800mm shooting moon, stars

I am having some fun at night with this thing shooting the moon and such. Photos are fairly good on a tripod with miror lockup and the timer. I press the shutter buttom as gently as possible and ensure that the neck strab is not swinging aorund. Will I get even better images with a cable release? Or will the difference not be noticeable? I did get a photo of some planet (Jupiter?) with a small level of detail. I'd love to make that a bit more crisp.

Thanks!