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Blur from Haze and Refraction
Haze from moisture or dust obscures detail, and smog or smoke can turn a blue sky gray or brown. It is not so much blur as it is low contrast and color, but since it impairs distant detail, it must be considered a form of blurring.
Another type of blur which seems very surprising and strange if one has not previously observed it, is refractive blur — blur caused by varying air density e.g., “blobs of blur” almost like someone has finger-painted the image, smearing it.
Example — haze
Haze is a challenge with long telephoto lenses, even at relatively modest distances. Landscape photography with a long telephoto can be frustrating with even modest amounts of haze, even when the accommodating human eye perceives a relatively crisp scene. Blue light is especially troublesome, because many lens coatings and optics perform less well than with other colors of light.
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- Eases into photographic challenges with an introductory section.
- Covers aspects of digital sensor technology that relate to getting the best image quality.
- Technique section discusses every aspect of making a sharp image handheld or on a tripod.
- Depth of field and how to bypass depth of field limitations via focus stacking.
- Optical aberrations: what they are, what they look like, and what to do about them.
- MTF, field curvature, focus shift: insight into the limitations of lab tests and why imaging performance is far more complex than it appears.
- Optical aberrations: what they are, what they look like, and what to do about them.
- How to test a lens for a “bad sample”.
Intrigued? See Focusing Zeiss DSLR Lenses For Peak Performance, PART ONE: The Challenges, or (one topic of many) field curvature.
Canon 800mm f/5.6L IS