Autumn Path, Michigan. Depth of Field complements of a Hyperfocal Distance Chart

The following question came today via email. I occasionally post some of the questions that come my way, along with my answer.

Question: Does the hyperfocal distance of a prime lens remain the same when a wide angle converter is attached to the lens?

Answer:  It is hard to say because there are so many variables involved.

In an optically perfect world a wide angle converter (just like a wide angle lens) takes in a wider scene and renders your subject with smaller “circles of confusion” on the digital sensor or film. Smaller circles of confusion equals more depth of field. So, at least theoretically, the hyperfocal distance would be closer to the camera and you would have more depth of field when using a wide angle converter.

But in the real world, add on converters don’t always play nicely with the prime lens they are added to with a lot of optical gremlins creeping in like coma and chromatic aberration. The result is the circles of confusion get smeared so you can end up with less depth of field and a hyperfocal distance that is even farther away from the camera.

There are so many different converter/lens combinations (many of them resulting in poor image quality) that it is just impossible to say what will happen to the depth of field. The only way to get an idea is to do some testing with your particular combination. Do some depth of field tests with the prime lens alone using a hyperfocal distance chart.  Use the hyperfocal distance and aperture recommended by the chart for the focal length of the prime lens. Then examine the photos carefully.

Then repeat the tests with the converter added to the lens.  Take careful notes on what you are doing and try different focused distances than the ones indicated on the hyperfocal distance chart for the apertures you try. Then compare the two sets of photos. That will give you an idea what the real world hyperfocal distance is for your lens and converter. Don’t be surprised if you don’t like what you see with your particular lens and converter combination.

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Background Information

Hyperfocal distance charts tell you, all other things being equal, at what distance you should focus your lens to get the maximum depth of field for a given focal length and aperture setting. You need a different hyperfocal distance chart for different sensor sizes and different film formats. You can get started with the charts I provide on my web site for full size digital sensors (the same size as 35 mm film) and digital sensors with a 1.5x or 1.6x field of view crop like many DSLRs from Canon, Nikon, and other manufacturers.

My most detailed coverage on depth of field can be found in two full length chapters on depth of field (chapters 6 and 7) in my book, Digital Photography Exposure for Dummies. You will learn all about depth of field and “circles of confusion”. Best of all, you will learn several ways to control depth of field for more dramatic images. I haven’t found any other book on exposure with as complete a coverage of depth of field. Some don’t even mention hyperfocal distance charts much less provide you with ready-to-use charts, or tell you how to create your own chart for your particular camera’s sensor size and the final size print you want to make. You can learn more about the book here and buy the book at Amazon.com.