Autocorrelation plot inconsistency for early lags

Hello MATLAB community,

Background:

I'm having a problem using the xcorr function to auto-correlate signals from light scattering experiments. I'm using a Basler Pilot (2D CCD) Camera to capture intensities of light scattering. So I use the following to calculate the auto-correlation of each line, or row, of the 2D data.

   for k = 1:h
             line = frame(k,:);
             lineCorr(k,:) = xcorr(line, 'coeff');
   end

As you can see in the figure, the correlation looks pretty good, but zooming into the auto-corr for early lags (on the right), you can see there's an inconsistency of the auto-corr function.

Question:

Is there some sort of default behavior of the 'coeff' option in the xcorr function? I understand that it automatically sets the zero lag correlation to 1, but why does it effect the early lags of the correlation function as well?

Possible Solution:

Would it be better to just do a normal auto-correlation (i.e. use no options in the xcorr call), and normalize afterwards?