# How to compute sinc period in frequency domain and width of pulse

I have an image convoluted by a rectangular PSF of a blur kernel. The fourier transform of the PSF has pattern of a sinc function: $\frac{\tau sin(\pi \tau f)}{\pi f}$. The image size is 256x256.

Would my following assumptions about the PSF on its period in frequency domain and width of its pulse in the PSF be correct:

The rectangular pulse of the PSF will run with an impulse value of $f(x)=1$ from $\frac{-128\tau}{1}$ to $\frac{+128\tau}{1}$.

So the width of this rectangular pulse in the PSF is $128 \times 2 = > 256$ in width.

The sinc period in the frequency domain of the PSF would be the same, running from $\frac{-128\tau}{1}$ to $\frac{+128\tau}{1}$. (This is my most unsure part)