Outlined in this informative video are 4 different techniques for accurate focus as well as a discussion on DOF (depth of field) as it relates to each method. Additional information is provided on off-center focus using a rangefinder camera such as a Leica M. Video length: 12 minutes 11 seconds.
LINKS Discussed in the video:
CORRECTION!…. on the section related to Hyperfocal Distance the quick example is not accurate for the 90mm lens I was using as an example. In fact, the actual hyperfocal distance for that lens is 40′ and not 20′ as mentioned and as such in the example I gave it would have a depth of field from around 20′ to infinity and not 10′ to infinity.
One final note: You will notice that I have not posted any sample images featuring the above described techniques- this is on purpose… go out and shoot a roll of test film! Determine what is your best working solution based on your sharpness needs and shooting style.
I, for one, feel that focus is highly over-rated. As a matter of fact- for almost 2 years I would argue that none of my images were “in focus” or at least not sharp. Did that make them less photographic or less of an Artwork?
Focus is just one element of an image and not the most important by any means. I often find the bokeh (or the out-of-focus qualities) of an image much more engaging than an image with sharpness throughout.
All of this being said- how do you focus a camera to ensure the exact point or plan of focus that you have chosen is sharp? Easy! Just follow these 4 steps:
1. Turn off the F$#cking auto focus.
2. Turn your lens to the point of focus and then just beyond.
3. Now turn your lens back in the opposite direction and just past the point that appears sharp.
4. Now turn your lens back to the point of focus.
By focusing back and forth and with each pass closing in tighter and tighter to your chosen point of focus it allows you to see just exactly where the point of focus is and what it looks like just before and just after. This technique is really quite fast and will ensure the best possible focus…something which is really important when you are working with a fast lens say at f2.0 – there is no margin for error with a depth of field that shallow.
And one final tip…use good glass!