Lensbaby

I just bought The Muse. I have a Nikon D70. When I attach The Muse, I can adjust shutter speeds but the Aperture says F----. Two questions:

1. Why does it show F----?

2. Does Aperture matter or do I just use appropriate rings. Does the internal setting of the camera have to be set to match the aperture ring--or is the internal setting on the camera, not a factore?

The D70 is not getting any electrical signals, as it would from a Nikkor lens, so it shows this error message, but the camera will operate normally anyway.

The Muse (all models, actually) is a manual lens. You focus manually. You set the aperture manually, using the aperture rings. You set the exposure manually on the camera. Set your D70 to M Priority.