Massive Red and Green borders on Objects - is this normal?

[Daniel Raebiger]

Hey Folks,

i've noticed in my opinion massive red and green borders on the left and right part of the picture. Is this normal? What can i do to prevent this?

Thanks alot :)
-Daniel

[Dino Leone]

It's called chromatic aberration. It's lens-dependent.
I do get it too with my A1... sometimes. I'm not quite sure if it varies with the zoom factor. It should decrease when you close down the iris, as it usually is most pronouned with wide-open apertures.

[Chris Hurd]

Originally Posted by Dino Leone

It's called chromatic aberration. It's lens-dependent.

It's called fringing, and chromatic aberration is only one possible cause. However the primary culprit of fringing is most frequently a chroma sub-sampling issue common to the HDV format, as has been heavily discussed on this site many times before.

[Daniel Raebiger]

thanks for the info. i only get those errors on the right and left border of the image, not in the middle so i assume its a lens thingy?

Dino: by closing down the iris you mean increase the f value, by this increasing the depth of field sharpness, right?

:)

[Dino Leone]

Originally Posted by Daniel Raebiger

by closing down the iris you mean increase the f value, by this increasing the depth of field sharpness, right?

:)

Well, yes, if it's indeed because of chromatic aberration. However, if it's as Chris points out, due to chroma subsampling, then I don't know if stopping down the lens helps. I better start searching the forum too before I start babbling bs...
And yes, increasing f-value = stopping down = closing iris. You'll get increasing depth of field, but this has nothing to do with chromatic aberration.

[Dino Leone]

OK, I did my homework. :-)
Daniel, there's many threads about the fringing. Just enter "Fringing" in the "search this forum" and you'll get them.
Most interestingly (after reading some of the threads), the fringing seems to be amplified by some custom presets.

[Peter Jefferson]

Check your sharpness isnt too high, this also increases the edge fringing.

[Brandon Freeman]

I've found less fringing by having the CineGamma 2 and Black Stretch modes turned on.

[Shiv Kumar]

Dino,

Wouldn't chromatic aberration be more pronounced when you stop down? Ideally if you don't care much for a narrow depth of field you should keep the aperture in the "sweet spot" (normally mid way) and use NDs to cut down the light if needed.

I'm not sure about video cameras but from my photography experience CA is pronounced at the extremes of aperture. I also remember from reading (DV film maker or some other book) that smaller apertures cause CA to be more pronounced.

Daniel,

I don't quite see "massive red and green border" in the image you've posted :). Where exactly are they?

[Shiv Kumar]

Oh, I see them now (I had to make sure I see the full sized picture). These (red/green) borders are visible on all edges and not just the left and right borders of the image. For example, the borders of the mics as well as the faces and hair.