ND's, 85's and 80's...

[Ben Schwartz]

True or false: ND's, 85's and 80's have small, though definite, effects on the color, granularity and resolution of film.

[Michael Nash]

True or false: ND's, 85's and 80's have small, though definite, effects on the color, granularity and resolution of film.

<{POST_SNAPBACK}>

 

When's your paper due? ;)

 

How could a color filter like an 85 or 80 not have an effect on the color of the film?

[John Pytlak RIP]

Since you are modifying the spectral quality of the light with a colored filter, you certainly WILL affect color reproduction to some degree.

 

Since you are losing some light in going through a filter, you may need to use a faster film, so granularity may increase.

 

Any additional optical surfaces (filter) will have a sharpness penalty, and may decrease contrast due to flare.

 

But you knew all that, right? Good luck on the test. ;)

[Ben Schwartz]

Ha ha fellas, make fun of the film student.

 

No paper, no test...just trying to settle a disagreement I had with someone (I was right).

Edited January 11, 2005 by Ben Schwartz

[Michael Nash]

Is putting "Film Student" in your signature line on this forum the same thing as hanging a sign on your back that says "Kick Me"?  It would be nice to just get a straight answer without some dig at my student status.

 

<{POST_SNAPBACK}>

 

It wasn't a "kick," just a gentle poke in the ribs. Hence the "wink." ;)

 

Over the years here we've seen student posts here that are clearly just an attempt to have the internet community do the student's homework for them. Your question seemed... suspect.

 

If you could elaborate on the dispute, we could address the more particular points.

 

A change in grain of a given film is affected by the density on the negative. So if a filter in some way affects that density, it will affect the grain. If it doesn't affect the density, doesn't affect the grain. For example, if you added an ND filter to the camera but neglected to compensate the exposure by opening up the iris, you'd end up with a negative with lower-than-normal density. When you "print up" that image you'd see more grain than if the image had been properly exposed. But if instead you compensated the exposure loss from the filter by opeing the iris, there would be no change in density and therefor no change in grain.

 

With color filters you're altering the density in the different color layers of the film, so in theory there could be a change in grain in the least exposed layer if you were to try to color time the image back to normal. However, this is rarely an issue with 85 or 80 filters, especially if you compensate for the overall stop loss by opening the iris the proper amount.

 

Some diffusion filters like pro-mists can add a slight "texture" to the image that can appear like grain (or make exisiting grain look worse), but in reality it's not affecting the actual grain of the film. It's just sort of "dirtying up" the image and making it appear more grainy.

[Ben Schwartz]

Michael,

 

Ha, you quoted a post I later revised!

 

Thanks for your answer. To be honest, I've never really done any "homework" or taken tests in school...it's been all on-set learning and self-directed curricula, so there's nothing for me to cheat on! :D

 

The dispute was simple, and I don't think I worded my question properly: of course I know that 80s and 85s have AN effect on color. Let me rephrase. Say you have a daylight scene - does filter-corrected tungsten film render the true colors of that scene the same as daylight balanced film (excluding any color correction in post)?

 

You've answered my question about grain.

Edited January 11, 2005 by Ben Schwartz

[John Ealer]

I think you're splitting hairs here with your color query.

 

On a mythical "ideal" day exterior, where the color temp off all the light is exactly 5600K, an "ideal" tungsten 3200K film shot with an "ideal" 85 filter would theoretically render colors exactly the same as an "ideal" daylight 5600K film.

 

To pose the more useful question as to whether you'll get more accurate daylight color rendition with a daylight balanced film than with a tungsten film (of the same film stock "family") shot with an 85 filter, my answer would be not really. With modern film stocks and professional gear, the tolerances are so tight it would be impossible to tell the difference.

 

J

[David Mullen ASC]

Exposure and its affect on density has an affect on graininess -- if you used an ND6 filter and didn't compensate for the light loss and thus ended up two stops underexposed, you would have a thinner negative and more grain. If you did compensate for the ND filter, then the exposure on the film would not change and nor would grain.

 

Daylight-balanced film in daylight versus tungsten-balanced film with an 85B filter should yield similar results color-wise. There will be some differences -- for example, the blue layer is slower and therefore finer-grained with daylight film of the same speed as tungsten film.

[Dominic Case]

True or false: ND's, 85's and 80's have small, though definite, effects on the color, granularity and resolution of film.

Filters, if uncompensated for, will reduce the exposure on the film, and oviously alter the colour of the image. To the extent that an ND filtered image is underexposed, it will be grainer - but that's not necessarily the same as granularity.

I don't see how a filter can affect the resolution of film: maybe the minute trace of light scatter could affect the resolution of the image.

 

If the argument is whether an unfiltered daylight-balanced stock would yield the same results (in terms of colour, grain, resolution) as an 85-filtered tungsten stock, then you can't ignore the differences in the stock itself: so there's no argument. Tungsten-balanced stock has a faster blue layer to cope with yellow-balanced light: it's bound to be grainier than an equivalent daylight stock with a slower blue layer.