Macro Photography With Extension Tubes
A Little Macro Photography Using Extension Tubes
When people talk about macro photography, usually, they are referring to closeup photography, where the reproduction ratio isn't quite up to 1:1. To the higher levels of magnification where you are approaching 1:1 reproduction, you typically need a "macro" designated lens, which can focus up close. Examples of such would be the various 105mm macro lenses, which allows for extremely high quality macro photography.
However, such lenses will typically set you back at least $400, or more. For the enthusiast, such costs are prohibitive.
Enter, the extension tube. Basically, this is just a tube with lens mounts on it, matching those of your manufacturer's. The effect is that it moves your lens a certain number of millimeters away from the sensor. This changes the relationship between the sensor and the subject. Ie, given the same lens, you are able to significantly focus closer than the lens was originally designed for.
The cost for extension tubes? They start at $50 and go up to around $200 for a set of three.
The Issues of Macro Photography: Depth of Field
So, aside from the minimum focusing distance, what else is augmented? Well, for one thing, the depth of field is drastically reduced. Sometimes, from a window of several feet to that of several millimeters. This can prove challenging for when you want to take a "quick" macro shot, or if the subject is large enough that much of it will fall outside of the range of the dof of the augmented lens.
This can, however, also be used to creatively emphasis certain details of the subject, leaving all else obliterated by the shallow DOF.
The benefit of the extension tubes, especially the DG variant of the Kenko extension tubes, is that they also send the digital signals to the lens from the camera body, maintaining information about the lens' focal length, aperture control, etc. If the max aperture of the lens is large enough, you may even retain full use of autofocus.
Note that if you stack multiple extension tubes, the focus mechanism may become progressively more stiff. In which case, it would be wise to switch your camera to full manual focus.
As was the case with my setup, the focusing ring tended to behave like the zoom and the zoom seemed more to control focus. To get the fine level of focusing, I found it was significantly easier to just move the camera closer or further from the subject. A macro focusing rail would have helped. :)
Another Issue of Macro Photography: Light Loss
If you've used the 1.5-2.0x tele-converters for your lens to get a longer focal length, you will be familiar with the loss of light. It is a fair exchange, given the longer reach they give you. With extension tubes, you will likewise see a loss of light. The above two photographs of coins were shot hand-held, a task that should only be attempted, if you want any level of sharpness, if you have a strong lightsource and a wide open aperture.
For the remote, I placed the camera on the table and set a timer, allowing for a much sharper capture of the lettering on the remote. Though this required a 3 second exposure, something I don't recommend hand-holding.
You can typically work around this issue with the use of a higher ISO, but you will, unfortunately, introduce noise into the image. Something that will require noise reduction to take out.
For the images above, the Sony Alpha 700 does a great job of handling noise, even at ISO 800. However, I employed Adobe Lightroom's Luminance and Color noise reduction to produce a smoother image.
The three photographs above were tweaked in Adobe Lightroom for some noise, and color cast removal from the bedside light source. Yes, the coins were photographed on a roll of toilet paper under a nightstand lamp. The remote was illuminated by ambient light in my living room.
No cropping was performed on the images, the level of magnification you see in the shots is what came out of the camera without the benefit of software cropping, either in-camera or in Adobe Lightroom.
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