Variable Neutral Density Filter

Boofers · 20-02-2007, 12:12

Here is a link for the Variable Neutral Density Filter I ask about awhile ago. What do you think it is going to do. Will it work?
Singh-Ray Filters: Vari-ND Variable Neutral Density Filter

**Markulous** · 20-02-2007, 12:26

It was all looking great.......... 'til I saw the price!

Don't have any experience of, nor know anyone using, but the theory seems sound! It's just that price!

**Dabhand16** · 20-02-2007, 12:32

On face value, it will do what it says. As it is being marketed as a photographic filter, we can only assume that the quality is going to be fit for purpose.

How it achieves the variable density is the question. If you get two pairs of Polaroid sunglasses ovrlaid on each other, you will get a similar effect. This is because there are very fine lines in the lens. When the lines are at 90 degrees to each other, there is a reduction in the light that can pass through. If one set of lines is rotated, and the lenses are aligned so that when the lines are parrallel they form a 'solid' filter, between the two extremes ther will be a variable amount of light transmission. I think the technical term is 'Moire fringes'

The question for me is, if what I'm saying is right, (and i'm not sure that it is!) when you are at an intermediate point, will the shapes formed by the two sets of lines have any impact on your camera's meter, or the image?

Maybe someone else can add something to this?

**Markulous** · 20-02-2007, 12:43

Well, I assumed it's a couple of Circular Polarisers stuck together and so shouldn't interfere with the light meter (like Linear Polarisers can). So maybe shouldn't impact meter or image? Assuming that fairly good optics

**Dabhand16** · 20-02-2007, 12:55

Good point, Mark, but why market it as a variable ND? They might just as well market it as a polariser.

**Markulous** · 20-02-2007, 13:00

Because it'll work as a variable ND and no longer as a CP?

Les Meehan · 20-02-2007, 15:56

This is definitely two polarisers working together to control the light transmission. If you look at the top left corner rocks in the last two sample images you will see a noticeable polarising effect on the wet rocks. In fact, since the surface angle of the rocks varies so does the pola effect (which is normal) but this only goes to highlight that they are polarisers.

I have often used my pola filter as an ND when I needed to change exposure settings for whatever reason. It may be possible to obtain a variable ND using two ordinary polas, and it would be cheaper!

Most people think of polarisers as colour saturation improvers, which they are, but in fact what they really do is control reflections. A side effect of this is increased colour saturation. It is useful to think of them in terms of their ability to control subtle highlights on things like foliage, painted metal etc. It isn't always the best creative option to use the maximum polarisation of a filter as it can kill the subtle reflections from the myriad surfaces in a scene and make it look 'lifeless' and unnatural. Just an aside about polas, sorry!

**Dabhand16** · 20-02-2007, 17:29

Thanks, Les - that's cleared that up. Back to the original post, would it be any good, or is it better to use different dedicated ND's?

Based on whet you've said, I think the dedicated ND's would be better.

Rob Barron · 20-02-2007, 18:31

So what is gained from this VERY expensive vari-ND filter over two polarisers which would be much cheaper and potentially even more variable than the one being marketed here?

I have a Cokin polariser that I could use in front of my mounted polariser and get the same results.... but haven't tried that so might be talking out of my jacksie! I'll have to give it a go and see what results I get.

Also, whilst we know about the quality of some maufacturers filters, we know very little about Singh-Ray's filter (well, i don't anyway!) so they might have optical imperfections that would degrade the image of an L series lens or whatever? Has anyone seen any independent tests or reviews of this thing? My slight wariness is in the fact this filter has now (according to the copyright info on the pictures in the ad) been around for about 4 years yet I have not seen anything written up about it in a photographic magazine.

If anyone else has either used this filter or seen a trusted review, I'd like to receive details and read it.

Cheers,
Rob

orangepeel · 20-02-2007, 18:41

Quote:

Originally Posted by Markulous

Well, I assumed it's a couple of Circular Polarisers stuck together and so shouldn't interfere with the light meter (like Linear Polarisers can). So maybe shouldn't impact meter or image? Assuming that fairly good optics

that's what I thought at first. Then I tried it. it's not two cp's

**Markulous** · 20-02-2007, 18:44

Quote:

Originally Posted by orangepeel

that's what I thought at first. Then I tried it. it's not two cp's

No, no, you can't get away with just saying that! Tell ALL!

Les Meehan · 20-02-2007, 19:13

I don't think this would work with circular polas. The idea is that the lines in the pola interfere with each other which I don't see happening with CP's. But then I'm not an expert on CP's so this may be wrong but it makes logical sense to me.

In my professional opinion, I would go for high quality ND's in different strengths depending on your requirements. Also, remember that adding ND's together simply increases the effect i.e. two 0.3 NDs makes one 0.6 BUT of course the optical quality might reduce slightly because of the extra surfaces (but probably not enough to bother you). If adding two filters together any gap between them will more than likely incur internal reflections. I once saw a good example of this whilst using two Kodak CC gelatins with a shot including candles. Had multi images of the candle flames.

Boofers · 20-02-2007, 20:28

I haven't bought a filter yet, I read about a B+W variable that they stopped making. It is supposed to be a steal if you find one on e-bay. The same read said that they give you creative leaway. Reading here, I remember that I bought a polerizer on a trip, returned home and found that I already had one. Maybe I will try to stack them. I was informed that wasn't a good thing but I could try anyway seeing they are the same ones.
I think the wife might want this one on the thread, she works hard enough she can get it.

20-02-2007, 12:12	#1 (permalink)
Boofers Feet under the table Join Date: Jan 2007 Location: 40 miles south of St. Louis Posts: 2,318	Variable Neutral Density Filter Here is a link for the Variable Neutral Density Filter I ask about awhile ago. What do you think it is going to do. Will it work? Singh-Ray Filters: Vari-ND Variable Neutral Density Filter

20-02-2007, 12:26	#2 (permalink)
Markulous Pixalo Crew Join Date: Jul 2006 Location: Peak District Posts: 9,691	Re: Variable Neutral Density Filter It was all looking great.......... 'til I saw the price! Don't have any experience of, nor know anyone using, but the theory seems sound! It's just that price!

20-02-2007, 12:32	#3 (permalink)
Dabhand16 Pixalo Crew Join Date: Jun 2006 Location: Dunstable Bedfordshire UK Posts: 8,978	Re: Variable Neutral Density Filter On face value, it will do what it says. As it is being marketed as a photographic filter, we can only assume that the quality is going to be fit for purpose. How it achieves the variable density is the question. If you get two pairs of Polaroid sunglasses ovrlaid on each other, you will get a similar effect. This is because there are very fine lines in the lens. When the lines are at 90 degrees to each other, there is a reduction in the light that can pass through. If one set of lines is rotated, and the lenses are aligned so that when the lines are parrallel they form a 'solid' filter, between the two extremes ther will be a variable amount of light transmission. I think the technical term is 'Moire fringes' The question for me is, if what I'm saying is right, (and i'm not sure that it is!) when you are at an intermediate point, will the shapes formed by the two sets of lines have any impact on your camera's meter, or the image? Maybe someone else can add something to this? __________________ Graham

20-02-2007, 12:43	#4 (permalink)
Markulous Pixalo Crew Join Date: Jul 2006 Location: Peak District Posts: 9,691	Re: Variable Neutral Density Filter Well, I assumed it's a couple of Circular Polarisers stuck together and so shouldn't interfere with the light meter (like Linear Polarisers can). So maybe shouldn't impact meter or image? Assuming that fairly good optics

20-02-2007, 12:55	#5 (permalink)
Dabhand16 Pixalo Crew Join Date: Jun 2006 Location: Dunstable Bedfordshire UK Posts: 8,978	Re: Variable Neutral Density Filter Good point, Mark, but why market it as a variable ND? They might just as well market it as a polariser.

20-02-2007, 13:00	#6 (permalink)
Markulous Pixalo Crew Join Date: Jul 2006 Location: Peak District Posts: 9,691	Re: Variable Neutral Density Filter Because it'll work as a variable ND and no longer as a CP?

20-02-2007, 15:56	#7 (permalink)
Les Meehan Forum Regular Join Date: Jan 2007 Location: I conduct workshops in Andalucia, Spain Posts: 778	Re: Variable Neutral Density Filter This is definitely two polarisers working together to control the light transmission. If you look at the top left corner rocks in the last two sample images you will see a noticeable polarising effect on the wet rocks. In fact, since the surface angle of the rocks varies so does the pola effect (which is normal) but this only goes to highlight that they are polarisers. I have often used my pola filter as an ND when I needed to change exposure settings for whatever reason. It may be possible to obtain a variable ND using two ordinary polas, and it would be cheaper! Most people think of polarisers as colour saturation improvers, which they are, but in fact what they really do is control reflections. A side effect of this is increased colour saturation. It is useful to think of them in terms of their ability to control subtle highlights on things like foliage, painted metal etc. It isn't always the best creative option to use the maximum polarisation of a filter as it can kill the subtle reflections from the myriad surfaces in a scene and make it look 'lifeless' and unnatural. Just an aside about polas, sorry! __________________ Les Meehan www.zone2tone.co.uk www.creativeinsightworkshops.com

20-02-2007, 17:29	#8 (permalink)
Dabhand16 Pixalo Crew Join Date: Jun 2006 Location: Dunstable Bedfordshire UK Posts: 8,978	Re: Variable Neutral Density Filter Thanks, Les - that's cleared that up. Back to the original post, would it be any good, or is it better to use different dedicated ND's? Based on whet you've said, I think the dedicated ND's would be better.

20-02-2007, 18:31	#9 (permalink)
Rob Barron Loves the place Join Date: Sep 2006 Location: Poole, Dorset Posts: 5,200	Re: Variable Neutral Density Filter So what is gained from this VERY expensive vari-ND filter over two polarisers which would be much cheaper and potentially even more variable than the one being marketed here? I have a Cokin polariser that I could use in front of my mounted polariser and get the same results.... but haven't tried that so might be talking out of my jacksie! I'll have to give it a go and see what results I get. Also, whilst we know about the quality of some maufacturers filters, we know very little about Singh-Ray's filter (well, i don't anyway!) so they might have optical imperfections that would degrade the image of an L series lens or whatever? Has anyone seen any independent tests or reviews of this thing? My slight wariness is in the fact this filter has now (according to the copyright info on the pictures in the ad) been around for about 4 years yet I have not seen anything written up about it in a photographic magazine. If anyone else has either used this filter or seen a trusted review, I'd like to receive details and read it. Cheers, Rob __________________ Rob Barron robbarron@aol.com If you look down on other people, don't expect them to look up to you!

20-02-2007, 19:13	#12 (permalink)
Les Meehan Forum Regular Join Date: Jan 2007 Location: I conduct workshops in Andalucia, Spain Posts: 778	Re: Variable Neutral Density Filter I don't think this would work with circular polas. The idea is that the lines in the pola interfere with each other which I don't see happening with CP's. But then I'm not an expert on CP's so this may be wrong but it makes logical sense to me. In my professional opinion, I would go for high quality ND's in different strengths depending on your requirements. Also, remember that adding ND's together simply increases the effect i.e. two 0.3 NDs makes one 0.6 BUT of course the optical quality might reduce slightly because of the extra surfaces (but probably not enough to bother you). If adding two filters together any gap between them will more than likely incur internal reflections. I once saw a good example of this whilst using two Kodak CC gelatins with a shot including candles. Had multi images of the candle flames.

20-02-2007, 20:28	#13 (permalink)
Boofers Feet under the table Join Date: Jan 2007 Location: 40 miles south of St. Louis Posts: 2,318	Re: Variable Neutral Density Filter I haven't bought a filter yet, I read about a B+W variable that they stopped making. It is supposed to be a steal if you find one on e-bay. The same read said that they give you creative leaway. Reading here, I remember that I bought a polerizer on a trip, returned home and found that I already had one. Maybe I will try to stack them. I was informed that wasn't a good thing but I could try anyway seeing they are the same ones. I think the wife might want this one on the thread, she works hard enough she can get it.

20-02-2007, 23:55	#14 (permalink)
Liam O'Neill Getting Comfy Join Date: Nov 2006 Posts: 138