Macro on zoom lensesgreenspun.com : LUSENET : Canon FD : One Thread
Hello. There are several zoom lenses that offer 'macro' capabilities which allow the user to get closer to the object than the normal setting. My question is, "how different is 'macro' from the normal range from the mechanical point of view?" It seems like that "macro" on these lenses simply lets you rotate focus ring (or zoom ring) further so that you go beyond the minimum focus distance and nothing more. Then why wouldn't the manufacturers mark the lenses to just have that much normal range? For example my lense has 1.5-oo normal range and probably something like 0.6-1.5 macro range at the widest angle. Then why can't they specify it as just 0.6-oo if there is no special distinction between "normal" and "macro" in terms of mechanical construction?
-- Pil Joo (email@example.com), June 09, 2000
So, you've noticed the difference between a true close-focusing zoom design and the gimmicky "macro feature." First, most macrophiles consider a minimum of 1:2 magnification necessary for a lens to qualify as a macro. Few zooms do better than 1:3.
There's no simple answer to your questions and, frankly, I'm no expert on lens design. But the essential differences have to do with how the various elements in the zoom move in relation to one another.
In the good old days lens makers knew that it was prohibitively expensive to build a true close focusing zoom. So many of them opted to build varifocals, a design that requires refocusing as the focal length is changed. (In fact, some of today's autofocus zooms are varifocals, but nobody notices because of the AF feature.) The advantage is that while the user must refocus (only slightly), few optical compromises are made.
My Vivitar Series 1 28-90mm f/2.8-3.5 is one such design. It focuses reasonably closely at all focal lengths, but achieves maximum magnification (around 1:3, but I haven't measured it) at 28mm, which makes for some odd looking close ups thanks to wide angle barrel distortion. Still, it's an excellent lens overall, sharp at the center at all focal lengths and focusing ranges, and sharp out to the edges everywhere beyond 50mm at minimum focusing range.
To put it simply, it's the best zoom I've ever owned in terms of optical quality and value. There are better zooms, but not at this price.
The next step, also common with some Vivitar designs, was the zoom that was close focusing only at one focal length. The best bargain among these was a 70-210mm f/4.5 - not the fancy, expensive Series 1 - that achieved 1:2 magnification at 210mm. Pretty good, because you didn't have to get so close to those bitey, stingy, irritable bugs and critters. At all other focal lengths it would focus to 6 feet or so. Besides being a nice, compact design, you can sometimes find these zooms for $50 or less.
Finally was the ghastly design incorporated by even reputable lens makers like Canon and Tamron, in which a separate ring was twisted, or a button was pressed to permit focus ring overtravel, to achieve "macro" focusing at the minimum focal length, 70-75mm. These designs shifted an element inside the lens to permit close focusing - but not true macro - within a limited range. To regain infinity focusing you'd have to press that button and disengage the macro "feature."
Frankly, these designs stink. I've owned both the Canon and Tamron zooms in the 70-210mm range with this macro feature and while the Tamron was a much more sturdily built lens, it still stunk close up. Both were okay beyond 10 feet and out to infinity - even pretty good at some ranges, focal lengths and apertures. But macro? Gimme a break. Coma, spherical distortion, you name it, they got it.
Ironically, the macro magnification of these designs - roughly 1:4 - could be duplicated by simply focusing to the minimum distance at 200mm. No need for the "special macro feature." And the results were the same. They stunk. Few telephotos are at their best focused closer than 10 feet.
A variation of the close focusing design is my Canon FD 100-300mm f/5.6 non-L series zoom. It close focuses from 100-200mm, achieving maximum magnification at 200mm, and is quite good. It's a delightful, if oversized, portrait lens. Beyond 200mm it's good only when stopped down, otherwise it suffers from poor contrast and resolution.
In short, skip any zoom lens with a special macro ring, pushbutton or doodad that must be set to get close ups. Go for a varifocal or a true close focusing design, especially one which close focuses at the longest focal length.
But for the best bargain in macro doodads, get a Vivitar 2x macro focusing teleconverter. It's a top quality teleconverter and achieves 1:1 magnification. Combine it with a 50mm f/1.4 normal lens and you'll have a very good quality 100mm f/2.8 portrait lens that focuses 1:1 while giving you comfortable distance from the bitey, stingy critters.
-- Lex Jenkins (firstname.lastname@example.org), June 10, 2000.