[fishtank]

Hi,

I'm fairly new to the world of DSLR photography and am trying to do some night time shots of a tree, with a long shutter speed, so that I can light the tree up with a torch.
The tree is in the dark and it's pitch black, so the autofocus on the camera will not lock onto the tree.

I'm informed that the way to get past this is to use Manual Focus and set this to infinity.

I am able to put the camera onto Manual focus and understand about the focus ring and setting this to the maximum one way or another, I also appreciate that sometimes the focus ring doesn't have to be fully extended in either direction as infinity is sometimes slightly before this.

Is there any secrets / hints that people can give me to help me with achieving these pictures in focus? I struggle to tell, due to the light, whether the tree is in focus, through the viewfinder whether I light it with a torch or not!!!

Please help as this is something that I will not only use once and it's really frustrating me now!!

Thanks

Dan

[EDIT: I am using a Sony a390 with the 18-55mm kit lens]