Q. For years I had planned to “upgrade” from my camera with an APS-C sensor to a camera with a full-frame or even midsize sensor. Since I’m retired, I no longer print my photos or try to sell them. I have some very nice full-frame lenses from my film camera days, so I could use them with a full-frame camera. But I display my photos only electronically on a TV or photo frame, which can’t display all of the image data that a larger sensor could capture. So, wouldn’t a larger sensor just be overkill?

Photography is all about light, and unless you understand the inner workings of your camera’s metering system and know how to arrive at correct exposures you’re never going to be pleased with your photographs.

(Editor’s Note: The following is an excerpt from Andrew Darlow’s new book, Focus and Filter: Professional Techniques for Mastering Digital Photography and Capturing the Perfect Shot , from Ulysses Press. Darlow has been a professional photographer and educator for over 25 years, and this is his fourth book. You can also read his story with tips for taking safari-quality photos at a zoo here.

Have you ever noticed a yellow tint to the glass in a vintage lens? That may be because certain lenses in the 60s and 70s used a Thorium coating that yellows over time. Thorium has a high refractive index that improves light transmission, but it also turns out to be slightly radioactive.