Coin Photography is not easy

[rbenton]

I am new to this forum after reigniting my love of Lincoln cents from my youth in 1965. In the meantime I have enjoyed a career as a photojournalist (now retired but you can see some of my work at here (http://www.RandallBenton.com)) Having so much experience as a photographer, I thought photographing my coins would be easy. But like any new endeavor I discovered the learning curve was steeper than I thought. I have found a wealth of information and inspiration here, so now – with tremendous humility – I am finally going to post a photo for your amusement, and I invite your criticism. Thanks to all of you for the education.


http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158820&stc=1

[WaterSport]

I like both - the coin, and your photo! As you discovered, its not easy but very rewarding when you capture the look of the cent as it looks in hand. For me, it's proof cents, man o man what a challenge.

Keep them coming.

Bob

[makecents]

Looks pretty dang good to me for your first coin shot! I'm sure your career life will have you leaps and bounds ahead of most of us.:) You may want to hook up with a fellow photographer that is a member here, Ray Parkhurst. I have never seen better coin photography, than what he does. He has several he has posted here but here is a direct link to his site, where you can check out all of his work. LINK http://www.macrocoins.com/home.html
Very nice work though, Randall.

Jon.

[rbenton]

I have also discovered the challenge of Proof coins. I am continually "re-jiggering" my lighting to get the photos to resemble the actual coins. Sometimes I am satisfied with the color but not the contrast, and then vise versa. Just when I think I've got it all nailed down, the next coin reflects differently. It is a nightmare and I feel like I am chasing a moving target. But I am enjoying it. Here is an example of one that I am happy with.

http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158821&stc=1

[WaterSport]

Like Jon said - Ray Pankhurst will be glad to talk photography with you since he specializes in coin photography. My best shots seem to be at night with no other light around when shooting proofs. Then again, I can't explain why and I just hope I get a decent Pic LOL. Another challenge can be steel cents.

Bob

[rbenton]

I use the same method for all Lincoln cents except proofs. It is simple, repeatable, and gives me satisfactory results for red, red/brown, brown and steel. But the proofs...:squigglemouth:

http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158822&stc=1

[ray_parkhurst]

Hi @rbenton, and welcome to the forum! Indeed coin photography is tough. Getting everything right to have the traditional photographic values (framing, focus, exposure) is already tough since it requires macro techniques, but coin photography requires additional aspects such as

Luster
Color/toning
Surface detail
Contrast around design features

To complicate things further, these goals are different for different coin finishes and conditions. Proofs require different lighting vs business strikes, and BU coins different from circulated. I was recently stumped when I tried shooting some Canadian Maple Leaf bullion coins with "reverse" an mixed mirror finishes, and then again with some that had colorization. Fun, though.

If you're looking for constructive criticism, let's start the discussion. One thing though is I prefer to discuss on the forum, and for folks to disclose how they do things, show any improvements, etc, so that everyone can learn. So...are you willing to disclose how you lit the coins? I can probably guess how it was done, but it's better to hear from you. I can already see a few simple ways to improve the first and third photos, but can't make a specific recommendation until I know the specifics of the lighting method.

I also see from the histograms of your photos that you are doing significant post-processing. That's understandable and expected, but many folks don't understand the methods and results, so that is also part of the critical discussion.

I'm hoping you are interested enough to be open in discussing these things as it's been a while since I've had a good discussion on the topic.

Ray

[rbenton]

Hello Ray,

Thank you very much for the response. I would love to generate a public dialogue about this. It is the best way to learn, and I have learned a few things already from public forums. I have been a photographer for 60 years (35 years as a professional) so I am used to criticism of all kinds. I have a very thick hide so you are not likely to offend me no matter what advice you offer.
Maybe I can start by describing my methods. For everything except proofs I use the same lighting arrangement. By design it is very simple so that I get consistent and predictable results that I can set up quickly. I put the coins on a backlit box with a diffused glass top so that my backgrounds are featureless white and without any shadow from the coin. I use a Nikon D810 with a 105mm macro lens mounted on a copy stand. I use the built-in on-camera flash, but with a diffuser mounted on the lens.
I have tried countless lighting schemes for shooting proofs, but I will describe the method I used for the one I posted. I put the coin on the same backlit box, and I use the same camera/lens combination. However I have a box containing a semi-silvered mirror (mounted at 45 degrees) attached to the front of the lens. I use axial lighting provided by a speedlight in a small softbox. It seems that I am constantly fiddling with the lighting while shooting proofs and I almost never feel satisfied with the results. I am beginning to realize that part of my problem is that most of my proofs are really not very high quality.
I try to do as little post processing as possible to keep the results as true-to-life as I can. A habit from years of photojournalism I suppose.
I can post photos of my set-up if that would help anyone, but in the meantime hit me with your cruelest critiques.
Thank you very much Ray!

[ray_parkhurst]

Hi @rbenton,

Your methods are quite a lot different from mine, so will be interesting to see what could be a blending. For now, let's leave the axial lighting on proofs for later discussion and focus on the business strikes, OK? Axial is a whole separate discussion.

Your use of backlighting is interesting. I've heard from several folks who do this rather than doing black backgrounds. I personally prefer black backgrounds to my coin images, so it's natural (for me) to use a black background when shooting, but since you're publishing with a white background, the backlighting makes sense. I do wonder which makes more sense from a photographic perspective. Do you have any thoughts on this?

It's also uncommon for folks to use camera flash. Most folks instead use a pair of lights, or in some cases a pair of flashes. Your use of a single, diffuse source creates a hotspot at ~12:00, and resulting over-exposure. To fix this, most likely you can modify your diffuser to create a masked area at ~12:00 to reduce the illumination, effectively creating two sources out of one.

One other thing I see, especially in the third photo, is that you are publishing very bright. I usually end up too dark, so your images look really bright to me. I of course can't say if this is "correct" for the coin, but from a relative perspective your coin #1 is less bright, though still brighter than I expect from a circulated coin. Thoughts on this from an overall exposure perspective?


Given your comments on post processing, I assume you're shooting jpg, correct? You must know that camera settings are very important in jpg, as those settings determine how the raw image is mapped to the final image. If you're shooting raw, then indeed there is a lot of post processing going on whether you know it or not. So while I said "post" processing, those camera settings are doing a lot of processing on the image before it leaves the camera. I personally consider this "post" since it is after the image is exposed. I'd be curious what flow you are using, jpg or raw, camera settings, etc.

[rbenton]

Thank you for your thoughts Ray. Photoshop can precisely select the coin in an image automatically as long as the background is featureless and devoid of a cast shadow. This makes it easy for me to batch process dozens of images at once, cropping them to consistent size with an identical amount of white space around the coin. This is the only reason I chose to backlight the coins. If I only have a half dozen or so coins to shoot, I shoot them on whatever background is at hand and I'll take the time to select them manually, then cut/paste them into a blank frame. I had not considered until you mentioned it, but Photoshop can auto-select a coin on a solid black background just as well. Maybe I'll switch to black and simplify my kit even more. Can you recommend a good material that photographs as a deep solid black? I have posted a 1955 DDO with a black background.

I use flash because I have several laying around that I am familiar with, and old habits are tough to kill. My intention at lighting from 12:00 was to suggest a little bit of 'direction' from the light to bring out some contours. I see what you mean by a 'hot spot' however, so I will try your suggestion of masking the diffuser to see how that looks. In the meantime, I shot this 1915 rotated about 30 degrees counter-clockwise so the lighting 'direction' catches the front of Lincoln's face. (rotated back in post so the light appears to be from 2:00) I like this better and I don't think it looks as much like an accidental 'hot-spot.'

I also see your point about overall exposure being a bit bright. There is some subjectivity to this, of course, but I have experimented with this and felt these images looked right to me. Nevertheless, I processed this 1915 a bit darker, and now I think this version looks right to me! Maybe I'll break out the old Grey Card and expose for that. We'll see where that leads

I shoot everything in .NEF raw as that gives me the most flexibility in post processing, and again I can batch process dozens at a time in Photoshop's Camera Raw. And yes, I know how much processing the camera imparts before I open the image, but I try to do as little as possible to the image after that. Minor sharpening and exposure correction as needed.

So, for whatever it's worth, here is a bit of the metadata from the raw file of the 1915:

Lens (mm): 105
ISO: 320
Aperture: 16
Shutter: 1/250
Exp. Comp.: -0.3
Flash Comp.: 0.0
Program: Manual
Focus Mode: AF-S
White Bal.: SUNNY
ICC Profile: Adobe RGB (1998)

I am posting an unedited image of the 1915, paired with the finished image after some minor sharpening, and cropping.
I also posted a 1955 DDO with a black background.

Thanks again for your suggestions Ray. I sincerely appreciate it.

http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158898&stc=1 http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158899&stc=1 http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158900&stc=1

[ray_parkhurst]

Hi @rbenton,

I do see how shooting a white background would help with processing, and agree that a black background would allow a similar process, but doing the processing at all should be avoided IMO. Part of the reason I do "disappearing" backgrounds is to avoid such processing. You could also avoid it with the white background, simply doing a manual crop around the coin. Allowing Photoshop to mess with it creates an unnatural edge treatment. I've never done a post-processed black background on a coin that was shot on black, so am not sure it is any better, but I would expect so, since the transition from the darker coin edges to the background is a more natural one versus the dark edges to white. Publishing in black may mitigate this, even if you shoot backlit.

As examples, your 1915 edges with white background look very processed, but the 1955 edges do not, see below. However, your 1955 image is titled "55 ddo phone", and is lower quality vs the 1915 image. Was it shot and processed the same way? Can you process the 1915 (backlit) image with a final black background for comparison?

And not to be nitpicky, but your 1915 image seems a bit oversharpened. Sharpening level is a personal choice of course, and the images I am showing below are at 300% so suffer from pixelation, but at these zoom levels it's usually more apparent if oversharpening has occurred. You didn't mention how much sharpening you're using, or how it's being done. I see this type of oversharpening happen with Sony cameras (using Sony software), but I don't have any experience with the D810 and PhotoShop. Using LightRoom, I can create such adverse effects most easily using the Local Contrast adjustments, or with the Contrast by Detail Level adjustments.

If you want to try shooting with a black background, I use ProtoStar. It is the least reflective surface I have found which can stand up to background use, ie having a coin sit directly on it without damaging it. There are other materials and paints and such that are much blacker, but they are too delicate for such use. Even the ProtoStar material must have some maintenance to remove any dust before shooting, but it holds up well.

One more thing about the metadata...I find it odd that you're not doing MWB. How can you trust the color of your output?

http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158901&stc=1

http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158902&stc=1
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Edited to add: I see a couple other items in the metadata to discuss:

ISO 320. Because you're shooting hot, this works OK, but if you start shooting to avoid over-exposure, you will want to go lower in ISO (100 or lower) to improve shadow noise. This is especially important as you map shadows from raw to jpg. Note that if you use a black background like the ProtoStar, you'll lose some shadow detail unless you change the processing a bit since even the blackest backgrounds don't go to 0,0,0. I believe what you're doing with the backlighting and over-exposure is called "shooting to the right", while what you end up doing with black backgrounds is "shooting to the left".

Aperture 16. I assume this is the readout from your AFS lens, which will report effective aperture rather than nominal. However, EA16 is still quite small, and while it improves DOF, it also degrades resolution and sharpness. Your D810 pixel pitch is 4.88um, so your DLA is ~f/7. You say D810, not D810E, so you have an active AA filter that will degrade the DLA by perhaps 50% to ~f10, so you are losing 60% of your available resolution and sharpness by shooting at EA16.

[rbenton]

My method while batch processing does not cut/paste the coin image. The steps are: open the image, select the coin, crop tightly to that selection, then (after deselecting) enlarge the canvas size by 104% to add some white space around the tightly cropped image of the coin. The result is an image of the coin with backlit background, and some digitally added white space around it to give the coin some 'breathing room.' I only use this approach when I am dealing with dozens of coin images at once. It is much cleaner, more consistent, and faster than the way I would do a single coin. If I only have one coin to shoot, I use any blank surface as a background. This of course produces a visible cast shadow of the coin. In post I would then manually select the coin without including the shadow, then cut/paste into a blank white frame. That is what I did with the 1915 image and the artifacts you see around the edge are vestiges of the original background around an imperfect selection. The 1955 w/black background was done this way, but any remnants of background color that may have remained disappear into the blackness.

I add some sharpening in Photoshop's Camera Raw where there is a group of sliders to adjust values for Sharpening, Pixel Radius, Detail, and Masking. Sharpening here is much more limited than other methods in Photoshop, such as Unsharp Masking, or High Pass sharpening which can easily be overdone. I use 75% sharpening at 1.5 pixel radius and leave the other sliders alone.

When prepare to shoot a large number of coins, I take care to keep the plane of the camera sensor parallel to the plane of the coin, I manually focus using the live view zoomed in as far as possible then I lock the focus ring in place with gaffer tape. I adjust the backlight until it's just barely overexposing. Finally I shoot a grey target which I use to establish WB in post. I apply that value to all the coin images. If I am just shooting one coin, it's much more 'quick-and-dirty.' I hand-hold the camera and set WB for daylight which is usually close enough.

Finally, I think your advice about pixel pitch and DLA is very good. I will put that to use. Do you have a good resource for calculating this? I have a couple other cameras I use and the numbers would certainly be different if I shoot macro with them (Nikon D850 and D4S).

Here is a coin I shot today using all the 'batch' methods mentioned. So except for the 4% white border, the background is in-camera. The edges of the coin are complete and the color and exposure are as close to 'reality' as I could manage. (I used a 18% grey card for exposure and WB)

Thanks again, Ray. I love the learning process!

http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158923&stc=1

[ray_parkhurst]

When you increase the canvas size, do you scale the coin image? Non-integer scaling degrades sharpness, and sub-fractional scaling is the worst offender. I saw the "104%" and cringed, but if you're just adding space around the coin and not affecting the coin image itself, no worries.

I forgot to comment before regarding the image rotation. It's best to avoid this as it does degrade sharpness, though not as much as non-integer or sub-fractional scaling does.

As I said before, sharpening is personal and subjective, and there is a wide range of sharpening in various coin images on the web. I only commented because the result I see on your images was similar (though not as dramatic) vs what I saw on the A7Rm3 and A7Rm4 with pixel-shift.

Given your process, I would not see any advantage to using a wider aperture. Shooting at EA16 gives you enough DOF to compensate for the variations in critical focus distance when using fixed focus. Ensuring flatness is important for either fixed focus at EA16, or critical focusing at wider aperture, so is always a good practice. If you used a wider aperture you'd need to critically focus each shot at a mid-height feature.

Back to image rotation, I see that you did an ~45deg rotation CCW on this coin. This, plus your canvas expansion and the not-quite saturated backlighting, leaves some interesting background artifacts, see below. If I were using such a process, I'd further increase the backlight brightness to ensure background saturation, and adjust my direct lighting to compensate. I think this would eliminate some of the issues with artifacts and may possibly simplify the workflow as there would be no need to crop the coin and paste white around it...it would already be there. If the camera does not respond well, and does not push the background to 255,255,255, then a simple brightness or exposure adjustment in post should give the same result. I was pleased to see no over-exposure in the '09-S image, but you may need to do more exposure compensation if you increase backlight brightness to give room for the added post processing.

Thanks for the explanation of how you're doing white balance. I will often shoot with a grey background, especially with toned coins, to ensure I carry a reference in the image. Makes people believe the colors.

http://www.lincolncentforum.com/forum/attachment.php?attachmentid=158941&stc=1