Guide / Tutorial Photographing gold so that it looks like gold - Part 2 (more advanced techniques)

[Charliemouse]

This is a follow-up tutorial to:

This is for those with a little more time, who want to get accurate and visually satisfying results with their photographs

There are three main techniques here, which can be used independently or together.  None of them are expensive; in fact the third one is free; but they do take a little effort and knowledge.

1. Using grey cards (‘gray’ for Americans)

A ‘grey card’ is exactly that.  A piece of card that is grey.  A professionally produced photographic grey card, from a reputable vendor, will be fade-resistance and precisely calibrated to be a neutral colour, i.e. exactly balanced with no hue.  For coins and other precious metals, I would recommend a small card, maybe 2x4 inches or thereabouts.  Should definitely cost well below £10.

A white card will also do well, although grey cards are easier to use and are less likely to fade or discolour over time.  A piece of white paper may also help, but be wary as it is easy for the paper to be slightly off-white, and this will affect the colour balance significantly.

At the other end of the scale, you can take it further and buy colour cubes, colour reference targets, and specialist software to calibrate your photographs.  Those are beyond the scope of this tutorial - if you are in the market for those, I am not going to be teaching you anything here.

There are basically 2 ways to use a grey card: a) reference shot, or b) in shot.  Both have pros and cons.

a) Reference shot

Take photograph(s) of your coin(s) as normal, but just before or after, replace your coin with the grey card.  Put the card in the same place, and at the same angle, and photograph it.  This will provide you with a reference neutral colour, that you can then adjust to.

Using photo adjustment software, you would then measure the correct colour balance or adjustments using the reference shot, and apply exactly the same to the real shot(s).  There are too many different photography applications for me to cover exactly how to do this here, but you should find it under ‘white balance’.

Advantages: the coin photograph is unaffected, you don’t need to recompose or move anything, and you should be measuring the exact same conditions because the card is in the same place as the coin.

Disadvantage: takes a bit more time, needs post-processing software, should not be used when the lighting situation can change quickly, e.g. if you are using natural light, and a cloud covers the sun, it can make a dramatic difference.

b) In shot

Here, you include the grey card in the photograph with the coin.  The card needs to be at the same angle and under the same lighting as the coin.  Just widen the shot so that the card is in the frame.  Once taken, you can crop out the card before sharing your final image.

A variation of this is simply to use a white, lighter or grey background for the coin, but this is down to the desired aesthetics.

Advantages: quicker, may enable the auto white balance feature of the camera to make a better ‘guess’, useful when the lighting conditions may change between photographs.

Disadvantages: may be awkward to compose the image wider depending on space, should not be used if the lighting is very local, i.e. only the coin is lit, because the card would not be under the same conditions and the white balance may vary across the scene.

2. Photographic lighting

This falls into 2 main categories, flashes and monitor lights.  For the purposes of coin photography, flashes are unnecessary, difficult to use and expensive.  So for this tutorial, I will focus on monitor lights.

For between £50 and £150, depending on features and brand, you can buy a ‘monitor’, ‘video’ or panel light.  It should have a high CRI value (90+), which is a measure of its colour accuracy and how natural it is.  And it should either have a known fixed colour temperature, preferably around 5,600 Kelvin (daylight), or an adjustable temperature.  (White balance is measured in temperature Kelvin - don't worry about it - just know lower numbers are yellower and higher numbers are bluer. For this tutorial, it doesn't matter.)

Simply set it to a known value, set your camera’s white balance to the same value, and snap away.  This should be all you need to do.  A modification of this is to photograph in RAW mode, and then use software to set the white balance to the light’s known temperature afterwards - see below.  If you do not shoot using RAW, adjusting the white balance later will always be harder and a compromise.

You need to ensure that the monitor light is the only (or overwhelming) light in the scene.  Lights in the room, through the window, etc, will all influence the photograph, and change the final colour.  Also, lights will reflect off different surfaces of the coin, and produce odd colour patches.  Therefore, you may want to invest in a light box to cut out all the other light sources.  They are available for around £30 upwards, depending on size, or you can make one with a cardboard box and black cloth.

Another consideration is that having a single light source can lead to bright spots, or undesirable highlights on the subject.  This is especially a problem with precious metals that are prone to reflections.  You can easily solve this by diffusing the light using cooking parchment (greaseproof paper), net curtains or similar material, or photographic diffusion paper (a little more expensive, but a neutral colour).  Simply hang the diffusion material in front of the light, preferably making the light source bigger as a positive side effect.

3. Shoot RAW

(This has nothing to do with whether you wear clothes while photographing.  Although I strongly recommend it, as coins can be very reflective. 😁)

This one is a bit more technical, but is free to implement.  You just need some understanding of the principles.

All but the earliest of cameras and phones, have the ability to shoot in what is called RAW.  You can use free, 3rd-party camera apps, e.g. Open Camera, if necessary.

You are doubtless familiar with JPEG files, the ubiquitous image files used everywhere, and by default your camera will generate JPEG files.

However, JPEG files have several disadvantages.

• Lossy compression.  Detail will be lost, and noise added, in order to compress the file to a smaller size.  Worse still, every time you load the file into an editor, make a change and save it, the image will get worse.
• Narrow dynamic range.  JPEG can store 8 bits (256 values) for each red, green and blue value in the image.  Your camera is capable of capturing at least 10 bits, and the latest cameras 12-14 bits.  So at best, three quarters of the possible range of values are thrown away, and possibly 98% is discarded.
• In-camera processing.  An image, displayable in all browsers and devices across the world, needs to be produced.  So certain safe, generic assumptions are made, and baked into the file.  These include white balance, colour gamut, etc.

Ultimately, you need to turn your photograph into a universally acceptable format, for sharing online, and JPEG is a perfectly adequate choice.  You could use PNG, TIFF or numerous others.  So, if you need to use JPEG anyway, what’s the advantage in shooting RAW?

Firstly, for any work you need to do after the shot is taken but before sharing, i.e. post-processing, you should work in a format that does not degrade with each save, for obvious reasons.

Secondly, and most relevant to this tutorial, shooting in RAW does not apply white balancing to the image.  I will use a physical filter analogy.  Each time an image is changed from the original, it is like adding a coloured filter to a light.  You can’t take a filter away.  So you add a filter, but then you need to correct it slightly, so you add another filter.  And then you need to correct that, so you add another filter.

So the incorrect white balance applied by your camera, needs to be corrected with another filter, which inevitably won’t be a perfect solution, so should then be corrected, again, etc.

Instead, working with RAW files allows you to get everything right with the most original possible version of the image.  RAW files should be immutable - any changes can be undone, or are saved separately, so the original is always preserved.

Use a post-processing application (or phone app) to apply the right white balance to the image, get the exposure right, crop it, and when everything is right, save as JPEG and share.

Summary

• Shoot in RAW if at all possible (top advice!).  It makes everything else easier.
• Use a grey card to get an accurate reference for the white balance of the scene, especially if you are not in control of an accurate light source.
• Limit the number of different light sources.  You may want to use a photographic light and/or a light box.

Examples of colour calibrated photos of gold:

[modofantasma]

@Charliemouse thanks for putting this together I haven't time to read it properly right now so will be bookmarking and catching up soon but thanks for taking the time and helping us photographic whoppers with our snaps 👍🏼

[Rains]

Only just seen this @Charliemouse thanks will give it a read later on

[Scootermuppet]

... and then there's the 'out of your control' variable of the screens that people are viewing the pictures on - unless the Monitors / Screens are colour calibrated, the same picture will look different on just about everyone's screen to some extent.

It's a minefield alright ! 😏

[Charliemouse]

38 minutes ago, Scootermuppet said:

... and then there's the 'out of your control' variable of the screens that people are viewing the pictures on - unless the Monitors / Screens are colour calibrated, the same picture will look different on just about everyone's screen to some extent.

It's a minefield alright ! 😏

Yeah, I didn't want to get into that, since as you say, it's out of the photographer's control.

Fortunately, unless your monitor is configured really badly, then it will be good enough.  Old CRTs used to be worse, especially as people would fiddle with the dials.  Modern LCDs are generally stable and good enough.

What I'm trying to fix here is when people post pictures of sovereigns or gold brits that look silver.  They have no hue, because their phone has balanced it out.  Happens every day.

I'm not trying to fix precise colour matching, so you could hold your coin up to the screen and not see the difference.  Unless you have professional equipment in a studio, and regularly calibrate it, that will never happen.

[Scootermuppet]

Very true 😊

And you're right of course - using Auto settings on any camera leaves it wide open to inaccuracies on the white balance front.

I've always taken care when photographing anything I'm selling (not only PMs) as I believe a good, clear photograph can add value to your item - whatever it may be...

The amount of items on eBay (for example) with fuzzy, out of focus, blurry pictures is mind boggling - and not just cheap & cheerful items either, big ticket items too.

Hopefully your tips & tricks will help us all to improve our photos and potentially realise more for our PMs in the long run.

😁👍

[Charliemouse]

54 minutes ago, Scootermuppet said:

Hopefully your tips & tricks will help us all to improve our photos and potentially realise more for our PMs in the long run.

Thank you.

That is all I wish for.

[James32]

53 minutes ago, Charliemouse said:

Thank you.

That is all I wish for.

2 wishes left

Use wisely 👌 

[ShineyMagpie]

I have seen some people mentioning about "macro lense" apps for phone use other than the traditional phone camera app. Do people have any particular recommendations (free) on android?

[Solachesis]

I wondered why I never had to do anything to get lustrous golden colour in my photos, then realised the weighted blanked I take photos on is grey 😆 probably why.

[Charliemouse]

9 hours ago, ShineyMagpie said:

I have seen some people mentioning about "macro lense" apps for phone use other than the traditional phone camera app. Do people have any particular recommendations (free) on android?

This is a bit off topic, but briefly...

Macro photography requires a camera capable of focusing close to the subject - it's a physical / mechanical property.  If the lens on the phone is physically unable to do that, no software is going to fix that.  That said, the last couple of generations of flagship mobile phones have had lenses with close focus capability, so it is possible that there are specialised third-party software apps to make use of this.

Another possibility is that the applications are calling themselves macro as marketing, and are not true macro.  They allow you to crop in on the subject, as almost any software does.  The word "macro" is used loosely in a lot of photography marketing.

To specifically answer your question about good, third party camera apps, Open Camera is very well respected and supported.

Finally, there are physical macro lenses that attach to the phone.  I discussed this in another thread:

 

Edited January 19, 2023 by Charliemouse

[ShineyMagpie]

4 hours ago, Charliemouse said:

This is a bit off topic, but briefly...

Thanks for the answer, sorry to throw of topic but thought it would add to, so I can get my silver gold to gold, but then also in focus sensible image for a 1/20 or whatever size coin

[Charliemouse]

1 hour ago, ShineyMagpie said:

Thanks for the answer, sorry to throw of topic but thought it would add to, so I can get my silver gold to gold, but then also in focus sensible image for a 1/20 or whatever size coin

My advice is to just take the photo normally and crop in.  I can only speak from personal experience, and that has not been positive.  There are limits to what a phone can do, and strapping a cheap plastic lens to it probably isn't going to help much.  Sure, you will get some magnification, but the image won't be pretty.  To get better quality images, I would encourage you to buy a camera with a macro lens, and it probably wouldn't cost much more than a 'higher end' strap-on lens for a phone.

I will cover focusing in another tutorial.

Edited January 19, 2023 by Charliemouse

[Jake0111]

Light defuser is a god send for taking photos of coins, but im always to lazy to get my camera out and use my phone 🤣

[ShineyMagpie]

2 hours ago, Charliemouse said:

strap-on lens for a phone

Well I tried something different, and held a loop in front of the camera and cropped the image after, it's not by any means perfect, but I thought I would try 😅

[Charliemouse]

10 minutes ago, ShineyMagpie said:

Well I tried something different, and held a loop in front of the camera and cropped the image after, it's not by any means perfect, but I thought I would try 😅

Good white balance, because there's plenty of grey in the picture for it to lock onto.

As I mention in the other article, a big problem you will have when magnifying is loss of depth of field.  Keeping everything in focus will be very difficult.  And of course you are getting a lot of barrel distortion.

What phone are you using?  Just try taking the picture from far enough away that it can focus, and then crop it.  Anything with 10 million pixels or more will probably produce results good enough to sell the coin.  If you want something better, you are probably asking too much of a phone.

Edited January 19, 2023 by Charliemouse

[Charliemouse]

10 minutes ago, Jake0111 said:

Light defuser is a god send for taking photos of coins, but im always to lazy to get my camera out and use my phone 🤣

I'm afraid you are in the advanced tutorial - we don't do too lazy.  🤣

[Jake0111]

33 minutes ago, Charliemouse said:

I'm afraid you are in the advanced tutorial - we don't do too lazy.  🤣

The horror of 1st world problems 😅

[Coverte]

Thank you for these two - only just saw them - printed to PDF for future reference 👍

[Charliemouse]

On 31/07/2023 at 19:36, Coverte said:

Thank you for these two - only just saw them - printed to PDF for future reference 👍

No problem.  Feel free to ask any questions.  Happy to help.