Hobby Shooter said:
Hey, I'm in Asia so it's morning here. Later today, I will try long exposure for the first time. I went to pick up a grey filter last week, but they only had 3-stop filters. I only picked up one and didn't give it more thought. Now having read up a bit on it, I see that I would probably need more. I won't by another filter today so my question to you is the following, can I stack a CPL to the grey filter?
I presume the grey filter that you are referring to might be the Neutral Density Filter. If you are aiming to blur movement, a 3 stop ND filter has little effect unless you shoot in low light. A better investment should have been at least a 4 stop ND filter and/or a 10 stop ND filter. For this reason, stacking filters is the method that I usually apply to exploit cloud and water movements in not so low light condition. To give you some idea, here are some of my shots using the stacked filter method:
The day I saw the sun
Canon EOS 5D Mark III ı Canon TS-E24mm f/3.5L II ı Lee 1.2 ND Filter ı Singh Ray LB Warming Polarizer ı Lee 0.9 Soft ND Grad Filter ı 24mm ı 10s ı f/16 ı ISO 100
The day I saw the sun by
shutterwideshut on Flickr
The pavilion in black & white
Canon EOS 5D Mark III ı Canon TS-E24mm f/3.5L II ı Lee Big Stopper ı Lee 0.9 Soft ND Grad Filter ı Singh Ray LB Warming Polarizer ı 24mm ı 204s ı f/8 ı ISO 100
The pavilion in black & white by
shutterwideshut on Flickr
Dusk over Quezon Island
Canon EOS 5D Mark III ı Canon EF24-70mm f/2.8L II USM ı Lee 1.2 ND Filter ı Lee 0.9 Soft ND Grad Filter ı Singh Ray LB Warming Polarizer ı 24mm ı 20s ı f/8 ı ISO 200
Dusk over Quezon Island by
shutterwideshut on Flickr
Nature's Breath
Canon EOS 5D Mark III ı Canon TS-E24mm f/3.5L II ı Singh Ray 0.9 Reverse ND Grad Filter ı Singh Ray LB Warming Polarizer ı 24mm ı 15s ı f/8 ı ISO 100
Nature's Breath by
shutterwideshut on Flickr
Hobby Shooter said:
I will anyway give it a try, but are there any particular things I need to look out for?
Pre-compose without the filter and shoot in manual focus. Use the live view for precise focussing and the Mirror Lock Up method. Shoot in RAW format to have flexibility later in post to deal with color cast(if there is any). :

And most of all, don't forget your remote cable release and tripod.

Shooting long exposure is fun.

Good luck. Cheers.