My results with the pinhole cap on my Nikon FM2 were mixed. I remember it being sharper in the past, but I did most of my shooting without a tripod this spring.
Shooting a pinhole on an SLR is a bit odd, as the viewfinder and meter are useless. I used my neck strap and rested the camera against my abdomen. I thought a deep breath, a sold stance, and a cable release would provide adequate stability. It has in the past, and it did for some shots this time. Others weren't as lucky.
Black & white shots are FP5 stand developed in Rodinal; color is Ektar.