Cropping and critical focus

Aspect Ratios in Landscape Photography

I recently read a very nice article about aspect ratios in landscape photography. The article gave me some great food-for-thought: Aspect Ratios in Landscape Photography.

Critical Focus

Most dSLRs these days have two auto focus mechanisms, phase detection autofocus and contrast detection autofocus. If you use live view to focus, you're using contrast detection autofocus. If you use autofocus while looking through your viewfinder, you're using phase detection autofocus. Phase detection autofocus is significantly faster than contrast detection autofocus, but contrast detection autofocus is more accurate. If you're doing any photography without a tripod, using live view to focus and compose isn't piratical, so you have to use phase detection if you're autofocusing.

You can improve the accuracy of your camera's phase detection autofocus by fine tuning your camera's phase detection autofocus (if your camera supports this feature). Doing so can be a tricky procedure. Fortunately, there are tools available to help you with this. In the past, I've used LensAlign by Michael Tapes Design. It's a very helpful tool, but I've found that I have difficulty analyzing the results of my tests. Fortunately, Michael Tapes Design recently released a new software tool called FocusTune that will analyze the results for you. I spent a few hours last weekend calibrating my lenses, and wow, what huge difference it makes!

Here's a nice article I read some time ago on Luminous Landscape about why errors occur in phase detection autofocus and why focus fine tuning is necessary: Are Your Pictures Out Of Focus?.