Masking a Ground Glass for Cinema Aspect Ratios

[r.e.]

I'm interested in masking my 4x5 and 8x10 backs (Arca Swiss F-line) for four aspect ratios that are used in feature films. I have two questions:


What’s the best way to mask the ground glass so that it’s easy to remove the mask and easy to clean up marks or residue?

Are there any issues with this approach to defining the image area that I should look out for?

This is not something that I've done before. Thanks for your advice.


Context:

Initially, I want to try this with the 4x5 back and the following Rodenstock lenses:


APO-Grandagon f/4.5 55mm
Grandagon N MC f/4.5 75mm
Grandagon MC f/6.8 90mm

I plan to try the following aspect ratios in landscape orientation:


2.39:1 (anamorphic widescreen)
Mask: 5” wide x 2" tall

2:1 (Vittorio Storaro and some Netflix films; also 12cm wide x 6cm tall still photos)
Mask: 5” wide x 2.5" tall

1.85:1 (standard widescreen)
Mask: 5” wide x 2.7" tall

1.78:1 aka 16:9 (high-definition television and on-line video)
Mask: 5" wide x 2.8" tall

[LabRat]

In the studio, we would draw on mylar overlays for the GG... Most art directors would specify a proportion needed for an ad layout, and that had to be followed exactly through the shooting process...

Using a proportion rule scale was also constantly used on the GG also, and if you can still find one, a small one was made that is perfect for a camera GG...

Steve K

[r.e.]

Thanks guys for the replies. Looks like this will be straightforward.

[r.e.]

I'm attaching a table that might be useful to someone in the future. It applies the aspect ratios for seven cinema formats to 4x5 and 8x10 sheet film. The table assumes landscape orientation and full use of the film's long side. This means that the only new value is the height of the image.

I have not used the nominal film size (5"x4" and 10"x8") for the calculations. Instead, I've used the actual image area after taking into account film holder rebate. As there is variation in film holders, there will be variation in actual image area. However, subject to comments from others I think that my numbers are close enough. They are based on earlier posts in the forum and measurements of my own negatives. The English values below are a slightly rougher approximation than the metric values:

5x4 Image Area
4.75" x 3.75"
120mm x 94mm

10x8 Image Area
9.75" x 7.75"
247mm x 197mm


My Arca Swiss 5x4 and 10x8 ground glasses have metric grid lines. The 5x4 ground glass has 12 squares by 10 squares that are each 10mm x 10mm. The 10x8 ground glass has the same pattern except that the squares are each 20mm x 20mm.

I've used metric for the image heights in the table because that's what my ground glass grids use and because I prefer metric anyway. While the heights in the table are accurate to two decimal places, I will of course round these values in actual use. Accuracy to within a few millimetres strikes me as fine.

I'm particularly interested in trying a couple of the wider aspect ratios (1 through 4 in the table below) with a Rodenstock APO-Grandagon f/4.5 55mm, which I expect to receive this coming week.


Cinema Aspect Ratios Applied to 4x5 and 8x10 Sheet Film:

221860

[Greg]

I've used clear red negative masking tape in the past. Scotch 3M 616 Lithographers Tape. "Pressure sensitive - Red "Paklion" film. We used to use it to mask Kodalith negatives. Very important: it was easy to remove and or replace. PM me and I can send you a roll. Haven't had a use for it in probably 30 years!

[r.e.]

I've used clear red negative masking tape in the past. Scotch 3M 616 Lithographers Tape. "Pressure sensitive - Red "Paklion" film. We used to use it to mask Kodalith negatives. Very important: it was easy to remove and or replace.

Thanks Greg. I'm looking into the 3M tape and how easy it is to remove the tape and residue from my ground glass.

[r.e.]

The attached screen capture from RED Cinema Cameras shows the horizontal differences between certain of these aspect ratios overlayed on a single photograph. While not shown in this photo, RED Cameras are natively set up for the 2:1 ratio championed by Vittorio Storaro (e.g. Apocalypse Now). Netflix is using 2:1 (e.g. House of Cards), and 2:1 was also used for the 2018 Best Picture winner at the Academy Awards, Green Book.

From the table attached to post #4, note that a 2:1 image from 5" x 4" sheet film is about the same size as an image shot on 120 roll film with a 12x6/6x12 camera or roll film back.



221721

[r.e.]

I have two reasons for doing this. One is simple interest in what large format still images in some of these aspect ratios will look like. My practical reason is that I'm interested in making still images for incorporation into a video without letterboxing or cropping the images.

My interest in this was revived when I watched Chris Marker's La Jetée recently, a film that I last saw many years ago. La Jetée is a short film (28 minutes) made up almost entirely of still photographs*. In the opening credits, Marker calls the film a "photo-roman" (in English, a "photo-novel"). Terry Gilliam's film 12 Monkeys, as Gilliam acknowledges in the opening credits, is based on Marker's film.

If anyone is interested, La Jetée is available from Criterion** and there are copies on YouTube and Vimeo. NY Times film critic A.O Scott talks about the film in this video:

'La Jetée' | Critics' Picks | The New York Times


https://www.youtube.com/watch?v=tgC7Eh355E4&t=87s


There's also a Wikipedia article: https://en.wikipedia.org/wiki/La_Jetée


* Marker is said to have shot the film with an Asahi Pentax.

** Criterion sells more than one version of this film with respect to language. If you want the French original, note that the version that Criterion sells via the Apple Store in the U.S. only offers dubbed English. This copy on Vimeo (720p) has the original French with English subtitles. Under "CC" select English:


La Jetée, French with English subtitles (720p) (https://vimeo.com/257806726)

[r.e.]

Since writing the above posts, I've come across a 2004 thread that I missed on my initial search but which is useful: How best to mask ground glass to change aspect ratio (https://www.largeformatphotography.info/forum/showthread.php?9145-How-best-to-mask-ground-glass-to-change-aspect-ratio)

There's also a two page 2019 thread titled Aspect ratio of 10x8 and 5x4? (https://www.largeformatphotography.info/forum/showthread.php?154613-Aspect-ratio-of-10x8-and-5x4) That thread starts by dismissing the original poster's question. New to large format, he wanted to know what the aspect ratio is for 4x5 and 8x10. I think that it was a perfectly good question and I approach the issue differently from most of the posts in that thread. For my purposes, the nominal aspect ratio of 4x5/8x10 is 1:25:1. The aspect ratio for the actual image area is only marginally different at about 1.26:1. See post #4 and the attached table for what I mean by nominal image area and actual image area.

[Greg]

Thanks Greg. I'm looking into the 3M tape and how easy it is to remove the tape and residue from my ground glass.

Tape is very easy to remove, Honestly never left any residue. If it did I would first try some film cleaner, otherwise I'd use what I consider the best residue remover: Seal UNSEAL ADHESIVE RELEASING SOLVENT but only outside in the open. Warning on the side of can reads "IF INHALED: Move to fresh air. GET QUALIFIED MEDICAL ATTENTION"... it can't be good for you would seem to be an understatement.

[LabRat]

I would just use a marked overlay of mylar (free mylar from discarded lab processing sleeves), or you can develop out some fogged B/W sheet film and cut out a GG mask for your formats... You can add some kind of clip or hold down scheme for the focus panel... You can then change to any format in the field easily...

Steve K

[r.e.]

I plan to start experimenting with this over the weekend. Initially, I plan to use 4x5 sheet film to make photos that are 1.78:1 and 2:1.

4x5 at 1.78:1 aka 16:9

This is the aspect ratio for online video (e.g. YouTube) and many computer displays. I want to use this ratio to make photographs that I can include in videos without letterboxing or cropping the photo.

Metric: 12cm wide x 6.7cm tall
English: 4.75" x 2.65"


4x5 at 2:1

This will result in an image that is about the same size as a 6x12 photograph made with a 6x12 camera or 6x12 roll film back. Cropping the height of a 1.78:1/16:9 photo by about 7mm/0.28" also produces this size of image. The two aspect ratios are close enough that there's an obvious argument for shooting 1.78:1/16:9 and cropping when desired.

Metric: 12cm wide x 6cm tall
English: 4.75" x 2.38"

Masking

The photo below shows my Arca-Swiss 4x5 fresnel/ground glass. The grid of 1cmx1cm squares is 12cm wide and 10cm tall. I think that I can do this without masks. For example, composing at 2:1 is just a matter of ignoring the two top and two bottom rows of squares. However, masking may help concentration and the grid will make masking easy.


221896

[r.e.]

Out of curiosity, I made a version of the table attached to post #4 that includes a number of still photograph aspect ratios and the Golden Rectangle ratio. See the blue cells in the table below. To me, it's interesting that 6x17 and 4x10 are narrower than anamorphic widescreen, although 4x10 only marginally so. It's also interesting how close the aspect ratio for European theatrical release is to a Golden Rectangle.

221931

[CreationBear]

The photo below shows my Arca-Swiss 4x5 fresnel/ground glass.


Hmm, could you just back off the screws of the GG clamps a skosh so you can shim, say, an exposed 4x5 sheet with appropriate window cut in? (FWIW, I use a 4x5 negative carrier with a selection of such sheets as a "composition frame" in conjunction with a knotted string for different focal lengths.)

[C. D. Keth]

The easiest way is to create framelines in indesign or photoshop and print them onto clear acetate. That can then be placed over the back of the groundglass under the spring retainers. If the odd dust between those layers bothers you, you can use water with a couple drops of dish soap or photo flo to apply the acetate and use a squeegee to clear out bubbles.

[r.e.]

Follow up...

I use the Artist's Viewfinder Mk. II to roughly compose photographs. So far, I've found that using that app and the grid lines on my ground glass make masking the ground glass unnecessary. I talk about the Artist's Viewfinder in What Scouting/Planning Apps Are You Using in 2021? (https://www.largeformatphotography.info/forum/showthread.php?164815-What-Scouting-Planning-Apps-Are-You-Using-in-2021) There's a photo of my ground glass attached to post #12 above.

[Drew Bedo]

Full disclosure: I am an e-idiot and can barely use PS-Elements.

I am indeed a big fan of getting "IT" on film in the camera first, but . . . .

I wonder how much of the aspect ratio/framing can be done in photoshop?

[pendennis]

I've used Chart Pak tape for masks. It comes in .125" widths. I lay out the edges using a fine point Sharpie, then "connect the dots". Mostly mine is to demarcate 6x7, 6x6, 6x9 format for roll film adapters.