How reliable are variable ND filters?

ChristopherCoy · Mar 15, 2021

I tend to shoot at the wide open end of my lenses, and the 1/400th shutter speed limitation of the RB67 lenses became apparent very quickly. I can probably count on 1 hand the number of times I've shot at F16, but I had to do so many times over this past weekend.

I'm not sure whether something like a filter holder with individual square filters is better than a variable filter, especially because I see that some of the variables produce dark X's in the frames. I've never used an ND filter so I have no idea what to look for. The only thing I know for sure is that I'm not looking to spend hundreds of dollars out the gate, without gaining some experience using them first.

Can anyone shed some helpful advice on filter types, and the benefits and disadvantages of each, or what details I should be looking for? If I go variable, I'm thinking something in the 1-5 stop range should be sufficient for my needs.

BrianShaw · Mar 15, 2021

Why not use slower film?

BrianShaw · Mar 15, 2021

Asking about filter brands gets into near-religious discussion. I’ll just sit back and watch.

ChristopherCoy · Mar 15, 2021

BrianShaw said:
Why not use slower film?

I only shoot Tri-X, and I already shoot it at 200. I'd rather control the light hitting the film, than have to change the development process. It's just easier for me.

ChristopherCoy · Mar 15, 2021

BrianShaw said:
Asking about filter brands gets into near-religious discussion. I’ll just sit back and watch.

I'm certainly not looking for the brand fandom type of replies and arguments. I guess I should go back and clarify that question.

BrianShaw · Mar 15, 2021

Ok... here’s one (my) perspective. Almost any filter in combination with a lens shade will be fine. I stay “mid-grade” as much as possible - Hoya. The multi coating is a real pain to clean but might serve a purpose. Others will tell you about filter rings jamming or freezing and the absolute need for brass filter holders... I’ve rarely encountered that even with the aluminum holders of “lesser” filters.

Friendly suggestion: re-think the staunch decision to only use 400 film, especially if shooting wide open. It just makes life harder in bright light situations. But whatever works for you...

bdial · Mar 15, 2021

I believe the variable ND filters are just a pair of polarizers, one stationary and another that moves to provide the variable density functionality. I would probably look to minimize the amount of glass you need and use a fixed ND filter according to how much light you're looking to block most of the time. Say either a 2x or 3x, and you always have the option of over exposing by a stop which aside from giving you a dense negative won't usually present any problem for printing or your scene interpretation.
If you're going to have the filter on most of the time, it might as well be the best you can get, though "best" is highly debatable.

It's not entirely applicable, but here is Lens Rental's blog on filter stacking, and filter quality;
https://www.lensrentals.com/blog/2011/06/good-times-with-bad-filters/

Jim Jones · Mar 15, 2021

I've stacked filters to shoot solar eclipses and transits of Venus. Top image quality was less important than recording rare events. I've also used crossed polarizers for these shots, but prefer stacking filters.Remember, the variable ND filters have four glass-to-air surfaces, and usually introduce image artifacts when set for high attenuation.

StepheKoontz · Mar 15, 2021

I personally would stick with non-variable ones. And shooting B&W film, the "color cast" issue isn't an issue so I wouldn't worry about buying the high end ones.

ChristopherCoy · Mar 15, 2021

StepheKoontz said:
I personally would stick with non-variable ones.

Any particular reason why? My only concern is whatever "X" pattern they create, or IF it's even an issue with film photography. I've not been able to find anything strictly relating to film, it's mostly been digital problems.

Digger Odell · Mar 15, 2021

I would think that setting exposure with a variable density filter MIGHT be tough. Unless you have a through the lens type of meter. Otherwise just how many stops do you meter for?

ChristopherCoy · Mar 15, 2021

Digger Odell said:
I would think that setting exposure with a variable density filter MIGHT be tough. Unless you have a through the lens type of meter. Otherwise just how many stops do you meter for?

I'm not sure I understand the question, but if I meter and get f16 at 1/400th, I'd like to be able to take that down to f5.6 at the same shutter speed.

Digger Odell · Mar 15, 2021

The problem is that with a variable density filter, You don't "know" how many stops of filteration you have dialed up. Thus an off camera meter would be a guess.

Edit, Most filters just have a more-less setting. Some very high end ones do have calibrated click stops so it would work with an off camera meter. These are ~250$

ChristopherCoy · Mar 15, 2021

Digger Odell said:
The problem is that with a variable density filter, You don't "know" how many stops of filteration you have dialed up. Thus an off camera meter would be a guess.

Ahhh... I see your point.

btaylor · Mar 15, 2021

I would stay away from the variable polarizer types, they can cause artifacts you may not want as they are not ND filters but, as bdial says, actually 2 polarizer filters. Figure out what ND factors you are likely to use and buy those. And get a polarizer filter for when you WANT that effect.

ChristopherCoy · Mar 15, 2021

Ah, well there we go. Everything I needed to know. I want 77mm, fixed ND filters, in 2/3/4 stop increments that can be stacked.

AgX · Mar 15, 2021

Concerning the variable version:

Instead of buying such, one can just stack two generic polarizers. Not as neat in handling due to both panes being rotatable.
With a bit more effort one can take (if the diameter should fit) one polarizer pane out of its rotatable mount and put into a static one onto which the rotatable polarizer is screwed.

MattKing · Mar 15, 2021

f/16 on your RB 67 lenses will, if all other things are equal, give you similar performance (depth of field and diffraction) as f/8-f/11 on your lenses for 135.
The f/45 on your 180mm lens isn't there for decoration - it actually gives you excellent results, only slightly less excellent than f/11.
The depth of field at f/4.5 on the 127mm and 180mm lens is very shallow.
A single 3 stop ND in your bag makes sense.

ChristopherCoy · Mar 15, 2021

MattKing said:
A single 3 stop ND in your bag makes sense.

That's where I'm starting. I just ordered a Tiffen 0.9 ND and I'm going to start with that and learn how to use it before moving on to anything additional.

awty · Mar 15, 2021

Cokin P filters and adaptors can often be picked up cheaply on the second hand market. Thats what I mostly use on my RZ67. Just need to be careful not to scratch them as they are plastic.

wiltw · Mar 15, 2021

awty said:
Cokin P filters and adaptors can often be picked up cheaply on the second hand market. Thats what I mostly use on my RZ67. Just need to be careful not to scratch them as they are plastic.

You need to keep Cokins in their original case, which maintains airspace between the filter surfaces and the inner surfaces of the case.
About 30 year ago, I bought a bunch of Cokin filters, and stored them all in a filter wallet, for compactness. I went on a weeklong photo holiday in FL, and during that time period, there was enough dust accumulation durng outings that I discovered the dust ABRAIDED the Cokin filters, destroying them! I threw them all out, and never replaced them.

awty · Mar 15, 2021

wiltw said:
You need to keep Cokins in their original case, which maintains airspace between the filter surfaces and the inner surfaces of the case.
About 30 year ago, I bought a bunch of Cokin filters, and stored them all in a filter wallet, for compactness. I went on a weeklong photo holiday in FL, and during that time period, there was enough dust accumulation durng outings that I discovered the dust ABRAIDED the Cokin filters, destroying them! I threw them all out, and never replaced them.

Yes I know. Even the boxes that hold multiple filters can scratch if allowed to bounce around in your camera bag. But they often come up in the second hand market in package deals for not much money. Just need to make sure they are filters you can use. Graduation filters can be handy for landscapes with horizons.

Maris · Mar 15, 2021

I have and use a "Fader" variable ND filter that is made of two polarisers that can be turned against each other.
Not all wavelengths of light are equally attenuated so there is a slight colour cast introduced. I use black and white films so it's not a problem for me.
The ND effect is not precisely even over the field of view at strong attenuation values. This depends on luck and the individual quality of a "Fader".
A variable density filter depending on polarisers is still a polariser and the usual limitations apply; uneven wide-angle skies for example.
Near maximum attenuation values the dreaded "black cross" effect may be seen. This is caused by oblique rays not being extinguished the same amount as normal incidence rays.
My Fader is rated up to 10 stops ND but I don't set it beyond 5 stops to avoid the optical nasties that I can't really see through the dark viewfinder of my reflex camera.

ChristopherCoy · Mar 15, 2021

Maris said:
My Fader is rated up to 10 stops ND but I don't set it beyond 5 stops to avoid the optical nasties that I can't really see through the dark viewfinder of my reflex camera.

I wonder if a 2-5 stop variable would have the same issues as the 10 does at high values?

Maris · Mar 15, 2021

In theory exactly crossed polarisers like the ones used in my $30 Fader should block all light but they don't ... quite. I see on eBay a 2 to 5 stop variable filter for $400 which implies either very special partial polarisers or ordinary polarisers with a simple mechanical stop to limit rotation. I have no experience with this expensive article but I get up to a useable 5 stops ND on the cheap and no bad surprises.

How reliable are variable ND filters?

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