Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

After reading many reviews for the Nikon 80-400 AF VR 4.5-5.6 lens I was concerned that a photo-multiplier would not work with it, or at least not well. When I went to purchace my lens on the B&H website there was a section for accessories I might be interested in. The Teleprus PRO 300 DGX 1.4 AF was on the list. I read the reviews and decided that for the price it was worth the risk to try. I have been amazed at how well it works. Although as with all teleconverters you lose a few f-stops, the thing really works. I have used it sparingly in the few weeks I have owned it, but it has performed beyond my expectations.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Let me preface by saying that 4 stars may go up. The Kenko 1.4 tele for the Nikon mount works with auto-focus on the new D7000 body and the old Nikkor 80x400 AF VR. It is sharp as a tack on a lower zoom but it is terribly hard to focus manually zoomed out at 400mm. Perhaps this is my diopter setting on the body, but I have really worked on the fine-tuning there. At increased ranges, the tele is just shooting a bit blurry on enlargements. This is what often must be done with small birds at a distance. Be warned however y'all that when they say that the 1.4 will cost you 1 f-stop, it is at 80mm on this lens. F4 goes to f5.6 at 800mm. By the time you zoom out and the lens will shoot f5.6, the tele will not let you shoot below f8. If I can fine-tune the manual focusing issue, the enhanced ISO of the D7000 will make up for it. That was my plan from the beginning. I'm shooting a bit fuzzy though at extended ranges at 400mm.
Ray Swagerty
Charleston, SC

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I purchased this teleconverter for my Nikkor 80-200mm f/2.8D ED AF zoom lens on my d700 after reading reviews of how well it worked with this lens for sport photography. My 80-200mm is tack sharp, dead on pretty much all the time even when tracking animals and birds at high speed. With the teleconverter, I was totally dismayed at how soft the images were and there was loss of color depth. I tried shooting stopped at multiple apertures, but not too tight so as to avoid lens diffraction and I still had trouble. I did not try to fine tune the AF for this lens combination and maybe I should have though.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Using the Kenko on my Nikon D90 with the 70-300mm zoom lenses. Provides added reach without breaking the bank!

Loses an F-stop or 2, but works well. Little slow on the focus for sports pics.

Easily attaches to the Nikon lenses.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

You can't always get what you want. In this case, I got everything I wanted and then some. I read all of the reviews and I made my choice based on what I was interested in capturing. I am using it for taking pictures of the moon with my AF VR-Nikkor 80-400mm and it delivered wonderfully.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I use this TC on my D300 and Nikkor 80-400mm Vr All of functions: AF and VR are working properly and the image quality could be as good as my Nikkor converters which will not AF with this lens

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

bought this with the nikon 80-200 f/2.8 and it works well, haven't seen any problems yet

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Appears to be well made, but when I actually tested it with both Nikon & Sigma lenses, I found that sharpness really suffered. Try it for yourself. This store is good about accepting returns. If you cannot see the loss in sharpness, this converter would be great for you. I was trying to save money. It did not work. Next time I will pay more and stick to Nikon.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I am an avid amateur wildlife photographer, but needed significantly greater reach than my AF-S 70-300 VR provides. I had planned on purchasing the Nikon AF-S 300 F/4D with either the Nikon or Kenko PRO 300 1.4x TC to provide that longer reach while retaining a comparable speed lens with not too much additional weight to lug around. I chose the Kenko TC based on price and generally excellent reviews, with relatively few exceptions. The Kenko is also compatible with my 70-300 lens.

I am using the PRO 300 with my 70-300 pending eventually buying the Nikon prime. But to date I have been quite pleased with the 70-300/PRO 300 TC combination with both my D200 and D500 D-SLRs. I had two primary concerns with using the TC with this lens: auto focus under my typical lighting conditions and reduction in image quality. Recognizing that the 70-300 + TC with a combined f/8 at 420mm, it is one full stop slower than the 300mm prime + TC combo, I have yet to find a subject where AF didn't work. These shots have been primarily daytime birds against various backgrounds. Resolution in terms of lines per picture height have been around 25 -30% better than the equivalent non-TC shot cropped to capture the same image area. Aside from the numbers, I have been really pleased with the images themselves – beautiful!

Of course, the one stop slower lens combination limits action shots in other than relatively good lighting conditions without increasing ISO, with its associated increases in image noise. I have chosen to not push the ISO.

Can't wait to try it with the 300 F/4 prime – if and when my budget allows. But for now I'm a very happy camper!

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I just upgraded to Nikon's TC-14E II and the difference is obvious. The Teleplus performs well on close subjects. I think it's a good option if you have a third party lens, e.g., Sigma. If you are shooting wildlife at a distance, the image quality is too soft. If you spent $$$ on a Nikon lens, to go with the Kenko makes no sense just to save $250.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I use this on my AF 80-200 f2.8, and my AF 300 f4 to get a little extra reach. Auto focus works fine on both, a little slower and searches at times, but acceptable. In my initial testing, I shot birds flying with a cloudy background. If the bird moved out of the frame, the lens necessarily searches to focus on the clouds and takes a little while longer than anticipated to re-find the bird once I get it in frame.

Had a couple shots that exposure was way off (maybe 2 out of 100 shots). Not sure if that was a function of me or the converter mis-reading data. One was in a burst of shots, so that one shouldn't have been me.

While the extra reach is nice (especially at this price), I found the shots to be softer than I'd like. In my initial test runs, certain details of the birds were lacking with the converter on. I was further away than I wanted and to be honest, even with the converter off, my shots weren't as tack sharp as I had hoped for(particularly once I had to crop in in post-production). I may have just been too far away. Need to test with closer subjects, just haven't been able to get to it. Haven't tested all aperatures either. Most shots were done near wide-open due to lower lighting with the clouds. May sharpen up at smaller aperatures.

Contemplated returning it, but decided to keep it. Gives me extra reach, auto focuses with my lenses, wasn't overly expensive, doesn't take up much room. Might come in handy later, especially if proves to be sharper on closer subjects.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I carry a Nikon F5 and use two lenses bought from B&H Photo. One is a Nikon AF28-300VRED and the other a Nikon AFVR80-400ED. I use the Kenko 1.4 Teleplus Pro 300 teleconverter for wildlife images. I needed the extra reach to capture images last month in Yellowstone National Park. Moose, bear, bison, elk and wolves images were taken using the Nikon AFVR80-400ED and the Kenko teleconverter. I am extemely pleased with the results.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

AF works good on my Nikon AF-S 70-300 mm 1:4.5-5.6

my camera is a Nikon d90
regards
Kees Nix
The Netherlands

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Unit is suppose to still allow your telephoto lens Auto Focus to function as normal, but my experience is that it only works sometimes and is very slow to perform.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I rented a Nikon 1.4 teleconverter - used it with my 70-200 Nikon lens and loved it - I then read about the Kenko 1.4 and decided to give it a try. Bought it from B&H - rcvd it ASAP - frankly I think it works just as well as the Nikon - and am able to use it with more lenses than I could use the Nikon teleconverter.
I have used it with several Nikon lenses - no probs with autofocus at all.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I used it with my D-300 & 70-200 lens. When I put the teleconverter on my camera the Low Battery comes on even with 2 fully charged batteries. So I returned it for a new one & now I have the same problem again.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Using the camera on a tripod or hand holding it gave my 70-300 lens the reach I wanted. However I was Very disappointed that the auto focus does not work in the camera when using the telecoverter with my AF lens. I didn't find out till I couldn't autofocus and then read it in the insert instructions which came with it.

I will still use it but must manual focus which us o.k. With stationary subjects.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I've seen some threads on various forums discussing Kenko teleconverters and Nikkor DX 17-55 f/2.8 on a FX body. Consensus was inconclusive so I wanted to see for myself. The Nikon teleconverters are incompatible with this lens.

I ordered a Kenko 1.4x teleplus PRO 300 DGX teleconverter from B&H. Came in just a few days through Purolator ground.

A very quick 10 shot test shows that this product performs as advertised. The build quality is nice and solid, metal body and lens flanges. Nice fit and finish to the quality plastic barrel, nice even glass coatings, a very professional looking product.

Mounted my 17-55 f/2.8 AFS DX on my D700 and had a go.

When that lens is mounted directly to the d700 there is vignetting at all focal lengths and all apertures, and especially so with the petal lens hood.

With the teleconverter:

The mounted lens feels solid and secure, no wiggles.
The lens does not vignette at any aperture or focal length, even with the lens hood.
The teleconverter has contacts for lens and body and it has a chip in it. All camera and lens functions work just fine.

The camera now reports this lens as having a f/4.0 max aperture and will meter as such. You don't have to fool the meter or use exposure compensation to account for the reduced 1 stop aperture. Exif data shows the increased length and reduced aperture. A shot at max aperture and lens set to 55 mm gets reported in the exif as f4 and 77 mm. However the lens model gets reported as 17-55 f/2.8.

Image quality does not seem to be adversely affected, but I didn't do any 400% pixel peeping. At 100% crop this teleconcerter is essentially transparent, to me anyway.

It also works just fine with 18-77 variable aperture AFS DX.

I tried it with my 70-200 f/2.8 VR-I (not the new VR-II), all works just fine, as above, but with a pleasant little surprise. The corner sharpness of the image is a little better with the teleconverter. This lens now has the same great performance on FX as it did on my DX bodies but with a one stop loss of maximum aperture, supposedly because I am now only using the central area of the projected image. Don't read more into this than there is. The 70-200 VR-I on FX is a fantastic lens, teleconverter or not. If you have this lens and a new FX body don't go selling it off at a discount because some pixel peeper on a forum says it doesn't cut the mustard. Not true!

So far so good!

Pat

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I mainly take pictures of wildlife and often it is impossible to get physically close so high-strength telephoto lenses are a requirement.
Good lenses are also quite expensive though and for those of us on a budget a couple thousand USD on a lens is difficult.

This teleconverter however can give an inexpensive mid-range zoom much more useful range with a minimal impact on aperture (1 stop) and image quality.
It also works well with far more lenses than Nikon's own teleconverters.

There are caveats, of course- a lens that fully extended is f5.6 or more will probably have difficulty with autofocus, at least on a D90; there is also some image softening when using the tc.
But the extra range you get more than compensates for the few issues and in general any TC will have the same exact issues. (Note that Nikon's TC's don't tend to soften as much- and work only on Nikon 2.8 lenses, AND cost twice as much.)

If you are on a budget and need a teleconverter this is a good one.
If you want to use some non-F2.8 Nikon lenses with a teleconverter this is a good choice.
If you can afford to buy all Nikon stuff and f2.8 lenses- I am jealous.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I mostly shoot wildlife, often at ponds or lakes where it is impossible to get physically close.
I am an amateur on a tight (for photography!) budget.

I have a Sigma 70-300 which does well and an 80s vintage Nikon AF 70-210 F4 which is excellent, but neither gets me as close as I would like.
I simply cannot afford the equipment that would get both the quality and shots I would really like- but adding this teleconverter gets me closer at a relatively low cost.

Any teleconverter will require better light than a dedicated lens, and the fact that this TC works with lenses with a max aperture of F4 makes this even more noticeable- but it still makes it POSSIBLE to use such lenses with a teleconverter!

Without spending the money there is no way to get the quality of top-notch equipment and lenses that are designed for a single focal range, but for those who can't afford the cost (or WEIGHT!) of 200mm, 300mm and 400mm zooms in their camera bag, this teleconverter may be a big help.
*It works well with most lenses (at least on a Nikon D40 and D90.)
*Relatively low cost
*Decent image quality (worst at edges)
*It DOES need bright light to work well, but increasing iso can help with that a great deal. And ANY teleconverter requires better light.

The Kenko Pro 300 DGX 1.4 is a great addition to my camera bag and will be getting a serious workout this year.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

After reading many reviews for the Nikon 80-400 AF VR 4.5-5.6 lens I was concerned that a photo-multiplier would not work with it, or at least not well. When I went to purchace my lens on the B&H website there was a section for accessories I might be interested in. The Teleprus PRO 300 DGX 1.4 AF was on the list. I read the reviews and decided that for the price it was worth the risk to try. I have been amazed at how well it works. Although as with all teleconverters you lose a few f-stops, the thing really works. I have used it sparingly in the few weeks I have owned it, but it has performed beyond my expectations.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Let me preface by saying that 4 stars may go up. The Kenko 1.4 tele for the Nikon mount works with auto-focus on the new D7000 body and the old Nikkor 80x400 AF VR. It is sharp as a tack on a lower zoom but it is terribly hard to focus manually zoomed out at 400mm. Perhaps this is my diopter setting on the body, but I have really worked on the fine-tuning there. At increased ranges, the tele is just shooting a bit blurry on enlargements. This is what often must be done with small birds at a distance. Be warned however y'all that when they say that the 1.4 will cost you 1 f-stop, it is at 80mm on this lens. F4 goes to f5.6 at 800mm. By the time you zoom out and the lens will shoot f5.6, the tele will not let you shoot below f8. If I can fine-tune the manual focusing issue, the enhanced ISO of the D7000 will make up for it. That was my plan from the beginning. I'm shooting a bit fuzzy though at extended ranges at 400mm.
Ray Swagerty
Charleston, SC

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I purchased this teleconverter for my Nikkor 80-200mm f/2.8D ED AF zoom lens on my d700 after reading reviews of how well it worked with this lens for sport photography. My 80-200mm is tack sharp, dead on pretty much all the time even when tracking animals and birds at high speed. With the teleconverter, I was totally dismayed at how soft the images were and there was loss of color depth. I tried shooting stopped at multiple apertures, but not too tight so as to avoid lens diffraction and I still had trouble. I did not try to fine tune the AF for this lens combination and maybe I should have though.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Using the Kenko on my Nikon D90 with the 70-300mm zoom lenses. Provides added reach without breaking the bank!

Loses an F-stop or 2, but works well. Little slow on the focus for sports pics.

Easily attaches to the Nikon lenses.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

You can't always get what you want. In this case, I got everything I wanted and then some. I read all of the reviews and I made my choice based on what I was interested in capturing. I am using it for taking pictures of the moon with my AF VR-Nikkor 80-400mm and it delivered wonderfully.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I use this TC on my D300 and Nikkor 80-400mm Vr All of functions: AF and VR are working properly and the image quality could be as good as my Nikkor converters which will not AF with this lens

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

bought this with the nikon 80-200 f/2.8 and it works well, haven't seen any problems yet

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Appears to be well made, but when I actually tested it with both Nikon & Sigma lenses, I found that sharpness really suffered. Try it for yourself. This store is good about accepting returns. If you cannot see the loss in sharpness, this converter would be great for you. I was trying to save money. It did not work. Next time I will pay more and stick to Nikon.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I am an avid amateur wildlife photographer, but needed significantly greater reach than my AF-S 70-300 VR provides. I had planned on purchasing the Nikon AF-S 300 F/4D with either the Nikon or Kenko PRO 300 1.4x TC to provide that longer reach while retaining a comparable speed lens with not too much additional weight to lug around. I chose the Kenko TC based on price and generally excellent reviews, with relatively few exceptions. The Kenko is also compatible with my 70-300 lens.

I am using the PRO 300 with my 70-300 pending eventually buying the Nikon prime. But to date I have been quite pleased with the 70-300/PRO 300 TC combination with both my D200 and D500 D-SLRs. I had two primary concerns with using the TC with this lens: auto focus under my typical lighting conditions and reduction in image quality. Recognizing that the 70-300 + TC with a combined f/8 at 420mm, it is one full stop slower than the 300mm prime + TC combo, I have yet to find a subject where AF didn't work. These shots have been primarily daytime birds against various backgrounds. Resolution in terms of lines per picture height have been around 25 -30% better than the equivalent non-TC shot cropped to capture the same image area. Aside from the numbers, I have been really pleased with the images themselves – beautiful!

Of course, the one stop slower lens combination limits action shots in other than relatively good lighting conditions without increasing ISO, with its associated increases in image noise. I have chosen to not push the ISO.

Can't wait to try it with the 300 F/4 prime – if and when my budget allows. But for now I'm a very happy camper!

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I just upgraded to Nikon's TC-14E II and the difference is obvious. The Teleplus performs well on close subjects. I think it's a good option if you have a third party lens, e.g., Sigma. If you are shooting wildlife at a distance, the image quality is too soft. If you spent $$$ on a Nikon lens, to go with the Kenko makes no sense just to save $250.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I use this on my AF 80-200 f2.8, and my AF 300 f4 to get a little extra reach. Auto focus works fine on both, a little slower and searches at times, but acceptable. In my initial testing, I shot birds flying with a cloudy background. If the bird moved out of the frame, the lens necessarily searches to focus on the clouds and takes a little while longer than anticipated to re-find the bird once I get it in frame.

Had a couple shots that exposure was way off (maybe 2 out of 100 shots). Not sure if that was a function of me or the converter mis-reading data. One was in a burst of shots, so that one shouldn't have been me.

While the extra reach is nice (especially at this price), I found the shots to be softer than I'd like. In my initial test runs, certain details of the birds were lacking with the converter on. I was further away than I wanted and to be honest, even with the converter off, my shots weren't as tack sharp as I had hoped for(particularly once I had to crop in in post-production). I may have just been too far away. Need to test with closer subjects, just haven't been able to get to it. Haven't tested all aperatures either. Most shots were done near wide-open due to lower lighting with the clouds. May sharpen up at smaller aperatures.

Contemplated returning it, but decided to keep it. Gives me extra reach, auto focuses with my lenses, wasn't overly expensive, doesn't take up much room. Might come in handy later, especially if proves to be sharper on closer subjects.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I carry a Nikon F5 and use two lenses bought from B&H Photo. One is a Nikon AF28-300VRED and the other a Nikon AFVR80-400ED. I use the Kenko 1.4 Teleplus Pro 300 teleconverter for wildlife images. I needed the extra reach to capture images last month in Yellowstone National Park. Moose, bear, bison, elk and wolves images were taken using the Nikon AFVR80-400ED and the Kenko teleconverter. I am extemely pleased with the results.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

AF works good on my Nikon AF-S 70-300 mm 1:4.5-5.6

my camera is a Nikon d90
regards
Kees Nix
The Netherlands

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Unit is suppose to still allow your telephoto lens Auto Focus to function as normal, but my experience is that it only works sometimes and is very slow to perform.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I rented a Nikon 1.4 teleconverter - used it with my 70-200 Nikon lens and loved it - I then read about the Kenko 1.4 and decided to give it a try. Bought it from B&H - rcvd it ASAP - frankly I think it works just as well as the Nikon - and am able to use it with more lenses than I could use the Nikon teleconverter.
I have used it with several Nikon lenses - no probs with autofocus at all.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I used it with my D-300 & 70-200 lens. When I put the teleconverter on my camera the Low Battery comes on even with 2 fully charged batteries. So I returned it for a new one & now I have the same problem again.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

Using the camera on a tripod or hand holding it gave my 70-300 lens the reach I wanted. However I was Very disappointed that the auto focus does not work in the camera when using the telecoverter with my AF lens. I didn't find out till I couldn't autofocus and then read it in the insert instructions which came with it.

I will still use it but must manual focus which us o.k. With stationary subjects.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I've seen some threads on various forums discussing Kenko teleconverters and Nikkor DX 17-55 f/2.8 on a FX body. Consensus was inconclusive so I wanted to see for myself. The Nikon teleconverters are incompatible with this lens.

I ordered a Kenko 1.4x teleplus PRO 300 DGX teleconverter from B&H. Came in just a few days through Purolator ground.

A very quick 10 shot test shows that this product performs as advertised. The build quality is nice and solid, metal body and lens flanges. Nice fit and finish to the quality plastic barrel, nice even glass coatings, a very professional looking product.

Mounted my 17-55 f/2.8 AFS DX on my D700 and had a go.

When that lens is mounted directly to the d700 there is vignetting at all focal lengths and all apertures, and especially so with the petal lens hood.

With the teleconverter:

The mounted lens feels solid and secure, no wiggles.
The lens does not vignette at any aperture or focal length, even with the lens hood.
The teleconverter has contacts for lens and body and it has a chip in it. All camera and lens functions work just fine.

The camera now reports this lens as having a f/4.0 max aperture and will meter as such. You don't have to fool the meter or use exposure compensation to account for the reduced 1 stop aperture. Exif data shows the increased length and reduced aperture. A shot at max aperture and lens set to 55 mm gets reported in the exif as f4 and 77 mm. However the lens model gets reported as 17-55 f/2.8.

Image quality does not seem to be adversely affected, but I didn't do any 400% pixel peeping. At 100% crop this teleconcerter is essentially transparent, to me anyway.

It also works just fine with 18-77 variable aperture AFS DX.

I tried it with my 70-200 f/2.8 VR-I (not the new VR-II), all works just fine, as above, but with a pleasant little surprise. The corner sharpness of the image is a little better with the teleconverter. This lens now has the same great performance on FX as it did on my DX bodies but with a one stop loss of maximum aperture, supposedly because I am now only using the central area of the projected image. Don't read more into this than there is. The 70-200 VR-I on FX is a fantastic lens, teleconverter or not. If you have this lens and a new FX body don't go selling it off at a discount because some pixel peeper on a forum says it doesn't cut the mustard. Not true!

So far so good!

Pat

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I mainly take pictures of wildlife and often it is impossible to get physically close so high-strength telephoto lenses are a requirement.
Good lenses are also quite expensive though and for those of us on a budget a couple thousand USD on a lens is difficult.

This teleconverter however can give an inexpensive mid-range zoom much more useful range with a minimal impact on aperture (1 stop) and image quality.
It also works well with far more lenses than Nikon's own teleconverters.

There are caveats, of course- a lens that fully extended is f5.6 or more will probably have difficulty with autofocus, at least on a D90; there is also some image softening when using the tc.
But the extra range you get more than compensates for the few issues and in general any TC will have the same exact issues. (Note that Nikon's TC's don't tend to soften as much- and work only on Nikon 2.8 lenses, AND cost twice as much.)

If you are on a budget and need a teleconverter this is a good one.
If you want to use some non-F2.8 Nikon lenses with a teleconverter this is a good choice.
If you can afford to buy all Nikon stuff and f2.8 lenses- I am jealous.

Comments about Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter:

I mostly shoot wildlife, often at ponds or lakes where it is impossible to get physically close.
I am an amateur on a tight (for photography!) budget.

I have a Sigma 70-300 which does well and an 80s vintage Nikon AF 70-210 F4 which is excellent, but neither gets me as close as I would like.
I simply cannot afford the equipment that would get both the quality and shots I would really like- but adding this teleconverter gets me closer at a relatively low cost.

Any teleconverter will require better light than a dedicated lens, and the fact that this TC works with lenses with a max aperture of F4 makes this even more noticeable- but it still makes it POSSIBLE to use such lenses with a teleconverter!

Without spending the money there is no way to get the quality of top-notch equipment and lenses that are designed for a single focal range, but for those who can't afford the cost (or WEIGHT!) of 200mm, 300mm and 400mm zooms in their camera bag, this teleconverter may be a big help.
*It works well with most lenses (at least on a Nikon D40 and D90.)
*Relatively low cost
*Decent image quality (worst at edges)
*It DOES need bright light to work well, but increasing iso can help with that a great deal. And ANY teleconverter requires better light.

The Kenko Pro 300 DGX 1.4 is a great addition to my camera bag and will be getting a serious workout this year.