Chromatic Aberration - Difference between f/1.4 and f/1.6 on Canon 50mm

I had read that my Canon 50mm f/1.4 lens has noticeable chromatic aberration (CA) when wide open, but was really surprised how bad it was, and how it almost entirely goes away at f/1.6.

I really love this lens - this is a minor problem to deal with, but it's nice to know to expect it.

Below are crops from two out-of-focus shots I took while driving: the first at f/1.4, the second at f/1.6. Notice the purple fringing around most of the lights at f/1.4. This is caused by different wavelengths refracting differently through the glass. I put up a full shot at f/1.4 on Flickr, here.

50mm f/1.4	50mm f/1.6

Rock & Fossil Macro Shoot: Trilobite!

Check out my Flickr page for this shot, as well as other fossils and rocks shot with this setup.

I recently received a request for permission to use this photo in a non-profit magazine on Mexican biodiversity by the conservation group, Naturalia.  This particular trilobite will be featured in an essay about extinction.

SPOILER ALERT: trilobites have recently (around 250 million years ago) become extinct.

So, let's get down to how I shot this.  

I placed the sample on a couple of sheets of printer paper.  I then taped together a ring of printer paper to surround the sample.  I used my Canon ST-E2 infrared transmitter to fire off two Canon 430EX strobes that were placed right up against the ring of paper.  The paper acted as a diffuser, which bounced soft light all about inside the ring, reducing shadows on the fossil.  All of this light let me use f/22 with my Canon 100mm macro lens, which I hand-held at 1/250sec.

Here's my personal favorite from the shoot: