A book I got says "In bright sunshine you will probably find that ISO100 film allows a shutter speed of 1/500, even 1/1000, but in dull conditions, film of a least ISO400 will be required, in order to manage fast, action stopping shutter speeds" hope that answer your question. All the above were taken with a tripod and cable release. The bird in the top pic I have managed to get eating from a brid feeder, hopefully I have got some good close up photos with this lens.

Eggiwegs! I would like... to smash them!