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04-24-2010, 07:37 PM   #1
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What exactly makes a lens a "MACRO"?

I know what "macro" photography is in general terms: close-up shots where the subject is captured in "life size" or at some magnification factor greater than 1:1. What I don't quite follow is what lens characteristics qualify it to be called a "Macro" lens? With my previous (all point & shoot) digital cameras, the macro mode allowed them to focus at ridiculously close distances (e.g., my Konica-Minolta Z5 could focus as close as about 2" from the subject in good light).

As an example, I have what I believe is a Soligor (the lens itself doesn't have a name on it, but the matching case does) 135mm F2.8 that's got MACRO engraved on the front bezel:



It seems to take fairly good pictures (as good as my limited manual focusing skills allow), even in not-so-great light, but can't focus on anything closer than about 4-5 feet away.



The real question is that I don't quite understand what makes it a Macro? Can anyone explain this to a neophyte like me?

04-24-2010, 08:17 PM   #2
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That isn't a macro lens in any way. In some cases I think that some manufacturers are basically saying Macro on their lenses, to hopefully sucker more people into buying them.
In other cases they can focus a little closer than a sister lens.

Just so you know, I actually saw this fellows muscles tense up as he saw my lens getting closer and closer.

I was less than 2 inches away, using my DSLR.

So the close focus isn't limited to point & shoot's.
04-24-2010, 08:19 PM   #3
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What makes it a macro is that Soligor figured they'd sell more of them if they put that word there. You're not missing anything - it's no macro lens, not even close. But it's pretty common for manufacturers to abuse the word into meaningless. I suppose maybe this lens focuses marginally closer than other 135's available at the time? Or maybe it was originally sold with a match close-up filter tha allowed it to focus closer?
04-24-2010, 08:30 PM   #4
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In addition to closer focusing, a macro lens is "flat field" i.e. well corrected for barrel distortion edge-to-edge of frame, has minimal CA, and has high resolution and high contrast.

Is the Soligor a macro lens? Without any documentation, any comments would be mere guesses...

04-24-2010, 08:58 PM   #5
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Well, we can see it isn't anywhere even remotely close to 1:1. No guessing required there.
04-24-2010, 11:19 PM   #6
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and only a handful of macro lenses go to 1:1 without help of extension tube or TC. Guess we need another definition of "macro" than 1:1? If we know the closest focus distance of the Soligor (OP wrote 4-5'), the magnification at that distance can be calculated. For example, the M42 135mm Takumars only minimum focus to 1.5m/5', giving 1:8.9 (0.112x), but they are not macro lenses because not flat-field.
04-24-2010, 11:53 PM   #7
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QuoteOriginally posted by wedge Quote
What I don't quite follow is what lens characteristics qualify it to be called a "Macro" lens?
Most people, at least according to Popular Photography Magazine, agree that a macro lens is a lens that can focus to half life size (1:2 magnification ratio): image on film/sensor is at least half size of the real object.
04-25-2010, 01:31 AM   #8
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Wedge,

As Mark said a lot of makers used to slap the word “macro” on their lenses for marketing purposes. As a result “macro” as a photographic term became almost meaningless and muddied over time.

Back in the day (1980s) when I got my first SLR a macro lens was described as a lens designed to give sharp, flat-field images at close range and also to work well as a normal camera lens. Then as now most of them were in the 50 to 100mm range with the odd, very expensive, 180 to 200mm. Most macro lenses at that time would focuses from infinity to about 1:2 reproduction or half-life size. In this sense the term “macro” is a total misnomer. As I understand the term a “true macro” focuses down to 1:1 reproduction without extension tubes. Greater magnification can only be achieved by reversing some lenses or using extension tubes or bellows units.

My original macro lens was a SMC Pentax M 50/4 unit. I thought in my naiveté that this would give me 1:1. Duhhh – disappointment shortly followed. It remains one of my sharpest lenses and is the real sleeper in the M series line up in my opinion. Feeling the need to be further from the subject I later got the much more expensive Pentax A 100/2.8 macro which does give 1:1 reproduction without extension. I have a bellows unit should I feel the need to get really up close.

I can’t speak to the quality of the various “macro” zooms out there but virtually any macro lens (50mm, 100mm or longer) from a reputable maker such as Pentax is likely to be a very good to outstanding performer. As a result these lenses always carry a correspondingly higher price. In this case you do get what you pay for.

Tom G


Last edited by 8540tomg; 04-25-2010 at 08:27 AM. Reason: typo
04-25-2010, 10:09 AM   #9
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QuoteOriginally posted by 8540tomg Quote
... a lot of makers used to slap the word “macro” on their lenses for marketing purposes. ...
Not picking on you in particular. This is for anybody who says that. Please show us some documentation!
04-25-2010, 10:27 AM   #10
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Generally speaking, Pentax has never put the macro label on any lens with less than 1:2 (half of life size) ratio. It does get applied to some good zooms by Tammy etc that get labeled as macro as well. I personally use 1:2 as my lower threshold for closeup lenses and 1:1 and greater as macro.


Edit: I have a Sears PK/R 135mm lens that has dedicated positions under Macro that are marked as 1:7, 1:6 and 1:5 and a Sears 80-200mm zoom PK/R that has a dedicated macro setting labeled as 1:5. I consider these closeup settings, but at least they have the ratio accurately labeled.
04-25-2010, 01:40 PM   #11
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QuoteOriginally posted by rhodopsin Quote
Not picking on you in particular. This is for anybody who says that. Please show us some documentation!
The above lens is one example. Other common examples are the Sigma 18-50, Sigma 24-70, Tamron 18-200, Tamron 18-200, etc - do I really need to continue? None of these even get close to 1:2.
04-25-2010, 01:45 PM   #12
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QuoteOriginally posted by rhodopsin Quote
and only a handful of macro lenses go to 1:1 without help of extension tube or TC.
A handful? As far as I know, every single macro prime currently on the market from Pentax, Canon, Nikon, Sigma, Tamron, or Tokina does. But indeed, getting all the way to 1:1 is not necessarily required to be able to legitimately call a lens macro. But the lens in question appears to be, as I said, *nowhere near* that. 1:1 would mean you could focus close close enough to fill viewfinder with an object only one inch wide. Unless that person's head is the size of a strawberry, we're probably at least 10 times worse than that.

QuoteQuote:
For example, the M42 135mm Takumars only minimum focus to 1.5m/5', giving 1:8.9 (0.112x), but they are not macro lenses because not flat-field.
And because they are only 1:8.9! Doesn't matter how flat the field is if they can't get anywhere even *close* to 1:1.
04-25-2010, 02:40 PM   #13
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In very broad terms, normal pictorial lenses will get to around a 1:10 reproduction ration at closest focus.
Macro lenses used to be considered as lenses that would focus down to 1:2 or closer, but manufacturers started hanging the term "Macro" onto zoom lenses that were getting to around 1:4.
So, while by modern standards, a lens that gets to around 1:4 would be considered to be a macro by many people, technically, closer than that would be technically more accurate.
04-25-2010, 03:00 PM   #14
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there are two aspects to macro, one is the ability to close focus, which has mutated from 1:1 to 1:2 to 1:4 and has been beaten to death in the thread.

I will point out however, that internal focusing macros, while achieving 1:1 reproduction, do not do so at their native focal length. most if not all are internal focusing and the focusing causes a reduction in focal length as you focus. If you check for example a 100mm macro, I am willing to bet that you do not achieve 1:1 when focused to 8 inches, but something less.

The second thing that is important about macro lenses is they are designed to be flat field lenses, because one of the uses of a macro is as a copy lens. therefore the opticla design is not the same as a standard lens at the same focal length
04-25-2010, 04:13 PM   #15
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QuoteOriginally posted by 8540tomg Quote
... a lot of makers used to slap the word “macro” on their lenses for marketing purposes. ...
QuoteOriginally posted by rhodopsin Quote
Not picking on you in particular. This is for anybody who says that. Please show us some documentation!
QuoteOriginally posted by Marc Sabatella Quote
The above lens is one example. Other common examples are the Sigma 18-50, Sigma 24-70, Tamron 18-200, Tamron 18-200, etc - do I really need to continue? None of these even get close to 1:2.
Plenty of examples, yes. What I'm looking for is contemporary photographer outcry such as letters to editors and/or photo magazine articles that expose this use of "Macro" label by manufacturers as false advertising.

QuoteOriginally posted by rhodopsin Quote
and only a handful of macro lenses go to 1:1 without help of extension tube or TC.
QuoteOriginally posted by Marc Sabatella Quote
A handful? As far as I know, every single macro prime currently on the market from Pentax, Canon, Nikon, Sigma, Tamron, or Tokina does.
The context was pre-AF era manual focus lenses. Of course there are more modern examples.

QuoteOriginally posted by Marc Sabatella Quote
But indeed, getting all the way to 1:1 is not necessarily required to be able to legitimately call a lens macro. But the lens in question appears to be, as I said, *nowhere near* that. 1:1 would mean you could focus close close enough to fill viewfinder with an object only one inch wide. Unless that person's head is the size of a strawberry, we're probably at least 10 times worse than that.
QuoteOriginally posted by rhodopsin Quote
For example, the M42 135mm Takumars only minimum focus to 1.5m/5', giving 1:8.9 (0.112x), but they are not macro lenses because not flat-field.
QuoteOriginally posted by Marc Sabatella Quote
And because they are only 1:8.9! Doesn't matter how flat the field is if they can't get anywhere even *close* to 1:1.
Ah, now we're getting somewhere.

My speculative guess hinges on coincidence of computer-aided design improvements and beginning of the use of "Macro" on product labels:

Computer-aided design lenses of the pre-AF-era marketed with Macro label are well enough corrected for barrel distortion and CA, especially CA, to actually enable them to be used with tubes or bellows to achieve 1:1 resolution without the image breaking apart entirely. Some lenses actually have macro mode switching that moves elements/groups into different positions enabling closer focus and higher magnifications.
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