In what context \"The Achilles\' Heel\" term used in imaging field? Explain in details. Solution The greatest thing about interchangeable camera lenses is the variety of optical designs, from ultrawide to supertelephoto and everything in between, that offer an incredible amount of variety for visual expression, creativity, and optical performance optimized for different photographic situations. And while it may be sometimes completely and totally obvious what types of photography a certain lens excels at—for example, everyone knows that Macros are designed to capture close-up details; telephoto lenses are great for long-reach wildlife and sports from the sidelines—many styles of camera lenses have lesser-known secret superpowers that can be called upon to make a photo. Let’s take a look! Supertelephoto lenses Long lenses, like the Sigma 150-500mm F5.6.3, or 300-800 F5.6 to name two, are known to be great for making sports and wildlife images. Wide open, these lenses can isolate the subject from the background to really make the images pop. And of course, the wide apertures which give very shallow depth of field feel also yield the fastest shutter speeds, which are necessary to freeze a bird in flight, or an athlete on the move. Everyone knows supertelephoto zoom lenses are great for long-reach photography at widest apertures for freezing active subjects, like wild birds, with fast shutter speeds. Here, the Sigma 150-500mm is trained on an American Anhinga, at 500mm, wide open at F6.3. And Landscape, or should we say sky-scape, photographers also know that longer focal lengths also can make for huge suns and moons, the effect of which is amplified when the celestial orb is near earthbound features in the frame. Longer lenses can make the sun and moon much more prominent in the frame. Again, this was captured with the 150-500mm at 500m. 1/500 F6.3 ISO 100. The Lesser-known superpower of supertelephoto lenses: distance compression When supertelephoto zoom lenses are stopped down to smaller apertures, and focused at a longer distance, depth of field is increased, and the apparent relationship of distance between objects in the frame appears much more compressed than in a standard field of view. When you use smaller apertures with supertelephoto lenses, you can compress the expression of distance. It can be used for much more exciting purposes than showing some afternoon downtown traffic; but this image illustrates the effect with objects of touchstone size. Everyone know about how big a car, traffic light, and two story building is, so this offers an understandable sense of scale. This image was shot at 500mm at F/13, to maximize depth of field while managing diffraction. The next image shows a map view with the distance between objects in the frame. This Google Earth view shows that it is is just over one thousand (1,000) feet from my capture position to the hotel in the background. The yellow line shows the relationship of the objects in the fr.

1. In what context "The Achilles' Heel" term used in imaging field? Explain in details.
Solution
The greatest thing about interchangeable camera lenses is the variety of optical designs, from
ultrawide to supertelephoto and everything in between, that offer an incredible amount of variety
for visual expression, creativity, and optical performance optimized for different photographic
situations. And while it may be sometimes completely and totally obvious what types of
photography a certain lens excels at—for example, everyone knows that Macros are designed to
capture close-up details; telephoto lenses are great for long-reach wildlife and sports from the
sidelines—many styles of camera lenses have lesser-known secret superpowers that can be called
upon to make a photo. Let’s take a look!
Supertelephoto lenses
Long lenses, like the Sigma 150-500mm F5.6.3, or 300-800 F5.6 to name two, are known to be
great for making sports and wildlife images. Wide open, these lenses can isolate the subject from
the background to really make the images pop. And of course, the wide apertures which give
very shallow depth of field feel also yield the fastest shutter speeds, which are necessary to
freeze a bird in flight, or an athlete on the move.
Everyone knows supertelephoto zoom lenses are great for long-reach photography at widest
apertures for freezing active subjects, like wild birds, with fast shutter speeds. Here, the Sigma
150-500mm is trained on an American Anhinga, at 500mm, wide open at F6.3.
And Landscape, or should we say sky-scape, photographers also know that longer focal lengths
also can make for huge suns and moons, the effect of which is amplified when the celestial orb is
near earthbound features in the frame.
Longer lenses can make the sun and moon much more prominent in the frame. Again, this was
captured with the 150-500mm at 500m. 1/500 F6.3 ISO 100.
The Lesser-known superpower of supertelephoto lenses: distance compression
When supertelephoto zoom lenses are stopped down to smaller apertures, and focused at a longer
distance, depth of field is increased, and the apparent relationship of distance between objects in
the frame appears much more compressed than in a standard field of view.

2. When you use smaller apertures with supertelephoto lenses, you can compress the expression of
distance. It can be used for much more exciting purposes than showing some afternoon
downtown traffic; but this image illustrates the effect with objects of touchstone size. Everyone
know about how big a car, traffic light, and two story building is, so this offers an understandable
sense of scale. This image was shot at 500mm at F/13, to maximize depth of field while
managing diffraction. The next image shows a map view with the distance between objects in the
frame.
This Google Earth view shows that it is is just over one thousand (1,000) feet from my capture
position to the hotel in the background. The yellow line shows the relationship of the objects in
the frame. A is where I was standing, B and C are the cross streets with traffic lights, and D is the
front of the hotel building. The long focal length combined with narrow aperture keeps
everything sharp and seriously compresses the apparent relationship of distance.
The Achilles’ heels of telephoto compression
Stopping down a long lens to smallest apertures means you’ll need slower shutter speeds, so
Optical Stabilizer or a tripod is often a must for this style of shot. And while the more you stop
down the aperture, the greater the depth of field; going too far into the smallest diameter F-stops
can introduce diffraction, which degrades total image quality. And of course, slower shutter
speeds mean that objects in the frame that are not totally stationary—branches blowing in the
breeze, ocean waves, vehicles, clouds, and son on—may exhibit motion blur.
A little switch of position or a few moments in time can mean the difference between making
and missing the shot you want when trying to align distant objects through a telelphoto lens. I
used the Photographer’s Ephemeris to give me a reading on where the morning sun would be in
relation to the Sandy Hook Lighthouse. And then, of course, the sun moves through the sky in an
arc, so the position needs to adjusted every couple of minutes to keep the sun shining through the
lighthouse. The inset frame shows the difference of just a few feet over from where everything is
aligned correctly. 1/6400 F/11 on a 150-500mm. Please note: This sort of image is best framed
on a LCD in live view to avoid eye damage from the direct sunlight through a lens.
And as you zoom to longest focal lengths, the field of view gets very narrow. You need pinpoint
precision to align objects of interest at different distances from the camera. Changing position
even slightly, a few feet this way, or a couple of yards that way can mean the difference between
perfectly aligning the elements or not.
Ultrawide lenses
Ultrawide lenses, of both the Fisheye and rectilinear variety, are wildly popular among landscape
photographers, architectural specialists, and travel photographers for the ability to take in

3. sweeping fields of view. These lenses are perfect for capturing sunsets that seem to go on
forever; and capturing the total breadth and magnificence of buildings and monuments both
ancient and modern.
The Lesser-known superpower of ultrawide lenses: super-close-up imaging
As you may know, close-focusing distance of a lens is measured from the sensor plane (which is
marked on all cameras with this symbol: ø) and not the front of the lens itself. So, right off the
bat, the wide-open close-focusing point is nearer to the front of the glass that it may first appear
on the tech specs chart. So, for example, the Sigma 8-16mm ultrawide zoom lens is 4.2 inches
long, and the close focusing distance is 9.4 inches. Add in the mount-to-sensor distance of 1.75
inches on a Rebel, and that’s close-focusing of just 3.45 inches in front of the front lens element
wide open. Stopping down the lens to smaller apertures can cheat focus and depth of field to
even closer to the front glass of the lens.
This yardstick is actually resting on the edge of the lenshood and touching the side of the front
lens element of the Sigma 8-16mm ultrawide zoom lens. The lens is stopped down to F/16, and
as you can see, the ticks on the yardstick get sharp at the two and half inch mark.
This can be very useful for situations where you need to be right on top of something to make an
image, or to make a small nature feature the hero in the frame. And while the total magnification
doesn’t necessarily enter into the “true macro” classification, the significant depth of field can
help place an object in a context, unlike a traditional macro shot which has a very thin slice of
sharpness, even at smallest apertures.
We’re right on top of this display of heirloom tomatoes at a a farm market captured at 8mm with
the 8-16mm. The aperture was set to F/14 and the lens was manually set to its closest focusing
distance. The apparent size of foreground objects is exaggerated in this style of photo, as the
yellow tomatoes up front are of a golden cherry variety, and actually are much, much smaller in
radius and volume than the tomatoes a bit farther back in the image.
The Achilles’ Heel
Again, diffraction is the challenge here. As much as you gain more an an in-focus zone, stopping
down too much counteracts the gains, as edges may not be sharp enough for bigger prints and
presentations. Not very flattering for human subjects near the edge of the frame as the wide angle
field of views stretches and contorts.
Fast Standard Primes as Macros
A sharp, fast Fifty F1.4 is a beautiful thing—perfect for portraiture, documentary, and travel
photography. The combination of focal plane sharpness, gorgeous bokeh, and field of view that
nearly matches the human visual system can create astoundingly pleasing images that have a

4. classic feel.
A fast 50mm offers shallow depth of field for great subject/ground separation and a field of
view and relationship of objects in the frame that is very much like the human visual experience.
Here, a herring gull strolls in front of crashing waves on a jetty, captured at 1/3200 F2, ISO 100.
Lesser known superpower: lens-flip macro
In a pinch, many standard prime lenses can be reversed and held in front of the lens as a
manually operated macro lens for capturing close-up details.
The 50mm F1.4 DG HSM | A lens was turned around and held in front of the lens mount to
close-focus on a penny. In a pinch, a standard prime can be used as a macro lens, but usually it’s
full manual operation, with no control over the aperture diaphragm, so depth of field is
exceptionally shallow.
Achilles Heel of Lens-flip macro
Since the lens is not connected to the camera, there’s no way to adjust the aperture, so you’re
shooting wide open at maximum aperture. You’ve got to be careful with the front element
touching the lens mount to avoid scratches, and in dusty or sandy situations, it’s not the best idea
to have the lens removed from the camera for extended periods of time.
Telephoto Macros for longer-distance Photography
Sigma offers three telephoto range F2.8 macro lenses with life-sized reproduction, a 105mm
F2.8, a 150mm F2.8 and a 180mm F2.8 Macro. Each of these features Optical Stabilizer, a focus
limiter, and internal focusing paired with close-focusing at 1:1 magnification. Obviously, these
lenses are designed for, and excel at, close-up photography.
Macro lenses are named and known for the ability to capture tiny detail at high magnification,
such as this sloughed cicada exoskeleton as seen through the 180mm F2.8 EX DG OS HSM
Macro lens at 1/320 F/9 ISO 400 on a Reb T3i. But everything about Sigma’s three longest
internal focusing, optically stabilized telephoto macros also makes these great for sports,
wildlife, and other longer-reach subjects.
Lesser known superpower
Some may not realize that everything about the design and build of these lenses makes them
outstanding for longer-distance photography as well. In fact, the 180mm F2.8 Macro is just about
the perfect mid-telephoto prime lens for birding or sports photography. The Autofocus limiter
helps keep the focal range out of the macro zone for swifter long-distance response, and as a tele
prime, the real-world samples are mind-blowingly sharp on the focal plane with very pleasing
defocused rendering.

5. Here’s a gray squirrel seen through the Sigma 180mm F2.8 EX DG OS HSM macro lens at a
distance of about 30 feet, well out of the close-up, high magnification range of this lens. But the
AF limiter and hypersonic motor for fast focusing, also make it a perfect telephoto prime for
sports, wildlife and journalism work.
Achilles’s Heel of Macro for long-distance
There’s zero practical downside here. The only possible issue you may encounter is finding
yourself needing to explain to other photographers why you’ve chosen a lens that’s designated as
a Macro for longer-reach photography. And once they get it, they’ll get it, too.