[stoppingdown]

A thing that I want to practice about is the use of ND filters for long exposures in landscape. I did something in the past, but really just a handful of shots. For the most "extreme" shots I have the Big Stopper, but I've realised I need something less extreme for the most common scenarios. I'm interested in the variable filters, as they are expensive, but they are versatile.

 

Suggestions about the brand? I was undecided between Singh-Ray and B+W. I understand that Singh-Ray is probably better, but I wasn't able to find a dealer in Europe; B&W ships overseas, but with a not negligible fee...

[Brightcolours]

You can get the same effect by mounting a high quality linear pol. filer on a linear (or circular) pol. filter. As far as I know, all variable ND filters are stacked pol. filters, and will give interference patterns when you go too far, but I am pretty sure you are aware of that.

 

The Singh-rays are unnecessarily think, which may couse corner vignetting.

Bokeh issues:

http://jonasraskphotography.com/2014/05/...-variable/

I have read that the Hoya variable ND filter is better than the B&W.

[Studor13]

You can get the same effect by mounting a high quality linear pol. filer on a linear (or circular) pol. filter.

 

I don't know how true this is but I am absolutely certain that you can't just stack them onto each other. Apparently, you need to stack them back to back. So your first problem is to get a female to female or male to male filter ring. Good luck trying to find one.

 

I have a linear polarizer and have tried to achieve this variable ND filter effect by screwing in a CPL onto the lens and holding Linear one backwards with my hand. It didn't work for me. Maybe I needed to have held them in a different combination. Don't know really but I'm not going there again.

 

As far as brands go for standard NDs, I have a 3 stop and 5 stop Hoya, and a 10 stop Heliopan. Heliopan is good. Hoya leaves a blue cast. And with a CPL which is around 2 stops, I am basically covered. For example, if I drop my ISO to -1, I have 12 stops with the Heliopan 10 stop filter. Or if I bump the ISO to 400 the 10 stop filter becomes an 8 stop filter. And so on.

 

Filters are not big to carry. You can easily pack 6 filters in one small case.

 

Sometimes when you want an exact exposure at an exact time of day you need a certain ND filter. In the shot below I needed around 5 minutes but it had to be at time when the full moon was in a certain position above the mountains. For this type of shot you need a 3 stop ND.

[Brightcolours]

I don't know how true this is but I am absolutely certain that you can't just stack them onto each other. Apparently, you need to stack them back to back. So your first problem is to get a female to female or male to male filter ring. Good luck trying to find one.

 

I have a linear polarizer and have tried to achieve this variable ND filter effect by screwing in a CPL onto the lens and holding Linear one backwards with my hand. It didn't work for me. Maybe I needed to have held them in a different combination. Don't know really but I'm not going there again.

 

As far as brands go for standard NDs, I have a 3 stop and 5 stop Hoya, and a 10 stop Heliopan. Heliopan is good. Hoya leaves a blue cast. And with a CPL which is around 2 stops, I am basically covered. For example, if I drop my ISO to -1, I have 12 stops with the Heliopan 10 stop filter. Or if I bump the ISO to 400 the 10 stop filter becomes an 8 stop filter. And so on.

 

Filters are not big to carry. You can easily pack 6 filters in one small case.

 

Sometimes when you want an exact exposure at an exact time of day you need a certain ND filter. In the shot below I needed around 5 minutes but it had to be at time when the full moon was in a certain position above the mountains. For this type of shot you need a 3 stop ND.

Of course you do not need to stack them back to back. You do when you have a CIRCULAR pol filter in front, as that one is "directional". But if you have one linear pol. filter, it goes in front of the circular one, and you can just stack them. You can also of course stack two linear ones. Or do silly stuff and use two linear ones back wards, or back to back, or front to front  :ph34r:

 

You can test if a pol. filter is linear or not my holding it in front of a LCD screen backwards and rotate it. If you can change the amount of light coming through (and even black it out), it is a linear one. If it does not allow that, it is a circular one.

 

My guess is that your linear one actually is not linear.

 

What happens with a linear pol. filter is that light waves with a certain polarization (direction of the wave) don't fit through the slits of the pol. filter film. If you turn the slits, that light can get through. If you put one pol. filter with slits in a horizontal direction, and one behind or in front of it in vertical direction, all light will be blocked. If you adjust the filter in front, you can vary the amount of light coming through. If you put the slits of both filters in the same orientation, you get the most light through.

 

This is exactly what the variable ND filters are, 2 pol filters. 

 

In the SLR AF age, they added a layer behind the pol. film because when filtering  a certain direction of pol. light under certain conditions the AF sensor might not see anything anymore. So, the added layer changes the let through polarized light's wave orientation again, it turns the direction of the waves. 

 

One can use linear pol. filters just fine on (D)SLRs, by the way, just be aware of that in certain rare situations your AF might not focus lock. Good linear pol. filters give better image results than good circular pol. filters.

 

As for ND filters, I have a 9 stop Hoya HMC ND400 which has no colour cast, and a Marumi ND8 (3 stops) which has no colour cast either. I actually chose the Hoya ND400 after reading some tests which found it was neutral (no colour casts to speak of), and it is very decently priced (and does not introduce unsharpness issues). The Marumi is very good too, and very inexpensive.

[Studor13]

Yes, you are right. I managed to hunt down the linear polarizer and retried it.


It works but is not practical as turning the LPL also turns the CPL.


I'm surprised that you don't have issues with the Hoya ND400. I have two Hoya NDs plus a Kenko CPL which is Hoya glass, and they all have color casts. I used to use HiTech NDs but they are even worse.


Marumi on the other hand have been getting good reviews so maybe that is something the the OP (stopping down) could consider instead of the more expensive brands, if price is an issue.

[JJ_SO]

I'm relieved you had also bad colour cast with HiTech filters. Given their marketing blurb, it should be very close to neutral, but in fact it's nearly psychedelic. I haven't seen a single colour in the picture which was as seen, when using as white balance "daylight" things improved a bit with a white balance preset and sky high Kelvin number.


The variable ND filters originally were made for fade-in and -out with film cameras to keep the aperture in place. Which means, on the screen you don't see worse colour cast than the lower light intensity already creates when the picture gets darker, or comes out of the darkness into normal light.


But we do the opposite, we keep a certain brightness which makes the slightest color cast extremely obvious. It all depends what we choose to photograph, but a purple sky without long morning or evening shadows remain surreal, contrary to a waterfall in the woods with already dim light. Here a little more purple or magenta can make a better color.

[Brightcolours]

Yes, you are right. I managed to hunt down the linear polarizer and retried it.


It works but is not practical as turning the LPL also turns the CPL.


I'm surprised that you don't have issues with the Hoya ND400. I have two Hoya NDs plus a Kenko CPL which is Hoya glass, and they all have color casts. I used to use HiTech NDs but they are even worse.


Marumi on the other hand have been getting good reviews so maybe that is something the the OP (stopping down) could consider instead of the more expensive brands, if price is an issue.

I have no experience with other Hoya ND filters. A review pointed this one out to me as being pretty cast free, the reason why I chose it. 

[toni-a]

Would it work if I put 2 circular polarizers will I have a graduate ND ?

[stoppingdown]

Thanks for the info. I'm collecting them. I also ran into this:

 

Formatt Hitech 72mm-127mm Circular Firecrest ND Filters (SuperSlim Stackable)

 

The 72mm, 6 stop is listed at 78 GBP (excluding delivery). Any info about it? I know that the maker has got a reputation... but I see from the above comments that somebody had bad experiences.

[JJ_SO]

Long ago a Berlin photographer made a blog post about those expensive vs. cheap ND-filters: http://text.flowtographyberlin.de/neutra...ood-as-bw/

 

Here's a picture I made with a 150x150mm (6x6") Firecrest ND 3.0 (10 Stops) (150£... stupid, I know)

 



 

after a while I could get this result in Aperture

 



 

As you can see, there are some dust particles which will also become visible, because the filter needs some distance to the front element. Also, the corners get weaker, because a flat filter in front of a bulbous lens can cause distortion. and vignetting and reflexes, even to the holder