lens set at f22, which is a 100/f44 equivalent in full frame.  The distance from the coin to the lens element is 7 inches, or about 18mm. The coin is about 4mm in height when laying flat. I can improve the lighting of the reverse around the flan edge, but you will notice the entire coin is in focus for its full depth.


https://www.forumancientcoins.com/gallery/displayimage.php?pid=173453

Happy to hear people's thoughts so far - soon we'll get into the magical world of teleconverters, extension tubes, flash setups, etc.
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Offline Anaximander

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #2 on: December 12, 2021, 12:09:08 pm »
That is one fantastic primer on the photographic challenge of scyphate coins. You get high marks for readability, conciseness, and illustrations. 

The biggest problem I have photographing scyphate coins is getting enough depth-of-field. Flatbed scanners cannot do those coins justice.  Even using a quality macro lens on a decent micro four thirds camera can result in spectacularly bad photos if the technique isn't quite up to the task.  I struggle with lighting as well as depth-of-field. Owing to the deep cup-shape of my example, a Latin-era ruler, light does not easily penetrate into the depths of the reverse, and there always seems to be something too light and something too dark... 
 

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Offline Ron C2

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #3 on: December 12, 2021, 08:42:49 pm »
What lighting setup are you using Chris?
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Offline Anaximander

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #4 on: December 13, 2021, 03:26:37 pm »
I am using axial lighting, with a Godox S30 as the master, fitted with a SA-30 softbox. I supplement the Godox with direct light from 1 or 2 Lume Cubes fitted with diffusers and barn doors.  As needed, I use a handheld Lume Cube PanelMini.     

It throws a fair amount of light, but not quite enough for me to get as high as f/22.  I use aperture priority, but try to keep the shutter speed above 1/30th of a second. 

I'm going to be photographing some Carolingian coins and will take another crack at that scyphate coin again.
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Offline Ron C2

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #5 on: December 13, 2021, 08:37:02 pm »
I find that for the scyphates, there is no substitute for a good tungsten-based TTL ring flash designed for archival macro-photography.  The light boxes, point light sources, twin or tripple gun setups, etc. work great on the flatter coins and can be positioned around to emphasize relief detail - but on a scyphate, that rarely works out as planned - particularly shooting into the concave surface (as you noticed). 

This is the setup I'm currently using for these shots. 



Everything I hate about a ring flash (and there is a lot to hate), turns into an advantage when shooting a coin with a lot of depth of field

My biggest complaint about ring flashes is that they are at their best when photographing something flat with high contract.  If you shoot a "flat" coin with a ring flash, it exposes everything head-on and there are few areas of shaddow.  So it washes out the relief details that side-lighting can help accentuate.  I find every flat coin shot with a good ring flash actually looks like a weak strike of a worn die.  If you have one, try it, and you'll see what I mean.  I find the effect very pronounced on bright silver coins - it can turn an Extra-Fine specimen to an aVF without much effort - seriously.

Now when we use the same flash on a scyphate, those disadvantages become advantages.  The flan is not flat, so you are hitting the raised detail a bit from the side, but you are also still getting the "flattening" effect of a ring flash.  It shoots straight down onto the coin, so the middle of the coin will be completely lit - especially if you shoot in TTL Aperture priority.  Relief details are preserved, but with good exposure at depth. 

The main issue I still have is that the outer edge on the convex side of the coins can still be a bit under-exposed.  If you shoot in manual and play with the settings you can minimize the effect somewhat.  I need to play with some slave flashes to improve side-lighting though I think on the convex surfaces of my shots.
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Offline Anaximander

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #6 on: December 29, 2021, 04:47:00 pm »
I gave it a go, photographing my scyphate coin with a ring light. While I am not ready for prime time with this technique, I see the point of using a ring light for these challenging coins.

I photographed an AE Trachy, Latin imitative coin using three techniques: Axial, Direct, and Ring. Without further processing, none of them is outstanding.  Sample pics attached.

My using a gray or a white background made no difference. Axial uses an 18% gray background (because I can), but I was compelled to use a white background for the Direct and Ring techniques, as I had to change how to elevate the coin above the background. 

Axial photography is my mainstay and where I'm most comfortable.  If I were to move to using a ring light, I would want to upgrade from my current LED ring light.  As you can guess, different lights have different color characteristics, or "temperature" and my current ring light skews to cooler colors. Several months of effort to get an Olympus brand ring light came to naught (and I really was hoping for the newer model).
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Offline Ron C2

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #7 on: December 29, 2021, 06:25:54 pm »
I do find the inexpensive LED ring lights to not really work all that well.  I have one, and I never use it anymore.  The Olympus RF-11 I have is superb though.
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Offline Jay GT4

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #8 on: December 29, 2021, 07:47:43 pm »
Excellent write up Ron.  I don't have any cup cons but I agree with what you say about ring lights.  So easy to wash out a coin and make it look lifeless.  I think most auction houses use this technique to get a consistant look but I'm always surprised by how much nicer the coins look when they arrive.  You learn to develop an eye for what the coin will really look like in hand from these types of photos.

I'm using a Sony a5000 with a Sony 3.5/30 macro.  I always shoot coins in Manual or aperature priority and I have my camera mounted on a home made copy stand.  My camera doesn't have an auto stack feature but I use PS CS6 which has the ability to digitally stack.  Just means I'd have to manually take a picture at different focal lengths.  I've been meaning to give that a try but never seem to have enough time. 

Offline Ron C2

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #9 on: January 05, 2022, 05:54:28 pm »
Jay, I think you would probably find that 30mm to be less than ideal if you shoot any scyphates in the future, though if you figure out exposure and focus stacking, it would likely work

For coin photography in general, you might want to consider a longer macro lens.  The A5000 is an ASP-C sensor mirrorless camera, and the lens focal conversion factor is 1.5, so your lens is a 45mm full frame equivalent.  That actually does not give you very much working distance, and your depth of field and available lighting options would greatly improve with a longer lens. 

The 50/2.8 (better) or 90/2.8G (best) in e-mount would both be excellent choices in the Sony lineup. Sadly, yes, they are pricey.
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Offline Anaximander

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #10 on: January 06, 2022, 11:49:24 am »
I typically use a 16mm extension tube on my macro lens, an Olympus 60mm Micro four-thirds. The lens itself is equivalent to 120mm in the traditional 35mm camera world.  I am uncertain of my effective lens size with the extension tube, but I find it gives me more working room.

In fact, it should be possible to stack two or more extension tubes, one atop the other.

Instead of buying a new lens, couldn’t Jay use a set of inexpensive extension tubes. Optically, since there isn’t any glass in an extension tube, there isn’t any distortion, and image quality does not suffer, right?
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Offline Ron C2

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #11 on: January 06, 2022, 12:53:17 pm »
Extension tubes usually increase magnification, so you can fill more of the frame with the coin, but they don't usually change the focal length to the focal plane and often you get less working distance, not more, but with greater magnification. To get more working distance, a teleconverter can sometimes be paired with a macro lens, or you can try an extension tube on a telephoto lens, some lenses perform well as quasi-macro lenses this way.

In essence, the extension tube increases the distance between the lens and the sensor. you can then focus closer to increase magnification. The longer the focal length of the lens you pair with the tube, the greater the working distance you can achieve.

In terms of image quality, the extension tubes can introduce vignetting and can lower image quality for some lenses, depending on the lens element group design. I usually have to try it to know which lenses will have detectable image quality reduction.

There is a good primer here: https://shuttermuse.com/ultimate-guide-to-extension-tubes/#how

FWIW, you should not need an extender with a M43 60mm olympus lens.  I use the 50mm 4/3 version of that lens with an M43 adaptor and I don't need tubes to get good working distance and sharp images.
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Offline Virgil H

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #12 on: January 24, 2022, 01:04:28 pm »
I am going to throw one more option here that has been my best bet so far as I do not have a macro lens. And it is an inexpensive solution if you already have a camera with a lens that has screws for filters. It is a "macro attachment" that screws into the front of the lens and basically acts like a magnifying glass. Downside is you have to get pretty close to the coin to get an in-focus shot that fills the frame. I have the camera on a tripod for stability, so you need a tripod that will tilt the camera true 90 degrees without obstructing the view. If you look at the last few photos I have posted (one yesterday in Greek section), my results are acceptable, but I need to work on lighting. These are my best coin pictures so far using just what I already have. The phone camera does not work for me, but I have a crappy and cheap phone. These macro extensions have glass, and are pretty thin, they are not extension tubes. They are very inexpensive, you just have to make sure you get the correct thread size for your lens. I have used it handheld, but shaky hands is a real issue, hence the tripod or stand.

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Virgil

Offline Ron C2

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #13 on: January 29, 2022, 10:13:35 am »
Virgil, I can't say I've used a macro converter lens to photograph scyphates, but the few times I tried them in the film era, they usually did not produce great depth of field at magnification. That said, technology constantly improves and the new stuff might be decent.

Have you had good results with scyphates and these adaptors? Any examples to share?
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Offline Virgil H

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #14 on: January 30, 2022, 07:05:22 pm »
Ron C2,

I did an example of a photo with the macro attachment. This is my only cupped coin, a BI Trachy of Alexius I Commenus. I spent a little time working on this, but the huge caveat here is i know my lighting is horrible. That said, ignoring how bad my lighting is, for this coin, the macro attachment seems to capture detail pretty well. I think this may be an option for those with older cameras and no macro lens. You can get these optical attachments for around $10 these days. I attached a photo of the attachment. I have an inexpensive and rather old Epson EOS camera. And I know my lighting is my biggest issue.

Regards,
Virgil

Offline Ron C2

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #15 on: January 30, 2022, 08:19:54 pm »
Virgil, if you can find an adaptor or lens that would get the camera physically further away from the coin while still giving usable magnification, your shots would improve.  I can see the shadow of your camera on the coin image itself, likely because the lens face is close enough to the coin that it's impeding light from reaching the coin's surface during an exposure.

Hope that helps :)
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Offline Virgil H

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #16 on: January 30, 2022, 08:46:08 pm »
Ron,
I can definitely see that and part of it is just my not ideal setup. And I tried to work around it.  I know this can be improved, I just need to figure out how to do it. The biggest downside with these attachments is how close you have to be to the object. Not really bad in itself, all macro lenses require you to be close. Obviously, a real macro lens would be ideal., but they are expensive for what is a rather limited need for me. Maybe a bunch of soft light flooded in would work. I will keep working on it. Once I get it dialed in I will start a gallery, LOL.

Thanks,
Virgil

Offline Virgil H

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Re: Photographing scyphate (cupped) coins - what is your method?
« Reply #17 on: January 30, 2022, 11:14:08 pm »
My point was is that I think the detail is there with the attachment, it is the lighting that is my big issue. Depth of field seems fine. That said, I have never made a photograph of a coin I thought was any good under any circumstances. I think this method will work as good as more expensive options.

Virgil

 

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