Extension Tube for Marco Photography

sunny_sony · Jun 27, 2011

Hi Guys,

Hope you all having a great time. I need some guidance on Macro Photography. I actually purchased a set of extension tubes from eBay but they don't have any electrical connection so basically I can't change my lens aperture and also can't do auto focus. I am using SONY A390 DSLR camera and SONY 18-55mm Lens. Could you please recommend an extension tube which can provide good result and also having electrical contacts so that I can change aperture and also do auto focus. I am looking for cheap options and don't want to spend to buy Macro Lens at the moment to start with. Will appreciate your suggestions.

Thanks,
Raj

pgriz · Jun 27, 2011

Most of the time, when you're doing macro photography, you'll want to do manual focus because the depth-of-field is so narrow, and the camera has no clue as to what YOU want to be in focus. Not being able to change aperture, is however, a biggie. I'm not familiar with Sony, but Kenko extensuion tubes for Canon and Nikon work very well. Perhaps they have a version for Sony?

lyonsroar · Jun 27, 2011

I have el cheapo "Pro-Optic" ones from Adorama. Cost like $40 or something stupid. They are plastic and have the contacts in them, but my AF never works when they're on. It just searches and searches and never finds a focus point so I end up manually focusing anyway...

sunny_sony · Jun 28, 2011

Hi Guys.Thanks for the posts.Okay. I understand I need to manually focus for Macro photography. But which aperture I should be using? I guess F22 to get maximum depth of field?? But to change aperture to F22 I need electrical connection in Extension tube as my lens is not a manual one and requires the camera to change the aperture. And also which Lens to use for macro photography using extension tubes? I have 18-55mm and 70-300mm lenses. Appreciate your responses...Cheers..

pgriz · Jun 28, 2011

Yes, the rings you use should allow you to change the aperture. In terms of image quality with extension tubes, true macro lenses are probably the best, followed by primes, followed by zooms. Your zooms should give quite decent images, but they will not be as sharp as you'd get with a true macro lens.

Regarding the "real" aprture, adding extension tubes also increased the effective f/stop. Using a high aperture such as f/22 will give you better DOF, but at the expense of loss of detail due to diffraction. You will need to experiment a bit to see which apertures give you acceptable DOF with acceptable sharpness using your equipment.

When you are doing macro, focusing is usually done using slide rails, which move the camera back and forth. Depending on the magnification factor, and f/stop, you are dealing with DOF of a 0.5mm or even less, so everything about your setup has to be about minimizing unwanted movement. As well, you'll need LOTS of light so usually off-camera flashes are used to illuminate the subject. These also serve to keep the exposure short to minimize blurring due to movement.

When I do macro, the camera is on a sliding rail with focusing accomplished by turning a screw which moves the camera stage back and forth. The slide rail is sitting on a three-axis head, and that is on a very sturdy tripod. The lens is a macro lens set at a specific focusing distance (which determines the magnification). The subject is usually on a movable stage, also with micro-movement capabilities. The light is supplied by two flashes in manual mode, and I use a flash-meter to determine the right exposure. Although each flash has manual controls (adjustment of power from 1:1 to 1:128), you sometimes still have to fine-tune the light by moving the flashes closer or farther to achieve the correct balance. In addition, depending on the nature of the subject, you may need to use various light modifiers and diffusers, especially if the surface you are photographing is shiny. I've done my own sharpness tests, and have found that with my equipment, going above f/11 shows the loss of sharpness due to diffraction more and more.

For field work, magnifications above 1:1 are difficult because wind can make things move, the subjects you've shooting are moving about as well (assuming you're shooting insects), and you need a different strategy. I use a Manfrotto macro bracket that holds the two flashes aimed in the correct position, controlled by PC cables running out of an adaptor on the hotshoe. Whenever possible, the camera (and the associated bracket wth the flashes) will still be sitting on the focusing rail and rest of setup described earlier, and the focus, exposure, etc. are set in advance. Then I wait until my subject moves into view and press the shutter once it is in the correct position. However, it is very common to need to shoot lots of shots to get one or two that are acceptable from a composition point of view, even if you've nailed the exposure.

Edsport · Jun 28, 2011

With my canon lens i can change aperture by putting on the lens without the extension tube and set the aperture to what i want then hold in the DOF button and while holding it in unscrew the lens from the camera. Release the DOF button and put on the tube and lens. The aperture will be set. I've never had a problem doing it but do it at your own risk. I now have electrical contacts on my tube...

GooniesNeverSayDie11 · Jun 28, 2011

I use kenko tubes that were $160 for the 3 tube set and they work great ( 36mm, 25mm and 12mm ). Keep in mind that if you buy really cheap tubes, they may not hold up to the load. For instance, if you have 70-200mm f/2.8 or a 400 mm lens attaches to a 12 or 25mm tube, it would be a shame to have a tube break and your lens (or camera if using a collar ) to get dropped. I have never heard of this actually happening to anyone I know, but I get a little scared with the Kenko tubes sometimes and they are decent build quality.

2WheelPhoto · Jun 28, 2011

KENKO TUBES <---settle for no less

Kenko Auto Extension Tube Set DG for Nikon Lens AEXTUBEDGN B&H

NateS · Jun 28, 2011

I use the kenko tubes. A couple facts.

1. You can focus using tubes without a rail or tripod if you have a good flash. I have thousands of macro photos to prove it.

2. Most likely you will not be able to use much more than the smallest extension tube with your 18-55 kit lens. The design of those lens is often such that using very much extension will cause the MFD (minimum focus distance) to be shorter than the length of the lens...thus your focal plane is inside the lens making it impossible to focus on a subject.

3. Extension tubes should work great on the 70-300.

You would be best served to try the tubes on the 70-300 and if not satisfied, pick up a prime...something like a 50mm usually works pretty well and doesn't break the bank.