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Are Fresnels the only way to get sharp beams of light? (6 replies and 6 comments)

Shyam Ediriweera
9 months ago
Shyam Ediriweera 9 months ago

Hi Roger,

I have a shoot coming up and I was hoping I could trouble you for any advice about how to achieve sharp beams of light similar to the attached references from True Grit and The Man Who Wasn't There (notwithstanding, and it goes without saying, that the available lighting in my case is much more limited than those films).

I've attached a lighting diagram of the Church location:

A) is an overview of the space, that will be filled with haze. It is dark but for 2 x windows that I propose to light through. The 2 x windows are next to each other, and effectively comprise a single 3'x3' window, divided by a rail between the two. The beams that I'm seeking to achieve are highlighted in yellow. The beam throw/distance required is approx 16'. 

B) is a more detailed diagram of the proposed set up, which due to budget constraints is likely to involve 2 x M18s, one from each window, approx 3 feet from the window.

C) is an overhead view of the set up of (B) - my concern is whether the 2 x M18 beams may "bleed" into each other, as shown in RED.

D) is a top view of an alternative set up to (B) that I'm pushing for, to use a single 6K HMI Fresnel, approx 6' from the windows, to shine through both windows - and hopefully no "bleeding" of the 2 x beams created.

I'd be ever so grateful for any guidance that you may be able to provide as to which option, in the circumstances, is best suited for obtaining the sharpest possible, individual beams?

Is it correct that you can only achieve the sharpest beams with a Fresnel light?

Accordingly, do you think that a set up such as (D) with a single 6K HMI Fresnel could work?

Or is it possible to achieve the beams with M series lamps, such as the 2x M18s in set up (B) or is it likely that the beams will bleed?

Could a single M40 through both windows be a possible alternative, or is a fresnel lamp essential? 

My options are likely limited to 2xM18s, 1xM40, or at best 1x6K HMI Par Fresnel.

Thank you very much and kind regards

Shyam

 
https://www.rogerdeakins.com/wp-content/uploads/2020/10/True-Grit.png
https://www.rogerdeakins.com/wp-content/uploads/2020/10/Man-Who-Wasnt-There.png
https://www.rogerdeakins.com/wp-content/uploads/2020/10/Lighting-diagram-Church-scaled.jpg
trinethra
9 months ago
trinethra 9 months ago

Hey shyam,

I think both setups can be used to achieve the diagonal shafts that you're looking for but it depends on how far you can move the fixtures away from the windows.

If you cant move the fixtures too far then, id suggest going with two M18's as you will have more control of where the shafts are going to fall. The lamps can be placed at an angle to each other instead of setting them in parallel to avoid bleeding.

If you have the freedom to move the fixture further than 3ft then use a 6K fresnel and flag off unnecessary spills. 

To get the shafts right, you would need a haze the set area or dust a carpet to give the light something reflect and produce shafts. 

Roger Deakins
9 months ago
Roger Deakins 9 months ago

It looks to me that your drawings are a little misleading. You will need to have your lights a little further than 3' to 6' from the windows to get a good sharp beam. Your drawing has the beams overlapping, so you will end up with one wide patch of light rather than two separated beams. You might consider two lamps and then cutting each lamp from the other, as well as creating an angle between them such that they won't cross one another.

For the scene in 'True Grit' I was using an Arrimax lamp and it was, maybe 15' from the window. For the scene in 'TMWWT', I think that was 6K HMI (maybe a 4K) Par lamp close to the set so, as you see, the beam is conical in shape and not at all like sunlight.

Shyam Ediriweera
9 months ago
Shyam Ediriweera 9 months ago

Thanks so much Roger, Trinethra for taking the time to consider the diagrams and for your advice.

Apologies about my misleading diagrams and for thank you for your advice regarding the minimum distance to get a good sharp beam.

it's not very clear from my diagrams that the 2 windows are spaced very close to each other, so it is effectively one large window that is cut by a post in the middle. As such, perhaps a single 6K Fresnel as far back as possible could be the best option?

Providing the lights are at a sufficient distance from the windows, say 12 feet, do you still require a Fresnel lamp to achieve a good beam? 

Or, can you still get a sharp beam with a lensless lamp, such as the Arri M40?

Thank you very much 

Shyam

gabj3
9 months ago
gabj3 9 months ago

The quality of light is dictated by the size of the source relative to the subject (I believe is the common textbook answer).

To create a hard beam of light all you need is a small source (IE no reflector or panel etc) even if it be just a powerful bare bulb (which I don't recommend for safety reasons). However with a fresnel fixture without modifying it set it too full flood to achieve a sharp cut with the lens and reflector still attached. 

I believe a possible concern would be the required 16' of throw. Having lights close to the window will have rapid fall-off so moving lights further away (or bouncing off a mirror when limited on space) as well as giving you a harder cut will have a more accurate fall-off. 

So the ideal would be larger fixture and move it further away. But that's sometimes not possible. I remember listening to an interview of David Mullen about using multiple Leko's or Source 4's on a windows with small gaps. A Leko is relatively perfect for something like this as you have a lot more control of the cut and (as far as I'm aware) its designed to throw a small area of light a fair distance.

 

gabj3
9 months ago

Also I am probably wrong but I remember reading that a Leko or Source4 (ellipsoidal spotlight reflector yada yada) gives a more even throw. As in it doesn't follow the inverse square law of double the distance 1/4 of the light.

Shyam Ediriweera
9 months ago

Thanks so much gabj3 for all of this info, it is very helpful and much appreciated. I'll look into the Leko/Source 4 options.

dmullenasc
9 months ago

Multiple Lekos with narrow lenses (19 or 26 degree), if lined up properly, create multiple parallel beams that feel like a single beam being broken up by something outside (tree branches, etc.) However, they won't fill a large window without having a LOT of them, which defeats the purpose to some degree of saving money and/or wattage.
Any hard light can create a good beam IF it is backed up enough, even a multi-globed lamp like a 12-light MaxiBrute, you just don't get a perfect shadow on the floor with those (same goes for something like a Molebeam.) A fresnel is good when you want both a sharp light and a sharp window pattern on the floor. But a bright HMI Par will also create a sharp beam and OK window pattern if it is backed up enough.
These windows are probably too big to fill with only, let's say, three Lekos per window. Five or six per window, maybe, but that's a lot, and then have to be carefully set and angles so the beams are parallel.

Shyam Ediriweera
9 months ago

Thanks David for this information and your advice, it is much appreciated.

I read in an earlier, separate forum post that you noted that:
"A fresnel at full flood projects a very even, flat, sharp light that produces "clean" shadow patterns, whether from using flags to cut the light or passing the light through a pattern maker."
Please excuse my ignorance, but can I trouble you to please provide some further information on why a full flood setting provides a sharper beam than when it is spotted? Is this the case only with fresnels, or is it applicable to most lighting fixtures?

Thank you very much
Shyam

Al Duffield
9 months ago

Hey Shyam, long time!

Without wanting to steal Davids' thunder, and while haplessly over simplifying things, Fresnels are by their design, dividing up the light into concentric beams of light, interestingly, the reason they are stippled is to help hide the individual beams. When you flood a fixture you're both reducing the overlap of these concentric beams (due to the angle that the light strikes the lens) & (when the globe gets very close to the lens) reducing the number of concentric beams. The inverse is true when spotting the fixture. By reducing the number and overlap of these concentric beams you will gain lower intensity but increase shadow sharpness.

Have a little play with a studio 1k (dimmed down) and it'll illustrate things well I think.

Roger Deakins
9 months ago
Roger Deakins 9 months ago

No lamp, no source 4 or Leco, contravenes the inverse square law. The light from any source will fall off at the same rate. The distance of a source controls how rapidly the light will fall off over a subject, a room for instance.

I have in the past used a Wendy light to create a sharp shadowed 'sunlit' look. The Wendy is a very large lamp but it is a 96K source, so when placed far enough away from a subject, it will provide a bright hard source with relatively little fall off. The hardest source you could use is a bare bulb but a bare bulb, without a reflector behind it, is not a bright source. The reflector of a Fresnel lamp is concentrating the photons from a bare bulb into a directional beam instead of allowing the photons to project out in all directions. I used bare 10K and 24K bulbs on 'BR2049' to create very sharp light patterns, but the output of even a 24K bulb is pretty minimal at the distances I required for the light to appear at all like the sun. On one set I used two 24K bulbs and cut the side of one beam from the other so that it appeared as if a single source. The two bulbs were rigged to the same scaffold pole so that I could move both in unison, as if the 'sun' were moving. Of course, it really looked nothing like the sun!

Baudelaire
7 days ago

thats another nice clear lesson. Very appreciated.

Shyam Ediriweera
1 week ago
Shyam Ediriweera 1 week ago

Hi Roger and Forum Members,

I just wanted to thank you again for all your advice about how to achieve sharp beams of light to achieve a sunlit look.

Further to your guidance and advice, we were able to achieve a beam using an Arri M90 approximately 15 feet from the window.

I've attached a framegrab from the scene, and if you'd like to view the spot, titled "Trial Before The King", its available here: http://www.shyam.tv/tac»

Thank you very much and kind regards

Shyam

https://www.rogerdeakins.com/wp-content/uploads/2018/09/Trial-Before-The-King-Beam.jpg
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