What filters do you need for Red? A beginners' guide.

[Evin Grant]

This is a personal & creative choice but I think for the less experienced here it might be a good idea to give you guys a little primer.

First off are ND filters...
ND filters are neutral density, they allow you to shoot in bright light without stopping down to diffraction (ttp://en.wikipedia.org/wiki/Diffraction) limiting apertures like f11 or greater. Basically a set of sunglasses for your camera. The Red has a native sensitivity of ISO 500 which means that if you were to shoot in basic daylight (Sunny 16) conditions a proper exposure would require you to set your lens to f86!
Most lenses don't even go to that aperture but you probably wouldn't want to shoot there anyway becasue of diffraction (http://en.wikipedia.org/wiki/Diffraction) which can Limit your resolution on digital imaging sensors. ND filters come in stregths from .1 to 1.2, each .1 correspond to 1/3 of an f stop so an ND filter of .9 is a three stop attenuation.

Here is one from Schneider in 4x4".
http://www.schneideroptics.com/Ecommerce/site/images/Photo2/68-040644.jpg

Here is a list of common ND filter and aperture combinations at 1/48th of a second shutter speed which is equivelent to a 180º shutter in a film camera.
1/48 @ f14 +1.2
1/48 @ f10 +1.2 & .3
1/48 @ f7.2 +1.2 & .6 (Or Pola)
1/48 @ f5 +1.2 & .9

As you can see a minimum of an ND 1.2 and .6 (Or Pola.) is necessary for a reasonable aperture (f7.2) in direct sunlight.

Next would be a Polarizer (http://en.wikipedia.org/wiki/Polarizer)...
This filter is very useful for a variety of applications. For more technical details about how it works click the Wiki link above. Basically a polarizer allows you to eliminate haze, deepen blue skys and control certian reflections on water, metal and glass. It also acts as a .6 (2 stops) ND filter.

Example:
http://www.bhphotovideo.com/images/largeimages/474370.jpg

Graduated Neutral density filters can be usefull as well...
They are basically the same as regular ND filters but only cover half the filter and incorperate either a soft or hard edge transition to clear. By doing this they can help even out the exposure of certain wide landscape type shots that typically have very great differences in exposure from the top to the bottom of the frame.
http://www.schneideroptics.com/Ecommerce/site/images/Photo2/68-050244.jpg
http://www.bobatkins.com/photography/tutorials/digital_filters/ndgrad2.jpg

There are many color versions of the ND grads but they have mostly fallen out of favor these days with the advent of the digital intermediate.

[Mark Thorpe]

Thanks Evin,
Sterling work to date. A great resource.

Cheers,
Mark.

[Shawn Nelson]

Carrying on with filters, this thread http://www.reduser.net/forum/showthread.php?t=3910 deals with which brands are good and goes on to talk about what strengths of NDs are ideal and has advanced descriptions of qualities of NDs.

[Jaime Vallés]

Thanks for the info, Evin. ND's and a polarizer are must-haves for this camera. I need to get some myself. ;)

[WAYNE GLOVER]

This is a personal & creative choice but I think for the less experienced here it might be a good idea to give you guys a little primer.

First off are ND filters...
ND filters are neutral density, they allow you to shoot in bright light without stopping down to diffraction (ttp://en.wikipedia.org/wiki/Diffraction) limiting apertures like f11 or greater. Basically a set of sunglasses for your camera. The Red has a native sensitivity of ISO 500 which means that if you were to shoot in basic daylight (Sunny 16) conditions a proper exposure would require you to set your lens to f86!
Most lenses don't even go to that aperture but you probably wouldn't want to shoot there anyway becasue of diffraction (http://en.wikipedia.org/wiki/Diffraction) which can Limit your resolution on digital imaging sensors. ND filters come in stregths from .1 to 1.2, each .1 correspond to 1/3 of an f stop so an ND filter of .9 is a three stop attenuation.

Here is one from Schneider in 4x4".
http://www.schneideroptics.com/Ecommerce/site/images/Photo2/68-040644.jpg

Here is a list of common ND filter and aperture combinations at 1/48th of a second shutter speed which is equivelent to a 180º shutter in a film camera.
1/48 @ f14 +1.2
1/48 @ f10 +1.2 & .3
1/48 @ f7.2 +1.2 & .6 (Or Pola)
1/48 @ f5 +1.2 & .9

As you can see a minimum of an ND 1.2 and .6 (Or Pola.) is necessary for a reasonable aperture (f7.2) in direct sunlight.

Next would be a Polarizer (http://en.wikipedia.org/wiki/Polarizer)...
This filter is very useful for a variety of applications. For more technical details about how it works click the Wiki link above. Basically a polarizer allows you to eliminate haze, deepen blue skys and control certian reflections on water, metal and glass. It also acts as a .6 (2 stops) ND filter.

Example:
http://www.bhphotovideo.com/images/largeimages/474370.jpg

Graduated Neutral density filters can be usefull as well...
They are basically the same as regular ND filters but only cover half the filter and incorperate either a soft or hard edge transition to clear. By doing this they can help even out the exposure of certain wide landscape type shots that typically have very great differences in exposure from the top to the bottom of the frame.
http://www.schneideroptics.com/Ecommerce/site/images/Photo2/68-050244.jpg
http://www.bobatkins.com/photography/tutorials/digital_filters/ndgrad2.jpg

There are many color versions of the ND grads but they have mostly fallen out of favor these days with the advent of the digital intermediate.

What about soft focus filters which erase wrinkles?
I understand Tiffin is coming out, or has already come out with a sizable offering of software filters for use in post, but can you erase things like wrinkles in post using software?

[Uli Plank]

Sure you can do that it post, and you can limit the effect to skin color. Since you have far more control over the effect while color grading, it's not really advisable to get rid of detail while shooting…

[bellaing]

Did anyone work with a white frost or black frost on a Red lens ?

It might be interesting to brake the "sharpness" of digital imaging in high light, for instance.

[Brook Willard]

The "sharpness" you speak of is not inherent to a digital image - it is inherent to over-sharpened HD. Since there is no sharpening in the RED, there is no sharpness to fight against.

I've found that diffusion is effectively useless in front of the RED.

[Alexander Nikishin]

I've found that diffusion is effectively useless in front of the RED.

Not true Brook, white promist does have its uses on RED....

http://www.reduser.net/forum/showthread.php?t=7873

It's a matter of taste.

[alex boom jedi master sr.]

Would a filter kit like this be a smart beginning set to go with?

http://www.schneideroptics.com/ecommerce/CatalogItemDetail.aspx?CID=1410&IID=6270

Thanks in advance

[Alexander Nikishin]

I'd go with a circular pola, not linear.

[Mark Pedersen]

Here's what I have and would suggest as a basic set:

* Horizontal: ND Solid: .3, .6, .9, 1.2
* ND SEV (vertical grad) .3, .6, .9 (vertical so you have more room for moving the filter up and down to accommodate horizon lines)
POLA - 138 Round one-stop

I don't have but will probably get an optical flat...

HIGHLY recommend Schneider filters.

I have an MB 20 II two stage mattebox

M

[HD Bubaloo]

You need Formatt's hot mirror/ND filters. They put the hot mirror (IR) and ND into the same filter in the center of the glass. Also another popular filter with ASC members is HD Soft Gold 2, circular polarizers (do not use linear), ND grads, Whisky and Tobacco filters, Coral grads are a fav. All Formatt filters use Shott-Desag B270 Crown Optical Glass in all the filters.

[Rubancam]

ND , ND Gradient and Circular polorizing filters are very useful.

ND to cut out light so we could use smaller aperture ( Bigger opening iris such as 1.8/ 2.8) especially in sunlight to achieve the better depth of filed.

ND Gradient will help to reduce the skyline light which is always 2 to 3 stops more than the rest of the area in the frame. So it is very helpful to retain all in good exposure.

Polarizer will cut down any reflection from Water and glass surface, not from any metal though.

Other than that we could use every thing else in post including soft focus.
It is not a good idea to shoot with the soft focus filter, once you shot with it, you can never go back. These effect can be applied while color grading very effectively and selectively.

[Wayne Schulman]

You should not use a linear polarizer with this camera. My advice is to rent and see what you like.
ND, ND grads and a circular polarizer for sure. Try some diffusion filters. Formatt HD Clear Soft Effects. Schneider Frosts, Tiffen diffusion, Formatt Soft Gold.

[Ash Bolland]

Has anybody tried the redrock filters?

http://shopping.netsuite.com/s.nl/c.472981/it.A/id.469/.f?sc=2&category=864

thanks...

[Pawel Achtel]

You should not use a linear polarizer with this camera.

Why?


I'd go with a circular pola, not linear.

Why?

[Stephen Strangways]

After lurking for a long time, I had to register to comment on this. As Pawel said, why? Why should you not use a linear polarizer?

First of all, let me clarify a common misconception about polarizers: both can be freely rotated to change the angle of polarization, and thus the effect of removing reflections or deepening the colour of a blue sky.

Both do the exact same thing to light entering them. To try and simplify, light "vibrates" in all directions when it leaves a light source, whether artificial or natural. When it is reflected by most surfaces (other than metal) it becomes polarized, only vibrating in one direction. Reflected light from a horizontal surface is horizontally polarized, and vice-versa for vertical surfaces.

A polarizer is simply a screen, it only transmits light that is polarized in one direction, and rotating the polarizer alters that direction. So, if you have a reflection from a horizontal surface, and you rotate the polarizer until it ony allows vertically polarized light to pass, it effectively blocks the reflected light, and therefore the image of the reflection.

The difference between the two types of polarizers is in how light leaves the filter. A linear polarizer simply lets the light, now polarized in one direction only, continue on it's way. A circular polarizer uses a "quarter-wave retarder" to essentially un-polarize the light, and get it vibrating in all directions again... still minus the reflection, of course.

With a linear polarizer, it doesn't matter which direction the filter is facing, the effect is the same either way through the filter. With a circular polarizer, it must be correctly oriented so that the quarter-wave retarder is facing the lens. Otherwise, no polarization. It's an easy way to make a visual check, by eye, if a pola is linear (works both ways) or circular (only works one way.)

The reason for this is that some Single-Lens Reflex still photography cameras use polarization in their autofocus and/or exposure systems. Light vibrating in a specific direction passes through the mirror reflecting light up the viewfinder, and hits a secondary mirror sending it down to a metering and/or autofocus sensor system. It's polarizing light.

The problem is that if your metering/AF system takes the vertically polarized light, and your polarizing filter is only letting through horizontally polarized light, the sensors receive no light at all, rendering them useless.

With a circular polarizer converting the light that is polarized in only one direction back into light polarized in all directions, the secondary mirror is able to do it's job, and has light it can direct to the sensors.

I hope you followed along with all of that. But here's the catch:

As far as I know, the RED ONE does not have anything in it's optical system that is affected by the polarization of light. There isn't a semi-polarized mirror in between the exit pupil of the lens and the sensor. A high-pass/infrared filter in front of the sensor won't be affected by polarized light.

Why spend more on the circular polarizer? Probably because the safe bet has seemed to be splurging on the circular just in case. I also find it common for people to believe that "circular" means it's the only one you can rotate to vary the effect. Misinformation, uncertainty, and doubt.

Put it all to rest now. If you're looking to buy a polarizer, get a linear if it'll save you money. In fact, why not, try and find a clean, scratch-free used one?

Granted, I don't own a RED ONE. So if anyone out there wants to actually test it in the real world, please do, and post your results here.

[Pawel Achtel]

After lurking for a long time, I had to register to comment on this. As Pawel said, why? Why should you not use a linear polarizer?
....
Put it all to rest now. If you're looking to buy a polarizer, get a linear if it'll save you money.

Absolutely! In fact, linear polarizer is better than circular because it does not have a de-polarizer, which means it does it's job without the extra overhead of an additional layer.

[fde101]

I thought RED One had a "native" ISO/ASA of 320, not 500?

[Harmonica]

I hope you followed along with all of that. But here's the catch:

As far as I know, the RED ONE does not have anything in it's optical system that is affected by the polarization of light. There isn't a semi-polarized mirror in between the exit pupil of the lens and the sensor. A high-pass/infrared filter in front of the sensor won't be affected by polarized light.

Why spend more on the circular polarizer? Probably because the safe bet has seemed to be splurging on the circular just in case. I also find it common for people to believe that "circular" means it's the only one you can rotate to vary the effect. Misinformation, uncertainty, and doubt.

Put it all to rest now. If you're looking to buy a polarizer, get a linear if it'll save you money. In fact, why not, try and find a clean, scratch-free used one?

Granted, I don't own a RED ONE. So if anyone out there wants to actually test it in the real world, please do, and post your results here.

Great post! I was planning to get a linear pola for these same reasons, but I ended up going with circular because of the auto-focus and optical viewing systems that are coming out.

[adolfox]

Awesome post. Other explanations about filters are always targeted to people that already know a lot about photography. I loved the way you simplified the purpose of ND filters--I paraphrase, "basically a pair sunglasses for your camer."

I think that a lot of people, many authors of books included, give complicated explanation just to sound intelligent and validate their own knowledge. I truly believe that if you really know something, it can be explained in very simple terms. Richard Feynman, famous particle physicist, is of the same mind. He says that you really don't know something until you can explain it in simple enough terms that anybody can understand.

Thanks for the great post.

Anybody know any books that go into other aspects of photography/cinematography in a similar way to Evin's post?

[Kujtim Ereqi]

I never used lens filter before.
My question: is it possible to use more than one filter in the same time, and how? Do we need another tool or something..

thanks in advance

[MacKenzie Smith]

Another new user question.

Is there a filter set out there that fits onto the lens? I've had these for my DSLR. Right now the only lens I have is the RED 18 - 50. Also, is there just a plain glass one out there so that I have something to protect the glass? I've looked around a bit but can't find anything specific for this lens.

Thanks,

[Pawel Achtel]

I never used lens filter before.
My question: is it possible to use more than one filter in the same time...
yes


... and how?
slide it in


Do we need another tool or something..
Matte box

[Pawel Achtel]

Another new user question.

Is there a filter set out there that fits onto the lens? I've had these for my DSLR. Right now the only lens I have is the RED 18 - 50. Also, is there just a plain glass one out there so that I have something to protect the glass? I've looked around a bit but can't find anything specific for this lens.

Thanks,

"Plain glass" is never used. Optical clear flat is also not used unless you are filming hazardous situations. The reason is that any additional glass decreases optical performance of the lens. Protective filters are for kiddies. Real men do not use protection...

Long lenses sometimes have internal filter slot. Red 300mm has one.

Happy shooting :biggrin:

[David Mullen ASC]

Another new user question.

Is there a filter set out there that fits onto the lens? I've had these for my DSLR. Right now the only lens I have is the RED 18 - 50. Also, is there just a plain glass one out there so that I have something to protect the glass? I've looked around a bit but can't find anything specific for this lens.

Thanks,

If the front of lens does not have a threaded filter screw mount, then you'd use a clamp-on adaptor ring to hold a round filter, one that is slightly bigger than the front of the lens.

But at some point as you use multiple lenses with different-sized fronts, and multiple filters, it will be easier to use a mattebox and rectangular filters.

But you may also want some round clamp-on filters and a rubber sunshade for more handheld situations.

If the lens has a filter tread in front, you can buy screw-on filters for that thread size usually. But at some point, it gets a bit awkward with lenses with huge front elements which is why most don't have filter threads.

[Edmundo Díaz]

Can someone comment on their experience with the filter TRU-CUT IR-750? I have a situation of external actors with plenty of sunshine and I am concerned about the purity of the blacks.

[Alexander Alexandrov]

i've read a few filter review posts on here. since some time has passed, new filters released since latest reviews (redrock, formatt, etc.), what is the beginner filter set you'd recommend?

as i understand it, the nice package is:
- .3, .6 regular NDs by Tiffen
- Rosco True Color (anyone knows if they started doing "sandwiched", protected models by now?)
- .9, 1.2, 1.5 Panchro IRNDs

- any thoughts on the above kit? or any other recommendations due to new items in the market
- also which Polarizer would you recommend? (this one? http://www.filmtools.com/schneidtruep.html)
- what is the order to stack / not to stack these? (i'm assuming polarizer to go in front of everything (except IRNDs); rosco - 1st to the lenses, then NDs?)
- any thoughts if new RED cameras coming out will change the game with IR and other filter results?

thank u

[Alexander Alexandrov]

anyone?

word on the street that the formatts are really nice, but no tests to date

[Lawrence Daufenbach]

Do you need IR+ND combos when shooting on the red? Also what if you stack and ND3IR and and ND6IR? Is that too much IR going on? Trying to understand it better. Or is it better to have separate ND filters and an IR filter?

[Pawel Achtel]

Do you need IR+ND combos when shooting on the red? Also what if you stack and ND3IR and and ND6IR? Is that too much IR going on? Trying to understand it better. Or is it better to have separate ND filters and an IR filter?

It depends what you mean by "better". It all depends. The goal is to get rid of IR contamination and avoid side effects such as vignetting or colour shifts. Different solutions work on different principles. Dichroic filters cut off certain spectrum. Pancro mirrors, for example, reflect both visible and IR equally and therefore can not be separated into IR and ND filter.

Performance of a dichroic IR filter will also differ depending on the angle of your lens as they introduce cutoff frequency shift towards corners. Some users reported reflections when using Pancros. Mine seem work perfectly on the lenses I have.

Read the tests performed here, test yourself and then chose what works best for you and your lenses.

[John Heaney]

Hi Guys, I have a RED T3 18-50mm and 50-150 Zoom lens. Should I use a screw fit filter to protect the glass? if so, which one?

Thanks,
John

[Evin Grant]

Wow, way to resurrect a thread. I would recommend a matebox and 4x5.65 size filters for versatility and coverage. Most of us only use protector filters or optical flats for FX work where there is debris flying at the camera.

[Richard Foster]

Yes - I learned that the hard way shooting a sparkler on an 8x10 Deardorff with a 10" Rodenstock lens that ended up with an area of melted glass on the front element from a flying piece of molten metal. I sold that lens - at a loss:–(

[D Fuller]

Yes - I learned that the hard way shooting a sparkler on an 8x10 Deardorff with a 10" Rodenstock lens that ended up with an area of melted glass on the front element from a flying piece of molten metal. I sold that lens - at a loss:–(

A big loss, I'm thinking. Ouch.

[Richard Foster]

Yes, but that's why we're called "trained professionals." We have experience, and experiences, which is experience picked up the hard way.

[LCamak]

This is a very good thread but I am wondering if any information needs to be updated in light of the MX sensor? This thread started long before that.

Also, many operators have some extensive time under their belt now with the filter combos they bought. Any thoughts on what they'd have done / purchased different? What are the current reccomendations for "must have" filters? And brands please?
I'm adding a 6x mattebox for some anamorphics and I am re-evaluating what I need to pruchase this time.
Thanks!
lael

[JamminJG]

Hardly any mention of a Hot IR filter. In the oldnen days, long long ago, before time was measured, one used to have to have a "hot IR" when shooting at elevation. I live at 7000 and that's a "thing" out here. Our sunlight is closer to 5800k than 56 and we have uv bouncing all over the place... So, the question is: Is that still an issue with the new sensors and with the Epic and/or scarlet?

Inquiring minds need to know!

thanks

[David Jean Schweitzer]

I only use Hot IRs when I pile on a lot of ND. The theory behind this has to with the ratio of visible light to IR. When one knocks down the visible light by a major amount using ND filters you do not reduce the IR. The atmosphere does absorb much of the IR at sea level. At 7000' of elevation there will be more more IR than at sea level. In answer to your question about the newer sensors, yes they are less sensitive to IR than the pre MX RED One sensor. Nonetheless, like I said once I starting adding significant amount of ND combined with high altitude I add a HOT IR dichroic in the filter stack.