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What is the purpose of a 9k hmi or equivalent?


Edith blazek
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The M90 is a great tool, particularly for small to mid size work, and the reason why is almost about everything else than the lamp itself.

With half the draw of an 18k, a M90 requires substantially less power infrastructure, this is particularly true in countries that operate on 240v power. In Australia, we commonly run 50 Amp 3 phase distribution on set, so an M90 with a real world draw of about 43-44 amps means we can run one with our existing standard power distribution and minimal additional work. 

The size of an M90 is a big factor- you can set it up, move it, and wrap it much quicker, and with a smaller crew, and it takes up less room in the truck.

All those pros, and in the real world, output wise it is only about 1/2 stop less than a 18k Frez. 

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4 hours ago, Matthew Parnell said:

The M90 is a great tool, particularly for small to mid size work, and the reason why is almost about everything else than the lamp itself.

With half the draw of an 18k, a M90 requires substantially less power infrastructure, this is particularly true in countries that operate on 240v power. In Australia, we commonly run 50 Amp 3 phase distribution on set, so an M90 with a real world draw of about 43-44 amps means we can run one with our existing standard power distribution and minimal additional work. 

The size of an M90 is a big factor- you can set it up, move it, and wrap it much quicker, and with a smaller crew, and it takes up less room in the truck.

All those pros, and in the real world, output wise it is only about 1/2 stop less than a 18k Frez. 

Ok then, could you tell me a situation where the 1/2 stop difference would matter where there would be something you flat out could not do with a 9k or below light, as a working professional?

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It seems like an odd thing to question making a range of lights by degrees of strength, size, weight, power draw, rental cost...

It's a bit like asking why rent a 50mm lens if you have a 35mm and a 75mm lens.

You use a 9K because sometimes an 18K is too much and a 6K isn't enough. Also, an 18K is like 110 pounds versus an 9K which is 88 pounds. There are times when that weight difference would matter.  There is also the power management issue, the rental cost issue... let's say that an M90 rents for $1000/day and an Arrimax 18K rents for $1300/day.  Let's say your location has ten windows in a row that each need a big HMI... that's an extra $3000 if you opt for an 18K in each and if you can get away with 9K's, which will also be easier to rig, to take on and off of the truck, take up less space in the truck, etc. then why would you rent ten 18K's? Not to mention you have to take into account your generator load.

Also, if you need a really bright HMI and you don't have the money for an 18K but you have the money for a 9K, then you rent the 9K because that's what you can afford.

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1 hour ago, Edith blazek said:

Ok then, could you tell me a situation where the 1/2 stop difference would matter where there would be something you flat out could not do with a 9k or below light, as a working professional?

He was just saying that the 9K is only a 1/2-stop less bright than an 18K, so if it is bright enough for what you need plus smaller, lighter, pulls less power, and is cheaper to rent... why would you rent the 18K? Just because it is bigger, heavier, needs more power, and costs more to rent?

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Your questions seem to be coming from someone who doesn't want to own every incremental degree of equipment in a line, which is fine. There are a lot of degrees of focal lengths in a set of Cooke S4's but not everyone can afford to rent all of them nor wants to carry all of them around. So you make judgement calls as to what to skip in a line, but not everyone thinks the same way or has the same requirements. For some projects you may want more degrees in the shorter focal lengths because that will be the range that the majority of your shots will be, or because you're shooting on locations where the walls cannot be removed so you have space issues that will require shorter focal lengths more often than longer focal lengths. But other projects might not have those space restrictions.

Same goes for lights. Some projects it makes more sense to get more units even if they are smaller rather than get fewer but more powerful units. Other projects the opposite is true. A gaffer will also take into account the storage capacity of the truck, the size of the crew in managing equipment, weight restrictions on location, power load and distribution, etc.  Maybe sometimes it makes more sense to get three 6K's and one 18K, maybe other times,  it makes sense to get four 9K's and no 6K's and no 18K's.

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1 minute ago, David Mullen ASC said:

He was just saying that the 9K is only a 1/2-stop less bright than an 18K, so if it is bright enough for what you need plus smaller, lighter, pulls less power, and is cheaper to rent... why would you rent the 18K? Just because it is bigger, heavier, needs more power, and costs more to rent?

I know that, in fact that's kinda the essence of my question as hearing the practical output difference is making me wonder the usefulness of the 18k or equivalent. I'd think the 9k would be enough for pretty much anything I can think of but that's the problem, I don't know if I'm underestimating how much light I need which alot of people tend to do, I just don't want to be caught with my pants down on set where I don't have enough light  hell, I didn't even know the softsun existed up until a few months ago. So I'm really just curious, what is a scenario where an 18ks extra output meaningfully does wonders.

3 minutes ago, David Mullen ASC said:

Your questions seem to be coming from someone who doesn't want to own every incremental degree of equipment in a line, which is fine. There are a lot of degrees of focal lengths in a set of Cooke S4's but not everyone can afford to rent all of them nor wants to carry all of them around. So you make judgement calls as to what to skip in a line, but not everyone thinks the same way or has the same requirements. For some projects you may want more degrees in the shorter focal lengths because that will be the range that the majority of your shots will be, or because you're shooting on locations where the walls cannot be removed so you have space issues that will require shorter focal lengths more often than longer focal lengths. But other projects might not have those space restrictions.

Same goes for lights. Some projects it makes more sense to get more units even if they are smaller rather than get fewer but more powerful units. Other projects the opposite is true. A gaffer will also take into account the storage capacity of the truck, the size of the crew in managing equipment, weight restrictions on location, power load and distribution, etc.  Maybe sometimes it makes more sense to get three 6K's and one 18K, maybe other times,  it makes sense to get four 9K's and no 6K's and no 18K's.

I agree, I can fully vouch for having more focal lengths in a set, that's practically the core of my business model with renting out lenses, and I am fully in the camp of using many, smaller units over using fewer more powerful units. To be honest I only used the 9k hmi bit as an example of a concept, I'm not actually considering the m90, I'm eyeing the digital Sputnik ds3 beam which is alleged to have a similar output to a 9k hmi but is comprised of 18 lights, not unlike the maxi brutes of days past, so power draw is moot as it's far lower, the reason for all of this is I'm just inundated with the fear of missing out, but with light output. I'm afraid that what is alleged to be a 9k equivalent just won't be enough in a particular situation, that is why I'm asking if there legitimately is a situation where it can only be done with something like an 18k or any type of ultra powerful like again, a softsun, or a maxi brute, or a Wendy light.

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I lit some night exteriors with two 18Ks on a condor and it was barely enough for the size of the shot, but that’s what I could afford so I shot wide-open and was a bit underexposed. Some of this can be plotted using photometric data but often in filmmaking you make do with what you can get.

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The m90 has been extremely common here on productions which can afford it and in most cases the gaffers seem to skip the 18k's entirely unless they have to use them for some reason.

I think the m90 should actually have slightly more light output than an old 18k fresnel (the fresnel design internally wastes some light to heat compared to max or par design) and it is easier to rig and handle consuming less power which allows using smaller and cheaper genny which is easier to manage by the crew

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4 hours ago, Edith blazek said:

I know that, in fact that's kinda the essence of my question as hearing the practical output difference is making me wonder the usefulness of the 18k or equivalent. I'd think the 9k would be enough for pretty much anything I can think of but that's the problem, I don't know if I'm underestimating how much light I need which alot of people tend to do, I just don't want to be caught with my pants down on set where I don't have enough light  hell, I didn't even know the softsun existed up until a few months ago. So I'm really just curious, what is a scenario where an 18ks extra output meaningfully does wonders.

I agree, I can fully vouch for having more focal lengths in a set, that's practically the core of my business model with renting out lenses, and I am fully in the camp of using many, smaller units over using fewer more powerful units. To be honest I only used the 9k hmi bit as an example of a concept, I'm not actually considering the m90, I'm eyeing the digital Sputnik ds3 beam which is alleged to have a similar output to a 9k hmi but is comprised of 18 lights, not unlike the maxi brutes of days past, so power draw is moot as it's far lower, the reason for all of this is I'm just inundated with the fear of missing out, but with light output. I'm afraid that what is alleged to be a 9k equivalent just won't be enough in a particular situation, that is why I'm asking if there legitimately is a situation where it can only be done with something like an 18k or any type of ultra powerful like again, a softsun, or a maxi brute, or a Wendy light.

As well as output level, you also have to take into account light quality when choosing a lamp. An 18k Frez has a much cleaner beam, and a much more even spread than the brutality that is the ‘M’ Series. Which makes it much more suitable as a hard light, especially in situations when you want clean shadow lines. 

 

It’s important to remember one of the core functions of location lighting is to create consistency. Sometimes you are shooting a 3-4 minute scene over several days. So to keep the look consistent, not only are you dealing with the changes of sun with the time of day, but you are also battling the variability of the weather over those days. This is where big units, big frames and machinery come in really handy. 

 

The DS lamps in terms of the world of LEDs are pretty old technology now, and being the first of their kind are a bit unrefined. I must admit I’ve been really underwhelmed by them and their system. I find the optics, and colour science to be perfectly usable, but problematic. In my experience they aren’t particularly user friendly, and their ergonomics when you start moving to the larger arrays is pretty poor (the DS3 Beam you are talking about is both heavy and rather awkward).

 

Regardless, they do have a number of big advantages in having the ability to control them in terms of colour and dimming, but that does come at a cost, and to be honest the only time I would consider supplementing a HMI on location for a DS Array would be if I absolutely needed those features. 

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I'm late to the party on these replies, but as a gaffer, I'll say this.

If on the truck you carry two 18k's, and two 9k's.   I'm leaving those 9k's on the truck.  Beyond rigging, cost, planning for a long day of whatever -

the 9k and 18k on most US sets use the same power rig/run, require the same logistics, same crew power, and generally the 18k is more balanced than the front heavy 9k, while also being more able to cope with temperature/weather.

And trust me when I say, when its 116 in the Georgia heat, we only want to set one lamp, and we're super happy to clamp as many scrims as will fit in front of that 18k, rather than swap out the whole lamp because its "not enough".

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