Classical Greek Astronomy

History is a building process, each successive event building on the last. In the greater picture of civilization as a whole, the one culture that probably did more to shape the modern Western world was that of Classical Greece, defined as the period starting with the first Olympic Games in 776 B.C. And ending (this is open to debate) with the death of Alexander the Great in 323 B.C. During this fruitful period of 450 years, great advances were made in many fields, including political theory, philosophy, the arts, and science.

The birth of permanent settlements gave rise to civilization as we know it, which in turn spurred the growth of agriculture. With agriculture supplanting hunting and gathering as the primary means for feeding oneself, it became matter of life and death, literally, for early farmers to get their planting done at the correct time. Having no abundance of entertainment as we do today, early people often looked to the sky. Looking up, these early people started to notice patterns to the sky, such that, following a regular cycle, the same stars would be visible in the same season year after year. In time, it became apparent that the appearances of various stars could be used to predict the weather on Earth and thus help in the odds for a successful crop. Such tidbits of astronomical observations would eventually find their way into the earliest of Greek literature, with the poet Hesiod (c. 700 B.C.) stating that “when Orion and Sirius come to the middle of the sky and the rosy fingered dawn confronts Arcturus, cut off all your grapes and bring them home with you.”

As with all peoples interested in the sky, astronomy would start out as practical knowledge essential to matters of everyday life, however, the sky would soon be hijacked by people who exploited the heavens to bring themselves power on Earth.

Up until the Greeks, people had explained the way the world works through mythology and/or all-out religion, which served as the fuel for superstition and irrationality. Obviously, not everyone was intimately familiar with the annual motions of the stars. As a result, when a priest said that, for example, that the gods were angry and may not provide a favorable spring (whose coming the priest knew was evidenced by a star), the masses could be fooled into offering sacrifices and/or imploring the priest to intercede on their behalf with the gods and, as if by some human intercession, spring would come, the priest would be validated (he knew spring was coming by looking at the stars) and the people impressed. By 600 B.C., every culture had a deeply-rooted mythology describing why the world came to be the way it was, the Greeks included. At this point in history, it seemed as though the world would never wake up to reason. However, in Asia Minor (modern Turkey) science as we know it was born.

In a city called Miletus, there arose three great thinkers in the 6th century B.C. Now, looking back at the ideas of these three men and comparing them to what we know as fact today, the theories proposed were often wrong in both main idea and reasoning. However, science is a self-correcting process that builds on itself so, while the ideas of these first scientists were incorrect, that's not important, the rational approach they used was the innovation.

Thales of Miletus
The first of the great scientists from Miletus was a man called Thales, one of the legendary Seven Sages of Ancient Greece and, so far as we know, the first man to try and explain the world through reason, not myth. In his profession, Thales was a merchant and, having to travel all over the known world to sell his goods, came into contact with many different peoples and ideas. Of all the places he went, the one where Thales learned the most was Egypt. In Egypt, Thales learned to calculate distances and heights by using geometry (which would later factor into astronomy) and was even said to have predicted a solar eclipse. However, of all the ideas proposed by Thales, perhaps the most awe-inspiring was one of evolution. Thales believed that the world was all water at one point and this is where life got its start, gradually evolving from simple to complex organisms. At the same time, the water started to evaporate, exposing dry land (no need for a God/gods to intercede here), and eventually life moved out of the water and colonized the land. This was over 2,000 years before Charles Darwin and Alfred Russel-Wallace.

Anaximander
A young contemporary of Thales was a man called Anaximander, who would eventually become the second of the three great scientists hailing from Miletus. While Thales was not a career astronomer, Anaxaminder spent a lot of time thinking about the heavens and what the objects in them were to the point where he is now considered the father of cosmology. As far as history records, Anaximander was the first man to come up with a mechanical, not mythological, model of the solar system. As for the universe proposed by Anaximander, it was this: the Earth was a cylinder floating freely (without support) in space and the Sun, Moon, and stars were all fire-filled wheels with holes that allowed the light we see to escape.

Anaximenes
Like Anaxaminder was to Thales, Anaximenes was to Anaximander, a student. In terms of theory, Anaximenes wasn't as revolutionary as his predecessors (Thales = the world can be explained rationally, Anaxaminder = the heavenly bodies are physical places), his idea would be much longer-lasting. In the model of the Universe proposed by Anaximenes, the stars were no longer fire-filled wheels, but were bright points of light fixed to the inside of a sphere, in which were the Earth, Sun, and other planets. In time, this idea would grow into the celestial sphere, which would be central to astronomical thought for about 2,000 years.

After the three scientists from Miletus, the rational approach to explaining the world was well established and would continue to be refined as new ideas were put forth in the coming centuries.

Pythagoras
More famous for his famous triangle theorem, Pythagoras was also interested in astronomy and, despite living from 582-500 B.C., put forth an idea about the mechanics of the solar system that was surprisingly accurate. The first fundamentally correct insight by Pythagoras was this: the Earth moves. Second correct idea: all celestial bodies were spherical. Now, despite having these main ideas correct, Pythagoras also got a lot of things wrong, too. First, instead of the Earth simply revolving around the Sun, the Earth revolved around what was termed the “Central Fire,” which was invisible because it was blocked by a “Counter Earth.” Obviously, these ideas are extremely abstract, needlessly complicated, and would have been confusing to the masses. Obviously, for all of his brains, Pythagoras never heard of Occam's Razor. As for how Pythagoras came to the conclusion that all heavenly bodies were spherical, that's lost to history.

Anaxagoras
The next great figure in classical Greek astronomy, besides being a great thinker, was also somewhat of a martyr for free thought. This man was Anaxagoras, who moved to Athens in the middle of the 5th century B.C., the time at which Athens was at its peak of political and intellectual power. In Athens, Anaxagoras became a close friend of Pericles, the man who is credited with making Athens the great city it was while also sowing the seeds of its downfall at the same time. It is believed that this friendship with the city's leader is what put Anaxagoras on a collision course with the religious authorities in Athens. In his cosmology, Anaxagoras was remarkably rational and proposed natural explanations for eclipses, meteors, and rainbows, all while creating his own ideas of the solar system. In his model, Anaxagoras was, so far as we know, the first man to make guesses as regarding the sizes of the heavenly bodies when he declared that the Sun was a giant, blazing hot piece of metal in the sky bigger than all of Greece. Also, Anaxagoras thought that the planets, Moon, and stars were all part of Earth torn from the planet and ignited by rapid rotation. Also, Anaxagoras was the first man to profess that the Moon shines by reflected sunlight and that the stars are suns infinitely far away. Obviously, while Anaxagoras was correct about some things and wrong about others, what was important was the fact that, for the first time, someone dared answer the question of where the Sun, Moon, and stars came from.

Unfortunately, for some people, this was audacity gone wild.

The Greeks were an interesting people when it came to their thought processes. At no other time in history has a people ever been so logical and superstitious at the same time as was the case in Classical Greece. At the same time Thales was teaching that the world came about naturally, Anaxamenes was proposing mechanical models of the solar system, and Pythagoras already knew that Earth was spherical, other Greeks were basing important decisions on oracles and divination through, among other things, examining the entrails of sacrificial animals. It was this second group who, with Anaxagoras, decided to make an attack upon reason.

Whatever his accusers' motives were is unknown, but several leading men of Athens, who just happened to be political opponents of Pericles, accused Anaxagoras of impiety, a religious crime, because of his teachings about the universe. Result: Anaxagoras found himself imprisoned for shocking the sensibilities of everyday people and insulting the Olympian gods. It was only through the influence of Pericles that the charges against his friend Anaxagoras were finally dropped. However, in Athens, the tide had turned, the spirit of free thought that had propelled the Greeks to greatness was giving way to a drive for conformity. With the philosophical-religious climate so hostile, Anaxagoras, now free from prison, was forced to flee to Lampsacus, where he lived out the rest of his life, continuing to teach the ideas that enough leading Athenians deemed too dangerous for the good of the people. After his death, the people of Lampsacus built an altar to reason, which they dedicated to Anaxagoras. This hostility to free thought would come to a head in 399 B.C. when the Athenian assembly condemned the famed philosopher Socrates to death for, among other things, blasphemy.

After Anaxagoras, Greece would be plunged into the on and off 30 year struggle that was the Peloponnesian War, in which Athens, Sparta, and their respective allies fought an on and off war with the goal of becoming the supreme power in Greece. Obviously, with so much fighting going on, time for any science that could not help out in the field of military development was limited. Then, finally, after peace returned, the scientists of Greece once again took up the struggle to understand the universe.

Eudoxus
In the late 300s B.C., Eudoxus refined the model of the solar system to a new level of sophistication, or cumbersomeness, your call there. In the model of Anaxamenes, the Earth was at the center and was orbited by the planets with the stars lining the inside of a spherical vault. However, in its simplicity, the old model of Anaxamenes failed to address some undeniable observations about solar and planetary motion. First, while the Sun moves through the sky from East to West, it also moves along the Zodiac. Why was that? Also, planets appear to slow, stop, reverse course, move backwards, stop again, and continue in their forward motion. Why could this be? These are the two questions Eudoxus sought to answer.

In explaining the seemingly inexplicable motions of the stars and planets, Eudoxus set them on multiple celestial spheres. Starting with the stars, whose motions were easiest to explain, Eudoxus set them on a single sphere that rotated from East to West once per day, easy enough. However, this simplicity wouldn't last long. The Sun, besides moving across the sky once a day, also moves through the Zodiac once per year and both of these motions had to be rectified in the model. So, to explain why the Sun does what it does, Eudoxus set the Sun on two spheres, one moving East to West once per day and the other going Eastward once per year to account for the movement through the Zodiac. Sound confusing? It gets better. The planets need four, (yes, four) spheres. Sphere 1 rotated Westward once per day for the daily motion of the planet. Sphere 2 rotated Eastward once a year to account for the planet's motion through the Zodiac. Spheres 3 and 4 were slightly inclined to each other and were used to explain retrograde motion of planets, which occurs in an elongated figure 8 motion if observed carefully. In retrospect, this model was needlessly cumbersome and failed to account for the sometimes very obvious change in planet brightness. However, at the time, it was the best thing going.

Aristotle

After Eudoxus, the field of astronomy would not see advances for a time, but the discovery of “proofs” for some of the already postulated ideas. The man responsible for these, a philosopher whose shadow would stretch nearly 2,000 years into the future as the center of western thought: Aristotle. By the time of Aristotle, who lived from 384-322 B.C., several ideas had been proposed, but no real proofs made. Aristotle was the man who changed this. At this time, it was widely believed that Earth was spherical. Aristotle came up with two proofs of this fact. First, some stars are seen in Greece that aren't in Egypt, and vice versa. Second, the shape of the Earth's shadow on the Moon during an eclipse. If Earth was flat, the shadow would be a line. Next, if Earth was spherical, what about the other heavenly bodies? Again, looking at the Moon during an eclipse, if the Moon was a two-dimensional circle, Earth's shadow would be perfectly circular, yet, it was slightly distorted because, as Aristotle correctly inferred, the Moon was spherical, too. So, if Earth and Moon were spherical, was it out of the question to assume that the stars and planets were circular, too? According to Aristotle, no.

Unfortunately, for all his brilliance, Aristotle also had some wrong ideas that were to be very long-lasting in their influence. Building on the earlier, and wrong, idea of Empedocles, who was the first man to find physical proof of air, Aristotle also assumed that the universe was made up of four elements: Earth, water, fire, and air. Now, by looking at the world, one notices that Earth and water are on the ground while fire and air go into the sky. So, taking this logic to the universe as a whole, Aristotle assumed that the heavy elements (Earth and water) are all on Earth while the light ones (fire and air) are in the sky. So, since the planets and stars are in the sky, they must be fire and air. So, what sense does the idea of a moving Earth make if it's so heavy? This was Aristotle's reasoning that would confine most scientists to a geo (Earth)-centered universe for almost 2,000 years.

However, there was one rebel to this orthodoxy before Copernicus in the 1500s: Aristarchus of Samos.

Aristarchus of Samos

Aristarchus lived from 310-230 B.C. On the island of Samos. Besides being an astronomer, Aristarchus was also a mathemitician and, so far as we know, the first man to try and measure the distances to the heavenly bodies, namely the Sun and Moon. Problem: no one knew how big the Earth was at the time. So, while Aristarchus used sound geometry, his incorrect assumed size for Earth resulting in his computations of distance being way off the mark. However, if Aristarchus had been lucky enough to live half a century later (more to follow), humans may have known that the Moon was about 250,000 miles and the Sun 93 million miles away before the birth of Christ. Unfortunately, it wasn't to be.

However, while Aristarchus was the first man to try and find the distances to the heavens, his major achievement was that he was the first man to reason that the Sun, not the Earth, was at the center of the solar system. Sadly, no original works of Aristarchus survive, only mentions of his ideas by later writers. How thrilling it would be to read Aristarchus and discover his reasoning process that led him to discover how the solar system really worked. A start is with geometry. Thanks to later writers, we know that Aristarchus calculated the Sun to be about 7 times bigger than the Earth. So, as a start, Aristarchus may have reasoned that it made no sense for a giant Sun to orbit a tiny Earth. To finish his model where the Sun, not the Earth, stood at the center, Aristarchus argued that the motion of the sky was only apparent, caused by the motion of the Earth turning on its axis once a day. However, save Seleucus of Seleucia, the ideas of Aristarchus met a wall of resistance.

First, if Earth moved, why wasn't there a great wind caused by it speeding through the heavens? Second, if Earth rotated on its axis once a day, why do falling objects still land directly under from where they fell and not to the West? However, the third argument, the unchanging nature of the stars, was perhaps the most compelling. If the Earth moved and the stars remained still, according to mainstream Greek thought, two things should happen: first, the stars should move relative to each other (stellar parallax) and change in brightness as the Earth moved around the Sun. Unfortunately, the critics of Aristarchus never considered the idea that the stars could be almost infinitely far away, thus negating both stellar parallax and brightness changes.

Eratosthenes
The man who could have helped Aristarchus discover that Moon was really 250,000 miles and the Sun 93 million miles away was Eratosthenes, who was the first man to measure the circumference of the Earth. The whole drive to do such an audacious thing came from curious stories coming out of Egypt. In Syene, Southern Egypt, it was said that at noon on the longest day of the year, and only on this day and at this time, the Sun would illuminate the water at the bottom of a deep well that was in shadow at every other time in the year. However, in Alexandria, where Eratosthenes served as chief librarian of the great Alexandria library, the Sun cast definite shadows at noon on the Summer Solstice. So how could this be?

Well, Eratosthenes was quick to realize that, for this to happen, the Earth had to be spherical. However, while lesser minds may have been content in this knowledge, Eratosthenes was not, he thirsted for more. Calculating the angle of the shadows, Eratosthenes determined that the shadow in Alexandria was at an angle of about 7.2 degrees, or about 1/50th of a circle. Thinking in terms of the big picture, he reasoned that the distance from Alexandria to Syene was about 1/50th the distance around the Earth. So, finding the distance between these two cities and then multiplying by 50 would give the circumference of the Earth, easy in principle but not in practice. As hard as it may be to believe, Eratosthenes hired a man to pace out the distance between the two cities! Despite no one having paced out such a great distance before, the distance was determined with remarkable accuracy, which resulted in Eratosthenes coming to a circumference within a few percent of Earth's actual circumference of just under 25,000 miles.

Not bad for the 3rd century B.C.

Hipparchus
After Erathosthanes, the next great astronomer was Hipparchus, widely regarded as the classical world's greatest astronomer. At the time of Hipparchus, it was believed that all stars were constant and unchanging. So far as we know, Hipparchus was the first man to notice a variable star, which served a the impetus to create a catalog of stars' brightness, which he did, creating the magnitude system in the process. As major of an achievement as this was, Hipparchus had far more to offer the world. In creating his star catalog, Hipparchus, when comparing older charts, noticed that every star he observed was about 2 degrees away from where it should have been. What was going on? While Hipparchus didn't know the reason for such motion, he had, nevertheless, discovered precession of the equinoxes.

After Hipparchus, there was a period of stagnation in classical civilization as the Greeks/Macedonians gave way to the Romans as the dominant power in the known world. So, after all the wars, stability, and free time for learning, returned, producing the last of antiquity's great astronomers, Claudius Ptolemy.

Claudius Ptolemy
Going back a few centuries to Eudoxus (and discounting the ignored correct model of Aristarchus), the picture of the solar system hadn't really changed in several centuries despite the fact that the Eudoxus model was extremely complex to say the least. With Ptolemy, who lived from 90-168 A.D., what would be the final word on the solar system for nearly 1,500 years would be written. Taking the failure of Eudoxus to explain the brightness change of the planets and the overall cumbersomeness of his model, Ptolemy streamlined the solar system and explained planetary brightness change in a single stroke. Like Eudoxus, Ptolemy put the Earth at the center of the solar system. Outside, the Moon was put in orbit around the Earth with the planets and Sun (in correct order) outside the Moon. Result: a much simpler, easier to understand model of the solar system. Now, as for the planets' change in brightness, Ptolemy solved this by adding epicycles to the orbits, which explained both retrograde motion and brightness changes at once. The system was so well received that was accepted without challenge for nearly 1,500 years.

After Ptolemy, the Greco-Roman civilization would start into its long, slow decline thanks to political and then religious instability. In 180 A.D., Marcus Aurelius, the last of the 5 Good Emperors, died, leaving the throne to his mad son, Commodus, the first in a pretty much unbroken string of lunatics to rule Rome. At the same time that the secular government was going to pieces thanks to reckless spending, corruption, and murder, the religious fabric of the Roman Empire was being torn to shreds as the Christian Church started making inroads against the old Pagan faith. In time, Christianity would win out and, in order to consolidate their religious power, Church leaders did everything they could to stamp out Pagan culture, which included the free, inquisitive spirit that inspired the Greeks to set out to try and understand the world way back in the 6th century B.C., starting with the Ionian scientist Thales of Miletus. With the collapse of the Western Roman Empire in 476 A.D., the Catholic Church was unrivaled in power and, with eternity at stake, no one dared question Church position on anything, including the cosmos, which the Church deemed to be centered around a flat Earth that never moved and populated by a collection of perfect, unchanging heavenly bodies.

In the end, the Western world would have to wait over 1,000 years for the second flood of free inquiry that was the European Renaissance.

More Ancient Astronomy
The Planet of Bethlehem?
A History of Cosmology: Prehistory to Present
Galileo's Fingers Go on Display.
Renaissance Astronomy: Part 1
Renaissance Astronomy: Part 2
Renaissance Astronomy: Part 3
The Equinox and a Magic Show from the Maya
Ancient America: the Moundbuilders
Ancient America: the Southwest
Ancient Egypt
Classical Greece
The Summer Solstice Sun and the Size of the Earth
The 1833 Leonids: History's Greatest Meteor Storm
The 10 Brightest Comets of All Time
Ben Franklin and the Truth About Daylight Savings Time

 
 

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In-Depth Review: Tokina 80-200 f2.8 AT-X

The Tokina 80-200 f2.8 AT-X lens


Tech Specs
Focal Length: 80-200mm
Dimensions: 7.5” x 3.3”
Weight: 3ibs.
Maximum Aperture: f2.8
Minimum Aperture: f32
Diaphragm Blades: 9
Front Element: Rotates, extends about half an inch
Autofucus Mechanism: Micromotor (Canon version)
Closest Focus: 4.9 feet
Filter Size: 77mm

Background
Ever since as ascension of the zoom lens as a legitimate photographic tool in the late 1980s, constant f2.8 lenses in the 70/80-200 range have been extremely popular among both professionals and amateurs. Why? Simple: reach and speed make for a handy lens. As a result, everyone who makes lenses produces such optics, both manufacturer and third-party. To meet this need, Tokina started producing fast 80-200s almost as soon as AF became the norm. The lens reviewed here is the original AF 80-200, which commenced production in late 1980s.

Build Quality: 5

Tokina is a company known for its high standards of construction and the 80-200 f2.8 AT-X doesn't disappoint here, putting all lenses except the top of the line manufacturer versions to shame in a big way. Made out of solid metal, this lens is built like a tank and, weighing in at around 3 pounds, feels like one, too. With both its size and weight, this thing could legitimately be used as a weapon! Moving into the mechanics, it's a mixed bag. The zoom ring is absolutely buttery smooth without being loose and feels as though it's floating on air. One finger zooming with this lens is easy. As for the focus ring, well, it isn't a ring at all, but the inner barrel of the lens that is textured to look and feel like a ring. When it comes to focusing, the lens will extend about half an inch when focused at its closest distance. In terms of movement, the focus “ring” is a bit sloppy (at least on my lens). However, this being an old lens, this could also be from 20+ years of wear, too. Being in the first generation of Tokina AF lenses, this 80-200 doesn't incorporate the famous Tokina AF/MF clutch mechanism of the later version. However, as a whole, the positives of the solid metal construction and internal zoom trump the cheapish manual focusing mechanism.

The lens is built like, and weighs in like a tank too! Note the tripod collar: it rotates, but you can't take it off.

Autofocus Operation: 2

Being vintage 80s, the Tokina 80-200 f2.8 AT-X does not feature an ultrasonic drive, but a micromotor/mechanical drive, depending on your make. In terms of accuracy, the Tokina is good so long as the subject isn't moving fast and the lighting is reasonable. In fact, it's dead on in these situations 100% of the time for me on my Canon 30D. Unfortunately, the speed and tracking abilities of this lens leave a lot to be desired. To put it plainly, this is no sports/wildlife lens unless you'll be shooting golf and/or turtle races! In practice, I find that I only get about a 25% keeper rate with this lens when birding with it, not good. I'm just thankful that I'm shooting digital and not blowing wads of money with film and the cost of getting it developed! In terms of sound, the lens it pretty loud, but still nowhere near as loud as the slap of the SLR's mirror.

NOTE: the successor of this lens, the 80-200 f2.8 AT-X PRO (with the AF/MF clutch and internal focusing) is said to be a lot faster in terms of AF.

 The focus ring isn't a ring and the lens extends a lot when focusing up close.

Optics: 3
Since there is so much to a zoom lens, it was only fair to test the Tokina 80-200 AT-X throughout the focal range. For this test, I used the focal length settings that are marked on the lensd, testing from wide-open f2.8 to f8.

Sharpness, a contest of tank vs. brick wall: which one wins?

Sharpness

Lens at 80mm
At its widest focal length setting, the Tokina 80-200 f2.8 AT-X performs quite well, especially considering its age. Wide open, the images are very sharp right from f2.8 . In terms of corner to corner sharpness, the entire field is good, with only minimal sharpness falloff in the corners, which in itself is eliminated by stopping down to f4.

Lens at 100mm
See the 80mm analysis, as the lens is identical in most regards except that the corners are sharper wide open at f2.8, no need to stop down here.

Lens at 140mm
Come the middle of the focal range, the lens starts to soften up a bit. Wide open, I personally wouldn't consider the result usable, thought it may be to people who don't have a problem applying a lot of sharpening in post-processing. No, it's not awful, but it sure isn't good, either. The good news is that, stopped down to f4, things improve a lot. Corner to corner sharpness is still consistent at all apertures.

Lens at 200mm
Fortunately, the lens has gotten over some of its issues by the end of the focal range. At 200mm, sharpness improves a bit, but it still isn't as good as it was at the 80/100mm settings. Corner to corner performance is still good here, too. In fact, I'd rate extreme corner performance at 200mm as better than it was at 140mm. Unfortunately, to get optimal sharpness, one has to stop down to f5.6 as f4 no longer gets the job done at the longest focal setting.

Pincushion distortion appears at 200mm

Distortion
Being a modest 2.5x zoom lens, the Tokina 80-200 f2.8 AT-X has a minimal amount of pincushion distortion at 200mm. Other than that, straight lines were straight at the other tested focal lengths.

Vignetting
On the sub-frame Canon 30D, there is obvious vignetting across the focal range when the lens is wide open, which is somewhat disappointing when considering the fact that this lens was built for 35mm film cameras. The good news is that, by f4, the shading disappears. Unfortunately, not owning a FF dSLR (or wanting to waste film shooting the sky), I can't tell you what it would do here. Note: color removed, contrast booted to exaggerate vignetting patterns.

CA can be quite disturbing in extreme contrast situations in bright light (80mm top, 200mm bottom)

Chromatic Aberration
In terms of chromatic aberration, this is probably the weakest link in the optical chain that is the Tokina 80-200 f2.8 AT-X. The good news is that the performance can vary but, in the most extreme situations, like a white fence on a sunny day (see below) the amount of CA is truly disturbing, being easily visible before the image is even blown up. In terms of where the lens is worst, this is on the wide end, with CA not disappearing until about f8. On the long end, the CA is still there, but nowhere near as insidious. Expect to do some post-processing work to vanquish the violet when shooting on a sunny day. Under cloudy conditions, CA is pretty much a non-issue, as the second set of shots showcase.

CA is less obnoxious in cloudy weather (80mm top, 200mm bottom)

Here's a full shot to show just how heavy the crops are.

Flare/Ghosts
When it comes with the ability to resist flare/ghosts, the Tokina 80-200 f2.8 AT-X is good. One has to literally try and get it to flare/ghost for it to do so. My advice, don't be like I was below and keep the Sun/bright point sources of light out of the corner of the frame and you'll be fine. I'm sure a hood would make things better but the lens I bought didn't come with one.



Value: 3
Typically, constant f2.8 short telephoto zoom lenses will cost at least $700 for third-party products and up to around $2,500 for name brand glass. On the used market, the Tokina 80-200 f2.8 AT-X typically sells around $300, with the 'PRO' successor going for more. Well, what can I say? It's a $300 f2.8 telephoto zoom, so it's hard to say it's a bad deal but on the other hand, don't go expecting magic as just about anything in this category will be better, albeit pricier. However, I would still rate this lens as better than the dime a dozen, $200, f4-5.6 75-300s out there as, at least with this lens, you have the option of stopping down to improve image quality and still maintain decent shutter speeds.



In the Field:
While short, constant f2.8 telephoto zooms are among the most useful optics out there for photographers who don't need faster glass, the fact that the autofocus on the Tokina 80-200 AT-X is so bad severely limits the photographic applications for this lens. Normally, such lenses are the bread and butter of action/low light shooters. Unfortunately, this lens is crippled in these situations, so what is it good for? Well, how about casual snaps? Yes, this lens can produce some great photos when the AF mechanism operates in its comfort zone of slow/stationary subjects and good light. For even better photos, stop down to f4 or, if light allows, f5.6 to slightly sharpen up the resolution and kill a bit of the chromatic aberration. Oh yes, did I mention that this 3 pound, solid metal beast could double as a weapon?

NOTE: Yes, there are no real life pictures withthis lens just yet, but I'll be sure to dig up some in the coming days. For someone who does mainly wide-angle and macro stuff, this focal length lens does not spend a lot of time on the camera.



Astrophotography

The Tokina 80-200 AT-X is a great lens for astrophotographere because, even on digital cameras, infinity is infinity, which means no need to fiddle with focus, pulling it back just a touch from infinity to get sharp stars. With this lens, disable the AF, focus to infinity, and forget about it!

For crisp astrophotos, focus to infinity and forget it. Yay!

Competition:

Now that zooms are seen as legitimate photographic tools and not gimmicky toys for casual snappers too lazy to walk around to frame a photo, the short, fast telephoto, after the fast standard zoom, probably competes in the tightest market for photographic lenses as everyone makes such optics. As for the competition in regards to the Tokina 80-200 f2.8 AT-X, everyone makes such a lens/a crop cam equivalent for one. In all, the only places where the old Tokina comes out on top is price (but you get what you pay for, remember, this is a $300 lens!) and with a tie in build quality for some of the current models. In terms of optics and autofocus, the old 80-200 Tokina will undoubtedly get blown away. Given the choice of this or the Canon 70-200 2.8L IS that I rented awhile back, the choice is clear. However, for bargain shooters who want fast glass and can live with some shortcomings, this could be just the lens for you.

Conclusion: 3.25/5

In conclusion, there isn't a lot of middle ground on the Tokina 80-200 f2.8 AT-X lens. Build quality is on par with the top-grade manufacturer lenses in this class, which often cost at least 4 times as much. Another plus is the distortion and tendency to flare (or lack thereof), lastly, image sharpness from corner to corner shows little falloff. On the bad side is the terrible chromatic aberration and autofocus capabilities, especially regarding speed and low-light performance. In the so-so area are the optics, with the wide end not being good until a stop down at f4. In all, bad + good = average, which is what this lens is considering all of its drastic self-contradictions. Recommendation? A 'yes' if you're on a budget and must have fast glass and a 'no' if focusing speed and overall image quality wide open (especially on the long end) are top concerns.

The Tokina 80-200 f2.8 AT-X: a lot of glass for only a little cash!

Tokina Fan? Check Out These Reviews!

Tokina 100 f2.8 ATX-PRO Macro
Tokina 80-400 f4-5.6 AT-X
Tokina 17 f3.5 ATX-PRO
Tokina 28-70 f2.6-2.8 ATX-PRO

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Examiner for Week of 11/21

A day late, but the weekly Examiner roundup is here.

Astronomy
Featured sight for week of 11/21: The old-fashioned Blue Moon
More cool photos from Comet Hartley
Mercury and Mars at dusk
Is the 'top secret' space plane returning to Earth?

Photography
Local ex-councilman arrested for taking pictures
Obese man loses weight after is picture shows up on Google Street View
Black Friday starts today at Amazon with Deals Week
Best of Black Friday: digital cameras
Why extended warranties are scams
Don't be fooled by crafty salesmen this Black Friday
 
 
 
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Image Quality Showdown: RAW vs. JPEG and P&S vs dSLR

For normally civil people who also happen to be photographers, few topics can bring up a firestorm of controversy as the whole RAW vs. JPEG debate and the question of whether point and shoot cams are good for anything at all. Want proof? Just go to online photography forums, read away and get some laughs out of the sometimes overly impassioned arguments. However, if one really wants to see if there is a RAW advantage or whether P&S cams can take good pictures, there needs to be hard, photographic evidence that say one way or the other. Providing such evidence is what the following tests are all about.

The painting used for the test shots


Round 1: RAW vs. JPEG.
While there are some undeniable advantages to the RAW format that have mainly to do with post-processing flexibility, the question arises: do RAW pictures actually look better than JPEG files? On paper, RAWs should for one big reason: they are uncompressed, which is a fancy way of saying that a RAW file is raw data as captured by the camera that has not been processed in any way, which means 100% data retention. In contrast, JPEGs have been run through an in-camera Photoshop of sorts before they even hit the memory card. Want proof of data loss? Just look at the size of a RAW and JPEG file. On my 8Mp Canon 30D, RAWs are typically around 15MB while JPEGs are around 3MB.

But does the large file size mean better image quality?

Yes and no. On the Canon 30D, picture quality is identical at base ISO levels of 100-400. Split pixels as you may, even the most ardent pixel peeper would be hard pressed to find any differences in image quality with regards to color rendition and noise, the pictures are just plain identical. In summary, at low ISOs, RAW and JPEG are equal in terms of technical image quality.

ISO 100: no difference

ISO 200: no difference

ISO 400: still no difference

Moving up the ISO scale, the differences start to appear.

At ISO 800, the effects of noise reduction starts appearing. On the house, the ridges of paint left by the artist's knife are starting to look a little blurred and the smearing of the canvas detail and brush strokes in the trees is noticeable. Also, this is more a point of debate at this time, the colors in the OOC JPEG file seem slightly less vivid than those converted from the RAW. However, bu ISO 1600, all the doubts about color rendition are no longer questions but fact, the colors have a lot less punch to them in the OOC JPEG as compared to the RAW. Also, in the OOC JPEG, the fine details are undoubtedly being smeared away at this point, which is the camera's top native ISO setting (the 3200 setting in the 30D is a boost). Yes, not all is rosy in the RAW file, either, as the grain is very obvious. However, with all that grain comes fine details that the camera has arbitrarily decided to destroy in JPEG. It doesn't take a genius to figure out that it is impossible to put details into a picture with post-processing that were never captured in the first place.

ISO 800: slight softening of the JPEG

ISO 1600: Obvious loss of detail in the JPEG

So what does this all mean?

First of all, at low ISO settings with noise reduction set to normal default, image quality between RAW and JPEG is indistinguishable, with the only RAW advantage being in post-processing. Moving up to mid ISOs, noise reduction will start to creep in, blurring the graininess, and all-important fine details at the same time, resulting in pictures of lower quality. Now, in the case of the 30D, this point is somewhere between ISO 400 and 800, (no, I don't have time to test the 1/3 stop ISO increments), your camera may differ, so it's important to play around with it to see at what point image degradation from noise reduction becomes unacceptable to you. However, at top ISO settings, OOC JPEG files from all cameras are sure to stink as the noise reduction becomes more and more apparent as the ISO is increased. In this vein, you should see why cameras have native ISO ranges and boosts afterward: the boost ISOs stink for pure image quality.

Recommendations? RAW is great in that it allows easy, click a button and forget it post-processing while JPEGs do not. So, if you're confident of your ability to get on the spot results, especially in regards to the all-important white balance (if you screw up your white balance, go here for tips on how to fix your pictures), save some memory card and hard drive space by shooting JPEG in well-lit settings as no one will be able to tell the difference. Shooting in low light? Well, the trade-offs have been explained quite thoroughly, so you make the call there.





Round 2: P&S vs. dSLR
Like with the question of RAW vs. JPEG, all one has to do is go browsing around an online photography forum to see the whole debate of whether P&S cameras can take good pictures take on some serious passion not imaginable to anyone who does not enjoy taking pictures. Yes, it is a given fact that dSLRs can produce pictures of far higher image quality than point and shoots, but is the dSLR advantage overblown or in proportion to the facts? Let's see!

Different sensor sizes + same Mp count = different-sized pixels.

The whole reason dSLRs and P&S cams produce such different pictures lies with the sensors they use: big ones for dSLRs and tiny ones for P&S models. Most dSLRs feature what is called an APS-C sensor, which measures around 24x18mm in regards to width by height, however, there are both larger and smaller sensors, too. On the P&S front, sensors are a lot smaller, just a few millimeters in width. The problem arises when considering the pixel density of the sensor, which is just a fancy term for answering the question of how many pixels you can jam into a given area. Obviously, if you have a pair of 15 million pixels (MP) sensors, one being a big dSLR sensor and the other being a tiny P&S one, the only way to get equal amounts of pixels into areas of different sizes is to change the size of the pixels. Result: P&S cams have high-density sensors loaded with tiny pixels while dSLRs have low density sensors with big pixels.

Herein arises the problem.

All electronic devices produce background noise, camera sensors included. The problem with pixels of different sizes comes in the ability/inability of the sensor to capture enough light in order to drown out the noise. Not being scientific, let's say we have two hypothetical sensors: a dSLR and a P&S one, the dSLR can capture 100 units of light while the P&S can only capture 25 units and they both have the same inherent noise levels. At ISO 100, let's say that both sensors have 2 units of noise. Now, whether it be the 100 units of light on the dSLR or the 25 on the P&S, the noise will be well drowned out by what is called the signal. Now, up the ISO to 3200 and both sensors are producing 20 units of noise. Now, the problem with the P&S becomes obvious, while 100 units of signal vs. 20 of noise are still no big problem for the dSLR, the ratio of 20 noise to 25 signal in the P&S means that there is barely any signal left to overcome the noise. Result: grainy picture ion P&S cams at high ISO.

So, let's examine the situation with pictures.

In this test, I used the same Canon 30D dSLR (8Mp) and a pair of P&S cams: a Nikon Coolpix s550 and an Olympus Stylus 550WP, both of which are 10Mp models. To get pictures equal in the crops, I downsized the 10Mp P&S images top the equivalent of 8Mp and then started taking the big crops. For the P&S cams, doing this actually makes them look better than what they are at full resolution, which means a slight handicap in favor of the P&S models right out of the gate. That catch aside, let's examine the results.


 

At base ISO of 100, all three cameras are looking great, producing vivid colors and crisp details in their images. In fact, it is interesting to look at the Nikon because, with the very aggressive sharpening, it actually produces the best looking image of the three by virtue of the fine detail it renders.

                                                                   

Upping the ISO to 200, the difference in picture quality starts to appear. While the image produced by the 30D and its big sensor looks the same as it did at ISO 100, the P&S images start to look different in their own ways. First up, the Nikon. Remember all of those razor-sharp details that made the ISO 100 image from the Coolpix look the best of the three? Well, they're gone, the Coolpix is already softer in appearance. Onto the Stylus, while the details look about the same, the color rendition suffers as the picture has a slightly washed-out look to it when compared to the ISO 100 shot.

Boosting the ISO to 400, the 30D still looks the same as it did at ISO 100. Unfortunately, the image degradation in the P&S cameras starts to become more and more obvious. On the Coolpix, the fine details are noticeably absent, look at the fine textures to see the effect of noise reduction. Onto the Stylus, the images are also getting softer, but even worse, the color rendition starts to take a dive, especially in the dark shades of foliage.

Upping the ISO again to 800 only makes things much worse, except for the 30D, which is still looking pretty darn good. The Nikon and Olympus? Not so good. The Nikon shows a very dramatic drop in detail retention at ISO 800, which basically cuts the line at 400 being the top setting for usable results as anything higher looks like mush. The color starts to take a dive here as well. On the Olympus, the color quality hasn't taken a dive, but, just like the Nikon, the detail retention, which was already on the mushy side at 400, takes a major hit by 800.

Topping out at ISO 1600, the cameras are all taking hits in their image quality yet again, even the seemingly untouchable 30D, which is now showing some softening of the fine details and a slight drop in color rendition. With the Nikon, the fine details are gone, as is the good color rendition, with the dark areas being especially prone to graininess that is so severe that it looks as though salt was sprinkled all over the picture. On the Olympus, ISO 1600 brings another dramatic drop in color rendition and another great step backward in terms of detail retention. The sensor has gotten so noisy that, even with the camera's heavy-handed approach to eliminating the grain, the picture is now extremely coarse-looking

What does this mean?

First, the assumption that P&S cameras can't keep up with dSLRs is true at anything but the lowest ISO settings, namely 100-200. At base ISO, point and shoots can produce tremendous pictures, with the Coolpix being arguably better than the 30D at ISO 100 and the Stylus every bit as good. However, in anything but ideal light that allows using of low ISO, the dSLRs will start to pull ahead thanks to their big pixels, which gather a lot of light that then can drown out background noise far better than the tiny P&S pixels. As the ISO increases, the dSLRs will widen the image quality gap on their P&S competitors.

Recommendations? If image quality is your thing and you expect to be doing a lot of outdoor photography in good light, a P&S camera will more than suffice. Much smaller than a dSLR, the P&S will go in your pocket while the dSLR will result in sore neck or having to carry a bag around wherever you go. However, if frequent low light shooting is your thing, it's no contest: get a dSLR because, despite its bulkiness, it will deliver the goods in terms of image quality a lot longer than a P&S can.



The Complete Picture
Until now, all you've been getting are single comparisons at a given ISO between the three cameras tested. Below are combination pictures taken from crops of each camera at ISOs ranging from 100-1600.

Canon EOS 30D

Nikon Coolpix s550

Olympus Stylus 550WP

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Examiner for the Week of 11/14, Other Updates

Another wek, another examiner roundup.

Astronomy
The Leonid Meteor Shower
Listen to the Leonids
How to avoid buying a junk telescope
Incredible new photos from pace, where have the dark skies gone?

Photography
High-speed cameras reveal physics of how cats drink
Consumer Reports is looking out for you
Park like an idiot? The whole world may soon be laughing at you!
Security may 'touch your junk' for refusing full body scans
Government responds to full body scanner controversy
The government is storing full body scanner images
Want to protect your valuables on a flight? Pack a gun
Local ex-councilman arrested for taking pictures


New Photos (sort of)

I went digging through old photos on the computer and found a couple that escaped attention when I originally did the astrophoto galleries, so here they are now:

Full Moon and Venus photos added to August gallery

Cool contrails added to September



Page Updates

October's photos can now be found under the Astrophotography Gallery

The Messier Object Gallery has been updated with October's photos, too.


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October 2010 Astrophotography

Here they are, the astrophotos for October 2010, including many of Comet Hartley, Enjoy.



 Comet Hartley meets the Double Cluster.

Comet Hartley mid-October

Comet Hartley approaches the Double Cluster, 100mm lens

Comet Hartley mid October, 100mm lens

The Flame and Horsehead Nebulae in Orion

M36 in Auriga

M38 and a neighboring NGC in Auriga

M34 in Perseus

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