Now, however, macro extension rings with electronic contacts are available at a low price. They are marketed as Meike, Skyblue, Neewer, and probably more names, and one pack includes two rings: One 10mm thick, and one 16mm thick. My rings look like this:
They appear to be a cheaper copy of the Kenko macro rings which work in the same way.
The Sony NEX E-mount version of the macro rings is labelled "MK-S-AF3B". When separated, they look like this:
The first impression is that the macro rings look a bit cheap. The mounts appear to be some black nylon-like plastic, and the tubes are unexpectedly light. When mounting them on the camera, they fit somewhat looser than most lenses do. However, they still appear sturdy enough, and I am not worried using them with a large lens.
Since the rings transfer the electronic signals between the camera and lens, the camera can control the lens as usual. This means the focus, the aperture, power zoom, optical image stabilization (OSS), and so on.
The rings go between the camera and the lens. They mount on the camera just like any lens, and you can decide yourself if you want to use only one of the rings, or both, with extensions of 10mm, 16mm and 26mm possible. As a general rule, you need more extension for longer lenses. So, if you use a wide angle lens, use the smallest extension, 10mm. For a tele lens, use 26mm.
While these rings will fit any lens, they don't make sense for the widest lenses. For example, if you put the 10mm extension ring between the camera and the Yasuhara Madoka 180 circular fisheye lens, you will find that pretty nothing is in focus. But the extension ring is hardly needed for that lens. It can focus down to objects nearly touching the front lens element.
How to best use these rings depend on what you want to photograph. But generally speaking, if you want a large working distance, the distance between the subject and the front lens element, then go for a long lens. You can use a tele zoom lens in the longest position, for example. This can be good for photographing insects which are shy and tend to scram if you put a lens in their face.
On the other hand, if you photograph static items at a close range, then you can use a normal kit zoom or a short prime lens, but with a shorter extension.
In theory, you get the most magnification by combining a short lens with a long extension. However, the focus distance becomes short as well, in many cases too short to be usable.
In the following video, I demonstrate how to mount the rings between the Sony NEX-3N camera and the Sony NEX 16-50mm f/3.5-5.6 power zoom lens. There is also a demonstration of how the autofocus works:
From the video, you may notice that I have put a 40.5mm to 52mm step up ring on the front of the lens. This is to act as a small lens hood, to protect the front lens element against objects touching it accidentally. If you want to use this solution, then you also need a 52mm front lens cap.
Magnification and working distance
By combining various lenses with the macro rings, you can achieve various magnifications and focus distances. Here's a table that sums up some of the possibilities:
|Lens||Focal length||Extension||Working distance||Magnification|
|Sony NEX 16-50mm f/3.5-5.6||50mm||None||0.21m-∞||Max 1:3.8|
|Sony NEX 16-50mm f/3.5-5.6||50mm||16mm||0.10m-0.20m||1:1.6-1:3.3|
|Sony NEX 16-50mm f/3.5-5.6||50mm||26mm||0.08m-0.13m||1:1.1-1:2.0|
How to read this table: Take the Sony NEX 16-50mm f/3.5-5.6 at 50mm with 26mm extension as an example. Using this combination, you can only focus from 0.08m-0.13m (measured from the tip of the lens to the subject), which is a quite narrow range. Within this range, you can use autofocus.
Still using the same lens and extension combination, you can achieve the largest magnification (at the closest focus distance) of 1:1.1. This corresponds to photographing an object 1.1 times the size of the sensor, i.e., 26mm x 17mm.
All these images were taken on freehand, without the support of a tripod. I used the centre area AF mode, to avoid having the camera focus on the background.
Sony NEX 16-50mm f/3.5-5.6 at 50mm, f/16, 1/60s, ISO 800, and 26mm macro extension:
and a 100% crop:
Sony NEX 16-50mm f/3.5-5.6 at 50mm, f/11, 1/160s, ISO 200, and 16mm macro extension:
and a 100% crop:
It is even possible to use the built in flash of the Sony NEX-3N camera as illumination. The following two images were taken at 50mm, f/14, 1/60s, ISO 800, 26mm macro extension, and using the flash for illumination:
The built in flash is of course not ideal for macro use. You would prefer to have a bigger flash, with a diffuser, to spread the light out more evenly. But as an "emergency" light source, it is quite adequate.
The Meike/Skyblue/Neewer macro rings, are cheap, light, and appear solidly made. They are easy to bring along, to have a macro option easily available. They can be combined with almost any lens, and enable autofocus, aperture operation, and EXIF information. Ideally, you can combine them with a tele zoom lens, for example the Sony NEX 55-210mm f4.5-5.6, but even a basic kit zoom lens will do, but preferably in the long end of the zoom range.
The macro rings are a good addition to the equipment list for anyone who is curious about macro photography. For protection, you could add a rear lens cap and a body cap, which you can put on the macro rings when not in use.
The rings are made of mostly plastic. I'm fine with that. If you prefer a metal alternative, there are more pricey alternatives available with metal mounts.