Kenko C-AF 1.4X Teleplus MC4 Teleconverter

[TWX]

Bought a used Kenko C-AF 1.4X Teleplus MC4 Teleconverter today. Since Kenko's website is rather poor, figured I'd remark on my initial observations here so if anyone else is considering one of these they'll at least find something.

So far I've only used it with my Tamron 70-300mm f/4-5.6 VC USD, and it seems to work mostly properly. The light metering capabilities are inconsistent, meter seems to report darker than it's actually exposing, though admittedly the outside light was a bit harsh and I have no practice with this adapter. The teleconverter otherwise appears properly affect lens data, zoomed all the way in the camera claims 420mm at f/8 instead of 300mm at f/5.6. Autofocus works but not as well as normal, image stabilization seems to work just fine. Contrast on the resulting images is poorer and I might be seeing some diffraction, but the lighting didn't make my tests ideal.

So, some comparison photos:

First, no teleconverter:

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, 300mm f/5.6 1/160th second ISO 100, scaled 50%

Then with the teleconverter:

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/8 1/160th second ISO 100, scaled 50%

The difference between 300mm and 420mm is noticeable. Bear in mind this is a 1.6x crop, so akin to ~480mm and ~670mm equivalent full-frame.

A crop of the teleconverter image:

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/8 1/160th second ISO 100, crop of original

After running the original image through GIMP's sharpening tool:

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/8 1/160th second ISO 100, crop, sharpened in GIMP

And lastly, an animated gif of a crop of the original teleconverter and sharpened images:

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/8 1/160th second ISO 100, comparison GIF

So the image quality is definitely reduced with the teleconverter. I suppose for me the question is if the reduction is mild enough that the extra zoom makes it worthwhile, and if learning to use the device will result in better image quality. Bear in mind these photos were shot handheld with lens vibration compensation turned on, not on a tripod, so these preliminary results might be meaningless in the longrun.

These birds were hanging out on a tree in my backyard. Picture taken over the workshop from the front yard:

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/8 1/250th second ISO 100, 50% crop

And after some color correction and sharpness filtering:

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/8 1/250th second ISO 100, 50% crop, color and sharpness corrected

I think it has potential, but I'll need practice, both with the component specifically light metering, and with post-processing.

 

[Derrel]

Good post!

 

[dunfly]

I think your observations are dead on. I have a Kenko 1.4 teleconverter also that I use on a crop sensor camera. I rarely use it for a couple of reasons. First in changes the f-stop you are shooting at and second, I can crop my straight images down to the same field of view and get as clean an image. Part of this may be due to camera shake. At 300mm on my lens without the teleconverter, I can shoot hand held a about 1/250 with no shake. With the teleconverter, I have to shoot at a higher shutter speed but I'm limited by the increase in f-stop, so I have to raise the ISO. It would work OK with a tripod, but I don't like it for handheld.

 

[TWX]

I paid literally forty bucks for it (I seem to pay forty bucks for a lot of things, the 50mm f/1.8 Mk I comes to mind), so I'm not displeased, if anything it's a cheap way to play with longer focal lengths. Next time I go up to South Mountain I'll bring it along, see what optical problems will manifest when snapping pictures of downtown from several miles away.

Most of what I took with it yesterday was at ISO 100, I could easily go much higher and still have decent enough quality out of the sensor, so I could play with aperture and shutter as well, see if there's anything closer to optimal.

Palm trees make good test subjects here if only because they're unobstructed and far away, I can take shots from my driveway.

 

[TWX]

Had an epiphany. This camera has a viewfinder preview button next to the lens mount on the left side when holding. I should probably get used to using it if I'm going to use this teleconverter. Probably will need to get used to using it without the teleconverter first, so that I'll know what I should be seeing with it installed.

 

[Braineack]

I heard these work with the Tamron 70-200 sp vc. I've always wanted to try it, but hard to find the earlier version which you need apparently.

 

[TWX]

I heard these work with the Tamron 70-200 sp vc. I've always wanted to try it, but hard to find the earlier version which you need apparently.

The seller had some kind of 70-200mm, I did not catch if it was the Canon or Tamron, that unfortunately this particular teleconverter did not work with.

I briefly put it on my EF 50mm f/1.8 Mk1, it gave me 70mm f/2.5, full-frame equivalent of about 112mm. Depth of field was correspondingly still fairly narrow on the couple of mildly artsy-fartsy up-close shots I took. Quality up close looked decent on the camera screen, haven't yet looked on a PC.

So possibly it might be more useful to someone intending to travel as light as possible while still retaining reasonably wide apertures, a wide prime like an EF 24mm, a 50mm, and a telephoto prime like say 85mm where this teleconverter lands halfway in between would yield ~33mm, 70mm, and 119mm. Granted, a 24-105mm would probably be better or easier, but this may be cheaper.

 

[TWX]

I was at a regional airport yesterday, took a few more shots with the teleconverter.

First shot, the closest, the airport control tower.

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/11.3 1/800th second ISO 800, 50% scale, no other corrections

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/11.3 1/800th second ISO 800, crop from full-sized image, no other corrections

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/11.3 1/800th second ISO 800, crop from full-sized image, no other corrections

It's weird what is and isn't good. The antennas on the roof are wavy, as are the lines in the metal of the wall. The shadows cast by the grating are pretty decent though.


Next, a helicopter as it approaches, further-out first, then closer-in:

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/11.3 1/125th second ISO 100, scaled 50%, no other corrections

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/11.3 1/125th second ISO 100, crop from full-sized image, no other corrections

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/11.3 1/125th second ISO 100, crop from full-sized image, no other corrections

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/11.3 1/125th second ISO 100, scaled 50%, no other corrections

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/11.3 1/125th second ISO 100, crop from full-sized image, no other corrections

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/11.3 1/125th second ISO 100, crop from full-sized image, no other corrections

Horizontal lines seem to be reproduced more cleanly and sharply than vertical lines. I don't know what the source of that distortion is, but where edges bend from horizontal to vertical it's pretty noticeable. I was shooting handheld, so I can't deny the possibility that subject-motion was the cause though.

And now the furthest-away, a Boeing 737 that took off from the commercial airport more than fifteen miles away, that had to climb to clear this general aviation airport's airspace.

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/8 1/640th second ISO 400, scaled 50%, no other corrections

Canon EOS 77D, Tamron 70-300mm f/4-5.6 VC USD, Kenko 1.4x Teleconverter, 420mm f/8 1/640th second ISO 400, cropped from full-sized image, no other corrections

So this teleconverter seems to be a nice toy at long zoom, and could even be useful for photography where artistic merit isn't the goal, like reading text, confirming enough to determine a model, even possibly getting enough detail to possibly identify a person based on face, but for fine photography it's not so good, at least not scaled.

But I paid so little that I don't feel bad about it. It's told me that paying good money for a teleconverter, it would need to be pretty high quality to bother, and the higher the resolution of the camera with the quality of the regular lens, the less useful a teleconverter is when a cropped image is probably going to be just as good if not better quality anyway.

My guess is that if I ever get into extreme telephoto photography I'll be just better off buying a new lens.

 

[Derrel]

With today's higher-megapixel cameras, it is often possible to just crop and get a better image than you would get when using a 1.4x telephoto converter. The optical degradation in most telephoto converters is at the edges of the frame, and on aps-c those edges are not fully recorded. Back in the 2.7 and 4 and 6 megapixel days, the 1.4x converter was quite useful, but today with 18-50 megapixels, it is often better to get a sharp, crystal-clear image from a good lens and then to take that image into software and crop it. Introducing degradation in the form of a 1.4 X or 2x converter is no longer as good a strategy as it used to be. Some subjects such as people and birds in flight are still useful with a telephoto converter, but if there is important detail or subject matter of interest at the edges of the frame the degradation caused by a telephoto converter may not be acceptable. It really depends upon your use and your quality standards... Sometimes it is better to get the shot, no matter what it looks like.

As far as the wavy antennae:I think that is heat mirage, which is an environmental factor.

 

[Derrel]

Sometimes a 1.4× converter gives quite a good result, such as when the Nikon TC 14e is paired with a 200,300, or 400mm prime. Most teleconverters work better with a prime lens than they do with a zoom lens. It is highly dependent upon both the converter and the lens in question. One really has to do his or her own tests and consider the end-use.

 

[DarkShadow]

I used a Kenko pro 1.4 along with the Nikon AF-S 300mm f/4 IF ED it was still sharp after a severe back focus adjustment needed with the TC. I Figured the lack of a rear element lens with the TC would help keep some dust out plus the extra reach would be good which it was but there was a little more play then i liked between the lens and the converter and camera body and sometimes the AF would stop working i had to half release the lens twist lock back.on. IMO it was not worth the loss of light from f/4 - 5.6 and the less then perfect connection plus there was some inconsistent results in focus that was a none issue without the TC. i gave up with it and just gave it away. Good post BTW.