Kenko Pro 300 1.4 dgx converter review
Kenko Pro 300 1.4 dgx converter review
Kenko Pro 300 1.4 dgx converter review
Update:28/10/2014
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Version
This is the newest type of Kenko Pro 1.4 dgx converter with a blue dot version.
This version lacks the three pins, that is responsible to stop focusing in case of the brightness is less than f/5.6 in Entry level and Prosumer Digital single reflex camera bodies, f/8 at Canon Mk I series Dsrls.
Explanation
Pro 300 means in the name of professional lenses above 300mm focal length.
Other version of the Kenko 1.4 dgx converter
There is an other version of Kenko 1.4 converter also called 1.4 dgx without the Pro note in the name.
The two Kenko 1.4 dgx converters compared
Both converters are very sharp. The “Pro” version is a little sharper at the center, the 1.4 dgx is little sharper at mid frame and at the corners. The Pro version is a little more expensive, than the non-Pro version.
Build quality
The built quality of this Kenko converters are not up to the Canon L converters. The Kenko converters are lighter as well, than the Canons.
What does it mean? Some wobbling can be expected, minor, but there, not with the Canons which are rock solid.
Doesn’t mean that not attached properly, just not so solidly. If you have a really heavy, expensive lens, perhaps need to check this converter better than the Canon.
Optical quality
Optically this Kenko converters are very fine. Excellent sharpness, contrast, and colors, perhaps a little flare, which is not very disturbing.
Compare to Canon 1,4x converter
The Canon 1.4 Mk II is a little sharper in the center according to lab measurements, but this is not very visible at all in real time use. In case this Kenko Pro300 1.4 dgx seem sharper to me than the Canon 1.4 Mk II.
The Canon has a significant drawback: not compatible with third party lenses, or even many Canon lenses, except primes of 135mm and longer, and some long zooms, and autofocus speed is also slower.
The converter has a protruding element, which not fit to normal lenses just a lenses with a hole inside. Cannot fit to the 50mm for example, which the Kenko can easily can be attached.
I didn’t check the Canon’s Mk III version, which has been constructed to fit the newest Canon lenses, (or this newest Canon lenses construct to fit this Mk III converters…Sorry Canon for the joke 🙂
As other reviews suggests the Canons Mk III version essentially is not sharper than the Mk II version, little better for contrast and chromatic aberration.
For info the Canon Mk I version is identical with the Mk II version of converters. See the sample picture below the Canon 200f2.8L attached with the Kenko Pro 300 1.4 dgx on Canon 30D resized to 800pix:

100% crop from the above picture:

I would say the sharpness is exceptional. The only limiting factor is the “mother lens” where we attach the converter. The original picture is 5.8 MB which is huge for a 8 Mpixel Canon Eos 30D. This is also shows the amount of detail captured.
Picture f4 wide open iso 400
100% Crop of the above image
Results with the Canon 200mm prime lens
The sharpness quite good at f4 280mm wide open with Canon Ef 200 f2.8 L. Cannot guarantee this sharpness with any lens. Obviously the converter doesn’t make lenses sharper. The original lens is much sharper and has better contrast without the converter.
Price/performance
A very good converter at much cheaper price, than the native Canons. It depends though sometimes used Canons is possible to get at cheaper prices.
Colour 280mm, f4:
I checked this converter with the Canon 200 f2.8L (the primepipe) lens. Although for 200mm lens the non-Pro version of Kenko converter suggested primarily(the non pro version suggested for 200mm lenses), this converter also works with it flawlessly.
Recommendation:
Very nice converter, with excellent optical quality, and moderate price, highly recommended, if build quality is a high priority perhaps the Canon preferred.