Jump to content


Photo

A cheap method of lighting that probably won't work


  • Please log in to reply
19 replies to this topic

#1 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 30 August 2017 - 09:28 AM

I'm going to get high CRI leds - the seller claims they're CRI 95 -  put them in cheap parcans that I wouldn't dare use with hotter emitters, then bounce them off white ceilings the way I would flash, gelled to match the ambient. I'll use one in a home-made sabre light - basically a vertical metre long tube lined with reflector on one side and a window with diffuser material on the other - when I want a back light.

 

Any thoughts on how bad the result will be, or suggestions, before I do this? I want natural looking, quick to carry about, safe, the ability to run off mains power, and cheap. 


Edited by David Mawson, 30 August 2017 - 09:30 AM.

  • 0

#2 Adrian Sierkowski

Adrian Sierkowski
  • Sustaining Members
  • 7107 posts
  • Cinematographer
  • Los Angeles, Ca

Posted 30 August 2017 - 10:21 AM

I mean i won't necessarly be bad, but CRI is a bad way to evaluate LEDs, as they can have a high CRI and still massive spikes / color casts on camera. You want to look at the TLCS for it.

A better bet might be these guys:

http://www.hoffmanen...ulb-Replacement

 

http://ledt8bulb.com...m-retrofit.html

 

I bet they'd be close in terms of "quality" to whatever Leds the "seller" has


  • 0

#3 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 30 August 2017 - 11:50 AM

I mean i won't necessarly be bad, but CRI is a bad way to evaluate LEDs, as they can have a high CRI and still massive spikes / color casts on camera. 

 

That was one of my main fears, but coming from a stills background I didn't have the terminology - thanks, that's very useful!

 

...The spikes shouldn't matter if I shoot in b&w? (I'd rather have the option of colour, but I'm willing to shoot mono if it lets me get experience with less cost and weight and quicker light set-ups.)

 

I should add that I'm in the UK, re. vendors. Otoh, $300 for one light is more than I want to pay at this stage.


Edited by David Mawson, 30 August 2017 - 11:55 AM.

  • 0

#4 Adrian Sierkowski

Adrian Sierkowski
  • Sustaining Members
  • 7107 posts
  • Cinematographer
  • Los Angeles, Ca

Posted 30 August 2017 - 11:52 AM

I have a feeling Phil Rhodes would have some good resources for you; I'd PM him and ask him to chime in.


  • 0

#5 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11916 posts
  • Other

Posted 30 August 2017 - 12:00 PM

Did someone mention my name?

It'll probably work somewhat. Bear in mind that 100w LEDs you could put in a parcan will still need serious heatsinks and fans, something like a computer's CPU cooler, so unless the devices you have include that, you'll have to figure out how to do it. And quietly.

95CRI LEDs are unlikely to be absolutely awful in my experience, but as Adrian quite correctly says, the CRI system is not very good at characterising discontinuous-spectrum light sources and anything is theoretically possible. Great thoroughly, but I wouldn't necessarily tell you not to do it.

What I would advise is looking into ceramic metal halide. They have reasonable color rendering and come in various sizes up to 150 watts. Types over 70W don't hot start easily, but they are cheaper per watt than LEDs, about as efficient, and don't need noisy coolers. They work well in source four pars.

Borrow mine if you like!

P
  • 0

#6 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 30 August 2017 - 12:23 PM

Did someone mention my name?

It'll probably work somewhat. Bear in mind that 100w LEDs you could put in a parcan 

 

I had no idea there were such things as 100W LEDs - the most powerful I could find were 20W! I've been sloppy and should have given more details. I was going to put one LED in a small ebay parcam and then make a fitting to let me attach 3 or 4 to a table tripod, put the thing on the floor, and bounce. I'd deal with any heat problems by increasing the distance between the very small cans. The idea of keeping them low was (is?) so they can be shot over and hidden behind furniture.

 

The CMH bulbs seem like a good idea - although given the links returned by the search I just did, I'd worry that I was going to end up on "person of interest" lists kept by the police...

 

Btw - what does "hot start" mean? Or can you recommend a link explaining terminology?

 

And thanks again to everyone responding - my OP really isn't well-phrased, I don't know nearly enough about the basic issues - I did do web searches but the info I found really wasn't great.


  • 0

#7 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11916 posts
  • Other

Posted 30 August 2017 - 12:43 PM

Hot start is a capability of metal halide gas discharge lighting such as HMIs and similar technology which allows it to be restarted immediately after being turned off. Otherwise, a five or ten minute cooldown period will be necessary, which is a bit of a pain in the arse on a film set, but not usually the epic disaster it sounds like it'd be.

Even 20W LEDs are likely to require forced air cooling, or at least a very large heat sink. You could link the devices you're intending to use, and we could talk in mid detail, but generally unless it's a finished device it will overheat and destroy itself almost immediately otherwise.

Not sure what you're seeing in search results for ceramic metal halide parts. I tend to get, well, lighting equipment. It's widely used in shopfitting, although being replaced by LED at this point. You can sometimes even dumpster dive it.
  • 1

#8 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 30 August 2017 - 01:53 PM


Not sure what you're seeing in search results for ceramic metal halide parts. I tend to get, well, lighting equipment. It's widely used in shopfitting, although being replaced by LED at this point. You can sometimes even dumpster dive it.

 

I'm seeing "Here is how to grow lots of marijuana!!!" articles. Or maybe growing tomatoes in cellars is a more popular hobby than I thought...


  • 0

#9 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 30 August 2017 - 02:29 PM

And I was planning on clusters of these

 

https://www.everythi...10->cri-95-50w/

 

..3 to a stand, probably using 2 stands plus daylight to light an average size domestic room.

 

These look interesting but cost more

 

https://cocolighting...0-vivid-95-cri/

 

http://luxreview.com...-led-mr16-3000k

 

I think I need to think some more about how much light I need. This link looks promising -

 

http://wolfcrow.com/...deo-part-one-q/

 

..I think I feel a headache coming on. Possibly combined with the desire to buy an f0.95 lens...


Edited by David Mawson, 30 August 2017 - 02:33 PM.

  • 0

#10 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11916 posts
  • Other

Posted 31 August 2017 - 11:13 AM

I think you'll find that a little 20W LED will need to be used in clusters of lots to be useful. I have some lights which take six MR16 LEDs which are fine, but at barely 120W they're still pretty small lights by anyone's standards. Panavision showed one of its GU10-equipped multi-light devices at a trade show recently, retrofitted with Soraa LEDs. With 144 units, it was a pretty serious light.

 

Ah, yes, the "hydroponics" people. I find if you ask for 150W stuff in G12 base, you'll get something a bit more sane, and a bit more affordable. They come in sizes up to a couple of kW, but the 150W options are cheap, available, and can be practically run from something like a car battery via a mains inverter.

 

Some of the things we're discussing here involve mains wiring and naturally you take responsibility for that, as well as safety around the high voltage ignition pulse produced by metal halide ballasts. Ensure you know what you're doing.

 

Anyway, the lamps look something like this (G12 base)

 

hcit-g12.jpg

 

Or this, if you want something double-ended (Rx7 base):

 

s-l225.jpg

 

The ballasts look something like this:

Lighting6.png

 

Get them both used from eBay. I have three source four PARs which all have different brands of ballast and the results are not perceptibly different.

 

Get electronic ballasts, like the one above. Avoid iron ballasts, like this:

Sodium-Lamp-Metal-Halide-Lamp-IEC-Electr

 

Electronic types typically don't create flicker problems, are lighter, more efficient, and easier to run from inverters and generators.

 

Get lamps with three-digit colour codes beginning 9, which indicates (or at least claims) a CRI in the 90s. The most common types are 942, which suggests a colour temperature of 4200K, which can be gelled to either tungsten or daylight. They're used a lot in shopfits because they give things a clean, sparkly look without being overly cold. Most of the lower colour temperature types begin with an 8, as in 830 for 3000K. Avoid these - they're really just sort of amber. Look for the rather rarer 930 colour code. Higher colour temperatures are rarer in G12 base; there's a lot of 6000K types going around which I get the feeling are all made by one company. 5200K doesn't seem to exist in G12, I've seen it once, though Rx7 options are mentioned online.

 

I've mainly used these to retrofit existing lighting. The golden ticket is to find a shop that's being refitted and intercept its lighting on the way to the skip. The technology we're discussing here is used in absolutely huge numbers in that situation and they often look like they could be rigged to a lighting stand quite nicely, but they're horrendously expensive to buy new. Actually this one isn't bad, but I don't know how good it is. It's just an example.

 

P


  • 1

#11 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 31 August 2017 - 02:20 PM

Thanks, Phil - buying used isn't an option I thought of, but I can see that store lighting will be designed for a huge life.

 

One final question: do heads like https://www.lyco.co....50w-silver.html have built-in ballast, what with being CMH specific?


  • 0

#12 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11916 posts
  • Other

Posted 31 August 2017 - 02:49 PM

I'd imagine that's what's in the cylindrical part at the rear end. Make sure it's electronic, not magnetic.

 

Yes, those ballasts are pretty well built, from what I've seen. Designed for a long service life. Not built like cheap consumer electronics. They can be expensive, new.

 

Or hang around ebay, looking for cheap Chinese copies of source four PARs which are already 150W CMH. All you have to do is replace the (inevitably magnetic) ballast with an electronic one. Bit large for the power level, but very functional.

 

P


  • 1

#13 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 31 August 2017 - 03:40 PM

I think that covers everything - again, thanks.

 

The other option I've seen - that you've probably discarded as inferior for good reason, but which I thought I'd mention in case it interests you - are high CRI CFLs. Photosel seem to be the main high CRI brand in the UK and they claim one of their 100W bulbs will replace 500w of incandescent. (The CFL bulbs are monsters though - physically huge.)

 

 

..I tried to research the pros and cons of the two technologies with google, put I just got pages of results on pot growing.


  • 0

#14 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11916 posts
  • Other

Posted 31 August 2017 - 05:26 PM

You can quite happily just go to B&Q and get some work lights, and replace the tubes with the Philips TL-D 90 series, which are available in daylight, tungsten, and pretty party colours.

 

Again, the electronic-vs-magnetic ballast issue pertains.

 

I have one similar to the ones shown in that video and it is...

 

...ehhh.

 

P


  • 1

#15 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 01 September 2017 - 07:40 AM

I'm guessing that iron ballasts are cheaper and I should assume that they are the default, especially with work and security lights?

 

This seems to be the biggest problem in buying on ebay - very few people say what type a ballast is. You posted pictures, but to be honest the iron and electronic both look the same - except one is white and one is black, which I doubt is a reliable guide... 

 

I did find a great page on ballasts though -

 

http://hid.ventureli...llastTypes.html

 

..Actually, that link seems to say that electronic is now the default, except for very high voltages...


  • 0

#16 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11916 posts
  • Other

Posted 01 September 2017 - 12:03 PM

The way to look at ballasts is that the magnetic ones tend to look like a transformer (they're a big coil of wire wrapped around some iron) but the electronic ones look like a little flat box. Magnetic types normally seem to have screw terminal blocks on the end, whereas the electronic ones often have the little push terminals.

 

Do a google image search for "magnetic 150W metal halide ballast" versus "electronic 150W metal halide ballast" and train your eye. Those searches, from what I'me seeing here, do leak a bit, so you see one in the other, but you should be able to figure it out. The magnetic ones do seem very often to be white, but not always.

 

Yes, if it's built into a bit of kit, it's more difficult.

 

P


  • 1

#17 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 01 September 2017 - 01:31 PM

Now I've done that image search and know what I'm looking for, yes, the difference is clear. 

 

I found this link on diy CMH systems -

 

http://www.personal....mhlighting.html

 

This part seems a little worrying

 

One problem with the electronic ballasts is that they often have to be tuned to the specific bulb or classes of lamps. This may be a problem if you want to change from say a US made lamp to a German or Japanese lamp, since it requires sending the ballast back to the manufacturer for re-tuning.

 

This also looked useful -

 

http://www.kindgreen...h-light-system/

 

I hadn't realised

 

While all HPS bulbs can burn in any position, a MH bulb must be purchased specific to the mounting position you intend to use. There are MH bulbs made specifically for horizontal placement, base-up placement, vertical (base down) placement and also universal placement. The universal type bulbs can burn in any position, but are not quite as bright (maybe 5% less) as the position specific bulbs.

 

I think I'll treat CMH as a project and start with CFLs to find out how much light I want and how I want it deployed - I can just grab CFLs and holders cheaply and plug them together with no hassles. If the results aren't great colour-wise, I'll turn them to b&w. I'll carry on researching and ebay stalking CMH, then when I have a better definition of what I want and a feel for the hardware, I can switch.


  • 0

#18 Phil Rhodes

Phil Rhodes
  • Sustaining Members
  • 11916 posts
  • Other

Posted 01 September 2017 - 01:48 PM

I've been buying any 150W CMH ballast and throwing it in with any 150W CMH lamp and I've not had a problem, nor have I seen any paperwork that suggests there's a problem. The site you mentioned quote a site from nearly 20 years ago - I haven't even heard of this before.

 

The only time I had an issue was with running 575W HMIs from 600W CMH ballasts. This doesn't work very well, for complex reasons, but then you're running something that isn't ceramic metal halide (an HMI) from a CMH ballast.

 

 

The single-ended CMH stuff is mainly universal position. Double-ended is often limited.

 

P


  • 0

#19 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 02 September 2017 - 05:59 PM

I've been buying any 150W CMH ballast and throwing it in with any 150W CMH lamp and I've not had a problem, nor have I seen any paperwork that suggests there's a problem. The site you mentioned quote a site from nearly 20 years ago 

 

The google results on this subject are very strange...

 

I'm grabbing a 100W CFL for a tenner. It's supposedly equivalent to a 500W incandescent and I'm guessing maybe to a 75-100W CMH in both light and heat output. (The second is important because it will be a constraint on modifier design.) I'll use it, and maybe a couple more like it, to prototype my light set-up and then hunt for CMHs when I know more about what will work for my lighting look.

 

Thanks again!


  • 0

#20 David Mawson

David Mawson
  • Basic Members
  • PipPip
  • 79 posts
  • Other
  • Manchester

Posted 13 September 2017 - 08:16 AM

Follow-up for anyone finding this thread via the site search or google:

 

So far I've experimented with a single 100W "daylight" CFL sold for photographic use:

 

- Light colour seems reasonably good (but my standards are probably low) and the power is enough to even out the dimmer parts of an unevenly lit small room (15 by 20ft?) in daylight, which is the most I hoped for from 100W. It's definitely several times more powerful than 100w of incandescent.

 

- The bulb is too big for cheap dish type reflectors and parcans - it's about the size and shape of a 75cl water bottle, which means bouncing the way I planned is out.

 

- So I I either use it as fill for a whole (small!) room letting it shine evenly in all directions or with a reflector behind it. In either role I should really add a diffuser to protect the performers's eyes. The bulb does not seem to get hot - I wouldn't worry about putting several between a reflector and a diffuser as long as there was a bit of an air gap, but obviously, use common sense.

 

The most attractive points for me seem to be that CFL is cheap, reasonable quality, simple - you just put a bulb in a very normal socket, no ballast or cooling - safe, and that it will be easy to build a versatile system. Holders cost less than a couple of coffee and the light can be shaped with paper and card, so 3 bulbs could be used together or separately as needed.

 

The downside is probably that CMH has better colour and is easier to put into powerful compact parcan type units. And that CFL bulbs need some care handling. Overall I'd rate them - so far! - as low barrier to entry system that produces tolerable results for people who need to light small areas where they'll have access to main power. In my case, good enough to take the pressure off while I work on halides.


Edited by David Mawson, 13 September 2017 - 08:17 AM.

  • 0


Opal

Willys Widgets

Glidecam

Broadcast Solutions Inc

Visual Products

Gamma Ray Digital Inc

CineLab

Abel Cine

Metropolis Post

CineTape

Media Blackout - Custom Cables and AKS

FJS International, LLC

Aerial Filmworks

Technodolly

rebotnix Technologies

Wooden Camera

The Slider

Rig Wheels Passport

Ritter Battery

Paralinx LLC

Tai Audio

Wooden Camera

CineTape

Rig Wheels Passport

Broadcast Solutions Inc

Opal

Technodolly

Media Blackout - Custom Cables and AKS

Tai Audio

FJS International, LLC

The Slider

rebotnix Technologies

Abel Cine

Ritter Battery

Visual Products

Metropolis Post

Aerial Filmworks

Paralinx LLC

Gamma Ray Digital Inc

CineLab

Glidecam

Willys Widgets