The MC-DC1 does work on the D70s for long exposures and has a shutter lock. I have done up to about 15 minute exposures with my D70s. After that it does seem that amp noise does effect the pic. The long exposure NR does seem to help but kind of pain to use IMO.
Here is an attempt to get a meteor shot during the Perseid Meteor Shower in August.
The light coming from the right is from the moon. On the left side I guess is amp noise or something like that. This pic is an 8 minute exposure and was taken in Bulb mode using the MC-DC1 external release.
