Variable ND Filter

[Paul-UK]

Are the variable ND Filters any good, or better put what are the advantages and disadvantage situations.

I can visualise them being good for reflections, water, windows, etc.

Can the darkening help, is can it be a pain on days when light is bad?

Trying to think about it myself, with my little knowledge, It would seem you couldn't use a lens hood, but could they cause issues between manual focusing then turning the filter ring?

The idea seems good, but I am sure you guys will have tried, tested and found out if they are useful or not.

Paul

 

[Petrochemist]

All variable ND filters are made by stacking 2 polarisers so they can be rotated relative to each other.
Their biggest disadvantage is they can give rise to a dark cross right across the image, particularly with wide angle lenses. Sometimes I've not found this a problem but on occasion it's been really extreme.

They are not especially good for reflections, a single polariser that can be aligned to maximise or minimise reflections are MUCH better for this.

The darkening is exactly what they're used for, and obviously they should be removed when that is not desired. At their palest they reduce light by a stop, twist the ring 90 degrees from that position & they will be nearer to 8 stops.

You can use a lens hood, but how easily depends on the hood :
Some hoods have a panel that can be removed to allow adjustment of filters. I've got examples of these from both Pentax & Panasonic.
Other filters screw into the filter threads and these can simply be turned to adjust the filter.
If your hood doesn't have either of these, you can adjust the filter, then fit the hood afterwards - sometimes a bit of a pain.

 

[Ozzie_Traveller]

G'day Paul

A single CPL filter is most useful on some occasions - and as recommended above

A double-pola filter as is the 'variable' style have for me been a pain in the neck, with the dramatic darkening of some of the image sometimes, and turning the images purple the rest of the time. Then junked after that 'visual excitement'

Phil

 

[Paul-UK]

@Petrochemist , @Ozzie_Traveller

Many thanks for your replies they are very helpful.

I visualised they could darken an image, an odd stop could help on some situations I thought, hence the question. But one to eight stops, is a massive range to lose light, especially for a beginner, I think I need to learn how to obtain the best settings without unnecessary darkening, the polarizer sounds the best option, when I am ready for going further with my photography, at present all I take is in our garden, flowers, birds, squirrels, and aiming to get sharper closer shots.

Maybe, I am thinking, the variable ND filter could be useful on a bright sunny day, but not for me with the type of shots I take. I read the best light is early and late in the day, avoiding midday where possible.

Great replies and most helpful, thank you.

Paul