Hola de nuevo, en principio solucionado, leyendo y releyendo, en el manual que se incluye en el archivo
"magiclantern-2011Oct14.550D.60D.600D.50Dalpha0.zip" pone que para la 50d hay que hacer la tarjeta boteable:
Step 1. Preparing your camera
∙ Fully charge your battery.
∙ Remove any accessories from your camera (such as battery grip or external flash).
∙ Make sure you have a simple SD/SDHC card for first-time install (SDXC will not work).
∙ Make sure you have a SD card reader; you won’t be able to copy ML files via USB cable.
∙ Upgrade your Canon firmware:
– for Canon 550D / T2i / Kiss X4: upgrade to firmware 1.0.9
– for Canon 60D: upgrade to firmware 1.1.0
– for Canon 600D / T3i / Kiss X5: upgrade to firmware 1.0.1
– for Canon 50D: upgrade to firmware 1.0.8
∙ Rotate your mode dial to Manual (M) position.
∙ Restore your camera to default settings (Clear all camera settings, Wrench 3 menu)
Step 2. Installation
∙ Format the SD card from the camera (low level, from Wrench 1 menu).
∙ Unzip all the files from from Magic Lantern zip archive on the root of your SD card.
∙ Launch the Firmware Update process. For this, start the camera and select Firmware
ver 1.x.x from the Wrench 3 menu.
∙ The installer (ml-*.fir) will perform two actions:
– enables the BOOTDISK flag in NVRAM by calling the EnableBootDisk() function
from Canon firmware. This change is persistent, but it can be reverted easily.
– (for all cameras except 50D) makes the card bootable, by writing the BOOTDISK and
EOS_DEVELOP strings on the SD card according to Bootdisk page.
∙ Once you see the green confirmation screen, restart your camera.
∙ 50D only: make the card bootable with a special utility: EOSCard for Windows, Mac-
Boot for Mac, or make_bootable.sh for Mac/Linux in command line.
Asique probé, me baje el archivito, y ahora si que me arranca con ML, ahora me queda trastear a ver que hay de nuevo, aunque a primera vista hay muchas muchas cosas....
Lo que no se es porque yo he tenido que hacerla boteable y vosotros no

Gracias.
salu2.
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