Photo lighting

[peterpil19]

Here are 3 photos of the same coin using different lighting set ups.

A. Direct light diffused with baking paper as earlier Faustina I coin.
B. Indirect light.
C. Axial lighting.

C.  produces an image with the clearest features though it totally misrepresents what the coin looks like in hand.
B. is the closest to the coin as it appears in hand. Less clarity than C (axial lighting). Also appears flatter due to indirect lighting source.
A. did not come out as well as I expected...

I found this to be a particularly difficult subject to photograph as it is shiny with smoothed fields and the legends are not clearly visible on the reverse.

Peter

[dougsmit]

If the coin is green, B has to be best but  it might be possible to balance the colors better on the others.  Glare does tend to go blue.

[peterpil19]

I have settled for B.

On close inspection the coin appears to be tooled on the reverse as well as smoothed - I don't think it deserves any more photos... I really wish people would stop and think before irreversibly damaging a piece of ancient history.

I will try your suggestion on working on colour balance on the next series of coins I post here using different lighting set ups.

I am learning that lighting is horses for courses. The same set up rarely yields the same result with a different coin. I suppose that is part of the challenge and fun in photographing ancient coins! If you had the perfect set up and simply had to press a button to take a photo it would hardly be an engaging hobby!

Peter

[peterpil19]

Hi,

I have been experimenting with axial lighting. I have never used this technique before.  

The typical set up as I understand it from various sources on the internet is to place a pane of glass above the coin at a 45 degree angle with the light source perpendicular to the coin so that light travelling from the source is reflected directly onto the coin and then straight up towards the lens of the camera as though originating from there. This lighting method removes shadows from the image and makes legends easier to read.

Many of those sources also recommend blocking extraneous light by e.g. placing an object in front of the coin so it is not exposed to he light source directly other than as reflected from the pane of glass.

I have found that I like the photos when I do not block the light from hitting the coin directly from the light source i.e. so there is a combination of direct light and axial lighting.

I have illustrated this with 2 photos. The first was taken without blocking the direct light, the second taken, with an object completely blocking direct light from the light source.

Do others experience this also and use a combination of the two?
Or is likely related to the manner with which I have taken the photos and the preferred approach is not to have direct lighting.

Also, when do others use axial lighting? I have found it results in nicer photos for some coins but not others.


Peter

I have retaken the Faustina sestertius using my most recent lighting set up (more diffused lighting) which is working better for me - I still get 'depth' in the coin whilst reducing overexposed highlights.

It is the third photo below. The first two photos were taken using the lighting set ups described in the quoted post above.

I am still not perfectly happy with this photo but believe it to be a significant improvement.

Peter

[dougsmit]

I agree that itis better.  The reverse strikes me as very good but I can not say just what needs to be done to the obverse  Perhaps change nothing in the lighting but prop the coin on a small bit of clay that would allow t to be wiggled a bit.  Take several with tiny tilt differences ad see if one is better than the others. 

[peterpil19]

Thank you Doug,

I will post some photos later after playing around with the angle of the obverse as you have suggested. It is unbelievable how changes to lighting can have such a profound effect on the overall appearance of the coin. Even subtle changes can mean the difference between a bad and good photo.

[peterpil19]

Taking decent photos of highly convex coins like the Philip II bronze coins I have posted in this thread has proven to be a challenge.

1) Light does not fall evenly on the coin like a flatter coins. This results in overexposed parts which I can either choose a) diffuse the light to a degree but can make the resulting coin look bland; or b) as Doug has suggested - move the coin until the highlights rest on the part of the coin which looks the least terrible. At the same time there are also underexposed parts unless the light comes directly from above using axial lighting or a ring light (which I do not have). 2 lights, one on each side, seems to have a better result than bouncing the light onto the underexposed parts using e.g. a white card.

2) Keeping all parts of the coin in focus is not possible with my compact camera, even at higher f-stops. I did try to merge a couple of images taken from focusing on different parts of the coin, but the difference was nominal.

The photo below is the result of countless takes. Particularly difficult due to the texture on the coin and soft, less defined features.

Can anyone share their techniques for taking photos convex coins like this one?

Peter

[dougsmit]

Digital photos that are overexposed do not postprocess well into good images.  I would suggest setting the camera to give two stops less exposure and try again with other things being the same.

[peterpil19]

Thank you Doug,

Reducing the exposure does lead to better outcomes in post-processing. That is proven in the case of this coin in the photos below.

Focus still remains a primary issue for me with highly reflective concave coins.  Higher f-stops does not increase depth of field enough to keep most of the coin in focus. On this coin the lower half the coin (particularly around the mouth) is still hazy with not enough detail picked up. I think it is due to the reflective nature of the coin combined with the concave surface of the obverse.  I seem to get better photos of flatter toned coins or coins without shiny surfaces. It may be limitation of the lens and sensor of my compact camera and one I must live with until I get my dSLR (very soon, I hope!). I may have to accept a degree of post-processing and image sharpening in the meantime.

I have attached the same coin - the first image is unsharpened but with levels adjusted. The second image is the same photo but with unsharp mask applied.

Peter

[peterpil19]

Here is my final attempt.

Tilting the coin backwards so that more light hits the lower part of the coin assists somewhat. But I am still not pleased with the outcome.

First image is unsharpened. The second has had 'unsharp mask' applied to it. I don't like doing that as it feels like cheating...but I suppose it is there to be used and not all images come out sharp enough.

I will wait until I have better equipment before posting another photo of this coin.

Peter

[dougsmit]

Congratulations on arrival at an important stage in the process.  Your photo is as good as the coin but you realize that there will always be other answers.  I doubt better equipment will help a lot but it does make the process more fun and I keep wanting more, too.  Now do the same with other coins.  I find myself hesitant to buy coins that I fear I will not be able to photograph but learning which ones fit that group really is a difficult process.  The prettiest coins are not always the most fun to photograph.

[peterpil19]

Thank you Doug,

That's very high praise coming from you!

Given I intend to collect these rather concave / convex Philip II coins, I must grow proficient at photographing them no matter how difficult!

I have had a new batch arrive this week and all of them have been easier to photograph than the one above.

Hopefully others have found the above posts and your advice as helpful as I have with respect to understanding lighting and how it affects the quality of photos.

To summarise some learnings to date with such coins - from my experience with my equipment and set up which comprises a compact digital camera and copy stand with 2 mounted moveable lights:

1. making subtle changes to the angle of the coin leads to large differences. Continued experimentation is recommended.
2. on the obverse which is concave, using 2 lights, one on each side, produces a better outcome for those coins with a very high relief. Otherwise it is hard to get light to the other side of the coin unless there have the light directly above (e.g. axial or ring light).
3. shinier coins even ones with patina requires careful selection of the level of exposure - err on less exposure, not more.
4. Using a smaller aperture (higher f-stop) is necessary to keep more of the coin in focus.
5. Diffusing the light helps reduce the amount of overexposed white parts on the coin. Softening the light too much however can result in a bland lifeless coin.
6. The angle of the light makes a HUGE difference to the clarity of symbols, legends and other features. For instance, light falling from one side can obscure important features of the coin. However light falling from the other side might make them pop out.
7. Different lighting might suit one side e.g. the obverse and not the other side (reverse). For instance where I said above it is helpful to sometimes use two lights (one on each side), this is not true of the reverse which is convex. Two lights obscures the detail on the reverse.

Peter

[dougsmit]

Those 7 pretty well describe life as we photograph it.  Perhaps I'd add one more.

8. Keep practicing.  If you find you are getting frustrated, take a break. 

[EB]

I use gimp to edit my photos, and having a pure black background makes the job easier. Here are some notes regarding my implementation of Doug Smith's shadow tube.
 
In order to get the blackest background, it is best to have the background as far as possible from the light source. So the shadow tube should be as long as possible, within the constraints of your copy stand etc. A whiskey bottle box is a manageable size. Any whiskey can be used, but after much trial and error I decided on a mid-level single-malt.
 
The tube is lined with black velvet. There are various types of velvet. Go for the deepest black and avoid anything shiny. The fabric sheds lots of lint when it is cut. I lined the edges with glue to prevent further fraying. (Alternatively, one could buy some black flocking paper from an astronomical telescope supply company.)
 
My first photos were OK, but the background was not absolutely black. I use a ring light, and the bottom of the tube is perpendicular to the light source. That made me think of using a reflective cone to deflect the light away from the center. I thought about using an acrylic martini glass, or a plastic soda bottle, but the dimensions were not quite right. Finally I settled on reflective window film, which allowed me to create a cone of exactly the right dimensions.
 
In order to accommodate small coins I chose a thin dowel. To provide a stable base for larger coins, I cut up some old markers which can be fitted over the dowel to increase the diameter. Paper is spooled and inserted into the markers so that they fit snugly. Some of the markers are angled on top in order to get irregular coins to face up.
 
The dowel is inserted and into a wooden disk that fits into the bottom of the shadow tube. The wooden disk is glued onto a stack of old DVD's. The DVD's sit on the base of a DVD case with the spindle cut off at about 1cm. This allows the shadow tube to be rotated smoothly and easily.
 
In order to make further minor position adjustments, I mounted the shadow tube on a home-made X-Y positioning stage which, while functional, is not a good design, so I won't go into detail.
 
Finally, a stack of wooden shims allows me to raise and lower the X-Y stage (I don't have a copy stand which would allow me to raise and lower the camera).

[dougsmit]

I am glad to see so much thought put into this. I am currently happy with a shade producer made from a matte black plastic flower pot of the type you get buying flowers from a nursery.  I find that the tapered sides reflect less than a straight tube.  On top, I rest a plastic take-out food container with a hole cut just a bit larger than the coin.  I have four sizes.  My old fashion dowel support is now a steel rod which accepts various interchangeable tops.  Most coins use a tube from a plastic ball point pen with the silicon rubber soft grip pulled up so the coin rests on the soft material.  Larger coins use one made from a disposable syringe that came with liquid Baby Ibuprofen.   Smallest ones use a longer support tip made from a ball point refill with a tiny bit of clay on top.

I have never learned Gimp so continue to use Canon DPP freeware (comes with camera) and Adobe Photoshop Elements (far from free but I am used to it and resist change).

In the right image below, the tall post is the steel rod  while the other three are placed there for the photo on a rack made to keep them handy.  I may be able to give up collecting coins since making these Rube Goldberg photo rigs has become a hobby in itself. 

[peterpil19]

Doug and EB,

I can see that you both prefer black backgrounds.

What advantages are there in photographing a coin with a black background instead of photographing it with some other background e.g. white and filling it in later with black? Is it that it saves a step in post processing or do you notice that the coins photograph better when using the black background?

Peter

[EB]

Hi Peter,
For me it's the post-processing. I like to do a background fill (bucket fill in GIMP) to completely eliminate the background. White looks nice, but I find it much harder to get a clean edge.
By the way, for those who use GIMP, I will be posting in another thread some python scripts that I have written to semi-automate the process of background fill, crop, and arranging side-by-side.
Regards,
EB

[dougsmit]

I will be very interested to see your Python scripts. 

My observation is that light from a white background bounces around and creates flare that eats into coin detail reducing micro contrasts.  If you want white in the end, shoot on white.  If you want only a photo of the coin, the black background is nothing and does not interfere with the coin.  Black is the absence of light so we call it level 000000 or 00 of each red, green and blue; white is the presence of more light than the camera can record which is ff  (hexidecimal for 255) level for each color. It is easier to deal with zero than to stop exactly on 255.

[peterpil19]

By the way, for those who use GIMP, I will be posting in another thread some python scripts that I have written to semi-automate the process of background fill, crop, and arranging side-by-side.

Hi EB,

Do your python scripts cater for white backgrounds as well? What about where you do not have a perfectly white / black background? I rarely get white, especially when using indirect lighting. If I use direct lighting I get close but even then it needs some cleaning up.  I am currently using the fuzzy select tool to remove the background which is usually a matter of seconds, followed by feathering, then cutting and pasting the obverse and reverse images into a new image as new layers.

I upgraded my laptop recently (MacBook Pro) and installed the latest version of GIMP. For the first time ever it is crashing on me from time to time. It also does not remember my settings when I exit and go back in. Otherwise, I enjoy using it. I used Photoshop initially many years ago before moving to GIMP and thought the change was seamless as it is just as intuitive to use.

I will be very interested to see your Python scripts.  

My observation is that light from a white background bounces around and creates flare that eats into coin detail reducing micro contrasts.  If you want white in the end, shoot on white.  If you want only a photo of the coin, the black background is nothing and does not interfere with the coin.  Black is the absence of light so we call it level 000000 or 00 of each red, green and blue; white is the presence of more light than the camera can record which is ff  (hexidecimal for 255) level for each color. It is easier to deal with zero than to stop exactly on 255.

Hi Doug,

In your opinion, is the improvement in quality noticeable enough to warrant playing around with black background even where you plan to insert a white background later? If so, I may give it a try - though I doubt I can put together as impressive a set up as you and EB!

Peter

[dougsmit]

No, if you want white, I would shoot on gray and select out to white.  The trouble comes when the white is too bright when shot.  Of course the background white has to be the same color white as the coin illumination lights. 

White backgrounds will make coins look darker.  The two below are the same image but some of the black background was turned white in half.  Cut and paste from these images and you will see they match.

[peterpil19]

To my eyes, the colors look different, not just the level of brightness!

Thanks for clarifying.  I keep the original gimp files for each of my photos so it is very simple to change the background if I decide to do so in the future.

[PeterD]

For me it's the post-processing. I like to do a background fill (bucket fill in GIMP) to completely eliminate the background. White looks nice, but I find it much harder to get a clean edge.

Shoot with a coloured background with the coin above the background to avoid a shadow. One click with 'Magic Wand' (I use Paintshop Pro but I presume Gimp is similar) and the whole coloured background is selected. Then use flood fill to substitute with white, black, transparent or whatever. Nice clean edge and no leftover colour. You also lessen the problems mention by Doug with shooting a white background.

[EB]

Hi PeterD,
Thank you for the suggestion. I had tried shooting with a colored background, but shadows caused problems. However, after reading your post I think I will try again with more distance between the coin and the background.
Regards,
EB

[peterpil19]

Thank you Doug,

I'll make sure to post photos soon of the same coin once I purchase a dSLR.
I am curious to see the difference it will make!

Peter

I just purchased a DSLR with a 100mm macro lens.

A few hundred photos in, I find I have spent most of today photographing everything but coins!

I will post coin photos soon for comparison purposes.
From the few photos I have taken of coins I believe I am achieving superior results to my Canon Powershot G9X (compact camera). The biggest difference seems to be dynamic range.

My DSLR is also a Canon and the menu structure and features are largely similar to my compact camera.  This means that the learning curve is not as steep as I thought. Therefore hope to post something very soon.

Peter

[peterpil19]

OK here is a comparison of the same coin using 2 cameras.

The photo using the compact camera came out surprisingly well. But I have taken between 15,000 to 20,000 photos now with this camera so am very familiar with all functions and settings and which aperture / exposure works best with different types of coins.

The photo taken with the DSLR has a much greater resolution due to the macro lens allowing for a much larger photo (both cameras have around the same number of mega pixels).
The resulting image was much larger with more parts in focus. I used manual focus in the SLR photo. I am still experimenting with manual vs. auto focus. So far I have failed to see any difference in my photos using manual vs. auto focus.
 
The most notable difference is the greater range of colours in the photo taken using the DSLR. This is particularly visible when you focus your eye on the earthen fill.

I still have lots of experimenting to do with my new camera.
I will post further comparisons once I have had sufficient practice.

[Edit: I have added the final DSLR photo with the reverse]

Peter