The jjc disposable raincover for dslr is great in an emergency simply slide over the camera and lens with your external flashgun attached and use the draw card to cinch it tight around the end of the lens its large enough to take a lens up to 300mm long thats 300mm physical length not necessarily 300mm focal length if desired make a hole for the viewfinder and use the camera viewfinder eyepiece to keep it in place weighing around 30g the jjc disposable raincover packs into the smalles