One Picture, Many Pitfalls - Coin Community Forum

To participate in the forum you must log in or register.

Author	Replies: 6 / Views: 1,854
CaptainFwiffo Pillar of the Community United States 4132 Posts	Posted 08/03/2012 6:38 pm I was playing around with different methods of lighting this 1944-D Mercury dime - when I tried lighting it with direct, non-diffused Janjsös, I found a bunch of interesting things. 1944-D Mercury dime (reverse) by CaptainFwiffo, on Flickr (this is mostly unprocessed, so never mind if it looks a little off or dark) First up, tons of chroma noise due to the many fine die polishing marks covering the coin: Also, the fine, bright highlights expose longitudinal chromatic aberration. This is at f/5.6 with the 75ard1. The high points show purple fringing, and the low points show green. I boosted the saturation on the right half to make it more obvious (I now have a precise test to see if I don't have the coin dead level): 1944-D Mercury dime (reverse) by CaptainFwiffo, on Flickr Finally, the fine detail means that this photo suffers from the insidious gamma-related scaling bug that affects most image manipulation software. To make it clear, I've created an animated gif: The correct image (scaled in a linear color-space or a piece of software that is gamma-aware in its math) is brighter and sharper looking (both were scaled with bilinear interpolation). Report this Post to the Staff

rmpsrpms Pillar of the Community United States 4037 Posts	Posted 08/03/2012 9:49 pm The Jansjos have a fairly small emitter. All the light is coming from a 2mm diameter drop of phosphor, so appears more pinpoint than a typical incandescent and much more so than a fluorescent. This creates a high level of local contrast and seems to overwhelm Canon sensors/processors. I don't see this problem as much with my Nikon. But it's quite easy to get rid of with some diffusion, which is usually needed anyway in order to optimize illumination. Contact me for photographic equipment or visit my home page at: http://macrocoins.com Report this Post to the Staff
CaptainFwiffo Pillar of the Community United States 4132 Posts	Posted 08/04/2012 02:54 am Here's the shot I settled on. 1944-D Mercury Dime by CaptainFwiffo, on Flickr Report this Post to the Staff
brg5658 Pillar of the Community United States 627 Posts	Posted 08/04/2012 4:37 pm SuperDave went into great detail about the chroma-noise problem with non-diffused Jansjos in a previous thread. You may try to find that one so you aren't re-inventing the wheel with your experimentation. Your pics are looking great Captain -- welcome to the world of looking at your coins in more detail than we probably should! Report this Post to the Staff
CaptainFwiffo Pillar of the Community United States 4132 Posts	Posted 08/04/2012 6:43 pm This coin is a favorite of mine. In hand, it looks proof-like but with really strange sparkly luster which looks like it's coming from under the surface (which NGC decided was star-worthy.) The marks by the "B" in liberty look like a big flaw, but then when you get it under the loupe, they are clearly die gouges, and the whole surface is just completely covered in die abrasions. The higher the magnification, the more bizarre it gets. It must have been one of the first coins struck after the dies were polished, because some very, very fine die scratches are reproduced, beyond any level of magnification that I can achieve. Report this Post to the Staff
rmpsrpms Pillar of the Community United States 4037 Posts	Posted 08/04/2012 10:41 pm I see the long-CA on my 75ARD1 as well. Even though Rodenstock calls the lens apochromatic, it actually is an achromat with well-controlled long-CA. There are very, very few lenses out there which are truly apochromatic. Contact me for photographic equipment or visit my home page at: http://macrocoins.com Report this Post to the Staff
CaptainFwiffo Pillar of the Community United States 4132 Posts	Posted 08/04/2012 11:08 pm I actually find it to be a useful focusing aid. Report this Post to the Staff
	Replies: 6 / Views: 1,854

To participate in the forum you must log in or register.

All Forums Category: General Numismatic Forums Forum: Coin Photography, Image Editing, and Related Software

The First Dollar, your premier source for bullion and rare coins. See our bullion list on the site and the coin inventory on ebay.

Silver Gold Bull US is the United States leading bullion dealer. We deliver gold coins, gold bars, silver coins, silver bars and precious metals to your door. Order today!

View Last 100 New Topics

View Last 100 Active Topics

Disclaimer: While a tremendous amount of effort goes into ensuring the accuracy of the information contained in this site, Coin Community assumes no liability for errors. Copyright 2005 - 2026 Coin Community Family- all rights reserved worldwide. Use of any images or content on this website without prior written permission of Coin Community or the original lender is strictly prohibited.
Contact Us | Advertise Here | Privacy Policy / Terms of Use

Coin Community Forum

It took 0.24 seconds to rattle this change.