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#1
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Why do only primes have macro
Why is that macro capability exists only in prime (as in fixed focal
length!!!) lenses? Other than primes, only a few cheap telephoto zoom lenses seem to have macro. In contrast, all P&S digicams have a macro feature and some like the Oly C-750 that I owned had a super macro too. - Siddhartha |
#2
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Siddhartha Jain wrote: Why is that macro capability exists only in prime (as in fixed focal length!!!) lenses? Other than primes, only a few cheap telephoto zoom lenses seem to have macro. In contrast, all P&S digicams have a macro feature and some like the Oly C-750 that I owned had a super macro too. - Siddhartha There used to be a lot of telephoto zoom lenses with macro capabilities. A friend of mine had a Vivitar Series One 70-210 lens with macro capability. Don't know if they're still around, since I haven't been doing much photography for years. |
#3
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There is a diff between Macro and Close focus but people confused it. Macro
in prime lens is true Macro i.e "flat field" whereas those Macro on cheap devices are actually "Close focus" and not "flat field". Flat field = centre to corners focuses are sharp without barrel or pincushion aberration. "Siddhartha Jain" wrote in message ups.com... Why is that macro capability exists only in prime (as in fixed focal length!!!) lenses? Other than primes, only a few cheap telephoto zoom lenses seem to have macro. In contrast, all P&S digicams have a macro feature and some like the Oly C-750 that I owned had a super macro too. - Siddhartha |
#4
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"Siddhartha Jain" wrote in message ups.com... Why is that macro capability exists only in prime (as in fixed focal length!!!) lenses? Other than primes, only a few cheap telephoto zoom lenses seem to have macro. That's funny my Minolta 35-70 and Tamron 28-200 both have macro settings - the former only at 70mm, but can get pretty close, the latter over the entire range, but not as close. OTOH my 50mm f1.4 does not have macro. In contrast, all P&S digicams have a macro feature and some like the Oly C-750 that I owned had a super macro too. - Siddhartha |
#5
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In article . com,
Siddhartha Jain writes Why is that macro capability exists only in prime (as in fixed focal length!!!) lenses? Other than primes, only a few cheap telephoto zoom lenses seem to have macro. In contrast, all P&S digicams have a macro feature and some like the Oly C-750 that I owned had a super macro too. - Siddhartha First, some terminology. Whatever the opinions of the "words mean whatever I want them to mean" school of thought, this is a highly technical area, and if you don't use the right terminology you will not find the answers in reputable sources. General photography uses magnifications of 0.1. "Close up photography" is the term applied to the range of magnifications 0.1 to 1.0. "Photomacrography" is the term applied to the range of magnification from 1.0 to a rather ill-defined upper limit, usually about 50.0 (i.e. where the image is 50 times the size of the object). If you try to look up under the name "macrophotography" you will not find what you want in rigorous text books, as that means something else. There are mostly good reasons for this division; the equipment is generally different, and the simplifications of optics equations that work in one area break down (become inaccurate) in others. If a lens designed for normal photography is set in a mount which allows it to extend further from the position for normal photography - i.e. to focus a lot closer - then unpleasant things happen to the image. Spherical aberration (SA) rises sharply, contrast decreases, and astigmatism, coma and field curvature become obtrusive. To design lenses which work well in the m = 1.0 region and beyond, manufacturers have to use different design criteria. Different basic designs are often used, and may be used "back to front", i.e. the reverse way to that used in normal photography. Floating elements are often used to keep SA under control as the focus point moves, and to control field flatness. Steps also may need to be taken to control geometric distortion. Also, even after all these measures, it is necessary to limit apertures to f/2.8 or similar to keep SA within reasonable limits. With all this, you can see that it would be quite difficult to do this with a zoom lens, which already starts out with an often compromised design, lots of elements, and several complex cams to move the various bits around. So far as I am aware, there is no conventional zoom lens which is a true macro. You will see from the above that even most of the dedicated macro lenses for 35mm and related format DSLRs, used alone, barely qualify for the term macro. There is a whole world of specialised macro lenses for use in the range m = 1.0 to m = 50.0 which is rarely mentioned in these groups. These rarely have their own focussing movements, but are designed for use on bellows, adapted microscopes or dedicated stands. In truth it is not what the focus mount does which defines the lens, it is how well it works optically at the required magnification. (In case anyone raises it, the floating elements in many macro lenses with focussing mounts for 35mm cameras will often alter the focal length appreciably, so they might be thought of as a kind of zoom, or at least vari-focal lens. This however seems pure sophistry. Also, there exists among the true macro lenses for the region well above m = 1.0 at least one variable magnification lens, the Zeiss Luminar 2.5 - 5.0x. A zoom it is not, in any accepted sense at least.) Many manufacturers take close focus in their zoom designs to the point where quality starts to be compromised, and limit the action to this point. Others, rather dubiously, extend them to the point where they should know better, where quality is materially compromised, and then call them "macro". Frankly, they should be sued under trade description legislation. If you want to learn more about photomacrography, there are several good books and at least one discussion site on the subject. David -- David Littlewood |
#6
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"Siddhartha Jain" wrote in message
ups.com... Why is that macro capability exists only in prime (as in fixed focal length!!!) lenses? Other than primes, only a few cheap telephoto zoom lenses seem to have macro. In contrast, all P&S digicams have a macro feature and some like the Oly C-750 that I owned had a super macro too. - Siddhartha My Nikon 24-85mm "D" lens has a macro mode focusing to 1:2. Norm |
#7
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In article ,
"Norm Dresner" wrote: has a macro mode focusing to 1:2 That's the point. one half life size is a close up not a macro ratio. Lifesize 1:1 or twice life size 2:1 are true macro ranges. A really good macro lens does not focus to infinity and probably requires a bellows to focus it. Most camera lenses that focus to infinity and then into what is marked "macro" or "micro" are simply lenses that focus rather close. Some examples of true macro lenses are Zeiss Luminars, Rodenstock Apo Rodagon D and Schneider M Componon lenses. All of these look either like microscope objectives (Luminars) or enlarging lenses (Apo Rodagon D and M Componon). None are any good at infinity and none will work as enlarging lenses. -- To reply no_ HPMarketing Corp. |
#8
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They have what the manufacturer calls "macro" settings but those aren't
macro at all, they're a sales pitch. Macro is 1:1 and larger, those lenses do 2:1 or worse at best. "R. Mark Clayton" wrote in message ... "Siddhartha Jain" wrote in message ups.com... Why is that macro capability exists only in prime (as in fixed focal length!!!) lenses? Other than primes, only a few cheap telephoto zoom lenses seem to have macro. That's funny my Minolta 35-70 and Tamron 28-200 both have macro settings - the former only at 70mm, but can get pretty close, the latter over the entire range, but not as close. OTOH my 50mm f1.4 does not have macro. In contrast, all P&S digicams have a macro feature and some like the Oly C-750 that I owned had a super macro too. - Siddhartha |
#9
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A really good macro lens does not focus to infinity and probably requires a bellows to focus it.
True that! When I got my 65mm MP-E Macro lens I thought I'd also be able to use it as a carry-around 65mm. Wrong. Maximum focusing distance is about 4" with this lens so the only landscape shots I've done with it are bug landscapes. http://www.pbase.com/bret/macro |
#10
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"Siddhartha Jain" wrote in message ups.com... Why is that macro capability exists only in prime (as in fixed focal length!!!) lenses? Other than primes, only a few cheap telephoto zoom lenses seem to have macro. Because it takes a lot of engineering to get a lens that will focus that closely and still cover a 35mm image. The telephoto zoom lenses tend to go down to 1/4 size which is much easier to accomplish that the full size one gets with the fixed focal length lenses In contrast, all P&S digicams have a macro feature and some like the Oly C-750 that I owned had a super macro too. Because it is easier to accomplish.. By the way, do these lenses yield a full size image (that is, is the image on the sensor the same size as the object)? If it isn't full size, then you are comparing apples to oranges. Of course, this statement does not mean that such a feature is worthless. I have made many a photograph with a lens that will only go down to 1/4 size. Jim - Siddhartha |
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