Macro photography and colour balance

[SimonW]

W've just been photographing a recently found 400 year old coin - using the best equipment we had to hand. (I could only borrow the coin for a few hours). After trying to extract maximum detail to make it legible, we took a last shot including a ruler to illustrate the size.



All the photos are adjusted in Lightroom from the RAW files. For colour balance in the shot with the ruler I simply auto-adjusted by clicking on the ruler, and this shot shows the coin's (nice coppery) colour very accurately. I cannot get the colour balance settings right in any of the other shots no matter how I play with the sliders. The ruler is considerably thicker than the coin and must have modified the light distribution and colour, but surely I should be able to correct for that in the software?

Simon

[Hinfrance]

Simon, do you want to put the RAW files on Dropbox or OneDrive so we can have a look at them? I stopped using LR and PS some time ago, and now 'own' the latest Photo Director and Affinity versions, and 'rent' ACDSee Ultimate. So I've got three bits of software that work differently from Adobe to have a try with. Oh, and an old version of DxO.

I take it that you left the camera on auto wb? What light source did you use?

[Beaux Reflets]

Verdigris - the green stuff - is an accumulation of various salt crystals - How the Light reacts; bouncing off, refracting within and filtering (spectrum wise) through the crystals, will always play a roll in what is achieved or achievable, especially in closely lit situations. Also bearing in mind, that the salt crystals fluctuate and change their shape with the changing humidity within the surrounding air.

[SimonW]

I've come to the conclusion this isn't worth worrying about.

To answer H's question, the two bright LED array lights cost £4 each. The incandescent room light was on and there was light from a window. We knew colour balance would be all over the place, but because nothing was moved (till we put the ruler in) it should have been fairly consistent. (It wasn't my camera by the way as I don't have a suitable macro lens - it was a Canon).

This exercise has made me remember things and think a little - my conclusions might be of a little interest to others on here:-

1. Years ago when I bought my first digital SLR (Pentax K10D) all the reviews advised shooting in RAW to get the best out of it (which is why I still use RAW today). At that time I experimented by shooting RAW plus JPG, developing the RAW in the Pentax supplied Silkypix, Photoshop Elements and Paint Shot Pro. I found it impossible to exactly replicate the results from any one of the four resulting  jpgs in any other, and often found I preferred the results of a different one for different shots.

2. I can use the eyedropper tool in most software to see the RGB numbers for any colour in a shot, but cannot make adjustments using the sliders to get close to the same RGB numbers in another similar shot.

3. I normally have the camera set to Daylight white balance rather than auto, and the initial Lightroom view of the shot is of course based on that. I often see no need to adjust it, but if I do I find that clicking the eyedropper on something that should be white can quite often result in all the other colours being wrong. One reason is that the white object is actually reflecting (for example) the blue of a bright sky or the green of sunlit grass. I do need to use the sliders instead.

Conclusion - don't worry about any of this - if it looks like you remember it or how you like it then it's all good.

[Hinfrance]

Simon, just one observation - to get a corrected white balance you should click on a part of the image that should be as close to neutral grey (127.127.127 RGB) as possible. Hence the use of grey cards to establish WB when shooting in difficult/odd lighting conditions. A shot with you grey card is the reference point - even better if you can get the grey card in the shot somewhere, then WB is much easier.

That said, it is rare that I use anything other than auto with any of my cameras, and if there is any issue usually just clicking on auto in any of the software does a very good job. The only exception is that I sometimes set the camera to flash when using studio flash lights, but I usually forget!