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Glosgas

100-400 and 2x conveter Equipment question

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Hi,

I have a Sony ILCE-7RM2 and FE 100-400 f/4.5-f/5.6 G OSS.  I'd like to get the 2x converter, however the looking at Sony's compatibility tables the two aren't 100% compatible.
The information provided says:

  • Focal plane phase detection AF cannot be used, so Contrast AF will operate.
  • Aperture values over 64 in the Exposure Setting Guide will not be displayed correctly.

Whilst I'm not too bothered about the second point, I don't fully understand the first.
Does this mean that Auto Focus won't work properly and am I going to be disappointed with the results?

The main purpose I utilise the lens for is wildlife, mainly birds.

Thanks,

 

 

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If you use a 2X tele converter on a lens whose maximum aperture is F 5.6, with a 2X, your max aperture is now only F11. With the kind of limited light coming through the lens, AF is likely to have difficulty finding focus on anything. PDAF needs some light to achieve its phase detection so by having too limited light coming in, the PDAF sensors can not operate properly. This would be even worse as you close down the lens since then, you would limit even more the amount of light coming in and these mirrorless cameras stop down your aperture at your command (not just as you release the shutter)

It was the case before with traditional AF SLR's where when using any lens that had a max aperture of F 4.5, AF was unusable since the AF sensors could not operate. And as was the case with SLR's , they all focused at max aperture (stopping down the lens as you released the shutter)

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4 hours ago, Glosgas said:

Is the 10p-400 and 2x converter combination one that will work with my camera?

The autofocus slows down a little bit at the long end as your at the limit of the AF sensors (f8). I'd go with the 1.4x converter.

Personally i would leave the 2x to the big prime lenses. 

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4 hours ago, DancingMonkeys said:

The autofocus slows down a little bit at the long end as your at the limit of the AF sensors (f8). I'd go with the 1.4x converter.

Personally i would leave the 2x to the big prime lenses. 

That is what they are designed for in the first place

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14 hours ago, Glosgas said:

Is the 10p-400 and 2x converter combination one that will work with my camera?

I'm the proud and happy owner of both the SEL20TC and also the SEL100400GM and achieve very good results on my a9 with this combo. I do however, if the target allows, use manual focussing most of the time, and find the depth of view to be exceptionally shallow at the long end.

Also be aware, that any shakiness of your hands gets exaggerated at such long focal distances. Which is why you are advised to use exposure times shorter than the (reciprocal of the) fourfold of the focal length. For instance: @800mm you should expose for a 1/3200th or shorter, if you go for handheld. As @michelb already mentioned, you're also limited on the aperture end, which in combination makes TCs of any kind most suitable for very well lit situations only.

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