Focus – Summary

Focus summary

It’s not all about DOF; an equal amount is about shooting technique

A few final thoughts –

The previous lessons emphasized control of DOF placement and size. That’s only half of it when it comes to making images sharp. The other half has to do with technique – doing what has to be done to keep the camera steady. Camera shake will ruin all of the DOF theory in the world. Spend some time Googling and gain insight into proper shooting techniques. I won’t regurgitate it here except to note that it starts (not ends) with camera support (that’s spelled t-r-i-p-o-d).

  • Keeping your camera still is essential – always

Not everything has to be tack sharp – landscapes usually yes, portraits usually no, others – it depends. Instead, your guideline should be –

  • Everything is sharp that needs to be sharp

When stopping down your lens (higher f/stops) in an attempt to increase DOF, be aware of a phenomena called diffraction. The topic can get very technical but be aware of its existence and its effect –

  • While using smaller apertures to achieve a greater DOF at some aperture the softening effects of diffraction offset any gain in sharpness due to better depth of field.
  • This is a great topic to experiment with. Go to a scene like one suggested in the HFD assignment experiments and do some diffraction experiments. Shoot a number of shots – starting with the lens wide open and then stop down as far as possible in one stop increments (2.8, 4, 5.6, 8, ….). Open these images in your computer and view them at 100% (you may not see what you’re looking for at a small size). In general (besides the obvious increase in DOF that this will cause), you will see the sharpness (look at your prominent foreground element for this) increase, then peak at about 8 or 11, then decrease (softening) as you progress toward f/22 and beyond. There is a trade-off here between DOF and softening. I usually opt for DOF (the softening isn’t noticeable or objectionable for my style – but your mileage may vary. Try it and see.)

This concludes our look at Focus. For a tip on how to read the lesson in order – from the 1st post to this last post – read the item Viewing a Lesson in the blog Info section at the top of the right column.

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