Best way to do CP + ND filters?

wellman

I just came back from my first "real" waterfall shoot - i.e. tripod, circular polarizer, and ND filters all used together. It was a blast (and some results are here). My biggest gripe was that with the 10x ND I was using, plus the CP, I could barely see through the viewfinder, which made framing a real pain. I didn't want to be taking the filters (threaded circular) on and off fifty bajillion times, either.

I know there's this Cokin system people rave about. Would it be better for this type of situation? Or do you have any other suggestions? Thanks!
-Greg

claudermilk

While I now know better than to use Cokin's filters (lower quality resin, the ND's & CPL's are not really neutral), the square filter system is what you are looking for. You also have Lee and Hi-Tech making these. What some people have doen is get Cokin's P or XPro mounts (cheaper) and use Lee or Hi-Tech filters in them since the sizes are standard 4" square--though Lee is 4x6 to give you more flexibility with the graduated ND's.

At the least, you can get the ND's from these systems and just hold it over the lens while taking the shot.

pathfinder

wellman wrote:

I just came back from my first "real" waterfall shoot - i.e. tripod, circular polarizer, and ND filters all used together. It was a blast (and some results are here). My biggest gripe was that with the 10x ND I was using, plus the CP, I could barely see through the viewfinder, which made framing a real pain. I didn't want to be taking the filters (threaded circular) on and off fifty bajillion times, either.

I know there's this Cokin system people rave about. Would it be better for this type of situation? Or do you have any other suggestions? Thanks!
-Greg

If you can't see through the 10x - and they are dark I use one also sometimes - do you need a polarizer as well? I have never tried to use both - the more glass-air interfaces in the optical path, the more degradation of the image.

I am not saying that this is the wrong way, as I have just never tried or even thought of trying to use both simultaneously.

wellman

pathfinder wrote:

If you can't see through the 10x - and they are dark I use one also sometimes - do you need a polarizer as well? I have never tried to use both - the more glass-air interfaces in the optical path, the more degradation of the image.

I am not saying that this is the wrong way, as I have just never tried or even thought of trying to use both simultaneously.

The 10x was definitely enough to get my shutter speeds above 10 sec. I was using the polarizer to cut through some of the glare on the surface of the water. I don't have any good with/without comparisons developed.

You have a good point on the degradation caused by stacking. Does anyone make a "dark" CP?

wellman

One other thing I realized after the fact is that I could have run the ISO up to 1600 and opened up to max aperture to get a fast shutter speed, take the shot, and then check framing in the LCD before taking the "real shot." Not perfect, but I would have at least had some feedback.

michaeln

wellman wrote:

One other thing I realized after the fact is that I could have run the ISO up to 1600 and opened up to max aperture to get a fast shutter speed, take the shot, and then check framing in the LCD before taking the "real shot." Not perfect, but I would have at least had some feedback.

If it's that dark, why not do framing and focusing with the filters off, then put them on and shoot. If necessary you could use a little piece of gaffer tape to lock the focus ring.

Manfr3d

Do you guys mean 10 stops when you write 10x?
I always get confused because b+w for example
names them ND3.0 and then say its a 1000x filter
which i believe stops down 3 stops?!

LiquidAir

Sing-Ray sells a VariND system which is essentially a pair of crossed polarizers.
http://www.singh-ray.com/varind.html
It goes from 2-8 stops with a twist. I haven't used it, but that is a possibility and I think it will give you both polarization and ND in one compact package.

michaeln

LiquidAir wrote:

Sing-Ray sells a VariND system which is essentially a pair of crossed polarizers.
http://www.singh-ray.com/varind.html
It goes from 2-8 stops with a twist. I haven't used it, but that is a possibility and I think it will give you both polarization and ND in one compact package.

That's a cool filter, but it doesn't do CPL duty.

LiquidAir

michaeln wrote:

That's a cool filter, but it doesn't do CPL duty.

I talked to Bob Singh about it when I ordered my ND grads and it is in fact two stacked neutral circular polarizers. When it is at the light end of its spectrum it does polarize but as you stop it down you get less and less net polarization as you cross the two polarizers.

michaeln

LiquidAir wrote:

I talked to Bob Singh about it when I ordered my ND grads and it is in fact two stacked neutral circular polarizers. When it is at the light end of its spectrum it does polarize but as you stop it down you get less and less net polarization as you cross the two polarizers.

What I was thinking of is this: Let's say you are shooting a stream tumbling over rounded rocks, and it's too bright for the several seconds shutter speed you had in mind. You need ND to get the speed you want, but you also want to get rid of reflections off the rocks to increase the color saturation.

Sounds to me like you'd still need a CPL for the reflections ... but I'm not sure a regular CPL like the SR LB Polarizer I have would still work through the VariND.

LiquidAir

michaeln wrote:

What I was thinking of is this: Let's say you are shooting a stream tumbling over rounded rocks, and it's too bright for the several seconds shutter speed you had in mind. You need ND to get the speed you want, but you also want to get rid of reflections off the rocks to increase the color saturation.

Sounds to me like you'd still need a CPL for the reflections ... but I'm not sure a regular CPL like the SR LB Polarizer I have would still work through the VariND.

Hmmm. It ought to work if you keep the CPL parallel to one of the two CPL in the VariND. Look at it this way: each of the two CPLs in the VariND make one polarization 8 stops darker than the other which is why it is good for 8 stops total ND when you have them crossed: both polarizaions are now 8 stops darker. If you have a second CPL in there, then one polarization is 16 stops down and the other is 8 stops down. The net result is that your lens is still seeing polarized light. However, that setup is likely to be a bit of a hassle.