Questions prior to purchasing a set of graduated ND filters

Hi everyone, I was wondering if I can get some advices before I make a purchase on a graduated ND system. This will be for my 24-70 f/2.8 lens + Canon 5D MKII. I've never used a GND filter before, so I do not know if I am buying the correct items, or knowing what is a good brand to buy. Please let me know of these items are what I would need to purchase (I've gone with Lee because I've heard good things about this brand for its price):

Resin 4"x6" filter
http://www.bhphotovide​o.com …ated_Neutral_De​nsity.html

Lee filter holder
http://www.bhphotovide​o.com …howAll=1#more_a​ccessories

77mm Adapter. This is where I get confused. I see listings on B&H for two 77mm adapters. One is $27.95, while the other is $59.95. What's the difference?
http://www.bhphotovide​o.com …77_Adapter_Ring​_77mm.html

Also, is it necessary to purchase a filter holder and adapter? I've heard stories of photographers just manually holding their GND filters in front of their lens as they shoot. Is this practical and does it really work?

Cheers, and thanks in advance for any info.

Did you mean Neutral density filter?
If it is, I personally opt for B+W

http://www.adorama.com …tpl?page=il_ref​ine_search

If you are just starting out with GND filters, I would suggest initially purchasing two filters, a 2-stop (.6) soft and a 3-stop (.9) hard. Lee filters are excellent, as are Singh-Ray (which are more expensive) and Hitech (which are less expensive). Lee and S-R are both 4x6" filters and Hitech filters are 4x5". Stay away from Cokin filters, as they tend not to be color-neutral.

Many people prefer to hand-hold, instead of using a holder. I sometimes do so and other times I use a holder and/or a hood. The Lee holder is much better than the Cokin holder, which is the other option. You will need an adapter ring to attach the holder to your lens. The more expensive of the two is the WA adapter, which has a lower profile than the standard adapter ring and will vignette less on wide angle lenses. I would go for the WA adapter. Hope this helps...

Thank you much for the replies fellas. Very informative.