Quick thoughts: TC-20E III
By Jason Odell |
February 7, 2010 9:25 AM
I received a Nikon TC-20E III teleconverter a few days ago. I've not really been an advocate of 2x teleconverters, but this new design from Nikon contains aspherical elements (Nikon claims it is the first teleconverter with such a design) intended to drastically improve performance.
A 2x teleconverter is only intended for use on fast telephoto lenses. In fact, Nikon's design prevents mounting any of their teleconverters on non-AFS lenses. Because the teleconverter robs you of light (in the case of the TC-20E III, two full stops), autofocus performance may degrade and viewfinder brightness will diminish. Given that, I only have a couple of lenses in my arsenal that would be a good match for the TC-20E III:
- 70-200mm f/2.8 AFS VRII (becomes a 140-400mm f/5.6 lens)
- 200mm f/2.0 AFS VR (becomes a 400mm f/4.0 lens)
I also have a few lenses that might work ok, depending on my need for fast autofocus:
- 300mm f/4.0 AFS (becomes 600mm f/8.0 lens)
- 200-400mm f/4.0 AFS VR (becomes a 400-800mm f/8.0 lens)
- 600mm f/4.0 AFS VR (becomes a 1200mm f/8.0 lens)
So far, I've briefly evaluated sharpness and AF ability with each of these lenses in a non-scientific manner.
Continue reading for my first impressions...
First impressions with the TC-20E III teleconverter
- Nikkor 70-200mm f/2.8 AFS G VRII: Autofocus works fine (effective f/5.6). Fair image quality wide-open, good image quality by f/8.
- Nikkor 200mm f/2.0 AFS G VR: Autofocus performance is excellent (effective f/4.0), image quality is good wide open and very good by f/5.6.
- Nikkor 300mm f/4.0 AFS: Autofocus is OK in good light, but will be sluggish at times (effective f/8.0). I've had mixed results with image quality-- I'm seeing good performance on close subjects at f/8 (wide-open), but I'm having a harder time getting crisp images on distant subjects unless I stop down to f/22. Further testing is required.
- Nikkor 600mm f/4.0 AFS VR: Autofocus performance is OK in good light, but prone to hunt or track slowly, especially in low light. Image quality is good wide-open, and very good at f/11 or above.
- Nikkor 200-400 f/4.0 AFS VR: Autofocus performance is ok in bright conditions, but can fail to acquire a target in dim light. Image quality was good wide-open, and very good by f/11 or higher.
Not surprisingly, the TC-20E III does its best work on the best (read: expensive) glass. Autofocus still operates at effective apertures of f/8, but I wouldn't count on it in dim light or in situations where fast subject tracking is required (Nikon claims that AF is not supported at effective apertures smaller than f/5.6).
I never owned the TC-20E II, mainly because I'd never heard a favorable review of it. If you must stop down an additional two f-stops (or more) to use a teleconverter that is already costing you two stops of light, then it won't get a lot of use. On the best lenses, I got good image quality by stopping down only one stop from wide-open. In fact, with the 200 f/2 VR, I could probably use the TC-20E III with the lens wide-open; that's a testament to how good the 200 f/2 VR is. I was surprised that the 300mm f/4 AFS lens did not perform better in my testing; this lens is very sharp and works well with the TC-14E and TC-17E teleconverters. However, for wildlife shooters, f/22 hand-held is not going to be a feasible option in most lighting conditions. Perhaps a future redesign of the 300 f/4 lens would improve its compatibility with the newest Nikon TC.
Remember, when you use a TC, you are increasing focal length. Extra care must be taken to stabilize your lens to get sharp shots. Just because you can hand-hold it does not mean that you'll get sharp shots using hand-held techniques!
If you are interested in purchasing the TC-20E III, check out Roberts Imaging
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