Issues with CA from Canon EOS 5Diii and 50mm/1.2

Photolab 3 has confusing behaviour w.r.t. CA correction

Photolab v3.1.1 build 4314
Canon EOS 5D Mark iii
Canon EF 50mm f/1.2L USM
1/1250 s
ISO 100
+/- 0 EV (in Photolab corrected with Exposure +0.50)

See attached files (10) for details.
Note that the original RAW file shows no CA when displayed in Irfanview (v4.53).
In Photolab there is a lot of CA.
When zoomed in, you can clearly see the CA.
Afer heavy corrrection, no CA is visible anymore, still zoomed in.
Zooming out leads to CA again.
Pressing F11 for full screen display shows (almost) no CA for start.
After fully loading and processing the CA is back in the image though.
Exporting this image to disk leads to a result without CA.
Switching off CA correction and exporting again leads to a result with CA.


  1. Why does Photolab display CA in the first place, while the simple Irfanview does not?
  2. Photolab behaviour is very confusing. Can you please make it more consistent?

0. Original - ES5D7057.CR2 (28.2 MB)

  1. Irfanview is showing the processed embedded jpeg.

  2. PL is consistent, you have to be zoomed in to >75% to see the effect of some tools e.g. sharpen CA etc.

Hope this helps.

1 Like

There is indeed no problem on the side of PhotoLab.
As indicated by geordie, the display must be at least 75% to see the effect of this type of correction. This is the normal operation of PL.
In addition, the CA correction slider must be pushed further than the default value. I think this photo was taken behind a window, and it is not impossible that it significantly accentuates the AC.

Thanks for your reactions. I am sorry. I was not aware of the fact that Photolab should be zoomed in 75% to see the effect of CA correction. And indeed, this picture was taken from behind a window. I’ll try to remember zooming in in these cases.

All the tools that have an eye in the upper righthand corner or next to the tool’s name only show their effect if zoomed in at 75% or higher. it’s good to remember this…

1 Like

Hello @Erik,

So guys explained you the behavior for PL, thank you @geordie, @platypus and @gerarto.
As for this one:

  • You do not even need to remember as PL always notify you about it:


Svetlana G.