[stein]

Apologies for asking something that for experienced might be "oh, so obvious"... but... what is the difference between lenses labeled as "macro" and others that are not? Pentax SMC D FA 50mm f/2.8 Macro is a Macro lens, while Pentax SMC DA 50mm f1.8 is not, and I could make a longish list of lenses that are "similar", but in fact, completely different... I need some explanation to cure my curiosity (and if possible, without killing any cats in the process)

[Bronmar]

Macro lens is capable of reproduction ratios 1:1.

[stein]

Ok, I figure that much, however, how can I tell if a lens is in fact capable of doing that? So far, unless the manufacturer clearly states that the lens is a macro lens, I'm clueless... What I don't really understand is how can one 50mm lens come with significantly more magnification than the other? (The magnification factor of the DA50mm F1.8 is 1:5.87) What I mean, I don't understand how this works and it seems that my searching on the web didn't help a lot.

[pathdoc]

Macro offers two advantages - one is to get incredibly close (as in physically, sometimes practically ramming the front of the lens up the nose of your subject). The other is the 1:1 reproduction ratio detailed above. What this meant in the film days is that the image as imprinted on the film was the same size as the actual object, i.e the image on the film of a 30mm object would actually measure 30mm, and that meant impressive detail in larger prints.

Quite a lot of lenses labelled "macro", particularly zoom lenses from the 80s and 90s, are in fact merely close-focus, offering reproduction ratios of no better than 1:3 or 1:4 (i.e. a thirty millimetre object would be measurable as ten millimetres if the image were taken on film). Even so, they were and are valued for their ability to get in really close, which offers advantages if you want certain compositions, thin depth of field, and/or the background smashed into a creamy out-of-focus blur.

So far, unless the manufacturer clearly states that the lens is a macro lens, I'm clueless...

Unless the manufacturer clearly states that the lens is a macro lens, IT ISN'T.

Some lenses are capable of focusing to a closer minimum distance than others, and depending on the age of said lens (whether it's still in production) and how well know it is, you may be able to look this up and determine this for yourself. If you want to use a non-macro lens for macro, you need to get into things like reversing rings, extension tubes and/or bellows, of which the extension tubes are probably your cheapest option. Google is your friend

[pacerr]

"Macro" is "macro" in the eyes of the marketing folks today. Generally, it 'implies' that the lens is capable of focusing somewhat closer than others of its kind - just how much closer to satisfy the label is debatable.

Your best resource is the manufacturer's specifications and/or the description provided in such resources as PF's excellent lens data base.

Pentax Lenses - Pentax Lens Reviews & Lens Database

Third-Party Lens Reviews

[D4rknezz]

Well,

A Macro lens is capable of larger reproduction ratios, not always 1:1, but 1:2, or some such.
The major difference you'll probably notice is that the DA 50mm f1.8 will refuse to focus when you get closer than 4 feet. Or something like that.
A macro lens will get you much, much closer. This is very useful when you are trying to focus on a tiny wedding ring, for example. You can get within 5 inch from your subject and still obtain focus.

[Not a Number]

Beginning in the 1980s lens makers began adding a "macro" function to zoom lenses. What this meant in reality usually was that these lenses had a minimum focus distance of under one meter and a magnification power of 1/6x to 1/3x.

The definition of macro changes from decade to decade or even writer to writer. Common definitions 1/10x to 1/2x (0.1 to 0.5) = close-up, 1/2x to 5x = macro, 5x - 20x extreme macro, 20x+ = microphotography. Again there are no standard definitions but most will agree 1x is macro.
.
True macro lenses are almost always prime lenses although there have been a few zooms with shift function to put them in a 1x mode.

[stein]

Thanks to all I was never looking at that piece of information (magnification factor) I also have a Sigma 28-300 and that one also has a magnification factor that excludes the lens from the macro club.
My wife is an optometrist and she measured a macro filter I have and it's +13 diopters which is quite a lot but as you probably all know, not the best thing if one wants a really good macro shot. It serves the purpose for now, but I'm looking at a macro lens in the near future so I would like to know more about the subject before I waste my money on the wrong thing.

[TER-OR]

What kind of subjects are you interested in? I have two macro lenses, a 100mm and a 28mm and they're both nice.

[commongrounder]

Another aspect of true prime macro lenses besides close focusing is their optical design is optimized for flat field imaging. This is to say they have excellent edge to edge, as well as overall, sharpness. This usually comes at a trade-off of a slower maximum aperture. Many macro primes do make good all purpose lenses, but will be f-2.8 max aperture or slower. True macros are good for reproducing flat subjects like artwork, etc. as well as getting close to bugs, etc.

[pacerr]

You may find this useful:

https://www.pentaxforums.com/forums/122-lens-clubs/143202-macro-any-means-necessary-club.html

[desertscape]

Macro lenses are designed differently from non-macro lenses, in that macro lenses are used at close distances and must be corrected for spherical aberration differently. Since rays emanate in a diverging fashion at close distance (vs parallel at infinity) spherical aberration is corrected for close distances. Non-macro lenses can be used for macro use but stopping down is necessary to reduce the residual spherical aberration at those distances. Stopping down also gives you enough DOF to shoot flat subjects.

[stein]

What kind of subjects are you interested in? I have two macro lenses, a 100mm and a 28mm and they're both nice.

My primary field of interest is hunting down all kinds of insects/bugs and noticing and noting the beauty of the flowers in the process
Making photos of coins and static objects is not so interesting (for me) because I most likely enjoy "hunting them" rather than just recording facts... I found some really cheap (50-65€, older models, though) lenses in Serbia but I'm not sure what I really want, thus, I ask silly questions
What I prefer is to keep the expense at a reasonable level and to get the "best for the money", regardless of the origin... Of course, it has to match my K-S1, otherwise it doesn't make much sense...

[Na Horuk]

Macro just means high magnification. This is a mixture of focal length and minimum focus distance. Non-macro lenses can only focus to a magnification of 1:7 or 1:5. Macro lenses go to at least 1:2 or, as most modern macro primes, go all the way to 1:1. Beyond that it is enlarger lenses. The magnification of your lens is always highest at its minimum focus distance.
Unfortunately, many brands have started to advertise some zoom lenses, which are not true macro since they only go to 1:4 or so, as "macro." This is because labeling them as "these allow slightly nearer minimum focus than most other lenses of this zoom range, which allows magnification levels of 1:4 instead of 1:5!" is a bit long-winded. But this often confuses people who want to understand what exactly is going on.

My primary field of interest is hunting down all kinds of insects/bugs and noticing and noting the beauty of the flowers in the process

Tamron 90mm, Sigma 105mm, or the awesome Pentax DFA 100mm macro. All of these can be found for very fair prices and deliver amazing image quality, much better than the kit lenses or pretty much any zoom lens. I would advise that if you want a macro lens, you avoid zoom lenses. Btw, there are plenty of threads about macro. One even compares the angle of view between different focal lengths at the same 1:1 magnification.

[TER-OR]

Most of the time for insects you need magnification to avoid spooking them. That means 100mm range most of the time. The Pentax 100mm line is great. Tamron makes a 90mm which is well regarded and Sigma makes a couple in the range as well. Often you'll want some extra light unless you're out in full sun, too, since you'll stop the lens down and try to keep your shutter speed fairly high.

For my field macro work I use the FA100mm lens. I did find trying to get very small bees the 28mm was actually better, I think the DOF I could get was greater.