ND filter fixed or variable?

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brothergumbo

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Greetings,

I'm trying to understand videography and ND filters... my equipment is the nikon Z8 with a carl zeiss distagon 2.8 / 15mm lens. So far I've found this:


A fixed 10 stop ND filter which is 95mm however I think I require a variable ND filter - Which I can not find in the 95mm size. I am further confounded by the use of this filter. Can I use this 10 stopped fixed filter and adjust with ISO and shutter speed to achieve correct video exposures? Or do I need a variable filter? I am also considering the long exposure app NiSi, which I understand is excellent for stills but what about videography? Thanks for any clarity.
 
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The first question is why do you need an ND filter? The usual reason would be to slow motion…or rather smooth motion…waves, rivers, clouds, by allowing a much slower shutter speed as the filter keeps out so much light. I’m not a video person though, sorry.
 
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brothergumbo said:
Greetings,

I'm trying to understand videography and ND filters... my equipment is the nikon Z8 with a carl zeiss distagon 2.8 / 15mm lens. So far I've found this:


A fixed 10 stop ND filter which is 95mm however I think I require a variable ND filter - Which I can not find in the 95mm size. I am further confounded by the use of this filter. Can I use this 10 stopped fixed filter and adjust with ISO and shutter speed to achieve correct video exposures? Or do I need a variable filter? I am also considering the long exposure app NiSi, which I understand is excellent for stills but what about videography? Thanks for any clarity.
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VND if you can find it. PolarPro, K&F and others make it, go to B&H or Adorama. Your ISO should stay fixed at native (800). If you can't find a variable even with step-down rings, 3-5 stops is most usefull for outdoors. Nisi is probably your best bet.
 
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Patrick M said:
The first question is why do you need an ND filter? The usual reason would be to slow motion…or rather smooth motion…waves, rivers, clouds, by allowing a much slower shutter speed as the filter keeps out so much light. I’m not a video person though, sorry.
Click to expand...
Because he needs to shoot at ISO 800 and his shutter speed is limited by shutter angle to 1/50 to 1/250.
 
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well for stills certainly. but during bright sunny days i have been led (via the google) to believe that an ND filter is essential for videography. in fact i have a hoya variable ND filter for my 24x70 nikkor and fiddled with it yesterday and was surprise to find that it allowed me to video at 2.8 and dial in rather rich colors... tho i have not yet processed these clips as davinci resolve and i don't yet understand each other. so i can only answer questions that i know the answer too. I've never tackled video until i got the Z8... previously owned the D800 and D300

thanks for the reply
 
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i see that ISO 800 and shutter angle to 1/50 to 1/250 is required in Z8 video mode. this video explains a bit more and suggest a brand that has filters in the 95mm range.


i am vacillating between the 2 to 5 stop or 6 to 9 stop versions... they are expensive for my budget and i don't want to make a mistake.
 
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I wasted money on a variable ND filter. the filter is basically two polarized filters that can be crossed to achieve varying degrees of density. The problem I had was with strange polarized artifacts with wide angle lenses. I purchased a set of 10 stackable ND filters a few years ago. These were not high end, but quite adequate for my purposes.
 
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In terms of using ND filters, as Rixpx touches on, it's best to go with fixed ND filters for UWA or WA lenses and variable ND for FL's above 40-50mm. A basic explanation of the "Why? is that Variable ND's, using as they do, rotating polarizers will or can cause color shifts and uneven performance at the image edges and the problem is exacerbated the wider the lens you're using. This is primarily caused by the angle of incidence of the light impinging on the polarizers at the image corners. You will see this effect with polarizing filters used to reject glare for general purpose use, as well.

I have a Vari 1-5 stop 95mm that I use on my 600pf and 77mm and 52mm sets that cover from ND4 to ND64. Also have adapter rings to be able to use the Vari ND on my other lenses in the odd situation, though when you do that, forget about using a lens hood! :)
 
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Also, if you're shooting N-Log, there are several Lo settings below the 800 that actually work pretty good. You have to be really certain about your exposure because of how it works to maintain the dynamic range of the native ISO. I'd use is caredully at first, maybe giving you one ND-stop equivalence. In other words, if you found the perfect settings but maxed out the ND range, just go one step down from ISO 800.
 
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