Lens Focal Length Conversion table:

We calculated the resulting focal length when using the Extender EF1.4x II or Life Size converter EF and the Canon EOS 300D which has a crop factor of 1.6x.

Normal focal length Extender EF1.4x II or Life Size converter EF + AF (Y/N) 300D crop factor (1.6x) EF1.4x I or Life Size EF + 1.6x crop factor
EF17-40 f/4L USM X (N) EF27-64 f/4 L USM X (N)
EF50 f/2.5 Compact Macro EF70 f/3.5 Compact Macro(Y) EF80 f/2.5 Compact Macro EF112 f/3.5 Compact Macro (Y)
EF70-200 f/4L USM EF98-280 f/5.6L USM (Y) EF112-320 f/4 L USM EF156.8-448 f/5.6L USM (Y)
EF28-105 f/3.5-4.5 USM X (N) EF44.8-168 f/3.5-4.5 USM X (N)
EF 28-135 f/4.5-5.6 IS USM X (N) EF44.8-216 f/4.5-5.6 IS USM X (N)
EF35-350 f/4.5-5.6L USM X (N) EF56-560 f/4.5-5.6L USM X (N)
EF300 f/4L IS USM EF420 f/5.6L IS USM EF480 f/4L IS USM EF672 f/5.6L IS USM
EF100-400 f/4.5-5.6L IS USM EF140-560 f/6.7-8L IS (N*+) EF460-640 f/4.5-5.6L IS USM EF224-896 f/6.7-8L IS (N*+)
EF400 f/5.6L USM EF560 f/8L (N*) EF640 f/5.6L USM EF896 f/8L (N*)
Cosina EF19-35 f/3.5-4.5 X (N) Cosina EF30-56 f/3.5-4.5 X (N)
Sigma 75-300 f/4.5-5.6 DL X (N) Sigma 120-480 f/4.5-5.6 DL X (N)
EF28-80 f/3.5-5.6 III USM X (N) EF44.8-128 f/3.5-5.6 III USM X (N)
EF-S18-55 f/3.5-5.6 X (N) EF-S29-88 f/3.5-5.6 X (N)
EF75-300 f/4-5.6 III USM X (N) EF120-480 f/4-5.6 III USM X (N)

*With the EOS-1v and EOS-3, AF is possible with the centre focusing point.
+The Image Stabilizer does not operate with the following cameras: EOS 650, 620, 630/600, RT, 700, 750, 850, EOS-1, A2/A2E, 10s, Elan, Rebel/Rebel S, Rebel II/Rebel SII.