Yes you will need a filter To look at the Sun directly you need a proper solar filter. They are inexpensive and should be easy to obtain before the eclipse. Do not use anything other than a real solar filter. Coffee filters are for coffee and not for solar observing even though you will most likely find them near every observatory.

(c) Eclipse Nuts Cartoon by Bill Kramer. Uploaded Sun, 09 Apr 17 19:57:29 -0400