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#1
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Some basic questions about process lenses vs. "regular" lenses
I've never really understood the following -- maybe someone can
enlighten me: 1. What's the difference between "flat field" and curved field?" I know that enlarger lenses and process lenses have "flat fields" -- but what exactly does this mean? Is the subject-field flat -- or the "image-field?" What's a non-flat field? 2. If process lenses are used for general photography (landscapes, portraits, etc.), what is compromised or lost? If the answer is "nothing," then why don't we all use process lenses for everything? 3. Reproduction ratios (may not be the corret term). Some lenses are alleged to be "optimized" (whatever that means) for 1-to-1 reproduction. I assume that means that a 1-inch subect is rendered as a 1-inch image on the film. Is that correct? What is the optimal ratio for general photography lenses. Thanks for any help. Marco |
#2
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Ron Wisner wrote an article entitled "The Myth of the Flat Field Lens" that
discusses most of these questions in some detail. See http://wisner.com/myth.htm. "Marco Milazzo" wrote in message ... I've never really understood the following -- maybe someone can enlighten me: 1. What's the difference between "flat field" and curved field?" I know that enlarger lenses and process lenses have "flat fields" -- but what exactly does this mean? Is the subject-field flat -- or the "image-field?" What's a non-flat field? 2. If process lenses are used for general photography (landscapes, portraits, etc.), what is compromised or lost? If the answer is "nothing," then why don't we all use process lenses for everything? 3. Reproduction ratios (may not be the corret term). Some lenses are alleged to be "optimized" (whatever that means) for 1-to-1 reproduction. I assume that means that a 1-inch subect is rendered as a 1-inch image on the film. Is that correct? What is the optimal ratio for general photography lenses. Thanks for any help. Marco |
#3
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In article ,
Kirk Fry wrote: There are two main problems with process lenses: 1) they are usually huge and heavy (G clarons are an exception) and 2)Don't come and don't You're kidding, right? Because of their simple designs and small maximum apertures, most process lenses are significantly smaller than most modern large format taking lenses. A 19" Artar is significantly smaller than a 480mm "general-purpose" plasmat; and, as another point of comparison, I have used, over the years, as my standard 8x10 lens, a 14" Caltar (Commercial Ektar copy), a 305mm Computar -- which is a plasmat process lens -- and a 360mm Symmar-MC (which is almost exactly the same size as today's Apo Symmar and Apo Rodagon). Of all those lenses, the Comptar was by far the smallest, lightest, and fit in the smallest shutter. In fact, of the lenses I own that cover 8x10, only the 180mm Protar V is smaller -- and *that* is an f/18 lens in a Supermatic. -- Thor Lancelot Simon But as he knew no bad language, he had called him all the names of common objects that he could think of, and had screamed: "You lamp! You towel! You plate!" and so on. --Sigmund Freud |
#4
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Kirk Fry wrote (in part):
There are two main problems with process lenses: 1) they are usually huge and heavy (G clarons are an exception) Why would that be? They are usually 4 element four group symmetrical (or very nearly) air spaced lenses with maximum aperture f/9. I would expect them to be smaller and lighter than a normal Plasmat f/5.6 of the same focal length. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 10:15:00 up 28 days, 13:09, 4 users, load average: 4.25, 4.23, 4.23 |
#5
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Jean-David Beyer wrote in message ...
Kirk Fry wrote (in part): There are two main problems with process lenses: 1) they are usually huge and heavy (G clarons are an exception) Why would that be? They are usually 4 element four group symmetrical (or very nearly) air spaced lenses with maximum aperture f/9. I would expect them to be smaller and lighter than a normal Plasmat f/5.6 of the same focal length. You're kidding, at least about lens design, aren't you? I just took inventory of the process lenses I own. 6/2 double anastigmat: 240/9 G-Claron. Don't thump me about this lens, that's what Schneider says it is and a count of reflections agrees. Current G-Clarons are 6/4 Plasmats but older ones are Dagor clones. Tessar: 6"/9 Cooke Copying lens, tiny; 10.16"/9 Taylor Hobson Copying lens, very small; 30 cm/9 Cooke Apotal, big enough to see. Dialyte: 14"/10 Wray Apo-Process Lustrar Ser. II, large; 600/9 Apo Ronar, huge, weighs about 8 pounds. Four element double Gauss: 260/10 Process Nikkor, enormous. Sort of Heliar (5/3, anyway): 180/10 and 360/10 Boyer Apo Saphirs, both small. More complex: 210/9 Konica Hexanon GRII, this lens is not a 6/4 Plasmat. I appreciate that many Apo Artars and Apo Ronars, both dialyte types, come to market and that some of my lenses are less common. Still and all, it isn't safe to generalize about the category quite as broadly as you did. Cheers, Dan |
#6
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Jean-David Beyer wrote in message ...
Kirk Fry wrote (in part): There are two main problems with process lenses: 1) they are usually huge and heavy (G clarons are an exception) Why would that be? They are usually 4 element four group symmetrical (or very nearly) air spaced lenses with maximum aperture f/9. I would expect them to be smaller and lighter than a normal Plasmat f/5.6 of the same focal length. You're kidding, at least about lens design, aren't you? I just took inventory of the process lenses I own. 6/2 double anastigmat: 240/9 G-Claron. Don't thump me about this lens, that's what Schneider says it is and a count of reflections agrees. Current G-Clarons are 6/4 Plasmats but older ones are Dagor clones. Tessar: 6"/9 Cooke Copying lens, tiny; 10.16"/9 Taylor Hobson Copying lens, very small; 30 cm/9 Cooke Apotal, big enough to see. Dialyte: 14"/10 Wray Apo-Process Lustrar Ser. II, large; 600/9 Apo Ronar, huge, weighs about 8 pounds. Four element double Gauss: 260/10 Process Nikkor, enormous. Sort of Heliar (5/3, anyway): 180/10 and 360/10 Boyer Apo Saphirs, both small. More complex: 210/9 Konica Hexanon GRII, this lens is not a 6/4 Plasmat. I appreciate that many Apo Artars and Apo Ronars, both dialyte types, come to market and that some of my lenses are less common. Still and all, it isn't safe to generalize about the category quite as broadly as you did. Cheers, Dan |
#7
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In article ,
Dan Fromm wrote: I appreciate that many Apo Artars and Apo Ronars, both dialyte types, come to market and that some of my lenses are less common. Still and all, it isn't safe to generalize about the category quite as broadly as you did. Nonetheless, the generalization that _does_ seem safe, to me at least and I suspect to many others, is that for a lens of the same focal length, a modern fast Plasmat is about as _large_ a lens as you're going to get -- leaving older, lower-aperture lenses, especially f/9 or f/11 process lenses of any design, much smaller and lighter. Earlier in this thread we had a comment about the size and weight of a 1000mm Artar. This left me scratching my head wondering if the person who wrote that had ever seen a 1000mm or even a 600mm "taking" lens, whether a modern Plasmat or even an older Tessar type; either is _much_, _much_ larger and heavier than a 1m Artar is. -- Thor Lancelot Simon But as he knew no bad language, he had called him all the names of common objects that he could think of, and had screamed: "You lamp! You towel! You plate!" and so on. --Sigmund Freud |
#8
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In article ,
Dan Fromm wrote: I appreciate that many Apo Artars and Apo Ronars, both dialyte types, come to market and that some of my lenses are less common. Still and all, it isn't safe to generalize about the category quite as broadly as you did. Nonetheless, the generalization that _does_ seem safe, to me at least and I suspect to many others, is that for a lens of the same focal length, a modern fast Plasmat is about as _large_ a lens as you're going to get -- leaving older, lower-aperture lenses, especially f/9 or f/11 process lenses of any design, much smaller and lighter. Earlier in this thread we had a comment about the size and weight of a 1000mm Artar. This left me scratching my head wondering if the person who wrote that had ever seen a 1000mm or even a 600mm "taking" lens, whether a modern Plasmat or even an older Tessar type; either is _much_, _much_ larger and heavier than a 1m Artar is. -- Thor Lancelot Simon But as he knew no bad language, he had called him all the names of common objects that he could think of, and had screamed: "You lamp! You towel! You plate!" and so on. --Sigmund Freud |
#9
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Folks,
I agree it is not good to over generalize and I may have done that, BUT I will stand on the generally huge part (obviously there are exceptions as were pointed out). Let's start with one of the most commonly availble process lens out there, a 19in Goerz red dot APO Artar, a super duper optical performer. Almost always found in barrel (the in shutter ones were special and cost real money). The one I have weighs a bunch, not because of the glass but because it is mounted in a heavy brass barrel (Goerz didn't discover aluminum until way late just before they went bye bye). Then if you want it in a shutter you have pay $300 or $400 for a #3 copal shutter and get it mounted for another $400 (yes there is the Packard solution, another light weight, small affair, or there is the lens cap trick). So what is the compitition: A 450 M Nikkor in Compal #3, a bit smaller and lighter or a Fujinon C450 f12 I think in Copol #1, way lighter. So what about the 300 mm focal length. A 305 Apo Nikkor f9 copy lens is almost always for sale on E bay. Again very samll glass and huge heavy mount of brass. Again, very expensive to get mounted in a shutter. The compition; a 300mm M Nikkor in Copal #1 or Fujinon makes a C lens that is really small, also in 300mm focal length. So, do you every wonder why these originally very expesive lenses that are excellent optical preformers sell for pennies on the dollar on ebay? Let me stand on my original hypothesis, Huge and Heavy and not in Shutter. The ones in shutter and which are not huge and heavy are not cheap. Ya tend to get what you pay for. Have you noticed what 300mm G-Clarons (plasmats by the way) sell for? Why is that? And now let me close with the 300mm MC-Schneider f5.6 plasmat I own. This one makes a 305mmm f9 Nikkor copy lens look like a midget. They sell for pennies on the dollar compared to new prices, usually about 2X over what their copal 3 shutter is worth. Why do you suppose that is? Anyone with any sense using 4X5 bought a 300mm M Nikkor and how many folks are using 8X10 in the Studio any more? The huge and heavy part killed that lens too. In lenses, light weight and fast is good (along with a bunch of other stuff), process lenses never had to be carried anywhere so the light weight part was never even considered in the design. Kirk (Dan Fromm) wrote in message . com... Jean-David Beyer wrote in message ... Kirk Fry wrote (in part): There are two main problems with process lenses: 1) they are usually huge and heavy (G clarons are an exception) Why would that be? They are usually 4 element four group symmetrical (or very nearly) air spaced lenses with maximum aperture f/9. I would expect them to be smaller and lighter than a normal Plasmat f/5.6 of the same focal length. You're kidding, at least about lens design, aren't you? I just took inventory of the process lenses I own. 6/2 double anastigmat: 240/9 G-Claron. Don't thump me about this lens, that's what Schneider says it is and a count of reflections agrees. Current G-Clarons are 6/4 Plasmats but older ones are Dagor clones. Tessar: 6"/9 Cooke Copying lens, tiny; 10.16"/9 Taylor Hobson Copying lens, very small; 30 cm/9 Cooke Apotal, big enough to see. Dialyte: 14"/10 Wray Apo-Process Lustrar Ser. II, large; 600/9 Apo Ronar, huge, weighs about 8 pounds. Four element double Gauss: 260/10 Process Nikkor, enormous. Sort of Heliar (5/3, anyway): 180/10 and 360/10 Boyer Apo Saphirs, both small. More complex: 210/9 Konica Hexanon GRII, this lens is not a 6/4 Plasmat. I appreciate that many Apo Artars and Apo Ronars, both dialyte types, come to market and that some of my lenses are less common. Still and all, it isn't safe to generalize about the category quite as broadly as you did. Cheers, Dan |
#10
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Folks,
I agree it is not good to over generalize and I may have done that, BUT I will stand on the generally huge part (obviously there are exceptions as were pointed out). Let's start with one of the most commonly availble process lens out there, a 19in Goerz red dot APO Artar, a super duper optical performer. Almost always found in barrel (the in shutter ones were special and cost real money). The one I have weighs a bunch, not because of the glass but because it is mounted in a heavy brass barrel (Goerz didn't discover aluminum until way late just before they went bye bye). Then if you want it in a shutter you have pay $300 or $400 for a #3 copal shutter and get it mounted for another $400 (yes there is the Packard solution, another light weight, small affair, or there is the lens cap trick). So what is the compitition: A 450 M Nikkor in Compal #3, a bit smaller and lighter or a Fujinon C450 f12 I think in Copol #1, way lighter. So what about the 300 mm focal length. A 305 Apo Nikkor f9 copy lens is almost always for sale on E bay. Again very samll glass and huge heavy mount of brass. Again, very expensive to get mounted in a shutter. The compition; a 300mm M Nikkor in Copal #1 or Fujinon makes a C lens that is really small, also in 300mm focal length. So, do you every wonder why these originally very expesive lenses that are excellent optical preformers sell for pennies on the dollar on ebay? Let me stand on my original hypothesis, Huge and Heavy and not in Shutter. The ones in shutter and which are not huge and heavy are not cheap. Ya tend to get what you pay for. Have you noticed what 300mm G-Clarons (plasmats by the way) sell for? Why is that? And now let me close with the 300mm MC-Schneider f5.6 plasmat I own. This one makes a 305mmm f9 Nikkor copy lens look like a midget. They sell for pennies on the dollar compared to new prices, usually about 2X over what their copal 3 shutter is worth. Why do you suppose that is? Anyone with any sense using 4X5 bought a 300mm M Nikkor and how many folks are using 8X10 in the Studio any more? The huge and heavy part killed that lens too. In lenses, light weight and fast is good (along with a bunch of other stuff), process lenses never had to be carried anywhere so the light weight part was never even considered in the design. Kirk (Dan Fromm) wrote in message . com... Jean-David Beyer wrote in message ... Kirk Fry wrote (in part): There are two main problems with process lenses: 1) they are usually huge and heavy (G clarons are an exception) Why would that be? They are usually 4 element four group symmetrical (or very nearly) air spaced lenses with maximum aperture f/9. I would expect them to be smaller and lighter than a normal Plasmat f/5.6 of the same focal length. You're kidding, at least about lens design, aren't you? I just took inventory of the process lenses I own. 6/2 double anastigmat: 240/9 G-Claron. Don't thump me about this lens, that's what Schneider says it is and a count of reflections agrees. Current G-Clarons are 6/4 Plasmats but older ones are Dagor clones. Tessar: 6"/9 Cooke Copying lens, tiny; 10.16"/9 Taylor Hobson Copying lens, very small; 30 cm/9 Cooke Apotal, big enough to see. Dialyte: 14"/10 Wray Apo-Process Lustrar Ser. II, large; 600/9 Apo Ronar, huge, weighs about 8 pounds. Four element double Gauss: 260/10 Process Nikkor, enormous. Sort of Heliar (5/3, anyway): 180/10 and 360/10 Boyer Apo Saphirs, both small. More complex: 210/9 Konica Hexanon GRII, this lens is not a 6/4 Plasmat. I appreciate that many Apo Artars and Apo Ronars, both dialyte types, come to market and that some of my lenses are less common. Still and all, it isn't safe to generalize about the category quite as broadly as you did. Cheers, Dan |
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