Why is the EF 1.4x extender compatible only with lenses 135mm and over?

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e30jean Junior Member • Posts: 29
Why is the EF 1.4x extender compatible only with lenses 135mm and over?

Hi,

What is the reason behind extender working only on 135+ lenses?

https://www.usa.canon.com/internet/portal/us/home/products/details/lenses/ef/extenders/extender-ef-1-4x-iii

Focal Length & Maximum Aperture Magnification: 1.4x

Lens Construction 7 elements in 3 groups

Note
This lens is only compatible with fixed focal length L-series lenses 135mm and over, as well as the EF 70-200/2.8L, EF 70-200/2.8L IS, EF 70-200/4L, and EF 100-400/4.5-5.6L.

What's the technical reasoning for this? What would happen if you mount an 85mm or 100mm lens on it?

thank you.

 e30jean's gear list:e30jean's gear list
Canon EOS 60D Canon 6D Mark II Canon EF 85mm F1.8 USM Canon EF 200mm f/2.8L II USM Canon EF 100mm F2.8L Macro IS USM +1 more
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