Ok.. its time for a refresher on aperature -
Ever wonder about words like aperature, F/stop and why larger F/stop means a higher value.. when actually its just a tiny hole... ?
The F/stop is a dimension or partial distance across the lens diameter.
Lets say you have a lens that has a measured physical diameter distance across the lens of 60mm.
F stop value of:
f/2 would have an aperature opening size of 60mm/2 = 30mm wide
f/7 would have aperature opening size of 60mm/7 = 8.57mm wide
f/11 would have aperature opening size of 60mm/11 = 5.45mm wide
Smaller the f/value like f/2 means that the hole is wider
Larger the f/value like f/11 means the hole is narrower
What does this do for us:
The larger hole opening means more light can pass through the lens and the faster shutter can be used .
The smaller hole opening means less light can pass through the lens and the slower shutter speed can be used.
Then there is a wild term called Circle of Confusion (COF) which helps explain "focusing or light registration on the film plane or CCD sensor". Its definition is outside the scope of this forum. My dictionary and photography manual do not even discuss it. (must be old books). AND NO it is not a definition for one of Dave's panoramas.
And lastly Depth of Field (DOF), which is a combination of f/stop and shutter speed where combinations of foreground, middle ground and back ground remain in focus. Typically a wider hole like f/2 has a smaller mid image region of focus. Conversly, a smaller hole like f11 has a larger fore, mid and back image region of focus.
Luminous Landscape has a great article about DOF and COF at
http://www.luminous-landscape.com/tutorials/understanding-series/dof.shtml
But then you already knew this.
Dave
------------- /s/
Dave
Forum Moderator for
EasyPano - Panoweaver
Pano2VR
Visit 360texas.com
|