Lens (Extender) Question

[ccougar]

Would any benefit be gained by using a series III extender (x1.4 or x2.0) on a series I lens opposed to a series II extender - specifically an EF 500mm f/4 IS USM?

[Skirball]

The III is claimed to be slightly sharper, and the AD glass should reduce CA.  How much, and if it's noticable I cannot say.  It will not, however, speed up the AF.

It's a very popular lens to use with an extender, I'm sure you can find someone doing a comparison online.

[ebiggs1]

The series number of the "converter" is not related to the series of the given lens.  They are two seperate lenses.

I don't care for adapters but I have about 6 or 7 of them.  I guess I can't justify that statement of not liking them! 

I don't have the newest, III, version and I am not likely to buy any.  What I can't really get around is the f-stop penalty.  You usually use these things on a main lens that is fairly slow in the first place and can not afford to give up any light.

That said I have used the 1.4x II on my 300mm f2.8 (first series) and it works very well.  Also the 1.4x II on my 70-200mm f2.8  II zoom, very good, but in these cases you are only moving to f4.

[Skirball]

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@ebiggs1 wrote:

The series number of the "converter" is not related to the series of the given lens. 

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That's not exactly correct.  In fact I believe Canon even advertised that you need the new "Series II" Super Telephotos in order to benefit from the increased AF speed.  When Canon released the Series III extenders they also updated the 300mm, 400mm, 500mm, and 600mm primes to a Mark II, specifically to work with the Series III extender and provide faster AF speeds.  I'm sure they did these 4 lenses since these are the ones usually used with extenders.  The new AF technology wasn't backwards compatible with older models (most of which where Mark I), but new models such as the 70-200 II would have the new electronics.  So in a sense there was a correlation between the Series III extender and Mark II telephotos.  I assumed this is what the OP was referring to.

[MikeSowsun]

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Skirball wrote:

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That's not exactly correct.  In fact I believe Canon even advertised that you need the new "Series II" Super Telephotos in order to benefit from the increased AF speed.  When Canon released the Series III extenders they also updated the 300mm, 400mm, 500mm, and 600mm primes to a Mark II, specifically to work with the Series III extender and provide faster AF speeds.  I'm sure they did these 4 lenses since these are the ones usually used with extenders.  The new AF technology wasn't backwards compatible with older models (most of which where Mark I), but new models such as the 70-200 II would have the new electronics.  So in a sense there was a correlation between the Series III extender and Mark II telephotos.  I assumed this is what the OP was referring to.

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No, the Canon 70-200mm 2.8 IS II is not one of the new "Series II" Super Telephoto lenses so it not compatible with the new AF technology designed into the Series III teleconverters. 

There is slightly better optics with the 1.4x III over the 1.4x II and most say noticeably better optics with the 2x III over the 2x II so it still may be worth paying extra for the Series III with your older EF 500mm f/4 IS USM.  

[ebiggs1]

"There is slightly better optics with the 1.4x III over the 1.4x II and most say noticeably better optics with the 2x III over the 2x II ..."

While what you say is probably true, after the print is made I doubt anyone except the most serious pixel peper will see a difference.  When it comes down to it, I suppose tele adapters have a place but, you are really saying which one makes the end product less poor.   I do use the 1.4x II very sparringly.

However, I don't have any of the latest versions to test for myself. 

And, I have no intention of buying any version III's.