Buying first ND and polarizer filter need a little help

I am in the process of purchasing my first ND filter and also a circular polarizer. Looking at the Hoya Pro 1 ND4 MC and the Hoya HMC ND4 MC and would like to ask are these basically the same filter except the one being 3mm and the other 5mm. If this is true I don't think I have a lens that would make the 3mm really needed.
As far as the polarizer looks like the Hoya Pro 1 digital Circular Polarizer would be the one and is 5mm.
Am I on the right track and certainly any suggestions would be welcomed.
Also has anyone ordered or had any experiance 2filter.com buying filters from them.
Like to add another quick thing looking for external HD and have read lots of bad things about most do you have any suggestions on this.
Thanks for your help and time.
Dennis

You're correct with the differences between the two Hoya ND filters. Which lens are you thinking of mounting the filter on?

I use Hoya filters and am pleased with the results. The best deals I've found on them are at the eBay store SoBeFOTO, a trustworthy outfit.

Not sure what 'bad things' you've heard about external hard drives, but I use a 750GB Western Digital external hard drive ($145 at NewEgg) and it works great. I only turn it on about once a week to back up my work. Seems that one will always encounter more negative reviews than positive reviews of external drives because one doesn't hear from satisfied owners nearly as much as from the victims of HD crashes.

I own two externals, a Maxtor and a WD. I also only turn them on when I need to retrieve or backup photographs. My thinking runs this way. Heat is the enemy of computer drives. When they are on, they are generating heat, regardless of whether they're being used or not. So to leave them off unless they are needed seems like it would extend their lives.

The lens I would be using the filters on would be canon 100-400mm f/4.5-5.6L IS USM and 24-105mm f/4L IS USM so not sure what would be best. I will check the ebay and I was looking at Filter Connection site.
Thanks

I don't think you need a thin mount filter for those lenses unless you might choose to stack the polarizer on top of the ND filter in order to achieve even more loss of light.

I have a Maxtor and have good luck with it. But my SOP is probably a little different than most. I keep it disonnected all the time to prevent nearby lightning strikes, surges which get thru the surge protector or outages (which we seem to have a lot of) from damaging it. When I duplicate the C drive, I hook it up, duplicate, then disconnect. It also prevents it from running all the time.

Ken

Dennis here is a link to a store that carries New B+W and Hoya at the lowest prices I have found. I have ordered 4 filters from them over the last 6 months and have gotten 4-5 day delivery. I have been very pleased with their products and service. I just purchased a Hoya Pro 1 Digital 77mm circular polarizer for $109.

Brad

http://stores.ebay.com/Quality-Filters

That's $10 cheaper than the same filter at SoBeFOTO.
Great find, Brad!

Sadly, they don't carry Hoya ND filters, though.

The 24-105 may need a thin mount filter if you are using it on a full frame body like a 5D or 1Ds Mark 2 or 3. I have used the Filter Connection for years and like them a lot. I buy filters and ink from them. If you order $66 or more the first class shipping is free. They are located in CT so here in NY I don't pay sales tax either.

Check out www.2filters.com

Thanks to everyone for helping me on the question about filters and hard drives. Have filters on order and look forward to learning and using them. Get HD real soon!
Thanks

Dennis, this site may be a source of information http://www.nd-magazine.com/articles/art2.php
Andy Munford does a very good explanation for each of his pictures

Sorry for the late reply. I definitely prefer rectangular ND filters to circular ones. They are more flexible. You can slide them up or down, and even use them sideways. You also don't have to worry about fitting them on different size lenses. I hand-hold mine, so there's no real need for a special mounting bracket.

As for external drives, I just build my own. A good enclosure is very cheap and a good drive is cheap. This will usually cost you a bit more than a pre-built unit, but you can get the exact case you want, and the exact drive you want, all while knowing you can easily just swap in a larger drive in the future.

Vern

If you have the money for it I would definitly choose rectangular slot-in filters. As it was already said, they are much more flexible. Lee filters are probably the best if you don't mind spending $500+ for a complete set, but there are other less expensive options too.