ith MacOS X 10.4, code named Tiger, Apple made their operating system even better. Several new features, like the Automator and Spotlight, make it hard to understand, why 95% of all the people in the world continue to use outdated technology. Well, as a long term Mac user I was a happy camper just using my Macintoshes. With Tiger, things changed for me: there's a nice tool called Dashboard where you can put sort of a mini-webpage. Being a photographer and videographer, I remembered my long experience with programming much more complicated stuff and got into my first Widget project, the Depth of Field Calculator, or D.O.F.C. for short. I had a lot of fun designing this little Widget and to my surprise I had little difficulty slapping togehter the necessary Javascript code. The most recent version 1.7 came a long way through time and it reflects lots of great suggestions from real world users.

Instructions

Entering the focal length (80mm) and f-stop (f:8) in use yields the hyperfocal distance, marked with hf (in this case: 42.2 meters). Entering the distance to the subject shows (from button up):

• Near focus (3.7m) / beginning of DoF
• distance of sharpness to your subject (0.3m)
• distance from your subject to blurred background (0.4m)
• Far focus (4.4m) / end of DoF

And this is what the back looks like -- you won't need it that often:

• If you prefer feet over meters, check the proper radio button.
• Enter your lens correction factor (LCF) if you use a 35mm lens on a digital SLR or if you add a converter to your lens
• select the type of sensor/film from the pop-up menu

Once you're ready, click Done to get back to the main page.

Disclaimer

Mac OS X 10.4 Tiger is required. If you’re using Safari, click the download link. When the widget download is complete, show Dashboard, click the Plus sign to display the Widget Bar and click the widget’s icon in the Widget Bar to open it. If you’re using a browser other than Safari, click the download link. When the widget download is complete, unarchive it and place it in /Library/Widgets/ in your home folder. Show Dashboard, click the Plus sign to display the Widget Bar and click the widget’s icon in the Widget Bar to open it.

Download

 DOFC Widget Vs. 1.7 (115 kB)
Released October 13, 2007
The DOFC Widget Manual 1.0 (119 kB)

Donations

DOFC is free -- but if you want to support future development I gladly accept your donation. Stats so far: 40000+ downloads, 9 donations, totaling some 30 US$. Thanks to all of you guys who care for better software.

Depth of Field

Depth of Field, or DoF for short, is the distance from the camera which appears in focus. I use the word appear for good reason: Technically, there is only one single distance which is in focus. But as the human eye is easily fooled, there are adjacent areas in front and behind the subject which appear to be in focus as well. Sharpness depends on the circumstances, but in general people see things as being sharp if a single dot doesn't expand too much. For 35mm film, the Diameter of Least Confusion, DoLC for short, is 0.029 mm -- if a single dot gets bigger than this on your slide or negative, people will see it as out of focus. Other formats have other DoLCs, and it's not brain surgery to calculate them. But it's a major pain.
Everything outside this field will get blurred in the final picture. The blur can be used to make people or subjects stand out but sometimes blur is unwanted, as in landscape images. However, not knowing the DoF makes it difficult to get the right amount of blur. There's much to read about this, please note the links I provided on the left if you're curious abut the DoLC. If you don't care, as I do, no problem. There are tons of lists where you can look up the DoF for any given lens/f-stop combination, but with digital still cameras, everything changed. As lenses are specified with the same focal lengths as for 35 mm cameras, none of the former lists will work for your digital cam. The smaller sensor size of digital still cameras makes the focal length of your 35mm lenses longer and the DoLC gets tighter.

The Depth of Field Calculator

Knowing everything about DoF and DoLC doesn't help me in any real world situation. Having used my Nikon 35mm cams for years, I have a good feeling for all of my lenses. But the D70s changed everything. Even worse, switching between 35mm film, Nikon DX, 1/3" and 2/3" video cameras requires a lot of paper to be carried around to calculate the DoF in any given situation. Carrying my Apple iBook works for me, as all the glass and lighting are a lot to handle on location. Hence I remembered my roots as a programmer and made this little Widget.

The Solution

This Widget is a handy calculator for DoF, no matter what camera you've got. It is the perfect companion for the Apple PowerBook or iBook you probably carry to store and touch-up your digital images. DOFC will hopefully make a welcome addition to your shooting setup. If you have any questions regarding this little thing, please contact me.

If you want to see if there are any future releases, please bookmark this page.

Credits

Thanks to Ed Jones, San Francisco, California for proof reading the English version, Evgeny Savintsev from St. Peterburg, Russia, who helped me with the number formatting in version 1.6, and to all of you, who sent me comments and hints.