|
|
Are primes brighter and sharper than wide open zooms
Hi,
Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? - Siddhartha |
Siddhartha Jain wrote:
Hi, Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? - Siddhartha In a word NO. At least it is no if you are talking about real life situations. However ---- In general primes will be sharper unless the zoom is a much better quality lens. Of course that is possible and a really good zoom can outperform a poor prime any day. -- Joseph Meehan Dia duit |
A good prime should be sharper and exhibit fewer optical aberrations
compared to a zoom, with the aperture set wide open. Stopping the zoom down should improve sharpness, but then you may lose the desirable effect of limited depth of field, if that's what you wanted. Zooms typically have different geometric distortion throughout the zoom range, usually barrell at the wide end and pincushion at the tele end, being neutral somewhere in the middle. A good prime should be able to combine better sharpness, contrast and distortion characteristics compared to a zoom. But there are some outstanding zooms out there these days and the advantage of primes has been lessened as a result. As the apertures are the same, there should be no difference in brightness. The glass doesn't lose enough light in the way you fear to be a major factor. Ian Digital Photography Now http://dpnow.com Visit our discussion forum at http://dpnow.com/Forums.html "Siddhartha Jain" wrote in message ups.com... Hi, Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? - Siddhartha |
The prime may be slightly brighter than the zoom, something which may
be more important in the motion-picture industry They use a term called the "t stop" of a lens and it is a measure of the light loss through a lens. http://artsci-ccwin.concordia.ca/comm/lighting.htm The difference could be as little as a third or as great as (or greater than) a 2 stop difference between what the f-stop is and the t-stop, while the DoF will be the same and sharpnes is likely to be less with a zoom than a prime. In real life still photography I don't believe it would be noticable (the difference in brightness), because of a variety of factors. I personally would not lose any sleep over it. |
In article . com,
Siddhartha Jain writes Hi, Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? - Siddhartha Other things being equal, yes to both, though with well-designed modern lenses the difference may be small. Brightness: The conventional f-stop designation of aperture is a purely geometric measure and takes no account of the actual transmission properties of the lens. In reality, not all of the light going into a lens will come out at the other end, and some of the light that does come out will be scattered, and hence will reduce image quality. Attenuation takes two forms: absorption and reflection/scattering. Absorption is purely proportional to the depth of glass; a typical figure for normal optical glass would be 10% for a total glass path length of 100mm. Most photographic lenses would fall far short of this, though some big lenses may get there. This attenuation is entirely proportional to the length of the light path through glass; thus a zoom with 12-15 elements is likely to experience more absorption than a fixed focal length lens with 5-10 elements. The other form is reflection from glass-air interfaces. This is unavoidable, but can be reduced very greatly by coating. The percentage of reflection depends on the refractive index of the glass, but for typical n=1.50 optical glass (uncoated) the percentage is about 4%. This, remember, is at each glass air interface, two per lens element. Thus a compound lens with 15 elements will have 30 interfaces, and will only transmit (0.96)^30 or about 20% of the light. (In fact another 20-40% will get to the film or sensor as scattered light - giving an image of appallingly bad contrast). A single layer coating will reduce the reflection to about 1-1.5%, and modern multi-coating reduces it to around 0.3-0.5%. This still gives a transmission factor of about 83.5% for a 20-surface (10-element) system, against 91.4% for a 10-surface (5-element) system. Resolution: There is not the same direct relationship between complexity and resolution as that above between complexity and transmission. However, the compromises required to balance zoom ratio, overall size, mechanical complexity and cost at the same time as controlling the seven distinct varieties of lens aberrations mean that in almost every case the zoom lens will have lower resolution than the fixed focal length lens of similar quality of design and manufacture. You can see this from the MTF function curves published by most lens manufacturers. Having just checked some of these myself to answer your question, I am actually quite impressed by how small these differences are; a couple of decades ago the differences would have been much greater. (Be aware when comparing MTF curves that they usually show wide open and f/8 data; as a zoom will usually have a smaller maximum aperture than the comparable fixed focal length lenses, you should avoid comparing these - best look at the f/8 curves for a fair comparison.) David -- David Littlewood |
Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of
"prime." A prime lens is the camera lens as distinct from some other lens or lenticular device (close-up lens, tele converter, etc.) used with it. It has meant that since long before zoom lenses became commonplace, and therefore no need to use another term to mean "non-zoom." "Prime" is properly used in the sense of primary, main, chief or original--all dictionary definitions for "prime." There is NO dictionary definition for "prime" which means fixed focal length or single focal length, or fixed or single anything else. It would be nice if this nonsensical misusage, which obviously is based on someone's misunderstanding of the term some years ago (and then spread like cancer through the power of the Internet) could be stamped out. Surely "FFL" is at least as easy to type as "prime" anyway, and there never was any reason other than shortness to replace "fixed focal length" with the incorrect term. N. |
Nostrobino wrote:
Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of "prime." A prime lens is the camera lens as distinct from some other lens or lenticular device (close-up lens, tele converter, etc.) used with it. It has meant that since long before zoom lenses became commonplace, and therefore no need to use another term to mean "non-zoom." "Prime" is properly used in the sense of primary, main, chief or original--all dictionary definitions for "prime." There is NO dictionary definition for "prime" which means fixed focal length or single focal length, or fixed or single anything else. It would be nice if this nonsensical misusage, which obviously is based on someone's misunderstanding of the term some years ago (and then spread like cancer through the power of the Internet) could be stamped out. Surely "FFL" is at least as easy to type as "prime" anyway, and there never was any reason other than shortness to replace "fixed focal length" with the incorrect term. I am aware of the mis-usage of the term *prime* and so guilty of propogating the mis-usage but I feel its time the FFL camp realised that there is no turning back. - Siddhartha |
"Siddhartha Jain" wrote in message ups.com... Nostrobino wrote: Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of "prime." A prime lens is the camera lens as distinct from some other lens or lenticular device (close-up lens, tele converter, etc.) used with it. It has meant that since long before zoom lenses became commonplace, and therefore no need to use another term to mean "non-zoom." "Prime" is properly used in the sense of primary, main, chief or original--all dictionary definitions for "prime." There is NO dictionary definition for "prime" which means fixed focal length or single focal length, or fixed or single anything else. It would be nice if this nonsensical misusage, which obviously is based on someone's misunderstanding of the term some years ago (and then spread like cancer through the power of the Internet) could be stamped out. Surely "FFL" is at least as easy to type as "prime" anyway, and there never was any reason other than shortness to replace "fixed focal length" with the incorrect term. I am aware of the mis-usage of the term *prime* and so guilty of propogating the mis-usage but I feel its time the FFL camp realised that there is no turning back. Well, not necessarily, though of course the more people who misuse the term, the harder it will be to correct it. Most people do not want to use wrong terminology since it makes them look ignorant. In the case of "prime" being used to mean FFL, this has only spread because readers who have not seen the term before, and then see it used by people they assume are knowledgeable, naturally adopt it themselves. Thus newbies are caught up in the misusage and (perhaps partly because they feel using jargon will make them look knowledgeable too), contribute to the spread. Some will continue to use it anyway, but others will drop it (and some have dropped it) when the error is pointed out to them. N. |
"Nostrobino" wrote in message ... Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of "prime." A prime lens is the camera lens as distinct from some other lens or lenticular device (close-up lens, tele converter, etc.) used with it. It has meant that since long before zoom lenses became commonplace, and therefore no need to use another term to mean "non-zoom." "Prime" is properly used in the sense of primary, main, chief or original--all dictionary definitions for "prime." There is NO dictionary definition for "prime" which means fixed focal length or single focal length, or fixed or single anything else. It would be nice if this nonsensical misusage, which obviously is based on someone's misunderstanding of the term some years ago (and then spread like cancer through the power of the Internet) could be stamped out. Surely "FFL" is at least as easy to type as "prime" anyway, and there never was any reason other than shortness to replace "fixed focal length" with the incorrect term. N. Many now accepted meanings of words have been created through misusage. Perhaps you would prefer a dead language to English? Eric Miller |
"Siddhartha Jain" wrote:
Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? The rule of thumb is that it depends on the make and model. -- Mark Roberts Photography and writing www.robertstech.com |
"Siddhartha Jain" wrote in message ups.com... Hi, Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? - Siddhartha In theory, zooms will always be somewhat below the quality of prime lenses. Zooms typically have barrel distortion at one end of the zoom range, and pincushion distortion at the other. Older zooms, especially those that did not have decent multicoating, were more prone to flare and ghosting, because of the light bouncing back and forth off the air-to-glass surfaces. The margin of superiority of primes over zooms has narrowed, and many photographers find the convenience and economy of one zoom versus several primes to be more important than some slight degree of image degradation. I have a couple of Pentax zooms in K-mount that do a credible job, and it certainly is easier to carry two zooms than it is to carry 5 or 6 primes. Thirty years ago, I bought a couple of third-party zooms for my M43 bodies, and the results were just awful, relative to my SMC Takumar prime lens. Colors had a grayish cast, saturation was less than on the OEM lens, the aperture ring was operated in the reverse direction of my Takumar's (Pentax does it "backwards"), the front element turned when the focusing ring was moved, making polarizer use difficult, the lens front element was not the standard Takumar 49mm or 58mm, making it necessary to buy filters just for use in that lens, and the resolution was noticeably less than that of the OEM Takumar. The build quality was obviously less-good than the OEM lens. The focusing was not nearly as smooth, the zoom ring was a bit on the tight side, the lens barrel was not as sturdy and the lens lacked multicoating (this was 30 years ago). So, while I saved a few dollars, I got pretty much what I paid for and no more. I ended up putting that zoom lens up on the shelf, where it remains to this day, and I bought only OEM lenses after that. They cost a bit more, but the level of satisfaction that I derived from them made up for the higher price. And not a single one of the OEM lenses has failed, in 3 decades. British landscape photographer and author Brian Bower noted that, while his Leica R zoom lenses cost a lot more than non-OEM lenses, he felt that they were a good value because they retained their accuracy after over a decade of hard use. He noted in one of his books that the cheaper zoom lenses might see the elements go out of precise adjustment and the zoom mechanism might become very loose after a time, making it necessary to keep checking the zoom ring to be certain that the zoom ratio has not changed from whatever it was originally set to. Bower valued consistently good results more than lower price. He made his living with those tools, and he had little tolerance for lens failures. My own take on it is that if the proposed use of the lens is of a very casual nature, it is probably okay to go for the savings. But if top performance and reliability are paramount, one really has to think about whether the savings might be offset by potential future loss from poorly-performing equipment. I would rather have only a couple of really good lenses than a kit full of lenses of questionable reliability and performance. It seems that, in my own case, virtually every time I have tried to save money by cutting corners I ended up paying double. |
"Siddhartha Jain" wrote in message ups.com... Hi, Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? - Siddhartha I've heard it suggested that may high quality zooms are visually indistinguishable from their prime equivalents - however both can usually out-perform most photographers! |
|
"Nostrobino" wrote:
It would be nice if this nonsensical misusage, which obviously is based on someone's misunderstanding of the term some years ago (and then spread like cancer through the power of the Internet) could be stamped out. The use, or misuse, of the term "prime" is nothing new. The same discussion was around in the 1960s and 70s. It wasn't resolved then and probably never will be. So don't blame the Internet. Blame the manufacturers who chose to use this term as a marketing tool at various times in the last 50 years. ;-) |
Given two lenses, one a prime (say 28mm) and the other a zoom (say
28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? No. f/2.8 tells you exactly how bright the lens is. (It's almost like the old question about a pound of lead and a pound of feathers - they do both weigh the same.) - Will the prime be sharper wide open than the zoom at 28mm? Probably, particuarly if both lenses are in the same price range. On the other hand, there are lots of expensive zoom lenses that are sharper than cheap fixed lenses. -Joel ---------------------------------------------------------------------------- Free 35mm lens & digital camera reviews: http://www.exc.com/photography ---------------------------------------------------------------------------- |
"I would very much like to hear which particular lenses for DSLRs or
35mm SLRs produce a 2 stop reduction in illumination from that expected at any given aperture." 2 stops is an awful lot, although I suppose some ancient zoom lenses with lousy coatings might be that bad. One of the most complex zooms I'm personally familiar with has about 40 elements, but nevertheless suffers less than a 1-stop illumination reduction. Brian |
Yes, I'm sure the missuse of the term "prime lens" will go down in
history as one of the greatest tragedies of our generation ;-) Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of "prime." |
You make it sound like it's some kind of disease. In the grand scheme of
things, does it really matter? Languages are dynamic, and the meanings of words are constantly changing. The original meaning of "prime" in the photographic sense is just an invention anyway. Referring to the dictionary I find no mention of lenses as related to the meaning of the word "prime". Who is therefore to decide which usage is correct? You apparently! The first listing that I found at dictionary.com is... "First in excellence, quality, or value" I think therefore it's perfectly reasonable to refer to a high quality FFL lens in this way. Perhaps you should just "chill out" a little and stop preaching about who or who isn't ignorant. Well, not necessarily, though of course the more people who misuse the term, the harder it will be to correct it. Most people do not want to use wrong terminology since it makes them look ignorant. In the case of "prime" being used to mean FFL, this has only spread because readers who have not seen the term before, and then see it used by people they assume are knowledgeable, naturally adopt it themselves. Thus newbies are caught up in the misusage and (perhaps partly because they feel using jargon will make them look knowledgeable too), contribute to the spread. Some will continue to use it anyway, but others will drop it (and some have dropped it) when the error is pointed out to them. N. |
In message ,
"Cockpit Colin" wrote: I've heard it suggested that may high quality zooms are visually indistinguishable from their prime equivalents You can always bring out the difference in a large print or display, or with teleconverters or extension tubes - however both can usually out-perform most photographers! Not under good conditions. -- John P Sheehy |
Just some links you may want to check out...
http://photonotes.org/cgi-bin/entry.pl?id=Primelens http://en.wikipedia.org/wiki/Prime_lens http://www.absoluteastronomy.com/enc...prime_lens.htm Please stop spreading misinformation. The first usage of a term is not necessarily the correct one. If you start referring to zooms as "prime" you're just going to make yourself sound stupid. Whatever you think it meant originally, is not what it means now. Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of "prime." A prime lens is the camera lens as distinct from some other lens or lenticular device (close-up lens, tele converter, etc.) used with it. It has meant that since long before zoom lenses became commonplace, and therefore no need to use another term to mean "non-zoom." "Prime" is properly used in the sense of primary, main, chief or original--all dictionary definitions for "prime." There is NO dictionary definition for "prime" which means fixed focal length or single focal length, or fixed or single anything else. It would be nice if this nonsensical misusage, which obviously is based on someone's misunderstanding of the term some years ago (and then spread like cancer through the power of the Internet) could be stamped out. Surely "FFL" is at least as easy to type as "prime" anyway, and there never was any reason other than shortness to replace "fixed focal length" with the incorrect term. N. |
"Eugene" wrote in message ... Just some links you may want to check out... http://photonotes.org/cgi-bin/entry.pl?id=Primelens http://en.wikipedia.org/wiki/Prime_lens http://www.absoluteastronomy.com/enc...prime_lens.htm Please stop spreading misinformation. The first usage of a term is not necessarily the correct one. If you start referring to zooms as "prime" you're just going to make yourself sound stupid. Whatever you think it meant originally, is not what it means now. Totally sick post, bro'! Hectic! What a gay idea! |
In article . com,
Siddhartha Jain wrote: Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? F/2.8 lets the same amount of light through regardless of the lens design. F/2.8 is f/2.8. Being from the old school, I would expect a fixed focal length lens to be sharper than a zoom, but you may have to go to laboratory conditions to prove it. |
Eugene wrote:
Just some links you may want to check out... http://photonotes.org/cgi-bin/entry.pl?id=Primelens http://en.wikipedia.org/wiki/Prime_lens http://www.absoluteastronomy.com/enc...prime_lens.htm Please stop spreading misinformation. The first usage of a term is not necessarily the correct one. No, but it can be good to distinguish between slang terminology and standard terminology. For instance, in audio people often talk about "acetate masters" when they mean "lacquer originals." The slang terminology is wrong on two counts because the originals of disc recordings are made on cellulose nitrate lacquer and never acetate and they are originals, not masters, according to long established terminology. The use of the slang "acetate master" has caused very little real confusion over the 70 years in which it has been in common use, but it is still not correct because the disc is neither made of acetate nor a master. (Wikipedia gets the definition of "master recording" wrong, so I don't think it is a very good source for standard technical vocabulary.) An example in photography is the use of the word "macro" as a synonym for "extreme close-up." Photomacrography, from which we get "macro," has a very well established technical meaning requiring the image size to be equal to or larger than the object size. The Wikipedia article "Macro Photography" starts out with the standard definition which it calls the "classical definition" and then goes on to discuss the extended use of the term in photographers' slang without being particularly clear that the extended meaning is still non-standard terminology. BTW it is better to use "photomacrography" than "macro photography" since "macrophotography" can mean the making of large photographs by analogy with the difference between "photomicrography" and "microphotography" which should never be confused with each other. The use of "prime lens" for "fixed focal length lens" appears to originate in cinema where the need for a handy term for a non-zoom lens was felt long before such a term was needed in still photography. As a handy bit of slang, it has much to recommend it: it is easy to say and quickly understood. As a technical term, it has two major difficulties: the word "prime" has little connection to what is meant, and there was a prior use of the term in which the word "prime" actually made sense. If you start referring to zooms as "prime" you're just going to make yourself sound stupid. No, because you would always also be using an additional term such as "supplementary lens" or "teleconverter" which would supply the context which would make the meaning clear. Whatever you think it meant originally, is not what it means now. You know, sometimes words have two meanings. Most of us can live with slang terminology and standard technical terminology without getting particularly confused. Slang terminology can be very handy: I'm not going to stop saying "Hypo" when I know that fixer is actually thiosulphate. It isn't very likely that someone will think I mean the actual chemical "sodium hyposulphite" AKA "sodium hydrosulphite" which is AFAIK not used in photography. But it is still good to distinguish between slang and proper technical language. If I ordered "sodium hyposulphite" from a chemical supplier who served dyers it is just possible I might get the wrong chemical. Peter. -- |
Eugene wrote:
Just some links you may want to check out... http://photonotes.org/cgi-bin/entry.pl?id=Primelens http://en.wikipedia.org/wiki/Prime_lens http://www.absoluteastronomy.com/enc...prime_lens.htm Please stop spreading misinformation. The first usage of a term is not necessarily the correct one. No, but it can be good to distinguish between slang terminology and standard terminology. For instance, in audio people often talk about "acetate masters" when they mean "lacquer originals." The slang terminology is wrong on two counts because the originals of disc recordings are made on cellulose nitrate lacquer and never acetate and they are originals, not masters, according to long established terminology. The use of the slang "acetate master" has caused very little real confusion over the 70 years in which it has been in common use, but it is still not correct because the disc is neither made of acetate nor a master. (Wikipedia gets the definition of "master recording" wrong, so I don't think it is a very good source for standard technical vocabulary.) An example in photography is the use of the word "macro" as a synonym for "extreme close-up." Photomacrography, from which we get "macro," has a very well established technical meaning requiring the image size to be equal to or larger than the object size. The Wikipedia article "Macro Photography" starts out with the standard definition which it calls the "classical definition" and then goes on to discuss the extended use of the term in photographers' slang without being particularly clear that the extended meaning is still non-standard terminology. BTW it is better to use "photomacrography" than "macro photography" since "macrophotography" can mean the making of large photographs by analogy with the difference between "photomicrography" and "microphotography" which should never be confused with each other. The use of "prime lens" for "fixed focal length lens" appears to originate in cinema where the need for a handy term for a non-zoom lens was felt long before such a term was needed in still photography. As a handy bit of slang, it has much to recommend it: it is easy to say and quickly understood. As a technical term, it has two major difficulties: the word "prime" has little connection to what is meant, and there was a prior use of the term in which the word "prime" actually made sense. If you start referring to zooms as "prime" you're just going to make yourself sound stupid. No, because you would always also be using an additional term such as "supplementary lens" or "teleconverter" which would supply the context which would make the meaning clear. Whatever you think it meant originally, is not what it means now. You know, sometimes words have two meanings. Most of us can live with slang terminology and standard technical terminology without getting particularly confused. Slang terminology can be very handy: I'm not going to stop saying "Hypo" when I know that fixer is actually thiosulphate. It isn't very likely that someone will think I mean the actual chemical "sodium hyposulphite" AKA "sodium hydrosulphite" which is AFAIK not used in photography. But it is still good to distinguish between slang and proper technical language. If I ordered "sodium hyposulphite" from a chemical supplier who served dyers it is just possible I might get the wrong chemical. Peter. -- |
Eugene wrote:
You make it sound like it's some kind of disease. In the grand scheme of things, does it really matter? Languages are dynamic, and the meanings of words are constantly changing. The original meaning of "prime" in the photographic sense is just an invention anyway. Referring to the dictionary I find no mention of lenses as related to the meaning of the word "prime". Who is therefore to decide which usage is correct? You apparently! It's pretty much established jargon in the photo industry. I've seen it used in this sense since the mid-70s (when I started paying attention to photo stuff). I hardly think it can be blamed solely on the internet. |
Peter wrote:
You know, sometimes words have two meanings. Most of us can live with slang terminology and standard technical terminology without getting particularly confused. Slang terminology can be very handy: I'm not going to stop saying "Hypo" when I know that fixer is actually thiosulphate. It isn't very likely that someone Not to be pedantic, but I think you mean "Jargon" not "Slang". |
Dr. Joel M. Hoffman wrote:
Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? No. f/2.8 tells you exactly how bright the lens is. (It's almost like the old question about a pound of lead and a pound of feathers - they do both weigh the same.) Well, no. The F-stop is the ratio of the aperature to the focal length, which is constant regardless of the actual material(s) of the glass. In the extreme case of spraying black paint on the lens, you could have an F:2.8 lens with 0% light transmission. |
Randall Ainsworth wrote:
In article . com, Siddhartha Jain wrote: Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? F/2.8 lets the same amount of light through regardless of the lens design. F/2.8 is f/2.8. Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass, you can grind it into a lens shape, but if you use it as an element in a lens, you're going to get some reallllllly slow shutter speeds. Of course that's an extreme case, the difference between plain old glass glass, and exotic flouro-silicates is only a few fractions of a percent. |
I don't think it has anything to do with the internet really. They've
been called prime lenses for as long as I can remember, and yes I do pre-date the Internet ;-) I certainly don't think it's some kind of fad. I suspect it would have originated about the same time as zoom lenses. People needed a handy term to distinguish their FFL lenses from the new zooms. FFL may be easy and quick to write, but 'prime' is quicker to say. Also if we're going to get pedantic about linguistics then why not take offence to the term "zoom lens". Surely they should be called Variable Focal Length Lenses, or VFL lenses. That's much better... Now we just have to re-educate all the millions of poor ignorant fools using the incorrect terminology ;-) It's pretty much established jargon in the photo industry. I've seen it used in this sense since the mid-70s (when I started paying attention to photo stuff). I hardly think it can be blamed solely on the internet. |
The use of "prime lens" for "fixed focal length lens" appears to originate in cinema where the need for a handy term for a non-zoom lens was felt long before such a term was needed in still photography. As a handy bit of slang, it has much to recommend it: it is easy to say and quickly understood. As a technical term, it has two major difficulties: the word "prime" has little connection to what is meant, and there was a prior use of the term in which the word "prime" actually made sense. OK, fair enough. You make a valid point, but in the case of "prime lens", given the definition of the word, I don't think it's nescessarily incorrect or ambiguous. Shortening complex expressions is just how language works. Just a few other slang photographic terms I could think of would be "film", or "sensor", or "flash", or even "lens". Everyone knows what these terms mean, although none of them is strictly correct or complete. If you start referring to zooms as "prime" you're just going to make yourself sound stupid. No, because you would always also be using an additional term such as "supplementary lens" or "teleconverter" which would supply the context which would make the meaning clear. Perhaps my comments were a bit harsh. I just took offense to the suggestion that it was ignorant to use the widely accepted and understood term "prime lens". It seemed clear that the Nostrobino was just being undully pedantic and argumentative, and his comments added nothing to the thread. Whatever you think it meant originally, is not what it means now. You know, sometimes words have two meanings. Most of us can live with slang terminology and standard technical terminology without getting particularly confused. Slang terminology can be very handy: I'm not going to stop saying "Hypo" when I know that fixer is actually thiosulphate. It isn't very likely that someone will think I mean the actual chemical "sodium hyposulphite" AKA "sodium hydrosulphite" which is AFAIK not used in photography. But it is still good to distinguish between slang and proper technical language. If I ordered "sodium hyposulphite" from a chemical supplier who served dyers it is just possible I might get the wrong chemical. As an Australian I certainly have no problem with slang ;-) Mind you when I'm writing things for an international audience I'm careful to avoid terms that will confuse people in other parts of the world. If I wrote the way I would typically talk to other Aussies then a lot of people wouldn't know what I was talking about. I hardly think though that "prime lens" is one of those confusing obscure slang expressions. Everyone knows what it means. |
Eugene wrote:
I don't think it has anything to do with the internet really. They've been called prime lenses for as long as I can remember, and yes I do pre-date the Internet ;-) If only it was as simple as referring to all fixed focal length lenses as "prime" lenses. Most subscribers to this newsgroup probably aren't old enough to recall that some manufacturers used the term "prime" to refer to a high quality subset of their fixed focal length lenses. What made a particular fixed focal length lens design a "prime" lens was not clear. Why other fixed focal length lenses were not described as "prime" lenses was even less clear. But what is clear is that assuming all fixed focal length lenses were referred to as "prime" lenses is wrong. It was marketing, pure and simple. Since there is no accepted definition of a "prime" lens we should just drop the term, as it serves only to confuse. I like the idea of FFL and VFL, especially as so many VFL optics are not true zooms because they do not hold focus when zoomed. They are often termed vari-focal lenses (also "VFL"), which term could be extended to include the true zooms. FFL and VFL has my vote. ;-) |
OK, I stand corrected. This does make sense. Actually now that I think
about it I don't tend to use the terms "prime" and "zoom" much anyway. I'd nearly always just refer to the specific lens type. Like I'd just say 50mm f1.4 rather than 50mm prime. Adding "prime" is kind of redundant. If only one focal length lens is given then it's obvious I'm not talking about variable focal length. Also I think there would be very few situations where lumping everything into 2 distinct groups would make sense. For example "zoom" could equally refer to an EF-S 18-55, as it could to an EF 70-200 f2.8 L. Aside from the fact that both lenses can change focal lengths, they really have nothing much else in common. They serve entirely different purposes and an entirely different market. Likewise "prime" (meaning FFL) could equally refer to a 7mm circular fisheye, or a 1200mm super-telephoto. Grouping lenses by focal length ranges makes more sense, ultra-wide, wide-angle, medium-telephoto, super-telephoto etc. FFL and VFL, while correct and non-ambiguous are also I think too broad to be generally useful. OK, well I wont use the term "prime" or "zoom" anymore as I can see that they really don't add a lot of value. If only it was as simple as referring to all fixed focal length lenses as "prime" lenses. Most subscribers to this newsgroup probably aren't old enough to recall that some manufacturers used the term "prime" to refer to a high quality subset of their fixed focal length lenses. What made a particular fixed focal length lens design a "prime" lens was not clear. Why other fixed focal length lenses were not described as "prime" lenses was even less clear. But what is clear is that assuming all fixed focal length lenses were referred to as "prime" lenses is wrong. It was marketing, pure and simple. Since there is no accepted definition of a "prime" lens we should just drop the term, as it serves only to confuse. I like the idea of FFL and VFL, especially as so many VFL optics are not true zooms because they do not hold focus when zoomed. They are often termed vari-focal lenses (also "VFL"), which term could be extended to include the true zooms. FFL and VFL has my vote. ;-) |
Eugene wrote:
Perhaps my comments were a bit harsh. I just took offense to the suggestion that it was ignorant to use the widely accepted and understood term "prime lens". But "prime lens" is NOT a "widely accepted and understood term". Because of the history of its use, it is essentially ambiguous. It has only been used as a descriptor for all fixed focal length lenses in recent times, and only by people who are unaware of its prior usage, which was as a descriptor for a "high quality" subset of fixed focal length lenses. You might be too young to recall this. There was no accepted definition of which fixed focal length lenses were "prime" and which were not. It was merely an attempt by marketing people to promote some lenses as being "better" than others, the implication being that one brand was "better" than another because of the "high quality" of their "prime" lenses. The terms "high quality", "better" and "prime" are all essentially meaningless unless backed up with something more objective, repeatable and reliable. As we all (should) know, comparisons between lenses are qualitative at best. The most commonly used "objective" comparator - MTF - was never intended for making such comparisons. It was intended as an aid to lens designers and nothing more. As a result it misleads far more than it ever informs, and those who claim it is of any real value when comparing photographic lenses are suffering from delusions. |
In article ,
Tony Polson wrote: Since there is no accepted definition of a "prime" lens we should just drop the term, as it serves only to confuse. Feel free to go ahead. The rest of the world will carry on using it. You're tilting at windmills. |
On Wed, 28 Sep 2005 22:29:43 -0700, "Brion K. Lienhart"
wrote: Randall Ainsworth wrote: In article . com, Siddhartha Jain wrote: Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? F/2.8 lets the same amount of light through regardless of the lens design. F/2.8 is f/2.8. Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass, you can grind it into a lens shape, but if you use it as an element in a lens, you're going to get some reallllllly slow shutter speeds. Of course that's an extreme case, the difference between plain old glass glass, and exotic flouro-silicates is only a few fractions of a percent. So what was your point in bringing up a special case ulikely to be implemented? |
|
In article , Brion K. Lienhart
wrote: Nope. F:2.8 is solely based on the size of the lens. Obsidian is glass, you can grind it into a lens shape, but if you use it as an element in a lens, you're going to get some reallllllly slow shutter speeds. Of course that's an extreme case, the difference between plain old glass glass, and exotic flouro-silicates is only a few fractions of a percent. An f/2.8 lens is going to allow a specific amount of light to go through regardless of what kind of glass it's made of. |
Nostrobino wrote:
"Siddhartha Jain" wrote in message ups.com... Nostrobino wrote: Zoom lenses ARE prime lenses, notwithstanding the now-popular misusage of "prime." A prime lens is the camera lens as distinct from some other lens or lenticular device (close-up lens, tele converter, etc.) used with it. It has meant that since long before zoom lenses became commonplace, and therefore no need to use another term to mean "non-zoom." "Prime" is properly used in the sense of primary, main, chief or original--all dictionary definitions for "prime." There is NO dictionary definition for "prime" which means fixed focal length or single focal length, or fixed or single anything else. It would be nice if this nonsensical misusage, which obviously is based on someone's misunderstanding of the term some years ago (and then spread like cancer through the power of the Internet) could be stamped out. Surely "FFL" is at least as easy to type as "prime" anyway, and there never was any reason other than shortness to replace "fixed focal length" with the incorrect term. I am aware of the mis-usage of the term *prime* and so guilty of propogating the mis-usage but I feel its time the FFL camp realised that there is no turning back. Well, not necessarily, though of course the more people who misuse the term, the harder it will be to correct it. Most people do not want to use wrong terminology since it makes them look ignorant. In the case of "prime" being used to mean FFL, this has only spread because readers who have not seen the term before, and then see it used by people they assume are knowledgeable, naturally adopt it themselves. Thus newbies are caught up in the misusage and (perhaps partly because they feel using jargon will make them look knowledgeable too), contribute to the spread. Some will continue to use it anyway, but others will drop it (and some have dropped it) when the error is pointed out to them. N. Just because "popular usage" may not appear in a particular dictionary does not constitute "misuse". If you speak of a prime lens to photographers, they know what you're talking about. Perhaps this should be continued in rec.english.language.anal.purists |
Tony Polson wrote:
Eugene wrote: Perhaps my comments were a bit harsh. I just took offense to the suggestion that it was ignorant to use the widely accepted and understood term "prime lens". But "prime lens" is NOT a "widely accepted and understood term". Who here does not understand what is meant when the term "prime lens" is used? A show of hands please? |
John A. Stovall wrote:
On 28 Sep 2005 07:33:55 -0700, "Siddhartha Jain" wrote: Hi, Given two lenses, one a prime (say 28mm) and the other a zoom (say 28-75mm) and both with an aperture of f2.8 - - Will the prime be brighter than the zoom because it has fewer lens elements? - Will the prime be sharper wide open than the zoom at 28mm? Ofcourse, a lot will depend on the particular makes and models being compared but is there a rule of thumb? Rule of Thumb: A prime at any focal length and wide open is better than a zoom at any focal length wide open. Except when it's not ... like a really well made fast zoom lens being compared to a really poorly made slow prime lens. |
| All times are GMT +1. The time now is 06:56 AM. |
Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.
PhotoBanter.com