This was the best that one could manage with a Nikon D40..
Vedanthangal is about two hours from Chennai city. If one drives non-stop from the 'Kathipara' junction it would take about one and a half hours or even less.
The best time for watching is early morning till about 9:00 AM. One can however stay on for a little while longer and continue to picnic! In the evenings 4 to 7 PM (if it does n't get really dark) will be ideal. In this case, one can leave for Vedanthangal at about 2:00 PM
Forest Rest House
It may not be necessary to stay over, but it could be a real 'close to nature' experience, what with the lack of gadgets and abundance of insects, as mentioned earlier! If required, one can stay at the Forest Rest house, from which the bird sanctuary is at about 750 meters.
To book a room, the Wild life warden's office has to be approached and a written (yes, no forms are available for this purpose!) request to be furnished, addressed to the warden, and based on the availability, accommodation will be provided. A double room costs Rs. 300 per night. The check in time is 12:00PM. It is not like booking at a hotel, so be prepared for some typical 'government' office waiting. The warden's office is at the Guindy National Park and is open on tuesdays also (when the park is closed for public). Please make sure to go after 11:00 AM because the attending officer will arrive only at about that time!
Carry your own food. There are a few tea-shops around and nothing else. The people at the Rest house may prepare food and tea/coffee upon request. Also, mosquito repellants!
Binoculars are available at the sanctuary for rent (@Rs.20 I think), but they are not suited for effective viewing. There is a watch tower, and the guide has a mounted binocular and he also gives a description of the birds. By far it is the best way to have a close look at the birds. Since the sanctuary plays host to the similar birds every year, boards with a description of each type are placed every few meters.
We carried our own binoculars. We wanted to get hold of Olympus or Nikon Binoculars but they were not widely available. At Spencer Plaza and on Wallajah Road, there are shops that will provide with these on request, but they are priced at Rs.8000 or above! We settled for a Celestron 20 by 50, available at Camera Citi, Besant Nagar outlet (only!) which cost Rs.2800.
The best season for a visit is October-February.
I hope the above (I will add more if I remember!) is helpful. This post is my way of saying Thanks to a few bloggers who had written similar posts which helped our trip!