Variable ND Filters

[cascade]

I've been thinking of getting a neutral density filter and after looking around I've come across variable ones that go from 1.5 to 9 stops.
I was wondering how good they work or would I be better off getting a fixed one?

[outstar79]

I personally would go for the fixed ones, but it all depends on what you want to achieve with the ND filter. There are a whole wide range from the ND400 (9 stop) filter B&W 10 stopper or Lee, Cokin type filters.

You can pick up the ND400 and B&W at a reasonable price, other go all out for the LEE filter system - depending on budget

[cascade]

I personally would go for the fixed ones, but it all depends on what you want to achieve with the ND filter.

I was mainly going to use it on long exposure daytime shots and for water effects like waterfalls etc.

[Rattus79]

The Vari ND's are more useful then the straight 10stoppers.

I have a Singh-Ray one (they're not cheap though) and it doesn't cast at all, well unless you push it too far.

Uses include longer day time exposures - expect 1 - 2 seconds in bright light f18-22

I also use it on my 50 1.4 to get wide open in bright conditions that would otherwise overexpose at 1/8000 iso 100 f1.4

Also for the same reason with off camera flash. let's you open the aperture without blowing your subject out.

Things to note: Cheap ones will give a colour cast, don't push them past the max level, you will get all sorts of strange casting, and they're fat. Some of them will vignette on a UWA lens. Others do not have the ability to stack multiple filters too.

[Epoc]

I bought a cheap variable one just to have a play. It will not work at the full 9 stops on a wide lens like my 11-16mm. You get this weird X happing on your shots. Worked fine on my 70-200 though. Is this the same with expensive ones like the Singh Ray?

[Rattus79]

I never actually did the math to work out exactly how many stops I got out of it to be honest but yes. if you push it past the max limit it will give strange results.

[Dylan & Marianne]

Greg, did the singh ray one go all the way up to the reported 9 stops?
I got a 'fader' one which was supposed to be good but beyond 5-6 stops, you end up in the twilight zone with X cross polarisation happening across the image.
If the singh ray one works, it'd be really really useful as there are times in a forest setting I want to push exposure to say 1-2 minutes at 5 stops but not 15-30 minutes with a 10 stopper!

[Rattus79]

Hey Dylan,
I don't think it does go all the way. TBH I think it tops out at about 8 stops. I really need to do the math and work it out properly in a controlled environment.

If you ever find yourself in Brisbane, you're more then welcome to have a play with mine.

I discovered on the weekend that although it does not have any threads on the front (mine's the wide angle version) you can use a cokin filter holder and "drape" it over the front. It sits quite steadily, but I wouldn't trust it in the wind. Not that it's an issue for you since you hand hold mostly don't you?

I can post an example shot if you like?

[glennb]

I bought a vivitar 2 to 1000 still learning with but I don't like it, I like using the long exposure at 1000 end but I'm getting inconsistency of over and under exposed spots/ lines on the pictures so I'm looking for a 10 stop only now.

[Rattus79]

That will be the cross polarisation effect Glenn. Try not pushing it to the extremes so far. Push your aperture instead.

[glennb]

I was wondering if it was that cross pol, though I was only using 30sec exposure, will play with the aperture more. Cheers

[glennb]

I come across that ugly cross, see what you mean now had to back it off a fair bit though to get good consistent picture. Probably only getting max 7 stops. Think fixed is the go

[Rattus79]

7 is still better then none.

[mongo]

Mongo needs to get an ND filter of at least 7 stops. Looking for a 400 rather an a variable one.

Looked into a test of at least 6 of the best known ND filters including Lee and other expensive units. Very surprised to find that, overall, Tiffen makes about the best ND filter. Its far from the cheapest filter but still a long way from the dearest one. All other filters visibly knocked down the sharpness of the image except Tiffen. In other aspects of testing it was close to or equal to the far more expensive brands. So, overall, it came out on top. The fact that it is about 1/3 tp 1/2 the cost of the expensive ones doesn't hurt either. Of course, Mongo is now looking for one in 77mm.

Ps - also read that it may be wise to get a size or two larger than the lens it is to go on and some step-up rings to ensure no vignetting occurs.

[CarlR]

I have the Marumi variable ND. It is not as expensive as the Singh-Ray.

Whilst it has not had a heap of use, I haven't found any issues with colour casts but extending beyond its range will result in the same cross polarisation effects mentioned above.

One benefit not mentioned above over a fixed ND is the ability to frame the shot, focus and prepare with the ND dialled down, obviating the need to repeatedly fit and remove the filter.