Deepak,
Just got my Ortlieb medium handlebar bag and put my D70 (with a 28-105mm) in the bag. The interior dimensions of the bag are (roughly) 9 1/4" across the length x 7" deep (to the top edge of the bag-the lid extends another inch or two above the bag) x 4 1/2" to 5 1/2" wide (the opening of the bag is curved along the hinged edge).
Hope this helps.