After receiving quite a lot of positive feedback on my macro photos (particularly the Ant), I decided to quickly write a short tutorial/review on the macro extension rings and particularly the setup I use for macro work.
In the past, I’ve been using the reversing ring with the standard 18-55 mm kit lens – you can find our review with sample shots here. This setup worked very well, but it had two major drawbacks. The first was the inability to change the aperture on demand without having to turn the lens over (that could of course be solved by buying some old full manual lens and using those…but I’ve also seen an electronic-controlled reversing ring). The second one was having the rear part of the lens exposed to dust and when put back on the camera the normal way, it would actually introduce a lot of dust to the sensor. Also, you need a different ring for different thread diameter.
The extension rings offer a bit more sophisticated solution. The first thing is you can use them with anything that has the same mount (Sony E in my case…) as the rings, from wide angles to telephoto lens (not all focal lengths are suitable for this though…we’ll get to that later). Secondly, the amount of dust that gets to the sensor is greatly reduced…corresponds to pretty much just changing the lens. The aperture changing problem but still persists. This one is not difficult to solve, as you can get an electronic extension ring, which, apart from aperture, also enables autofocus. You’ll however wreck your focus with the slightest movement of your camera, so the AF is not that much useful. In my setup, I use old legacy glass, that has the aperture control on the lens itself, so I got only the non-electronic version of the extension rings.
Let me talk about my setup at this place, as it gives a good glimpse into the useful focal lengths for this method. I use the simplest and cheapest rings available (bought from China wholesale…) in combination with Industar-69 28 mm f/2.8 lens with the L39 – NEX adapter. Thanks to the lens being pretty much “pancake”, this setup is quite compact, but powerful at the same time. It’s also quite cheap :D. The rings come with the lens mount, body mount and 3 different size threaded rings. You can compose them any length you want, starting with just the mounts connected and ending with all the rings at the same time.
As a regular lens, this Industar has it’s issues. In order to be useable, you need to spent some time mechanically fixing it to allow infinity focus and to be able to focus closer than about 80 centimetres. But in macro use, you don’t really need to worry about that, do you? Really, turning the focusing ring with the extension rings has a much significance as farting in a bubble bath. It’s easier to just move your camera that millimeter or two in order to get things in focus, so I usually just set the lens to it’s farthest focus (screw it down as far as it will go) and leave it there. The focusing distance with all the macro extensions comes to about 3 centimetres. With the shortest configuration of the extension rings, the focusing distance is about 6 centimetres. A common macro photography problem is that extremely shallow depth of field. it makes no difference if you have the aperture at 2.8 or 4, the DoF is just a couple of milimetres. I usually keep it at 4, to avoid too much fringing and softness (after all, this lens is about twice as old as me!). The real size of this setup as about as big as the NEX 18-55 mm kit lens fully extended, so it’s not too big (and not very heavy, weighting about 200 grams).
Now, what happens if we put a different focal lengths at the extension rings? Maybe I should have mentioned this earlier, but what offsetting the lens from the sensor actually does is compressing the minimal focusing distance. I though it might be really cool what it would do with my Samyang 12 mm f/2.0, that focuses as close as 20 centimetres. No. The focusing distance actually shrinks to the point, where the lens focuses on the dust on a front element. That’s usually not what you want. So then I put the 18-55 mm kit lens on the extension rings. At it’s shorter end, it’ similar to the Samyang – the focus is still too close and the lens block a lot of light, casting shadow on the subject. At it’s longer end, the focus is quite far away, but it doesn’t have that awesome ultra-macro feel to it. The focal length of about 35 milimetres seemed to be ideal, so I put on the 28 mm Industar. This gives a balanced macro performance – usable focusing distance and magnification with a big advantage of this lens – the compact size.
I went further in experimenting with the focal lengths and put on Jana’s Canon EF-S 55-250 f/4-5.6. This lens is monstrous and bulky and with the extension rings, it seemed really weird on the little NEX. These longer focal lengths don’t have as strong macro effect – you can’t get a closeup of insect’s eyes, but for the whole creature, it’s ok 😀 I believe the area you can call useful ends at about 100 mm focal length. See the shots below, that I shot with my Sears 135 mm f/2.8. The focusing distance with this linger lens is about 40 centimetres, so you don’t obstruct the subject with the lens. Also, at this length, turning the focus ring has actually some effect and autofocus can be quite useful (that’s just my guess, as I don’t have any way of testing that). The pictures are processed only with my default RawTherapee profile, put together in Gimp and resized to fit the web. No cropping.
To illustrate on a scale you can more easily compare, I put on the extension rings in longest config with the 28 mm and 135 mm lens and took a picture of the screw in my quick release plate. I believe it shows the difference quite nicely. Ignore the noise – I don’t have a very bright light in my room, so I had to bump the ISO to 6400. You can see quite clearly, the 28 mm has better magnification and shallower depth of field, as well as a closer focusing distance. Well, both certainly have their pros and cons…
Well, that was exhausting. Hope you got something from this article and if you have any question or you feel I left something out, please leave us a comment below, we appreciate it 😉