ND filter, please help....

[bratkinson]

Try backing the filter off from the maximum density. A lot of variable NDs do that when turned to the very maximum.

Thank you, Helen! I would have never thought of that. I'll have to keep that in mind, which is getting more difficult by the day. (Does losing my memory equal losing my mind?)

But then, I've never had a need for NDs, much less GNDs. Maybe someday...

 

[cosmonaut]

You really don't need a variable one I use a three stop Cokin and it works for pretty much every situation I come across.

 

[Tee]

The water looks very still so creating any kind of movement would prove to be difficult unless you went into bulb mode for a really long exposure. Also, when you moved the camera into portrait mode it looks like you did not adjust the ring to go with it thus the vertical gradiation. I sometimes forget to move my CPL when I change camera orientations.

 

[elaukli]

remember to keep your iso low and pay attention to your aperture.

 

[jrizal]

Huh, I hadn't heard of variable neutral density filters before... do they work by using two polarizing filters at a variable angle to each other?

Variable Neutral Density (VND) filters or simply faders do exist and I have one myself. And no they may look similar but differs in the way they handle light. As far as what I'm concerned these VNDs do work to a certain degree but using them at their maximum density results in cross marks. This is an inherent design of VND, even the more expensive ones have it but to a much lesser degree. A more practical solution is to use normal or non-variable ND filters. By doing so you can also choose from solid, center or graduated ND filters of which the last two can produce results the VND can do. Unlike VNDs you would need to have several filters in order to select the right density you want for your shot. Screwing filters for every shot can be quite cumbersome. And this is the downside of regular ND filters. A solution to this is to use square filters wherein you have filter adapter on your lens and just swap your filter. Cokin is one of the brands that use this type of filters. The ability to change density without switching filters the primary advantage of VNDs albeit with some trade-offs. But for casual users a VND would be quite sufficient. But for me it is almost impossible to "capture" flowing water without those pesky cross marks with my VND! Other darkening effects are still fine though and I'm still saving up for a decent set of NDs. Just my two cents.

 

[jrizal]

You really don't need a variable one I use a three stop Cokin and it works for pretty much every situation I come across.

As per my experience, these Cokin or even knockoffs perform better than VNDs (at least the cheap ones). And if some asks why type of ND filters to buy, I would recommend an adapter based system mainly for better effects and much easier handling too. Lost my Cokin set years ago and just settled with a cheap VND hence the reason I can say that the adapter style filters are better over-all. And let's just say I'm still saving for something better.

 

[TCampbell]

Those dark bands occur when you use a POLARIZER with a wide angle lens. The amount of light blocked by a polarizer depends on the angle from which the light source originates. Since a WIDE angle lens is collecting light from a broad range of source angles, SOME of those source angles will have a stronger polarizing effect than others. Polarizers work best when the true angle of view is limited (which means you're using "normal" through "telephoto" focal lengths... but avoiding "wide" angle focal lengths.)

The ND filter in your sample shots is undoubtedly (as everyone else has already pointed out) really a polarizer. You can stack two polarizers to create the effect of a tunable variable neutral density filter... but that's not the same as a true neutral density filter (one that has a fixed density and cannot be "tuned" or adjusted.)

A true ND filter is simply decent optical grade glass which is evenly tinted to block light light equally at all wavelengths regardless of the polarity of the light. In other words, had you used a simply ND filter rather than a variable ND, then the light would have been blocked evenly and all would be well.