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Alexandre de Tolan

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I suspect you could put together a 400W HMI kit, which will be more powerful than the Hive and hot start, for less or similar money from any manufacturer other than Arri.

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I suspect you could put together a 400W HMI kit, which will be more powerful than the Hive and hot start, for less or similar money from any manufacturer other than Arri.

 

A quick look into B&H catalogue - ordered by ascending price - revealed that only 200W Jokers are cheaper than Hive Lights. That and the Chinese lights that they are selling through the brand "Came TV". Didn't know that even B&H sells them. I ask how they handle warranties.

 

Noticed the new Mole-Richardson Senior LED selling for about 4400USD. It's out of our budget but it seems like a fantastic piece of gear. Can't seem to find any European seller though.

Edited by Alexandre de Tolan

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Well, the Hive certainly doesn't start quick it takes a good 90 secs to reach temperature. I've never times a restrike but I think it might be around 2-3 mins to restrike. Personally I've never had an issue with that - if you're moving the light anyway (why else would you need to restrike?) then you can probably spare the 3mins.

 

I ended up getting the Hive for much the same reason as the OP - I was basically after the cheapest high output solution I could get that could still be battery operated (if needed) that gave a hard light (as hard can always be softened, but a panel LED can't really be hardened - and the Hive is more powerful than fresnel LEDs like the F8). The fact it's also flicker free to 1,000,000 fps was also a big seller for me (as I've been shooting a lot of high speed recently) whilst remaining still cool (very handy for macro high speed, which I've also been doing) and the quality of the light really is only bettered by tungsten. One extra bonus of it not running hot means you can use first cheap flash soft boxes with it no problem - so I got a nice 5ft octagon with it for around $200 - including speed ring!

 

A word of warning though: you can get hard-ISH shadows from the lamp with the super flood lens. Bare - or using the other lenses gives you a few split shadows because of the reflector. To get really hard shadows you either need to remove the reflector - or buy a standard source 4 lens. The lens replaces the barn doors (no need for any adapter) and boom! Instant daylight Leko, hard shadows included (another nice feature really).

 

I guess maybe the CDM might be a good alternative - maybe you should put together a Kickstarter to manufacture one Phil (seriously, people are always after cheap, good and robust) but Until there is one purpose built for film I'll stick with the Hives. I believe they're working on a more powerful unit as well - something more equivalent to a 1.2K HMI which would be awesome.

 

In terms of the cheap spectroscope, no need to break a set of binoculars, just get a gemmology pocket spectrascope, $30 from Amazon: http://www.amazon.com/gp/aw/d/B00D49E8XE/ref=mp_s_a_1_2?qid=1451405397&sr=8-2&pi=SX200_QL40&keywords=pocKet+diffraction+grating&dpPl=1&dpID=41LEhZ-p2kL&ref=plSrch

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I think if there was a worthwhile market for 250W CDM, Richard Andrewski would have done it at Cool Lights. The problem is that everyone's being terribly distracted by the shiny new toy of LED, even though it's expensive, dim, and cyan.

 

One manufacturer still lists a 600W G22 CDM which would give us something very similar to a 575W HMI, but they appear to be made out of unobtainium.

 

P

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(though HMI is hardly a dead flat spectrum)

 

What is meant by this? What're u describing about HMI light qualities? (I'm new to the lingo)

 

What Phil is saying is that HMI lighting is not "constant" on the RGB spectrum as a tungsten light for instance. Like fluorescents, HMIs have a kind of "spike" (sorry but I'm not a native English speaker and son't know how to explain it in other words), on their RGB spectrum that renders them a unique color caracter on how they debit red, green and blue.

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Exactly as Alexandre says, an HMI is not a great spectral source-- it's output does not hit all wavelenghts, rather it has spikes in it. Now usually this isn't much of an issue, as it's a very good source, but it's output doesn't have a nice, smooth curve across the wavelenghts as you get in a tungsten fixture. (as such too some gels perform differently in my experience on an HMI -v- a tungsten. )

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A point to bear in mind on light sources is spectrum spikes and gaps.

 

Spikes are not desirable as they will colour the subject - HMI, fluorescent and LED for example can have a large green spike and hence the subject looks green on screen.

This is often added by the source manufacturer as the human eye is very sensitive to green and hence the lights appear brighter.

 

Spikes are not so bad as you can add some gel and take out (subtract) the spike.

There is a gel called "Full minus Green" for example - full spectrum but take out green or "Quarter minus green" - full spectrum but leave some green in etc.

 

However some light sources have holes or missing sections of the spectrum and this is more of a problem.

You cannot add a gel and put the colour back.

 

Gels only work on subtraction so to get blue you remove all other light - hence the remaining blue light is low level and you find the gel burns out quickly because it is adsorbing all the other energy.

If the Blue section is not in the light source then adding gel will not produce it.

 

Tungsten is the ideal source as far as the spectrum goes as it is a black body radiator and emits visible light in all colours.

Plasma is also very near ideal and emits visible light in all colours

HMI and Fluorescent have spikes which can be controlled using gels.

LED often has missing sections and this is what makes it hard to work with.

 

Peter Daffarn

MD

Photon Beard Ltd

www.photonbeard.com

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Pictures are good...

 

Here's an spectragraph of an arbitrary CFL light... note the 'spikes' and the 'valleys' and how they match up with 'bright bands' or 'dark bands' in the spectrum below...

 

In fact, those bright bands associated with 'mercury' as well as other elements that make up the gas or elements in the bulb, and can be used to 'calibrate' a spectrograph.

 

 

cfl-spectra.jpg

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With practice, you can start to see generically crap colour output with the naked eye, at least when there are some saturated subjects being illuminated (ideally a Macbeth or some other sort of chart). Perhaps the best example of this is when we take an RGB colour-mixing LED source and turn on the red, green and blue all at once. The output looks strange and harsh.

 

HMI light is often described as looking "snow white". It has a certain rather difficult-to-describe even cleanliness that LEDs often lack.

 

P

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Would a spectrograph of a tungsten source be a straight line?

 

The above spectrograph of the CFL looks like mostly green spike, but also blue and red spikes?

 

The 'spikes' are labeled with the particular element that produces the spike. And various lights have spikes. Depending on the 'energy' in the spike, there will be a 'cast' but some 'spikes' are probably not really visually noticeably to the human observer.

 

Here's a sort of comparison set of lights, unfortunately I was not able to find a 'nice' presentation image that showed the graphs of the different lights... but the spectrographs should indicate where 'bright' spikes and 'dark' holes are for the 3 listed light types.

 

The 'take away' message is, spikes can be 'reduced' by filters, but at some point the lower light level isn't worth the use of the filters to eliminate the problem... and for 'holes' there is no 'corrective' filter to 'fill them in'... Now some is going to thing "well what about a phosphorescent screen that takes in energy from one band and produces light in a different band"... well... that's what the principle of some of the 'new' types of light work on... but it's not a simple 'put this gel on and all will be well'...

 

 

Source_ComparisonB.jpg

Edited by John E Clark

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