I'm curious as to what macro mode actually does in cameras such as mine. Is it perhaps simply biasing the auto-focus, or is something else mechanical happening in the lens?
I have outlined the two main areas that Macro mode affects in general terms below under "Background".
Following is a general comment on macro mode and how this may affect your images and what to look for to see it it has had any effect.
I have copied DPReview comments on the DMC-FZ20 macro facility - from here at the end of this post. It's surprisingly uninformative re what actually does happen to achieve the effect and what the limitations are, but does discuss results.
The most important answer to your questions is that
- if the photo is in focus and correctly exposed then it will be acceptable regardless of macro mode having been used.
Setting the camera to macro mode may have affected certain camera settings but these will have been in the acceptable range if the result is acceptable. There will be no "hidden affects" which are not obvious from a general inspection.
The two factors that are most liable to be noticeable (but still not "bad" is that the aperture may have been set to achieve largest possible depth of field (see below) and shutter speed may have been set to a specific value or range of values (also see below).
Some cameras when in Macro mode will not be able to focus to infinity - this may be the case with your camera and you may have been lucky wityh subject distance, or it may not apply in your case.
Wikipedias 'definition' is useful but not hard and fast
Macrophotography is extreme close-up photography, usually of very small subjects, in which the size of the subject in the photograph is greater than life size.
1 Classically a macrophotograph is one in which the size of the subject on the negative or image sensor is life size or greater.
2 However in modern use it refers to a finished photograph of a subject at greater than life size.
 The ratio of the subject size on the film plane (or sensor plane) to the actual subject size is known as the reproduction ratio. Likewise, a macro lens is classically a lens capable of reproduction ratios greater than 1:1, although it often refers to any lens with a large reproduction ratio, despite rarely exceeding 1:1.
(1) The most fundamental requirement which applies to (almost) any "Macro mode" settings, is to arrange the lens elements so that the minimum focus distance is "low enough" to allow a "usefully small" object to appear "large enough" in the image.
If the camera cannot achieve this is "normal mode" the manufacturer may move or insert lens elements to reduce the minimum focusing distance of the lens. The resultant arrangement may or may not allow focusing at infinity. It is possible that this lens arrangement makes results less acceptable distortioin wise at certain apertures but if so you would expect the manufacturer to also constrain the available range to suit.
I used the wonderfully vague low enough / usefully small / large enough on purpose. There is no absolute definition of where the boundaries are in each case and generally if a camera has a "mode" that improves macro (= "small object") photography then it is probably a compromise camera and a compromise macro arrangement. That is not meant to denigrate such cameras - simply to note that adding the facility to the camera as a whole is not the norm with top end cameras where the lens will be removable* and the macro capability is a lens function.
I say "almost any macro mode setting" as I have seen lenses labelled as having macro capability which do indeed allow small objects to be imaged at large size BUT have an extremely large minimum focus distance. I recall a 70-300mm "macro" zoom I owned which had a minimum focusing distance of about 3 metres / 10 feet but which was in fact still useful for photographing small objects.
(2) All that said, there is a separate related set of functionalities that a manufacturer may add. They may decide that to obtain an acceptable depth of field at small distances the aperture will be limited to smaller values or even the smallest available value (larger /f numbers). They may make decisions about white balance, shutter speed, ISO and more. Such decisions are specific to each manufacturer and even to each camera but will be aimed at optimising small object results.
SO your camera may be "good enough" with respect to 1. above that no action is needed to adjust the lens system to achieve closer minimum focus and all actions may be in the area covered by 2. In which case "macro mode" is usable to infinity. Trying this before you next need to use the feature 'in anger' would be wise.
I once owned (and still do - somewhere) a Sony Mavica camera with 640 x 480 maximum image size and floppy diskette storage. File size was typically a massive 50 -100 kB/photo. The Mavica had the ability to focus on the inside of the lens cap if you could work out how to get light in there !. This was without any advertising of a "macro mode". Very useful.
- A very few "top end" camera have fixed non interchangeable lenses, but these are usually niche specialist cameras and/or produced to address an enthusiast market - eg the APSC sensor rangefinder cameras being produced by several manufacturers with appearances and "optical feel" similar to those of the classic 35mm film rangefinders.
DPReview comments on DMC FZ-20 macrofocus capability:
From here (same web page as above).
The FZ20 has a rather unusual approach to macro focusing. There is no macro button, and in A, S and M modes the full focus range (from 5cm to infinity at the wide end of the zoom) is available all the time, whereas in P (fully automatic) mode you can only focus down to 30cm; presumably to speed up focusing in everyday snap shooting situations.
Then there is a separate macro mode (on the main mode dial) that offers fully automatic exposure - just like the P mode - but focuses down to 5cm (again at the wide end of the zoom).
As is common in zoom cameras the FZ20's macro capabilities are much better at the wide end of the zoom (5cm subject distance capturing an area around 43mm across), and there is inevitably some barrel distortion (and some color fringing). At the full 12x zoom position the close focus ability is less impressive - a subject distance of 200cm capturing an area around 12cm across, but there is no distortion at all.
Left hand photo above: Wide macro - 43 x 32 mm coverage
59 px/mm (1488 px/in)
Corner softness: Average
Equiv. focal length: 36 mm
Right hand photo above: Tele macro - 116 x 87 mm coverage
22 px/mm (557 px/in)
Distortion: Very low
Equiv. focal length: 432 mm