Kenko extension tubes.

[Jose Luis Silva]

Hello,

Does someone here use the "KENKO" extension tubes and can give your opinion about them, concerning image quality, for a Canon user like me?

Thanks in advance!
José Luis

[sluger020889]

Greetings,

I use the kenko 1.4x with my Nikkor 300 F4 AF-S. Its a great little piece of kit and really gives you a little extra reach, turning the 300 into a 420 F5.6.

This shot here is almost no crop and taken from about a mile away (crappy planning on my part lol).

http://jetphotos.net/viewphoto.php?id=6453519&nseq=21

I only see a drop in quality on hot and humid days, it can get a little soft and distorted, but I believe that's to be expected with any extender. Feel free to browse my photos, all photos taken with the extender say so in the equipment field.

What lens do you plan on using it with?

Joey

[Jose Luis Silva]

Greetings,

I use the kenko 1.4x with my Nikkor 300 F4 AF-S. Its a great little piece of kit and really gives you a little extra reach, turning the 300 into a 420 F5.6.

This shot here is almost no crop and taken from about a mile away (crappy planning on my part lol).

http://jetphotos.net/viewphoto.php?id=6453519&nseq=21

I only see a drop in quality on hot and humid days, it can get a little soft and distorted, but I believe that's to be expected with any extender. Feel free to browse my photos, all photos taken with the extender say so in the equipment field.

What lens do you plan on using it with?

Joey

Hello Joey,

Many thak about your reply. Also I would like to congrat you for an very nice pciture.

The lens I intend to use the "KENKO" tubes is the CANON 70-200mm F/4-5.6 L USM.

And I will go take a view on your photos of course!

Regards
José Luis

[seahawk]

An extender on a 5.6 zoom lense might not work properly. The AF will be seriously challenged.

[Jose Luis Silva]

An extender on a 5.6 zoom lense might not work properly. The AF will be seriously challenged.

Thanks Stefan,

So what will be your advice? Don't buy it? Your help is very needed about this.

Thanks for your time and patience but an advise for who knows better abt this will be very nice!

Regards
José Luis

[seahawk]

That is a hard question. You will end up with a 98-280 5.6-6.3 lens. And if that is better then the typical 70-300 5.6 is more then doubtful. On the other hand a good Canon 70-300 costs more then the extender and would not really make sense next to your current lens.
On the other hand it already costs 1/3 of a Sigma 120-400 DG OS 5.6, which would give you much more range and be a good partner for your Canon under sunny conditions. I would most likely go for that option. Or you could try to pick up a used Sigma 135-400 DG.

[Jose Luis Silva]

Stefan,

Thanks again. Your reply is clear as water! Thanks a lot.

My best regards to you.

José Luís

[Simpleboy]

Im not aware of a 70-200 f4-5.6L lens, just simply many 70-200s of fixed aperture.

that being said, are you talking about an extender for increasing magnification or simply an extension tube used for macro photography?

[Jose Luis Silva]

Hi,

Simpleboy, the intention is for increasing magnification.

Thanks

[Taliesin]

You will end up with a 98-280 5.6-6.3 lens.

Actually, you end up with a 98-280 5,6-8 Lens, unless you are using more of the front lens with the extension than without, which would be very odd.

[seahawk]

You might be right, I always used an extender only with constant aperture glass.

[Taliesin]

Even with constant aperture, the extender multiplies with the aperture. Assuming that the same opening is used, if you multiply focal length by 1,4 the aperture will multiply with 1,4 as well.
At least that was the case for the 1,4 extender I considered for my 70-300mm F4-5,6. It would have turned into an 98-420mm F5,6-8

[seahawk]

The one I have is working as a 6.3 on a 5.6 lens. It looses one aperture setting.

[Taliesin]

But one aperture is 1,4

Lets assume you have a 400mm lens with a 100mm front lens, that makes it an F4. Now you use your 1,4 extender and have a 560mm lens. In order to catch the same amount of light, you would now need a 140mm front lens. Because area is r²*pi or (D/2)²*pi, you only capture half the light you would with an F4 lens, or in other words, your image sees half the light per pixel, so it needs twice the exposure for the same effect.
Thus, 1,4 is called one aperture.
The step from 5,6 to 6,3 is called one third of an aperture. Read through here for more info

[seahawk]

You are right. That means you get a 280mm 8.0 in the end if you start with ANON 70-200mm F/4-5.6 L USM. Now that is practically useless.