Link below is to an article by PCGS photographer, Phil Arnold. Interesting technique called focus stacking allows high relief photography that is sharp from top to bottom. Requires fairly sophisticated photo processing program, like PhotoShop. Cal The link: https://www.pcgs.com/news/a-coin-ph...pJobID=1140668083&spReportId=MTE0MDY2ODA4MwS2
Interesting I use a similar technique called.. Focusing! But I understand his technique. (Photoshop kind of expensive) Thanks for sharing.
There are various tools for focus stacking available, ranging from free software (CombineZP) through software and hardware combinations running into the thousands of dollars (StackShot, etc).
Does GIMP do stacking? I started out with CombineZM, then CombineZP, which are both free. I now use Helicon Focus. Usually for full coin shots, stacking is not required unless the coin is not flat due to tilting, either intentional or un-intentional. Even high relief coins can be adequately imaged at the f/11 Phil mentions, but not if they are tilted. Where focus stacking is absolutely required is for higher magnifications. Above 1:1, the depth of field starts to get very shallow, and stacking is needed if you want a sharp final image.
Nope. My stacking workflow is RAW processing for color/sharpness -> CombineZP using Pyramid Weighted Average (seems to work best for coins) to stack -> Gimp for cropping and display sizing as required. Helicon Focus is on the list of future purchases, when both time and money allow me to do it right.
My only complaint with CZP is that it tends to over-sharpen the rendered image. I was starting to look at writing my own macros (which is as distasteful to me as sucking silly putty) when I just decided to go with Helicon. If you are good at writing macros then you could optimize CZP to give an excellent result. It's good already when downsizing for web publishing.
Would focus stacking work well to show the relief on ancient coins, or would the coins need to be tilted? I've seen coins with higher relief than the entire thickness of some modern coins.
No tilt necessary for the photo technique to show the full depth in sharp focus, but the tilt does give a better "impression" of the 3D quality of the coin.
Thanks so much for sharing the stacking article. I will try it though have been aware of it for a long time. This will just push me to DO.
I've used Helicon Focus for this. It works much better and quicker than CombineZP/ZM, and I think there's a free 14 day trial if you just want to dabble a little bit. Another is Zerene. I used this on a trilobyte my daughter had prepared. I'll try to find the pictures tonight. A friend of mine does this with micro-minerals, using up to 200 frames, spaced as closely as 2 µm. Some pretty cool stuff in his gallery on Mindat.
