SPECULAR HIGHLIGHTS - Bright light spots reflected from a shiny surface or an object's edges.
SPEED - A measure of the sensitivity to light of a photographic emulsion. May also refer to the sensitivity setting employed in a digital camera.
s. The brightess part of a highlight.
Stop. An alternate name for f-stop.
Specular highlight. Bright spots in an image caused by reflection of light sources.
A bright reflection from a light source containing little or no detail. within an image should not be used for Set Whitepoint.
Any area of the subject (except specular highlights) that is outside of this range is reproduced either too light or too dark in the final picture.
Imagine a point source of light such as a quite distant light bulb, a reflected , or even a star in the night sky. Anything that will appear to be a single point rather than a shape.
It adds a specular highlight to the image that becomes a focal point. If you’re not familiar with this trick, you need to play with it. Stop the lens down to f22.
Catchlights are s from a light source and draw attention to the subject's eyes.
"Dead" eyes are usually monotonously lit and without that specular highlight we usually see. Even if your goal is to convey a dead, empty look, getting light correctly into the eye is crucial.
s (such as reflections on metal or water), regions around the sun (such as in sunsets) and other direct light sources (such as street lamps) all appear perfectly fine when clipped.
This doesn't apply to bright, specular highlights (such as those found on water, for example), where the sun glints off of an object. This will always be pure white and probably should be, unless it's over too large an area.
Where we'd expect ghosting to be apparent are images which contain very small s, such as distant streetlamps in a night scene, or reflections from a shiny object which are - again - very small in the frame. Examples are shown below.
An unusual scene with a preponderance of light colors or specular highlights would have a higher reflectance; a reflected-light meter taking a reading would incorrectly compensate for the difference in reflectance and lead to underexposure.
The highlight detail is no longer clipped (the colored spikes on the right of the histogram are s and should be clipped). In addition, it appears that there might be a little bit more shadow detail than with the first tonal curve.
DYNAMIC RANGE: Film has a huge advantage in recording highlights. We take for granted the fact that specular highlights and bright sunsets look the way they do in painting and on film.
That's the way you photograph dark skin.... by bringing in s from both sides. Nor is it necessary to open up the lens any more than usual. Light crossing over the skin brings out great highlights.
This is done to avoid the common E-TTL problem of highly reflective materials causing specular highlights in a flash-illuminated image and throwing off the flash metering.
When a histogram shows pixels at the extreme ends of the range, in the 0 and 255 positions, it means details in those tones are lost or "clipped" in your image. These extremes should be reserved for s (reflections) and small dark ...
While, not needed, I highly suggest the Gary Fong Lightsphere II, which when used in bounce mode helps provide soft light from above and from the front and produces nice catch lights (the specular highlights in a subject's eye from a light source).
Measuring the light hitting a surface is particularly useful because it eliminates the possibility that the camera's meter is fooled by s. Bright areas of a scene like the sun, lights and other elements won't throw off the metering.
Usually reds will appear unless more than one channel is blown out. So unless my image has specular highlights that I’m willing to sacrifice I hold the alt key and slide the exposure up until the first red pixels appear then I back off a tad.
Because dust marks show up as dark specks and are unfixable, spotting Ilfochrome is, for me, usually for the purpose of removing defects such as people in landscape scenes, "hot spots" from s, etc.
See also: Highlight, Image, Photograph, Light, Camera