HEAVY NDs

[Medavoym]

Hi!

About the ND 1.2, 1.5, 1.8 etc... Because of EPIC's sensitivity, we will need to use these strengths more and more often.

Is it better (for heavy ND needs) to use two filters, or just one that is equally strong? For example, is it better to use one ND1.8 filter, or two ND0.9 filters together? I mean optically. I read someplace that using a single superheavy ND filter is not necessarily best. Although I cannot tell why.

Thanks!
Mike

 

[jimhare]

Hi Mike,

I don't think Epic's additional sensitivity will cause us to use heavier NDs. I will still shoot at 320 when I can, but use higher ISO when working in low light.

When the goal is to reduce light there is no motivation to up the ISO (though some like to up it in bright light to force them to stop down and help protect their highlights.)

As for stacking, I've heard strong opinions from both camps. I personally do not stack. For the R1 I use everything from .3 to 1.8 as individual filters, plus a separate hot mirror (I/R) in front if needed.

Some people prefer filters with I/R built in. In this case you can't stack them anyway.

 

[Carl Burke]

Forgive me if I am wrong but if the native daylight sensitivity of the epic turns out to be say iso 800. Will I not be compromising the dynamic range of my scene if I were to rate the camera at 320. Essentially overexposing by more than a stop?

 

[jimhare]

I'm pretty sure Jim has already said not to think of it in those terms.

There is no native ISO that I'm aware of, only optimal ranges for noise.

What Jim has said is that we can now get the same clean image at 800 as we are used to at 320. Nothing to do with DR.

Someone jump in and correct me if I'm wrong on this but I'm pretty confident.

 

[Stephen Strangways]

Generally, each filter you add is another piece of glass and two more air/glass interfaces, which can slightly degrade MTF and possibly introduce reflections. All other things being equal, I try to use as few filters as possible.

 

[Juergen Di]

@jimhare
You are right. A more sensitiv sensor doesn't mean the image is overexposured at at normal light with a normal iso-setting. It means you need less signal-gain to get a propper exposure. And so you get a better image-quality. Let say it like this: A certain ASA-Amount just means that you need a certain amount of light for a correct exposure. The NDs are very usefuel if you want shot with a low T-Stop to get a small depth of field but the situation is very bright.

Greetings from Germany
Juergen

 

[Charles Angus]

More filters = less good.