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Photo Forum / Digital Photography / DSLR Cameras / July 2006New Sigma lense, maybe good for portraits?
Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, that might be a wonderful "105 mm" on D-SLRs if it has nice bokeh. Any thoughts? http://tinyurl.com/rmzzg > Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, > that might be a wonderful "105 mm" on D-SLRs if it has nice bokeh. > > Any thoughts? > > http://tinyurl.com/rmzzg It might be a wonderful lens, but then again, I doubt they'd want to break with their long-standing tradition of producing mostly crap lenses. . > > Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, > > that might be a wonderful "105 mm" on D-SLRs if it has nice bokeh. [quoted text clipped - 5 lines] > It might be a wonderful lens, but then again, I doubt they'd want to break > with their long-standing tradition of producing mostly crap lenses. Sigma MACROs aren't bad, sharp, not a high level (at least I haven't read many) of complaints. But you want sharp for a macro, flat field decent focusing speed. The hair thin focusing of the boke crowd is starting to drive me crazy, choose your background well your portrait will work. Tom > Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, It's unlikely they would release any 70mm lens that wasn't a prime lens. What else could it be, a close-up lens? "Prime lens" means the camera lens as opposed to some other lens or optical device used with it. What "prime lens" does NOT mean is fixed focal length lens, notwithstanding the enormous popularity of this misusage. >> Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, > [quoted text clipped - 6 lines] > What "prime lens" does NOT mean is fixed focal length lens, notwithstanding > the enormous popularity of this misusage. An awful lot of the photographic world disagrees with your claim that prime lens does not mean "fixed focal length lens." But that's neither here nor there. >>> Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, >> [quoted text clipped - 9 lines] > An awful lot of the photographic world disagrees with your claim that > prime lens does not mean "fixed focal length lens." No major camera or lens manufacturer uses "prime lens" to mean fixed focal length lens, as far as I know. Certainly neither Nikon nor Minolta ever did, nor has any other major manufacturer whose literature I've seen. On the other hand, lens manufacturers such as Schneider and Zeiss have and still do use "prime lens" to mean lenses which are NOT fixed focal length, e.g. their variable prime cine and video lenses which are catalogued in just that way, "variable prime." Does it make any sense for people to keep misusing "prime" when lens manufacturers are using the term correctly? The misunderstanding of "prime" to mean FFL started several years ago (I first saw this misuse on the old Fidonet) and now, through the magic of the Usenet, has unfortunately become all too common. People now seem to use it just for the sheer love of unnecessary jargon. In your own example, describing a lens as 70mm already says it's fixed focal length, since a 70mm lens can hardly be otherwise. "Prime" WRT lenses is properly used in the standard dictionary senses of "primary," "main," "chief" or "original." There is NO dictionary definition for "prime" meaning fixed (or single) anything. Neil But that's neither > here nor there. >>>> Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, >>> It's unlikely they would release any 70mm lens that wasn't a prime lens. [quoted text clipped - 30 lines] > > Neil I first heard the word "prime" circa 1965 in the context we're discussing. The lack of a dictionary definition is meaningless. >>>>> Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, >>>> It's unlikely they would release any 70mm lens that wasn't a prime [quoted text clipped - 34 lines] > > I first heard the word "prime" circa 1965 in the context we're discussing. Certainly "prime" was used in connection with lenses then, and earlier. But I would be very, very, very surprised if you could come up with a ca. 1965 source showing "prime" used to mean FFL. In 1965 most lenses were still fixed focal length, and there was no reason to invent a term to distinguish them from non-FFL lenses. I first saw "prime lens" used (correctly) some time in the 1950s, in connection with close-up lenses. I first saw it misused to mean FFL some time in the 1980s on Fidonet. My guess is that someone saw "prime lens" used correctly in connection with a tele extender or some other device, and the example prime lens being FFL, wrongly assumed that's what it meant. But a zoom lens is just as much a prime lens when used with another device, and absent the other device there's no reason to use "prime" at all. > The lack of a dictionary definition is meaningless. Words MEAN things. Why would anyone have applied "prime" to any type of lens in the first place, unless the word already carried the meaning that they wanted to apply to that lens? Again, "prime" is still being used CORRECTLY by lens manufacturers. It makes no sense to use it incorrectly just because a lot of other people are doing so. Neil >>>>>> Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, >>>>> It's unlikely they would release any 70mm lens that wasn't a prime [quoted text clipped - 59 lines] > > Neil Language and the meanings of words evolve and change, sometimes dramatically. As an example, consider the word "conservative" in the context of American politics. In the 1960s and 1970s, it conjured up one set of meanings. Today, it conjures up an almost entirely different set of meanings. So, define "conservative" in the context of a changing society. Does it mean someone like, say, Barry Goldwater, or does it mean someone like, say, oh, Dick Cheney? These two are so far apart in attributes that matter that they cannot both be conservatives. >>>>>>> Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, >>>>>> It's unlikely they would release any 70mm lens that wasn't a prime [quoted text clipped - 64 lines] > Language and the meanings of words evolve and change, sometimes > dramatically. Indeed, that seems to be always one of the first arguments that occur to people who misuse terminology: "the meanings of words evolve and change." Language does evolve, but incorrect usage resulting from misunderstanding is not an example of evolution, just incorrect usage. Popularity of the misusage doesn't necessarily change this. There are terms that have been misunderstood and misused for decades, and are still wrong today. > As an example, consider the word "conservative" in the context of American > politics. In the 1960s and 1970s, it conjured up one set of meanings. [quoted text clipped - 3 lines] > Dick Cheney? These two are so far apart in attributes that matter that > they cannot both be conservatives. Sure they can. Conservatives do not always agree on every point or every issue. I'm not aware of any philosophical difference between Goldwater and Cheney, but there probably are some differences and clearly both men are examples of conservatives anyway. Similarly for leftists (or "liberals" as they are called in the U.S. for some reason). Neil > Words MEAN things. Why would anyone have applied "prime" to any type of lens > in the first place, unless the word already carried the meaning that they [quoted text clipped - 3 lines] > no sense to use it incorrectly just because a lot of other people are doing > so. What gains accrue to the photographers here to restrict the use of the words "prime lens" to the meaning "primary lens"? OTOH, it seems useful to 'allow' the morphing of that term to mean a fixed focal length lens. [ffll]  SignatureJohn McWilliams > What gains accrue to the photographers here to restrict the use of the > words "prime lens" to the meaning "primary lens"? There isn't anything about the word "prime" that has anything to do with "fixed focal length". Why change its meaning to that, destroying its original meaning, when there is already a perfectly good way to describe what you're talking about? Why not just call the color of the sky "green"? > OTOH, it seems useful to 'allow' the morphing of that term to mean a > fixed focal length lens. [ffll] Why have different words at all? Why not just have one word and "allow" it to mean everything? SignatureJeremy | jeremy@exit109.com >> What gains accrue to the photographers here to restrict the use of the >> words "prime lens" to the meaning "primary lens"? [quoted text clipped - 3 lines] > original meaning, when there is already a perfectly good way to describe > what you're talking about? Could you possibly address the question? And, what "original meaning" are we in danger of losing? Why not just call the color of the sky "green"? [reductio ad absurdum] >> OTOH, it seems useful to 'allow' the morphing of that term to mean a >> fixed focal length lens. [ffll] > > Why have different words at all? Why not just have one word and "allow" > it to mean everything? [reductio ad absurdum] You do know better. Signaturelsmft >>> What gains accrue to the photographers here to restrict the use of the >>> words "prime lens" to the meaning "primary lens"? [quoted text clipped - 16 lines] > > You do know better. In the non-church sense, "prime" first meant "first hour." Now, there are many meaning for the word. I suppose we should make such additional uses illegal. Or at least immoral. > In the non-church sense, "prime" first meant "first hour." Now, there > are many meaning for the word. I suppose we should make such additional > uses illegal. Or at least immoral. Words can have multiple meanings without one meaning supplanting another. It happens all the time, and is irrelevant here. SignatureJeremy | jeremy@exit109.com > Could you possibly address the question? Even if I hadn't, the answer is blindingly obvious: the gain is that we still have something that means "prime lens". > And, what "original meaning" are we in danger of losing? The primary lens. > [reductio ad absurdum] > > You do know better. You're advocating changing the meaning of perfectly good words so that they mean the same thing as other perfectly good words, losing their original meaning in the process. There is nothing good about that, and it *is* exactly the same thing as calling the color of the sky "green", and makes exactly as much sense. SignatureJeremy | jeremy@exit109.com >>> What gains accrue to the photographers here to restrict the use of the >>> words "prime lens" to the meaning "primary lens"? [quoted text clipped - 6 lines] > Could you possibly address the question? And, what "original meaning" > are we in danger of losing? Why do you say he isn't addressing the question? The original, still current (and logically correct) meaning is the camera's primary lens. The term is still used to mean that, but not often since there's generally no reason to use a term that only distinguishes the camera lens from some other lens or optical device. When so many people flood the photo newsgroups with the misusage, that obviously does endanger the original and still correct meaning. Newcomers see the misuse and, liking jargon, innocently pick it up themselves. That is almost certainly how 99% of people who misuse the term got started doing so. Surely there is no LOGICAL reason to use "prime" to mean fixed focal length. > Why not just call the color of the sky "green"? > [reductio ad absurdum] [quoted text clipped - 8 lines] > > You do know better. No, he's correct. This sort of reckless misusage is what I call Humpty Dumptyism. For those not familiar with "Through the Looking Glass," here's the relevant passage: (Humpty is speaking to Alice) 'And only ONE for birthday presents, you know. There's glory for you!' 'I don't know what you mean by "glory,"' Alice said. Humpty Dumpty smiled contemptuously. 'Of course you don't-- till I tell you. I meant "there's a nice knock-down argument for you!"' 'But "glory" doesn't mean "a nice knock-down argument,"' Alice objected. 'When _I_ use a word,' Humpty Dumpty said in rather a scornful tone, 'it means just what I choose it to mean--neither more nor less.' 'The question is,' said Alice, 'whether you CAN make words mean so many different things.' 'The question is,' said Humpty Dumpty, 'which is to be master-- that's all.' Neil >> Words MEAN things. Why would anyone have applied "prime" to any type of >> lens [quoted text clipped - 9 lines] > What gains accrue to the photographers here to restrict the use of the > words "prime lens" to the meaning "primary lens"? That's what the term means, and has always meant. Avoiding unnecessary confusion should be reason enough to use the term correctly. It still IS used correctly by some, and people who think it means something else won't understand what they're reading when they see it used correctly. Isn't that a good enough reason to stop the misusage? > OTOH, it seems useful to 'allow' the morphing of that term to mean a > fixed focal length lens. [ffll] About as useful as it would be to call a lens a shutter. How is it useful to misuse the term? Neil >>> Words MEAN things. Why would anyone have applied "prime" to any type of >>> lens [quoted text clipped - 20 lines] > About as useful as it would be to call a lens a shutter. How is it useful to > misuse the term? Well, since you are able to quote Lewis Carroll to make points, however stretched, I will respond to you but not ole Nixon, whose arguments are merely trollish, if not obtuse. If one's primary lens has been redundantly referred to as a prime lens, it's time to free up that second term. If one says my prime lens is the 500 ƒ4, he may not mean primary, but rather, his most prized lens. So, to avoid the confusion, best say what one means. And therefor one is free to assign ffl lenses the term, a prime lens. Time to come into the 21st Century, what? Signaturejohn mcwilliams >>>> Words MEAN things. Why would anyone have applied "prime" to any type of >>>> lens [quoted text clipped - 30 lines] > > If one's primary lens has been redundantly referred to as a prime lens, The term "prime lens" is redundant only when there is no other lens or optical device attached to it, or no other reason to distinguish it from such an attachment. The way the majority of people in the NGs use it, yes, it is redundant. > it's time to free up that second term. If one says my prime lens is the > 500 ƒ4, he may not mean primary, but rather, his most prized lens. He may indeed. "Prime," like most words in the English language, has many different meanings. None of them, though, have anything at all to do with the concept "fixed." > So, to avoid the confusion, best say what one means. In correct terminology, yes. It certainly does not AVOID confusion to use a word to mean something other than what it really means. To "say what one means" using the wrong words, and insist on doing so even after the error is made clear, is Humpty Dumptyism. > And therefor one is > free to assign ffl lenses the term, a prime lens. Sorry, but no. "Prime" is not free to mean FFL since, as already mentioned, it is used by lens manufacturers to describe lenses of VARIABLE focal length. > Time to come into the 21st Century, what? Lens manufacturers still use the term correctly in the 21st century, and are likely to still be doing so in the 22nd. Neil >> OTOH, it seems useful to 'allow' the morphing of that term to mean a >> fixed focal length lens. [ffll] [quoted text clipped - 4 lines] > > Neil Words mean different things in different contexts. Not too long along the N word was interned as a racial slur. I hear the N word all the time these days, but it's almost never with that same meaning. You wanna try to keep up with the English language and the year you're living in? http://en.wikipedia.org/wiki/Prime_lens ____ Slack > Words mean different things in different contexts. Not too long along > the N word was interned ------> make that *intended* >>> OTOH, it seems useful to 'allow' the morphing of that term to mean a >>> fixed focal length lens. [ffll] [quoted text clipped - 8 lines] > N word was interned as a racial slur. I hear the N word all the time these > days, but it's almost never with that same meaning. You hear the N word all the time from _black_ people, who have used it among themselves without offense for most of the 20th century at least and probably longer. Coming from a white person it is still regarded as a racial epithet. > You wanna try to keep up with the English language and the year you're > living in? > http://en.wikipedia.org/wiki/Prime_lens > ____ > Slack Signature--John to email, dial "usenet" and validate (was jclarke at eye bee em dot net) >>> OTOH, it seems useful to 'allow' the morphing of that term to mean a >>> fixed focal length lens. [ffll] [quoted text clipped - 6 lines] >> > Words mean different things in different contexts. Most do. This does not mean that they can be given any meaning at all, willy nilly. "Prime" has many different meanings, but "fixed" is not among them. > Not too long along the N word was interned as a racial slur. I hear the N > word all the time these days, but it's almost never with that same > meaning. I'm not aware that "the N word" has changed its core meaning. Before it became a racial slur so terrible that it had to be referred to as "the N word," it was just a slang term for "Negro" that was used by many writers without objection from anyone -- most famously Mark Twain, who used it repeatedly in his novel "Huckleberry Finn." The novel received mostly very positive reviews in its own time (the 1880s), but even the few negative reviews did not complain about, or even mention, his use of the word "nigger." Similarly, the word was used repeatedly and even in the title of Joseph Conrad's 1897 book "The Nigger of the Narcissus." No one complained. Thus the REACTION to it has changed over the decades, but the MEANING of "the N word" remains what it always did. There are now other extensions to that meaning which are based on the way the word is perceived. > You wanna try to keep up with the English language and the year you're > living in? > http://en.wikipedia.org/wiki/Prime_lens You should know that Wikipedia, while useful in many areas, is a non-authoritative source to which anyone can contribute anything he likes, and define any term the way he likes. If you will read that article thoroughly and go to the connected talk page, you will see that the definition given is strongly disputed -- and the disputing argument goes unanswered. If you really "wanna try to keep up with the English language and the year you're living in" you need to go into it a little more deeply than you apparently have done. Neil >>>> OTOH, it seems useful to 'allow' the morphing of that term to mean a >>>> fixed focal length lens. [ffll] [quoted text clipped - 45 lines] > > Neil As a graduate etymologist, I've had a bit of fun reading these scribblings on language, pigheaded as they may be, but have any of you any interesting speculations about the lens in question? I can hear these same arguments every time I attend my editorial meetings. I really am interested in the Sigma lens. >>>>> OTOH, it seems useful to 'allow' the morphing of that term to mean a >>>>> fixed focal length lens. [ffll] [quoted text clipped - 50 lines] > on language, pigheaded as they may be, but have any of you any interesting > speculations about the lens in question? It's a 70mm f/2.8 macro which nobody has one of yet. What sort of "interesting speculations" are you expecting? The discussion on proper terminology is far more practical and useful. > I can hear these same arguments every time I attend my editorial meetings. Then stop saying "prime lens" in your editorial meetings when you mean "fixed focal length lens." Would that all problems were so easily solved. Neil >> As a graduate etymologist, I've had a bit of fun reading these scribblings >> on language, pigheaded as they may be, but have any of you any interesting [quoted text clipped - 8 lines] > Then stop saying "prime lens" in your editorial meetings when you mean > "fixed focal length lens." Would that all problems were so easily solved. Ah, just say "No!". Since Mr. Harrington believes an un-refuted statement has more weight than a refuted one, I hereby refute each and every assertion he makes with regard to the use of the word prime. Prime is a fine term to denote a fixed focal length lens. Whinge all you want. SignatureJohn McWilliams >>> As a graduate etymologist, I've had a bit of fun reading these >>> scribblings [quoted text clipped - 17 lines] > than a refuted one, I hereby refute each and every assertion he makes > with regard to the use of the word prime. If a logical argument is not refuted by logical counter-argument, given plenty of time for the other side to do so, that does lend it weight. But key here is "logical counter-argument." Simply saying you refute something (with not even an attempt at actual counter-argument) carries no weight at all. You might as well be "refuting" the idea that the earth is round. > Prime is a fine term to denote a fixed focal length lens. Less so than, say, "egg," which at least can be taken as a symbol of unity and therefore by some stretch of meaning might have something to do with the idea of single focal length. This puts it way, way ahead of "prime" which not even the most strenuous stretch can take to such a meaning. So I suggest you call an FFL lens an "egg lens" if for some reason "FFL" causes you discomfort or confusion. "Egg" is even easier to type than "prime," which seems to be the only real reason for the misusage in the first place. "Prime lens" already has a meaning, has had the same meaning for at least half a century that I know of, people employed in the design and manufacture of lenses still use it correctly, and all these attempts to usurp it to serve some silly meaning cannot add anything but confusion. What is remarkable is that some people who have all this explained to them still insist on using the term wrongly, as though they revel in demonstrating their ignorance and will not be denied any opportunity to do so. Neil >>>>>> OTOH, it seems useful to 'allow' the morphing of that term to mean a >>>>>> fixed focal length lens. [ffll] [quoted text clipped - 58 lines] > > Neil We rarely get into camera talk, but maybe I can wangle a listing for prime lens and cite you with an example of archaic use. Maybe we should all go back to the subject of optics to resolve this debate. The word prime is used in optics in the context of prime focus. The site http://www.opticalvision.co.uk/content.asp?SEC_ID=11 defines prime focus as "The focal point of an objective mirror or lens." A fixed focal length lens has only one prime focus while a zoom lens has more than one prime focus. It seems a reasonable idea to associate fixed-focal-length to prime focus, to wit: (a) A fixed-focal-length lens has only one prime focus ... (b) Zoom lenses have more than one prime focus ... (c) The primary focal length of a fixed-focal-length lens is its prime focus ... (d) A prime lens has only one primary focus. Since photographers are photographers and not optical engineers it seems reasonable to just say "prime lens" instead of the tongue twisting fixed-focal-length lens. Notice that in order to make yourself understood you have to use jargon like FFL when "prime" would do very nicely. It is well understood in the photographic community. Your insistence on historical and scientific exactness forced you to resort to the very jargon that you deride. The etymology of prime lens from "primary lens" is rather hazy. Even if it were true, it is no longer useful since the context in which we need to distinguish between fixed-focal length and zoom lens occurs in interchangeable lens systems. There is no longer talk of a primary lens in interchangeable lens systems. What is the primary lens of an EOS 1Ds Mark II? What is the primary lens of a Nijon D50? Such questions are of course meaningless! Why insist then on preserving the term "primary lens" on a system that does not require a "primary lens"? As to Humpty-dumptyism, it is you, Mr. Harrington that is engaging in it. You decided that prime is derived from "primary lens" when it fact prime is derived from "prime focus." Yes, prime is still used by the optical industry in connection with primary focus and yes they are optical engineers. But we are photographers and not optical engineers. It is not the first time that tradesmen have taken words from specialized professions and turned them into something useful for themselves. For example: (a) Why is the narrow 28mm "wide-angle" while the wider 105mm "telephoto?" Shouldn't 105mm be "narrow angle?" (b) What do photographers mean when they say "dispersion?" (c) What is meant by "focal point" in the context of photography? (d) What is meant by "focal point" in the context of optics? (e) Macro means large and micro means small. What kind of photographs are you taking when you are taking macro photographs? Are these photographs of large objects or of small objects? (f) Plastic means "flexible." Is the plastic barrel of a Canon 50mm f/1.8 flexible? (g) Do you know what the word "lens" means in optics? How many lenses are there in an EF-S 17-55mm lens? (h) What is a mirror? What is the reflecting substance in a "glass mirror"? Is it the glass or the metal backing? It would be wonderful if photographers are as intimate with brewster's angle and Snell's law as they are with the rule of thirds; but with limited time on our hands we have to make compromises. > Maybe we should all go back to the subject of optics to resolve this > debate. [quoted text clipped - 63 lines] > angle and Snell's law as they are with the rule of thirds; but with > limited time on our hands we have to make compromises. Delicious. Thanks. > Maybe we should all go back to the subject of optics to resolve this > debate. [quoted text clipped - 7 lines] > A fixed focal length lens has only one prime focus while a zoom lens > has more than one prime focus. No, it does not. Any camera lens has an infinite number of prime foci as your source uses that term. A fixed focal length lens has only one focal length and can focus on only one plane at a time. A zoom or varifocal lens has an infinite number of focal lengths and STILL can focus on only one plane at a time. Your source is not actually considering the focal PLANE, which is what a photographer cares about; it speaks only of "the focal point of an objective mirror or lens," i.e. the point in space at which a lens or mirror will focus a given point on the subject. The focal PLANE comprises an infinite number of focal points, arranged in a plane (normally) perpendicular to the lens axis. Your source is not considering photographic optics at all, but optics as related to astronomical telescopy. It is mostly irrelevant to this discussion. > It seems a reasonable idea to associate fixed-focal-length to prime > focus, to wit: > > (a) A fixed-focal-length lens has only one prime focus ... Wrong, as your source uses that term. > (b) Zoom lenses have more than one prime focus ... Yes, an infinite number, just as FFL lenses do. > (c) The primary focal length of a fixed-focal-length lens is its prime > focus ... No. You are confusing terms that have nothing directly to do with each other. Q. What on earth is a "primary focal length"? A. It's a nonsense term invented by Anthony as he strains mightily (but hopelessly) to force unconnected concepts into some sort of coherent whole. Any lens has only one focal length at a time. "Primary" is meaningless as you use it. Is there a "secondary" focal length? What might that be? > (d) A prime lens has only one primary focus. Q. What on earth is a "primary focus"? A. Same as above. > Since photographers are photographers and not optical engineers it > seems reasonable to just say "prime lens" instead of the tongue > twisting fixed-focal-length lens. In fact, that is the SOLE reason for the misusage in the first place: it's just easier to say or write. Similarly, it's easier to say or write "aspirin" than "sodium 2-amino-3-(4-bromobenzoyl) phenylacetate sesquihydrate." So should we say or write "aspirin" instead when speaking of sodium 2-amino-3-(4-bromobenzoyl) phenylacetate sesquihydrate? No. Why not? Because aspirin is not sodium 2-amino-3-(4-bromobenzoyl) phenylacetate sesquihydrate. See how this works? The mere fact that a term is easier to say or write, though that does have an obvious utility, is not a good enough reason to use it when it's WRONG. > Notice that in order to make yourself > understood you have to use jargon like FFL How is "FFL" jargon? It's a long-established and logical abbreviation for what is being described. Do you think "SLR" is jargon? > when "prime" would do very > nicely. "Prime," misused in this way, is jargon. People who think it means fixed focal length use it when it would be completely redundant even if it did mean that. I'd like to have a nickel (okay, a dollar, considering inflation) for every time I've seen someone write something like "28mm prime" in these newsgroups. How many different focal lengths are there in a 28mm lens? Would there be any point whatever in saying "28mm fixed focal length"? What, as opposed to a 28mm zoom? So such people use "prime" purely for the sake of using jargon, which I suppose they think makes them appear knowledgeable to others. In fact, to anyone who understands what "prime lens" means it only makes them look like ignoramuses. "Prime," used CORRECTLY, serves the important purpose of distinguishing the prime lens from another lens or optical device used with it. For example, instructions for a +1 close-up lens would read, "A subject 39.4 inches in front of the close-up lens will be in focus when the prime lens is set at infinity." > It is well understood in the photographic community. Your > insistence on historical and scientific exactness forced you to resort > to the very jargon that you deride. > > The etymology of prime lens from "primary lens" is rather hazy. There's no haziness about it. "Prime" is used in the common dictionary definitions of primary, chief, main, original, etc. Your understanding of this may indeed be "rather hazy," but the term itself is not hazy in the least. > Even if > it were true, it is no longer useful since the context in which we need [quoted text clipped - 4 lines] > questions are of course meaningless! Why insist then on preserving the > term "primary lens" on a system that does not require a "primary lens"? The prime, or primary, lens in every case is the camera lens being used with some other attachment. The term "prime" has no other reason for existence in this connection, which is why it is seldom used -- correctly. > As to Humpty-dumptyism, it is you, Mr. Harrington that is engaging in > it. You decided that prime is derived from "primary lens" when it fact > prime is derived from "prime focus." As I have pointed out, your reasoning on this is completely garbled. The source you've given, which is devoted to astronomical telescopy, is just not very relevant to the subject of cameras. Their concern is not with focus as photographers think of it (i.e., focusing on objects at varying distances), but focus only within the instrument itself, the subject being some point always at infinity. And why you have gotten FOCUS mixed up with FOCAL LENGTH, I have no idea. You seem to believe they are the same thing. I honestly cannot even begin to comprehend your degree of confusion on this, and do not see how I can help you with your problem. Neil >> Maybe we should all go back to the subject of optics to resolve this >> debate. [quoted text clipped - 139 lines] > > Neil Perhaps another 500 of your carefully crafted words...or how about 1000? Here: http://tinyurl.com/bvnds [ . . . ] >> As I have pointed out, your reasoning on this is completely garbled. The >> source you've given, which is devoted to astronomical telescopy, is just [quoted text clipped - 13 lines] > > http://tinyurl.com/bvnds <chuckle> That's very good! Neil > A fixed focal length lens has only one prime focus while a zoom lens > has more than one prime focus. Well, if you want to go back to the fundamentals, the use of "zoom" to describe any lens that can change its focal length is incorrect, too. > (a) Why is the narrow 28mm "wide-angle" while the wider 105mm > "telephoto?" Shouldn't 105mm be "narrow angle?" Yes, it should. "Telephoto" describes an optical design, and is not a name for a lens with a long focal length. A narrow-angle lens need not be telephoto. Indeed, there are advantages to a narrow-angle lens that is *not* telephoto, particularly in large format photography, because the telephoto design moves the nodal point. In small format, most of our long lenses are telephoto, which leads to confusion as to the meaning of the term. A telephoto lens can be physically shorter than its focal length, but is slower, projects a smaller image circle, is heavier, and costs more. > It would be wonderful if photographers are as intimate with brewster's > angle and Snell's law as they are with the rule of thirds; but with > limited time on our hands we have to make compromises. Why must compromise include incorrect usage of words? SignatureJeremy | jeremy@exit109.com > Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, > that might be a wonderful "105 mm" on D-SLRs if it has nice bokeh. > > Any thoughts? Well, considering the rather high price, I am not so sure about it. I am looking for this kind of lens for my D200 and in the same price range currently I am more attracted to Nikon's 60mm macro lens, which is widely regarded as a true top quality classic. I have used the old manual variant of the lens and it is awesome. I don't know how Canon and other camera brand macro lenses are regarded, but in the Nikon world, the 60mm is a winner. In short, the Nikon is certainly excellent, while the Sigma has to prove itself. If you care about such things, the Nikon lens will also have a higher resale value. I think that for more attractive product differentiation, Sigma should have added a quick HSM motor. Such a motor is not useful for macro (but then you'd set it to manual anyway) but certainly useful for quick portraits. Anyway, I am still curious to read a detailed review of the sigma lens, and I will probably try both lenses side by side before I decide which one to buy. If anyone has a link to a test, please post. Tom >> Sigma is about to release a new prime 70 mm f 2.8 lens, a macro, >> that might be a wonderful "105 mm" on D-SLRs if it has nice bokeh. [quoted text clipped - 25 lines] > > Tom I'm not sure anything exists for testing beyond the announcement...yet. |
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