Interesting ND filter, Anyone tried?

[dEARlEADER]

Manlatiger, sorry the thread was somewhat hijacked into a discussion of polarization!

I only meant to convey that the effect of a variable ND filter could be achieved much cheaper than 300$ with two polarizing filters, but if the price dropped to 100$ and you are interested in having the ability to change a ND filter over a range, then perhaps it is worth it to buy a single filter that can do the job.

I cant say for certain, (in some circles 'polaroid' means a polarizing filter) but I suspect that this variable neutral density filter simply IS two polarizing filters mounted together, utilizing the effect I've been talking about. If someone were to ask me how to design a variable ND filter, i would give them two polarizing filters.

Anyway, I would still be a little hesitant to spend 100$ for an effect I think you could get buying a second 20$ polarizing filter (assuming you already have one) but it's up to you.

I am unsure of the science you speak of...

a basic polarizing filter reduces you exposure by approxmately two stops...


you can verify this simply by metering an image in manual overexposed by 2 stops...then add a polarizer to same exposure and find yourself equalized...... this is regardless of the position of the polarizer....

stacking another polarizer will double this effect... hence 4 stops ..

you are either much smarter than i...... or you are a dumb sh*t with a creative vocabulary....

i will submit to either result...... it is most likely that I am the dumb s*it so prove me wrong...

 

[Eldrich]

you can verify this simply by metering an image in manual overexposed by 2 stops...then add a polarizer to same exposure and find yourself equalized...... this is regardless of the position of the polarizer....

stacking another polarizer will double this effect... hence 4 stops ..

you are either much smarter than i...... or you are a dumb sh*t with a creative vocabulary.....

with my polarizing filter, testing my light meter, I get 1 and a third stop.
And to test my 'theory' that two crossed polarized filters will stop all light, I suggest you try it yourself, put two of them together, and rotate one with respect to the other, there will be an arrangement that doesn't let any light through.

Stacking two polarizers does not just double the effect, you have to look up the physics of polarization.

I will say I am a PhD candidate in the field of atomic and optic physics, so I am pretty sure I know what I'm talking about when it comes to polarization physics...

 

[Iron Flatline]

Lokks like they are trying to do a knock off of the Singh Rays. Their 77mm is only $340 and well worth it if you use one enough. Singh-Ray Filters: Vari-ND Variable Neutral Density Filter I personally though prefer stacking filters over paying alot for a filter that does it for me.

Thanks for linking to this, looks like an interesting product.

 

[dEARlEADER]

I will say I am a PhD candidate in the field of atomic and optic physics, so I am pretty sure I know what I'm talking about when it comes to polarization physics...

my apologies..... i am the dumb s**t ..... i was looking at it from a simplistic approach...(and at 3:00am and intoxicated one as well)

i don't have two to try it out.... but sounds logical...

FWIW.... most polarizers i've searched out are rated two stops or just under... i've personally been looking for one with less density.. i could only find a "warming" polarizer rated at 1 1/3 stop..... what brand are you using?

 

[AlexColeman]

The phrase that got me was "if you are tired of freezing the image, let it flows."

 

[Eldrich]

It is a Zeikos CPL filter, pretty cheap actually.

It could be that some of the polarizers have some additional loss for one reason or another.

You could certainly engineer two polarizers, and a dielectric coating (for a waveplate, and possibly antireflective), to get tunability between any range of ND. Which is probably what this company did. If they did have some AR coatings to reduce glare from stacking filters, that would add a lot to the cost, but would make it a little better than two stacked polarizers.

 

[Iron Flatline]

The phrase that got me was "if you are tired of freezing the image, let it flows."

I thought that was a good way of phrasing the potential of this filter.

 

[Joves]

The phrase that got me was "if you are tired of freezing the image, let it flows."

Yes but you can do that with a standard CP and low ISO with the f-stop closed down or, near down. Example this was shot at f/11 ISO 100 using a 1/4 second shutter.

Closing the aperture would have gained more effect but I had enough wind that it would have screwed any detail of the trees.

 

[Garbz]

The polarizing theory is right however perfect polarisers are very expensive. Even some of the filters in our optics lab produced irregularities accross their surface. Don't expect this to work with cheap filters.

 

[fotojunky]

i tried stacking two polarizers filters it doesnt work well as you get very bad vignetting i saw the fader nd on faderfilters.com it actually works great its amazing toy its worth every penny the effects are great its solidly made it cost me $129 on amazon it does drop 8 stops the only thing is the front lens cap size is not the same size so i had to hunt down another lens cap... saw on faderfilters.com website there releasing a hd version and was wondering if its worth it ?

 

[guerillawerkz]

Judging by the crappy English, and it's from china, it's probably low quality glass with a even crappier coating.

Crappy English means crappy quality? wtf is wrong with you?

 

[Garbz]

Crappy English means crappy quality? wtf is wrong with you?

I don't like feeding trolls but really you sign up to a forum simply to reply to a post that was made over a year ago, and you're asking what's wrong with him...

Nice.

 

[djacobox372]

If you're looking for a good filter look for the words "made in Germany."