Author Topic: DLO correction data in newer lenses  (Read 3928 times)


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DLO correction data in newer lenses
« on: April 14, 2017, 02:28:56 PM »
Hello everybody,

it looks like EOS M3, M5, 5D MkIV and maybe 80D and 1D-X MkII can
get lens correction data in three different ways:
1) Included in onboard firmware
2) Uploaded vis EOS Utility
3) Delivered onboard newer lenses

Can anybody shed a light on the format of these correction profiles?

In another discussion elsewhere a user reported the Sigma 150-600
Contemporary to be recognized by his 5D MkIV in full text.
Maybe this lens doesn't make use of a fake lens ID anymore,
rpvided that the camera supports lens profile loading from the
lens itself.

This opens new possibilities in correcting uncoupled "dumb" lenses
inside the camera by maybe building a module loader for extra profiles.

I am not a programmer, just a user with sometimes wild ideas.

Does that make any sense?

Regards, Michael

Lars Steenhoff

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Re: DLO correction data in newer lenses
« Reply #1 on: April 14, 2017, 02:49:04 PM »
Interesting and related to lens info as talked about here


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Re: DLO correction data in newer lenses
« Reply #2 on: April 15, 2017, 09:06:10 PM »
Here's an interesting non-technical article about Canon's in-camera lens correction.

Note that the last batch of firmware updates were mostly the same fix on several camera models:

Corrects a phenomenon in which when using the camera with the EF-S 18-135mm f/3.5-5.6 IS USM or EF 70-300mm f/4-5.6 IS II USM lens, even if lens aberration correction is set to "Enable", correction will not be applied.

I did a firmware update on the 700D and the places where the code was changes is rather obvious by looking at the shifts in the stub addresses. Seems like it was just a very minor fix around 0xff6300b8 but that might be the area where the lens correction code is located.


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Re: DLO correction data in newer lenses
« Reply #3 on: April 16, 2017, 04:17:14 PM »
in the reverse engineering subforum i posted some analysis of the LENS structure in camera.
see the "RE contributions" thread.
thats all i know about correction (till now)
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