Correcting vignette and distortion in PS

[sanj]

There is a lot of concern over the vignette on the new 16-35 which prompts me to understand:
What is the major concern with correcting vignette, distortion in post?

Do the issues matter in the final photograph?

Thank you

 

[GMCPhotographics]

It's only an issue wide open. So for landscapers, it's rarely an issue because f8 and smaller and generally the apertures of choice due to maximising depth of field.
Correcting vignetting is quite simple in light room...there's a slider for it, but exstream vignettings (say 4-5 stops) can be tricky as the pulled shadows can get quite noisy on some older canon cameras. Ex stream Shadow pulling increases iso noise quite dramatically on some canon sensors.
But it's only a problem if you want it to be. I actually like vignetted corners in some of my images...So it saves me a step in Light room. But that's just me.

 

[sanj]

My question is, sorry if I was unclear: What is the problem with correcting vignette and distortion in PS? How does the correction 'harm' the photo?

 

[jeffa4444]

It increases the noise.

 

[privatebydesign]

My question is, sorry if I was unclear: What is the problem with correcting vignette and distortion in PS? How does the correction 'harm' the photo?

It introduces lifting amounts that might become problematic, if you lose 4 stops to vignetteing you have to lift exposure 4 stops to correct for it. This puts the shadow detail in danger of noticeable failure particularly if you underexposed your image initially.

In practice, whilst it sounds like a real issue, I haven't found it to be one when using the 11-24. Also I think the comparison images shown on TDP are a bit misleading in that the writing has changed colour and the tones seem darker/more contrasty with the newer tests.

Bottom line, heavy vignetteing adds complications particularly for underexposed images and images you need to do a lot of post processing to.

 

[sanj]

Thank you!