Sigma 2x teleconverter

[Mtnbowhunter]

Hi. I am looking into getting a teleconverter for my nikon 55-300 lens. I am relatively new to photography and am not too sure if this is a good choice. I am looking to get more telephoto range. Will this make it a 110-600? Any help or insight will be greatly appreciated.

 

[SCraig]

It will double the focal length of the lens from 55-300 to 110-600. You will also lose two full stops of light through the lens changing it from an f/4-5.6 lens into an f/6.7 to f/9.5 lens. In addition you will lose some amount of image quality, how much depends on how optically good the teleconverter is. On most cameras you will also lose the ability to autofocus since most cameras don't autofocus well at apertures above f/5.6.

In my personal opinion, unless you get a very good quality 2x teleconverter you are better off without one. I have a bad one that I wouldn't use for a paperweight. I know some guys using the excellent Nikon TC-IIE and it works very well, but not with all lenses.

If you drop your requirements down some there are other alternatives. A 1.4x teleconverter gives you 40% more length (77mm to 420mm), you will only lose 1.4 stops of light (which will allow your autofocus to still work in most conditions), and the loss in image quality is less. I use a Kenko Pro series 1.4x TC frequently and it works very well (notice that it is the PRO series and not the "Standard" series which, in my opinion, are terrible).

 

[gsgary]

Don't do it on a zoom like that your photos will turn to mush, 2X converters are only good on good prime lenses

 

[orb9220]

As pointed out the 2x teleconverter or any of them are No-Go on slower variable f-stop lenses. Tried just a 1.4x on my 70-300vr for giggles. Pretty much lost AF and Impact to Image IQ took a major hit.

Teleconverts are designed for fixed f4 or faster like f2.8 lenses Zooms or Primes. It worked quite well on my Nikon 80-200 f2.8 AF-D and only took a 1-stop hit in speed meaning the f2.8 became a f4 and gave me 280mm working focal length. And hits in Image IQ were negligible.
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[SCraig]

As pointed out the 2x teleconverter or any of them are No-Go on slower variable f-stop lenses. Tried just a 1.4x on my 70-300vr for giggles. Pretty much lost AF and Impact to Image IQ took a major hit.

Teleconverts are designed for fixed f4 or faster like f2.8 lenses Zooms or Primes. It worked quite well on my Nikon 80-200 f2.8 AF-D and only took a 1-stop hit in speed meaning the f2.8 became a f4 and gave me 280mm working focal length. And hits in Image IQ were negligible.
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I disagree with that in part. A lot of the autofocus issues are within the body itself since the TC cuts down on the light entering the body. Some bodies will autofocus better with less light than other bodies will, however the rule of thumb is to start expecting problems around f/5.6. I use my Sigma 1.4x TC on my 70-300 f/4-5.6 Nikkor lens and my 150-500 f/5-6.3 Sigma lens frequently. I never have autofocus issues on my D7000 when using the Nikon lens and as long as there is good light the Sigma will autofocus fine.

 

[Patrice]

It will double the focal length of the lens from 55-300 to 110-600. You will also lose two full stops of light through the lens changing it from an f/4-5.6 lens into an f/6.7 to f/9.5 lens.

An change of two stops on a f/4 to f/5.6 lens becomes f/8 to f/11.

2 stops from f/4 is f/8.
2 stops from f/5.6 is f/11.

So, putting a 2x TC on a f/4-5.6 lens makes it a very slow f/8-11 lens.

 

[SCraig]

It will double the focal length of the lens from 55-300 to 110-600. You will also lose two full stops of light through the lens changing it from an f/4-5.6 lens into an f/6.7 to f/9.5 lens.

An change of two stops on a f/4 to f/5.6 lens becomes f/8 to f/11.

2 stops from f/4 is f/8.
2 stops from f/5.6 is f/11.

So, putting a 2x TC on a f/4-5.6 lens makes it a very slow f/8-11 lens.

You are correct. I don't know where I came up with those numbers, but thanks for correcting me.