138mm Round Filters vs 4 x 5.65 Filters

[Justin Allen]

I am looking at the ONE Tray by Bright Tangerine ( https://youtu.be/OiduOxbE-MY) and need a bit of education concerning filter sizes. As I have no filters at all I can easily go in any direction, but I want to make sure I am heading in the right direction. Is there a danger or difference in using a 138mm round filter size compared to using the 4 x 5.65 filter size. If it makes a difference my Matte box is the Bright Tangerine Misfit Kick.

Thanks for any thoughts.

Edited October 9, 2020 by Justin Allen

[Satsuki Murashige]

4x5.65 is a lot more commonly used and fits a wider range of matte boxes. They are also lighter, smaller, and cheaper than 138mm filters.

I would reserve 138mm filters for Polarizers and Diopters. Even with Polas, most people use Rota Polas in a 4x5.65 stage now. 

[Evan Walsh]

What Satsuki said, 138 (or 4.5 round) are useful for effects filters like Star's allowing you to dial in an effect. Pola's, Diopters and Stars will be the most common round filters you'll find. 

You may occasionally see round ND or Diffusion filters but those were intended more for the threaded mounts you would find in the photo or ENG world where you may not be using a mattebox. 

[Justin Allen]

Thanks everyone. One point I have found different than stated is the price information. I am looking at close to $500.00 per ND filter at the 4 x 5.65 size and the same ND filter by the same company at the 138mm size is half that price.

[Joshua Cadmium]

Another important point is that 138mm round filters will have less coverage than 4x5.65 filters.

Since we are always dealing with rectangular aspect ratios, a 138mm filter in the same 1.4125 aspect ratio of a 4x5.65 filter will cover about a 79.7mm x 112.6mm rectangle

A 4x5.65 filter covers a rectangle of 101.6mm x 141.5mm

So, 4x5.65 filters offer about 25% more coverage in both directions. But that's at a 1.4125 aspect ratio. As you go wider, the 138mm filter can make up some ground, but it still does not cover as well as a 4x5.65 does. 

At a 1.85 aspect ratio, a 4x5.65 covers a rectangle of 76.5mm x 141.5mm. A 138mm would cover 65.6mm x 121.4mm. That's about a 15% difference in coverage in each direction. 

At a 2.39 aspect ratio, a 4x5.65 covers a rectangle of 59.2mm x 141.5mm. A 138mm would cover 53.3mm x 127.3mm. That's about a 10% difference.

[Joshua Cadmium]

So, if you can deal with the lack of coverage, you might be okay, but 4x5.65 is the standard for everything besides rotating filters. The market for 138mm NDs is small, so resale will take a hit if you ever decide to step up to 4x5.65.

I know Formatt has their 138mm Firecrests on sale for $200, but they've been on sale for a while and no one is buying, if that tells you anything. 

[Satsuki Murashige]

1 hour ago, Justin Allen said:

Thanks everyone. One point I have found different than stated is the price information. I am looking at close to $500.00 per ND filter at the 4 x 5.65 size and the same ND filter by the same company at the 138mm size is half that price.

What specific filters are you looking at? 

I’ve generally found that the same filter brand/model to be more expensive for 138mm. For example, a Schneider Circular Tru-Pol is $391/4x5.65 and $423/138mm at B&H. Not surprising, as there’s more glass in a 138mm filter as well as a metal frame.

But that doesn’t take into account overstock and discontinued item deals. There’s no way a new 138mm filter would be half the cost of 4x5.65 unless there were some special circumstances. I’d just make sure that you’re not getting an older version of the filter or something.

[Joshua Cadmium]

I just double checked and Formatt is having a 50% sale on all of their Firecrest filters, including clearance ones, until Monday: https://formatt-hitechusa.com/collections/clearance

4x5.65 is $180 and 138mm is $99.

The older filters are exactly the same as the newer ones according to this: https://cdn.shopify.com/s/files/1/0267/9934/1677/files/Formatt_Firecrest_Ultra_Brochure_-_Updated.pdf

[Justin Allen]

On 10/10/2020 at 7:30 PM, Satsuki Murashige said:

What specific filters are you looking at? 

I’ve generally found that the same filter brand/model to be more expensive for 138mm. For example, a Schneider Circular Tru-Pol is $391/4x5.65 and $423/138mm at B&H. Not surprising, as there’s more glass in a 138mm filter as well as a metal frame.

But that doesn’t take into account overstock and discontinued item deals. There’s no way a new 138mm filter would be half the cost of 4x5.65 unless there were some special circumstances. I’d just make sure that you’re not getting an older version of the filter or something.

In looking at the ONE tray it looks like I can, in the space of one stage, add a circular 138mm ND filter instead of a 4 x 5.65 ND filter. The reason I am looking at this is because the price of a 138mm Tiffen ND filter is approx. $300.00 but that same filter at 4 x 5.65 is just over $500.00. Buy 3 of these and the ONE tray has paid for itself.
 

However Joshua above stated some really great reasons for not using circular filters and I also talked with Scott Balkum and he stated much the same thing.

I think I will just bite the bullet and get the 4 x 5.65 Tokina Cinema IRND filters I have been looking at.

[Satsuki Murashige]

1 hour ago, Justin Allen said:

In looking at the ONE tray it looks like I can, in the space of one stage, add a circular 138mm ND filter instead of a 4 x 5.65 ND filter. The reason I am looking at this is because the price of a 138mm Tiffen ND filter is approx. $300.00 but that same filter at 4 x 5.65 is just over $500.00. Buy 3 of these and the ONE tray has paid for itself.

I guess if you only ever use two filters at a time and never plan to use other matte boxes, then it would make sense. My observation is that one tends to upgrade matte boxes over the years, while filters stay the same and if you take care of them, they will last you a lifetime.

I probably have over 30 filters, mostly in 4x5.65. Some bought used, most bought new over the last 20 years. I still use all of the 4x5.65 and 77mm sizes on every shoot. My one 138mm filter is a Schneider Tru-Pol, which I never use anymore due to no longer using a matte box with a 138mm stage. I always end up renting a 4x5.65 Rota Pola instead. I never bought a Rota Pola at the time because I just couldn’t see paying $1K for a filter. But in the end, it would have saved me money.