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Kenko 2X KAX Teleplus MC4 Review RSS Feed

Kenko 2X KAX Teleplus MC4

Reviews Views Date of last review
3 22,073 Mon March 12, 2012
Recommended By Average Price Average User Rating
100% of reviewers $13.33 5.33
Kenko 2X KAX Teleplus MC4

The Kenko KAX Teleplus MC4 looks very similar to a Tokina model but apparently that has 7 elements so listed separately here. Apparently can be found wearing many other badges including Tamron (see reviews below).
Focal length: 2x primary lens
Aperture range: 2x the primary lens. "A" capability allows for aperture control from the camera body for most "A" lenses
Lens elements and groups: 4/4
Mount: Pentax KA(R) (no autofocus support). Ricoh-pin is low profile.
Mass: 109 grams
Length (excluding mount): 25.5 mm
Diameter (max): 62 mm
Origin: Japan
Price History:

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Registered: April, 2011
Location: Lost in translation ...
Posts: 18,040

1 user found this helpful
Lens Review Date: March 12, 2012 I can recommend this lens: Yes | Price: $18.00 | Rating: 5 

Pros: "A" feature, inexpensive, can be converted
Cons: IQ loss, etc.


I picked up a copy along with a lens in the UK and maybe paid too much for it, but it was cheaper than the prices I had seen in France on average. I purchased it to play around it and haven't truly used it a great deal ... I'll try to experiment with my DA lenses and maybe the D AF 100mm f2.8 Marco WR, too.

My copy is a "2X KAX TELEPLUS MC4" model, thus no problem here is with a "Ricoh pin". But be careful here and double check the model and possible pin issues.

I would love to try out this TC on a DA* 200 or DA*300 as mentioned in the previous reviews ... maybe it's now the only reason that I'm hanging on to this particular TC.

Allez et bon courage, J Frog
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Registered: August, 2011
Location: North Carolina, USA
Posts: 5,233

2 users found this helpful
Lens Review Date: February 22, 2012 I can recommend this lens: Yes | Price: $16.00 | Rating: 5 

Pros: Not bad for a cheap 2x; can be converted to extension tube
Cons: Poor edge performance, DA lens compatibility

From the photo and description I'm quite sure this is the same unit, in all but branding, as two 2x 4-element TCs I recently bought (cost shown is the average I paid). Both of mine are KR (i.e., Ricoh mount, like Pentax-A but with the extra "Ricoh pin"), as is the unit in the official photo above -- you can easily see the Ricoh pin, which is the extra contact at the very top (as the unit is oriented in the photo).

Removing the Ricoh pin is pretty easy to do, but you do have to be careful removing and replacing the mount ring. You can do this from either side (the lens-facing side or the camera-facing side) and there is not much difference, but I found it a little easier to do this on the lens-facing side (working from the camera-facing side, the pin for the lens-release mechanism is harder to keep in place). Remove the four screws holding the ring in place (a 0 phillips head is a good size), and very carefully lift the ring straight up. The key is leaving the six aperture contacts undisturbed. The Ricoh pin pulls out easily (two contacts connected by a spring). Again, be very careful replacing the mount ring, making sure to get all six aperture pins and the release pin properly seated; you may need a small flat-head screwdriver or similar tool to wiggle some of the pins back into the proper holes in the mounting ring.

[Update: from other reports, it is probably unnecessary to remove the pin; it has rounded ends that apparently will not cause the infamous "Ricoh pin" problem.

I bought the first copy (Tamron-F Tele-Converter 2x KR MC4) intending to remove the glass to get an A-type extension tube. However, after testing it as a TC, I was pleasantly surprised to find that it is not completely useless as such. Paired with my DA* 200, it is actually quite sharp in the center. Edges are pretty poor, but I decided it is worth keeping as a TC for those occasions when I am traveling with the DA* 200 and might want extra reach for birding etc. In those cases it is usually center performance I am most concerned with. I also tried it with my A 400/5.6, but with that lens the TC does not seem to produce results any better than cropping.

I then found an even cheaper version of the same unit (Focal MC 2x Converter). I removed the glass using these instructions, which were very helpful. While a little fussy it was not too difficult to remove the elements carefully and pack them up in the proper arrangement, in case I ever want to re-assemble the unit as a TC.

I've also seen Albinar and Vivitar branded TCs that look to be yet again the same unit.

Update: Unfortunately the TC is not fully compatible with DA-type lenses. As above, it works correctly with the DA* 200 (no AF, of course). However, testing it with the DA 18-55 and the Sigma 70/2.8 macro, the aperture range shown in the camera is incorrect for both lenses. I don't understand the differences between the DA and DA* mounts, but have noted that while DA* lenses are missing one of the standard 6 A-type contacts (pin 5), plain DA lenses are missing two contacts (pins 3 and 5). I guess there is some essential difference in how these contacts work in conjunction with the data pin to transmit aperture data. Given that, I'm surprised that my DA* lens works correctly with the TC, and can't say for certain that it would work with all DA* lenses.

With the DA 18-55 on the TC, the camera shows an aperture range of f/4 to f/22 (incorrect at any zoom setting for this lens). f/4 to f/22 happens to be the correct aperture range for the DA 16-45, and indeed that lens appears to work with this TC. Maybe just dumb luck. Or maybe the difference between a constant aperture zoom (DA 16-45) and a variable aperture zoom (DA 18-55). The Sigma 70/2.8 macro gives a different result: it has an actual aperture range of f/2.8 to f/22, but on the TC shows as f/1.2 to f/22. Go figure. Or, if you know the answer, please tell me!

Registered: February, 2008
Location: Hawkesbury
Posts: 1,461
Lens Review Date: November 9, 2011 I can recommend this lens: Yes | Price: $6.00 | Rating: 6 

Pros: Light, affordable, usable
Cons: Tendency for blown highlights, usual teleconverter flaws

The KAX Teleplus is a light weight teleconverter. Its "A" facility helps make it more user friendly, particularly for a lens without an aperture ring.
Using this teleconverter has taught me the value of shooting RAW. The converter when used with the DA*300 produces high contrast images, often too high. Blown highlights are a common problem. Resolution is adequate, certainly better than cropping photos made without it and there are no significant chromatic issues.

I picked my copy up for $6 and from that perspective it is worth it while we wait for Pentax to produce a teleconverter or two to match the DA*300.

I had not even though about the presence of the Ricoh-pin until I read the second review. It has given me no bother (so far).

Here is an image shot in combination with the DA*300.
I have included this example because it shows the high contrast nature of this lens combination and gives some idea of the focus fall-out characteristics and the uncorrected cool colour reproduction. The Pelican was hundreds of metres away.

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