A Perfect Tele-converter for Nikon Users of AF/AF-D lenses
Written: Dec 08 '02
Product Rating:
Pros: Excellent image quality, fast AF response, built quality, handling
Cons: none
The Bottom Line: Optical quality in a great package for Nikon users of non AF-S lenses. A great way to extend the focal length of your telephoto lens without being broke.
paulphoto's Full Review: Kenko Pro 300 DG 1.4x (Nikon) (kenkolens002) Lens ...
The Kenko Teleplus PRO 300 1.4X is the tele-converter to be attached between camera and lens to multiply the focal length of the master lens by 1.4 times. I recently bought this converter to use with my prime 180mm lens and 80-200mm zoom (both AF lenses) to get a longer reach. Although, the 1.4X tele-converter does not extend the reach of my lenses much (increasing the focal length only by 40%), it certainly does a wonderful job to help avoid the need to buy and carry a much expensive and heavier lens while at the same time save my bank account.
Previously, I have used the Nikon TC-200 manual focus 2X tele-converter, but often feared about destroying the electrical contacts of my camera, let alone losing AF and intelligent metering capabilities (on modern AF camera bodies). The sad part is that Nikon does not offer an AF tele-converter for AF-D lenses. They only produce the expensive tele-converters (TC-14E I & II and TC-20E I & II) for their AF-S series. I do not own the AF-S series lenses and therefore cannot use these converters on my AF/AF-D lenses; they simply do not fit. The Kenko tele-converter is the solution, because it offers full AF compatibility on my AF/AF-D lenses as well as intelligent metering capability and above all it produces outstanding image quality.
The Kenko Teleplus PRO 300 1.4X converts my 180mm f/2.8 lens to 250mm f/4. With my 80-200mm f/2.8 zoom, the combination becomes 112-280mm f/4. The tele-converter will increase the focal length by 40% but at the cost of losing the light (or aperture) by 1 stop. The difference on the effective focal lengths on these two lenses does not appear to improve much, but with the 300mm f/4 lens (or 300mm f/2.8) the effective focal length becomes 420mm f/5.6 (or 420mm f/4), which is quite useful.
The built quality of this converter is excellent, all metal body construction. It seems to match perfectly with my 180mm f/2.8 ED-IF lens and 80-200mm f/2.8 zoom. AF response on my camera is as fast as when used without the converter attached. It also balances quite well with either one of these two lenses for shooting handheld.
However, there is a limitation on AF capability. Nikon AF camera bodies require that the lens' speed must to be f/5.6 or faster to maintain peak AF operation and response. This means that when the tele-converter is attached between the camera and lens, the master lens must have an f-stop faster than f/5.6. This is due to the fact that the converter cuts the aperture down by one full stop. Therefore, if the master lens' aperture is f/5.6, the effective (new) aperture is f/8. Some camera bodies will not auto-focus at this new f-stop.
I have tested AF response on three camera bodies (N90, F4 and F5) with my 75-300mm f/4.5-5.6 zoom lens set at 300mm f/5.6; with the converter attached, the 300mm f/5.6 becomes 420mm f/8. Among the three camera bodies, only the F5 can auto-focus even on a subject with low contrast. The F4 hunts a bit. The N90 can barely lock on a subject, unless it contains high contrast. I also tested the three camera bodies on my Tokina 400mm f/5.6 AT-X SD lens (effective focal length of 560mm f/8 with the converter). The F5 can still lock in focus on most subjects, a bit slow though. The F4 hunts a lot but can lock in focus on high contrast subject. The N90 still has trouble to lock in focus. The manufacturer indicates that maximum aperture of a lens must be f/5.6 or faster to ensure AF operation. My test shows that AF operation is uncertain for a lens with f/5.6 and varies on camera body. Therefore, to ensure worry-free on full AF operation, the master lens must have an f-stop of, preferably, faster than f/5.6.
Image quality produced by this converter is outstanding both in terms of sharpness and contrast. Color is also excellent, or shall I say faithfully retained. I have made careful comparison of image quality between my 180mm f/2.8 (without the converter) and its effective focal length 250mm f/4 (with the converter). At 250mm f/4 shot wide open, sharpness and contrast are maintained from edge to edge. Exposure seems to be consistent throughout the film plane with no vignetting. Image quality on my 80-200mm zoom (112-280mm f/4) is also excellent without degradation in image resolution.
In terms on intelligent metering system, the converter is fully compatible with AF-D lenses. With my N90 or F5, 3D Matrix metering is maintained. However, both cameras still show the original aperture and not the effective or shifted aperture caused by the converter. For example, with my 180mm f/2.8 and converter attached, my camera still shows an aperture of f/2.8, while the effective f-stop now is f/4. Nonetheless, due to TTL capability, the camera's meter adjusts the correct exposure in spite of this anomaly.
In terms of compatibility on focal length, the converter works well on a lens with focal length of 100mm or longer. That is why the 80-200mm f/2.8 seems to be quite a perfect match for the combination. It should also work well with similar zoom in this focal range, such as 70-210mm f/4-5.6, 80-200mm f/4-5.6 or 70-300mm f/4-5.6. However, on some camera bodies, AF response with the zoom set at the long end with aperture of f/5.6 may not be 100% effective. This does not mean that there is incompatibility between the converter and camera/lens; it is the camera's AF sensor that cannot focus on a lens with f-stop slower than f/5.6. And when this happens focus can always be achieved manually.
There are several reasons why the converter should work better with the longer focal length lens (70mm or longer). First of all, light falloff or vignetting may occur with shorter focal length lens. Secondly, because a wide-angle zoom lens (such as a wide-angle zoom 20-35mm or 24-85mm) has its rear glass element sticking out at the end that may touch the front glass element of the tele-converter. For this reason, I have never attempted to mount my 20-35mm zoom on the converter. Furthermore, the reason why the tele-converter is needed in the first place is to extend the focal length for a longer reach, and therefore it makes no sense to use it on a wide-angle zoom lens, while a standard or telephoto zoom can do the job.
It is a common notion that the tele-converter not only multiplies the focal length of the master lens, it also magnifies everything it sees, including any flaws that the master lens characterizes. The magnification is more pronounced for a less sharp lens or by the power of the converter. Therefore the master lens ought to be of high quality optically. The Kenko Teleplus PRO 300 1.4X is no ordinary tele-converter, constructed using high quality optical glass material that seems to defy the combination of this common notion. This is very true if you are to compare the optical quality of PRO 300 series to their cheaper counterpart, such as the 2X MC-7 versions. Image resolution I gain using the Kenko PRO 300 1.4X is nothing short of being outstanding. Even though I primarily use the converter in combination with my 180mm f/2.8 lens, I have also used it on my 75-300mm zoom with excellent results, and I am not afraid to use this combination.
This Kenko Teleplus PRO 300 1.4X is clearly the only option for Nikon users of non AF-S lenses. Another contender in the 1.4x series is Tamron. They also offer their 1.4X tele-converter in two versions: The standard AF 1.4X and the PRO-series 1.4X SP AF. I have used the 1.4X SP AF in the past with results similar to Kenko PRO 300. For some reason, Tamron's SP AF 1.4X PRO-series is priced a bit higher than Kenko, which further makes the Kenko a better buy in terms of price/optics ratio. This converter is a perfect match for Nikon 300mm f/4 ED-IF or Tokina 300mm f/4 AT-X SD that I have tried recently.
I have not tried the Kenko Teleplus PRO 300 1.4X on Nikon AF-S lenses and therefore cannot commend on their compatibility. However, Kenko has stated that the converter will not "auto-focus" on the following Nikon lenses:
Obviously, if you can afford any of these lenses, chances are you will likely get the Nikon TC-14E or TC-20E series. For those of us who can only afford the Nikon 300mm f/4 ED-IF or an equivalent lens from Tokina, Tamron or Sigma, the Kenko teleconverter is really an excellent choice to extend the focal length. Therefore, I would highly recommend this unit.
While this review is aimed toward Nikon mount, the Kenko PRO 300 and Tamron SP AF Pro are readily available for other mounts as well. Both Kenko and Tamron are available in Canon, Minolta and Nikon-D mount.
Specifications: Kenko Teleplus PRO 300 1.4x
Model: PRO 300 1.4x AF
Magnification: 1.4
Depth of Field: 1/1.4 of prime lenses
Lens Construction: 5 elements in 2 groups
Lens Coating: Multi-coating
Exposure Magnification: approx. 1 stop
Barrel Width and Length: 67 X 19.4 mm
Weight: 132 grams
Specifications: Tamron 1.4x SPAF PRO
Model: 140F-FNS (1.4x SPAF)
Magnification: 1.4x
Depth of Field: 1/1.4 of prime lenses
Lens Construction: 5 elements in 4 groups
Lens Coating: Multi-coating
Exposure Magnification: approx. 1 stop
Barrel Width and Length: 67.5 X 19.4 mm
Weight: 138 grams
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