Newbee Question CANON 70-300 F4-5.6 IS

[Terry T]

Hi All
Has anybody used the CANON 70-300 F4-5.6 IS with the Kenko 1x4 Converter and how are the results.
I was about to purchase both on line and I received the following reply from the store it has confused me.

Hi
I cant recommend this converter with the lens in question, you will lose one stop of light by putting the converter on and I also believe you lose the ability to use the image stabilizer.

Many Thanks Terry

[eeyore]

Originally Posted by Terry T

Hi All
Has anybody used the CANON 70-300 F4-5.6 IS with the Kenko 1x4 Converter and how are the results.
I was about to purchase both on line and I received the following reply from the store it has confused me.

Hi
I cant recommend this converter with the lens in question, you will lose one stop of light by putting the converter on and I also believe you lose the ability to use the image stabilizer.

Many Thanks Terry

the maximum apperture of this lens is f5.6 at the long end so if you lose one stop of light as you do with a 1.4tc then it will be effectively an f8 lens - this will make the autofocus struggle in all but the brightest light and possibly the electrical contacts in the tc will not allow the is to function either.

personally i'd go with the sigma 135-400 which is arround the same price and learn to live without IS or save up for a canon 100-400 IS (commonly known as the pump)

[Interpreter]

Why wouldn't the IS work? This is part of the lens and should start once the shutter button is pressed half way down. I do not know about this for certain, but I haven't seen anything about this listed under the Canon 1.4 converter. At these focal lengths a solid tripod would be needed so perhaps the IS is not necessary.

[eeyore]

Originally Posted by Interpreter

Why wouldn't the IS work? This is part of the lens and should start once the shutter button is pressed half way down. I do not know about this for certain, but I haven't seen anything about this listed under the Canon 1.4 converter. At these focal lengths a solid tripod would be needed so perhaps the IS is not necessary.

I dont know for certain that it wont work but IS requires power from the camera batteries so if the electrical contacts arent there it is going to be as dead as the proverbial dodo

[Interpreter]

Canon, I believe, publish a list of lenses which are suitable for use with the converter. By this I assume that lenses which are not listed are not suitable. Whether or not third party converters are the same, I do not know.

[Terry T]

Many thanks for your replies
Terry

[Interpreter]

I knew somebody had information on which lenses were suitable for use with the Canon extenders. Here it is:-

Canon EF 1.4X-
The effective aperture of the lens is increased by one stop. Autofocusing does not operate if the effective maximum aperture is greater than f/5.6 (greater than f/8 on the EOS 1V and EOS 3).
Features
Dust and moisture resistant construction
Extends the master lens focal length by 1.4x
Minimum loss of lens performance
Reduces inner reflection for higher image quality

Canon EF 2X-
The effective aperture of the lens is increased by one or two stops respectively. Autofocusing does not operate if the effective maximum aperture is greater than f/5.6 (greater than f/8 on the EOS 1V and EOS 3).

Features
Dust and moisture resistant construction
Extends the master lens focal length by 2x
Minimum loss of lens performance
Reduces inner reflection for higher image quality

Both Extenders Compatible with the following lenses:
EF135mm f/2 L USM
EF180mm f/3.5 L MACRO USM
EF200mm f/1.8L USM
EF200mm f/2.8 L II USM
EF300mm f/2.8 L IS USM
EF300mm f/4 L IS USM
EF400mm f/2.8 L IS USM
EF400mm f/5.6 L USM
EF500mm f/4.5 L USM
EF500mm f/4 L IS USM
EF600mm f/4 L USM
EF600mm f/4 L IS USM
EF1200mm f/5.6 L USM
EF70-200mm f/2.8 L USM
EF70-200mm f/2.8 L IS USM
EF70-200mm f/4.0 L USM
EF100-400mm f/4.5-5.6 L IS USM

I assume that if your lens isn't listed you are on your own: it may or may not work. I also assume that third party manufacturer's extenders are at least of the same quality and would work in the same manner. If the Canon extender works, so should theirs. This may not be a correct assumption.
Your 70-300 lens is not listed.

[Boddie]

Maybe I have read it wrong but he is enquiring about the Kenko and not the Canon converter

[eeyore]

the canon converter is only compatible with the L series lenses because of the way it is constructed - however as bod notes this is a read herring as the enquiry was about the kenko

My experience is that the 70-300mm wont work well with any TC if you want the AF to function - whether you lose the IS is debatable as it depends on the contacts in the TC but i would give it the swerve anyway as although Autofocus isnt absolutely necessary loosing it will put you at a major disadvantage.

[Interpreter]

Originally Posted by Boddie

Maybe I have read it wrong but he is enquiring about the Kenko and not the Canon converter

Yes he made that quite clear. If you read my assumptions you will see that I have assumed that the quality and operation of third party manufacturers extenders are the same. As noted earlier if the connections are the same, I cannot see why the IS should not work.

Pressing the shutter release half way down, causes the automatic focus to operate and also starts the IS. Canon suggest waiting for around 1 second before pressing the shutter button fully down to allow the IS to stabilise. The IS is part of the lens and not the camera. The only part that the camera plays is via the shutter release button, which starts the system rolling. So it should work. The Canon extender is the only one for which I have information and therefor is used as an example only.

I would also suggest that one of the main suppliers for Canon be contacted to see if they would bring their price down so that a matched system could be obtained at a price closer to that of the third party manufacturers extender. You never know.