So I have three wide angle lenses - a 65mm Nikon Nikkor-SW f/4, a 75mm Nikon Nikkor-SW f/4.5, and a 90mm Sinar Sinaron-W f/6.8. (I think all have a 67mm front attachment filter thread.)

Should I spend an extra $400 to get a center filter to help with vignetting, or can I take care of said vignetting with Photoshop?

If you guys do recommend a center filter, which one(s) would you recommend?

Many thanks!