Monday, July 7, 2014

Budget Macro Photography : Meike Auto Extension Tube

Macro photography can be an interesting type of photography you might want to do, but it can be quite expensive to own a real macro lens. There are few options for real macro lens that would be compatible with full-frame and crop camera, namely:
  • Nikon 105mm f/2.8 ED VR
  • Canon 100mm f/2.8 USM IS L
  • Sigma 105mm f/2.8 EX DG OS
  • Tamron 90mm f/2.8 VC 

There are all above RM1000 range and even some model such as Nikon 40mm f/2.8 would also cost slightly below RM1000 point. Fortunately, there are few alternatives for creating macro works with cheaper equipment.
  • Close-up Filter
  • Extension Tube

I don't have experience with the close up filter and only have use the extension tube before. There are 2 kind of extension tube. One with electronic contact point, so you can maintain autofocus and exposure control from the camera body. The other one is without electronic contact. If you are using the latter one, your f-stop value will be F-- for Nikon body. You will need to judge the exposure by try and error. For the auto extension tube, there are many manufacturers and variants that produce it. Kenko (best quality) and Meike are among the more common brands you can get in Malaysia with price varies from RM250 to RM500++. Please take note that Meike did produce the auto extension tube with plastic mount and metal mount. For better quality and versatility, go for the metal mount although is a little bit pricey. 

Although it can retain the autofocus of most lenses, but its recommended to use focal length 50 and above. In general, the longer the focal length, the longer the minimum focus distance of the lens. This gives space for the extension tube to bring closer your subject (to allow you focus closer), and thus increase your lens native magnification ratio. Therefore, I recommend to use the extension tube with 50, 85mm prime, or even 70-300, 70-200 telephoto zoom. Forget your kit lens (18-55mm) if you intend to use it with, because you don't have much distance to work on with extension tube on it.

Here is how close you can shoot on a new 20 cents coin using all 3 segments of the extension tubes (12mm, 20mm, 36mm) stack up together with a Nikon 50mm f/1.8D prime. 
Nikon D90, Nikon 50mm f/1.8 D with Meike Auto Extension Tube + Nikon SB-600 @ 1/64 power | ISO 200 | 1/80s | f/22
The setup of the extension tube with 50mm prime.
Compare it with only the 50mm alone, this is as close as you can focus on the coin without using the extension tube (minimum focus distance of 0.45m for nikon version).
Nikon D90, Nikon 50mm f/1.8 D without extension tube | ISO 800 | 1/60s | f/2.8

How to use extension tube for macro photography:
  1. Mount the extension tube section from the smallest size to the largest one. You want to make sure your lens is still able to focus on the subject before adding another one.
  2. Set the camera exposure to manual. You can use the aperture priority to get a rough estimation of correct exposure and dialled in to maintain consistent exposure throughout the shooting. This includes your flash power as well. 
  3. Use Manual Focus, again, although the lens still retain auto focus function, you often want to get as close as possible for largest magnification. To archive that, adjust the focus ring to the closest that the lens can focus. and start moving closer or further away from the subject to acquire focus.
  4. Using smaller aperture, such as f/16 or f/22 because in macro, the depth of field is very limited. You might not be able to get the whole subject in focus. That's why dedicated macro lens can have aperture up to f/40 for more depth of field.
  5. Use a tripod with macro focus rail. With this, you can pinpoint where the focus point more consistently than handheld. You can do focus stacking as well with the macro rail where you shoot different part of the subject in focus and merge them in post processing. If you want to know more, you can search more on focus stacking.
  6. Use remote flash if possible. You can use TTL-cord or flash trigger if you have. This is because the subject you shooting is often very close with your camera. You on-camera flash might not be able to illuminate the subject.
  7. If you are using a heavy telephoto lens, such as 70-200, you better mount the lens on the tripod instead of the camera body. The extension tube might not be able to hold the weight of the lens on the body and you would likely ends up damaging both the lens and body mount.
You can mount it on telephoto zoom get better working distance for shooting the macro, especially shooting insects. Below is just an example you can shoot macro using extension tube with telephoto zoom.
Nikon D90, Nikon 70-200mm f/2.8 VR, Nikon SB-600 @ 1/64 power with 3 segment of Ext tube | ISO 200 | 1/125s | f/11
If you are interested in macro and cannot affort the macro lens, the macro extension tube is a good way to start. You will soon realize its limitation that you need more depth of field (f/40) and further focusing distance for shooting small insects. Then you may upgrade to real macro lens and you will never looked back. It's a stepping stone that worth investing in my opinion. In photography, you stop growing when you stop learning. 

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