DIY Softbox with TL950 bi-pin T8 bulbs?

[dh003i]

I'm considering making 3 softboxes with 8 TL950 bulbs each. Each TL950 bulb produces 2000 lumens, so each softbox would produce 16,000 lumens (with all 3 making 48,000 lumens). 1000bulbs.com sells a case of 25x 48in TL950's for $100 (http://www.1000bulbs.com/product/4722/F-32T8TL950P.html). They also sell ballasts, like this ballast (http://www.1000bulbs.com/product/2215/BG-GE432MAXH.html) (which with a 1.15 ballast factor would seem capable of driving a 2000 lumen bulb at 2300 lumens).

I've also found Medium bi-pin socket lampholders (http://www.elightbulbs.com/catalog_product.cfm?source=GoogleBaseCSE&prod=LW05900).

I'd like to have a way to make a portable "fixture" (the softbox) with the 8 TL950's in it, which plugs into an outlet. Does anyone know about wiring T8 bulbs & ballasts? What would I need to to do to make this? (I'd like to avoid buying 12 T8 fixture-ballasts (http://www.1000bulbs.com/product/53319/AW-NW232R8.html), as that would be $247 + $115 shipping). Although maybe buying Metalux 4-Lamp fixture-ballasts (http://www.lowes.com/pd_163653-337-2GR8-432A-UNV-L8735-_0_?productId=3014954&Ntt=t8+ballast&Ntk=i_products&pl=1&currentURL=/pl__0__s?newSearch=true$Ntt=t8%20ballast$y=0$x=0) from the local Lowes store would work. In any event, I still have no idea how to get them such that they can be powered by plugging into a wall outlet. Does anyone know how this could be done?

PS: I realize the TL950 or fluorescent bulbs aren't as good as other options, like Solux, for perfect lighting. But they seem like a good compromise for price, power-output, and also importantly heat-output (I don't want people I photograph to drip with sweat).

Also, Kino KF55 bulbs seem like they have a pretty good spectrum distribution (http://www.lightsonretail.com/Merchant/merchant.mvc?Screen=PROD&Product_Code=488-K55-S&Category_Code=Kino-Bulbs), are they going to be substantially better than the TL950's in practice?

Here is a spectral chart of TL950 (http://2.bp.blogspot.com/_FEYyD45_fAw/SjuRnCdUQcI/AAAAAAAADBI/LuMhzqrx-3M/s1600-h/spectrum.gif) ("philips tl90") and some other fluorescent bulbs.

[vinny]

You must use t8 ballasts with t8 bulbs. There are other t8 daylight manufactures tha make globes for the movie industry. Kino flos vare t12 and cost much more. Your're looking at a huge, heavy soft box. Why not daylight cfls? Or the biax style tubes like kino barfly fixtures use?

[dh003i]

vinny,

Ahh thanks for telling me that the Kino's are T12's, I hadn't noticed that.

The reason I'm looking at the Philips TL950 T8's is because they have a very high CRI (98). The highest CRI CFL's I've found are 42W Bluemax's (http://www.fullspectrumsolutions.com/42w_power_compact_bulb_412_prd1.htm), which have a CRI of 93. The BlueMax's have 3.5 times the deviation from a blackbody as does the TL950.

Just looking up high CRI biax tubes, I haven't found any with a very high CRI. The highest CRI ones I've found so-far are these CoolLights ones, at CRI = 87 (http://www.coollights.biz/watt-5600k-high-biax-bulbs-p-37.html). Its spectral energy distribution (http://www.coollights.biz/wordpress/archives/26) seems significantly more "peaky" than that of the TL950.

Are there any biax style tubes with a color-rendering performance as good as the TL950s?

[vinny]

Never heard of tl950's. Every motion picture production I've worked on in the last 10 years has used kino flo tubes and fixtures. If there were better options available, we'd be using them. If u make this giant softbox, how are u going to mount it and tilt up/down? You could mount them on a 4x4 sheet of thin plywood and add some diffusion directly over the tubes. Add some egg crate material over that for spill control and you'll have a large, soft source w/o the huge depth of a typical soft box.

[Jeff Bannow]

Would something like this help? They have a softbox that fits over it as well ...

C-1600 Cool Light (http://www.fotodiox.com/product_info.php?products_id=78)

[dh003i]

Never heard of tl950's. Every motion picture production I've worked on in the last 10 years has used kino flo tubes and fixtures. If there were better options available, we'd be using them.

I'm sure they're great bulbs. Their spectral distribution (http://www.lightsonretail.com/Merchant/merchant.mvc?Screen=PROD&Product_Code=488-K55-S&Category_Code=Kino-Bulbs) looks similar to GE Sunshine or Philips Natural Sunshine T12's, which "]Steve Kim compared to TL950s ([URL="http://www.stevekim.com/2009/06/lights.html). The TL950s also have a good spectral distribution and pass the tests they were put through. Steve Kim says he now uses TL950s (http://www.stevekim.com/2010/02/more-lights.html) in his studio and is happy with them.

It is a trade-off for me. The Kino Flo tubes have a slightly better spectral distribution, perhaps (only 2 major peaks instead of 3), but are significantly more expensive and aren't as efficient in terms of lumens/watt.

A case of 25 Philips TL950s for $102 including shipping (2,000 lumens at 5000K, or probably 1,818 lumens when filtered to 5500K x 24 = 43,632 lumens total). Two 6-packs of the Kino bulbs would cost $276 and produce 39,480 lumens. So I'd be spending more money to get slightly less total lumens from less efficient bulbs.


If u make this giant softbox, how are u going to mount it and tilt up/down? You could mount them on a 4x4 sheet of thin plywood and add some diffusion directly over the tubes. Add some egg crate material over that for spill control and you'll have a large, soft source w/o the huge depth of a typical soft box.

Yea, that's what I was thinking, to mount hem on plywood or something similar. Although maybe mount them on something a little smoother than plywood that won't give splinters.

Your idea about avoiding the huge depth of a typical soft-box is one of the things I was thinking of.

[dh003i]

Would something like this help? They have a softbox that fits over it as well ...

C-1600 Cool Light (http://www.fotodiox.com/product_info.php?products_id=78)

I was considering a DIY solution like that too, but with higher CRI bulbs. BlueMax 42W CFLs are 93 CRI (http://www.fullspectrumsolutions.com/42w_power_compact_bulb_412_prd1.htm). The bulbs that they're selling from the website that has the C-1600 Cool Light are only 85 CRI (I called and asked). Apparently, the Fotodiox fixture can only take 2.35in diameter bulbs at most, which means the BlueMax 42W bulbs are out, along with a host of other other bulbs. In any event, 85 CRI is very low compared to the 98 CRI offered by the T8 bulbs, and is also low vs. 93 CRI of some CFLs.

[erie patsellis]

I'm looking at the 950s as well, if you look at how cool lights mounts theirs, using a yoke, it's not terribly hard to duplicate it on a different scale. If you know somebody that has a shear and brake, you can make an nice enclosure using .040 white aluminum. I'll dig some sources up for the odd bits and pieces off my other computer and post them this evening, the aquarium hobbyists have access to some really efficient reflectors and such that make life easy.

Another option would be a 150 CMH bulb, Cool lights has the bulb for ~$30 and you can buy an electronic ballast for around $100 from several aquarium suppliers as well.
If you want more lumens, the Phillips 575MR bulb is used in most of the HMI lights, the bulb is around $125, ballasts are in the $225 range, and they put out a heck of a lot of light (~ 49k if memory serves me)

I'm doing this conversion to a couple of Broncolor heads I have that are missing the flashtubes (they cost $600 each, so I"m not replacing them) and it will give me the ability to use either continuous light (for my scanback) or strobe with my modifiers interchangeably.

[dh003i]

erie,

The issue for me is figuring out how to get the T8 bulbs wired up to the electronic ballast (http://www.1000bulbs.com/product/2215/BG-GE432MAXH.html)...

Re the 150W CMH bulbs and Philips 575MR bulbs used in HMI lights (I've been unable to find the 575MR bulbs), these are less efficient, hotter running bulbs than the fluorescents, right? (also, the 150W CMH lists a CRI of 85 (http://www.coollights.biz/cl15054-150w-5400k-quartz-metal-halide-single-bulb-p-74.html), although I'm not sure that means it is worse than the Philips TL950, because it may have a smoother spectral distribution without spikes).

Looking at the spectral distribution chart for the best CFL's I've found that produces more than 20W (the BlueMax 42W, 93+ CRI (http://www.bluemaxlighting.com/42w_power_compact_bulb_199_prd1.htm)), the I'm a little bit skeptical that they can compete with the TL950 fluorescent tubes:

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There are 3 fat hums and 3 major spikes in the blue-green range. I would like to comment BlueMax for actually providing a meaningful continuous spectral distribution chart. FarmTek / ValuTek just provides a bar graph for their 125W 93 CRI (http://www.farmtek.com/farm/supplies/prod1;ft1_lighting_fixtures_bulbs-ft1_light_bulbs_1;pg103995_103999.html) bulb, which does not show intensity spikes at narrow wavelength bands.

PS: See my comments on a DIY softbox here (http://www.flickr.com/photos/campalex/2450786870/) and also my comments on the DIY Spyderlight (http://www.flickr.com/photos/campalex/2435827940/) (I didn't write the article, my comments are posted under dh003i). At 95% reflective, Behr Premium Plus Ultra Pure White #7050 paint is an excellent reflective material. I've determined that about 43,000 lumens is what I'd like to work with.

These formulas are useful for determining how many lumens you need:


GN = Distance × f/stop

GN = √(0.005 × Lumens × shutter time × Reflector Factor × ISO) (http://photo.net/photography-lighting-equipment-techniques-forum/00VsPr)

I assume a Reflector Factor of 1.176 for a softbox, calculated from this statement (http://photo.net/photography-lighting-equipment-techniques-forum/00GmxD): "just under 10,000 lumens and gets you about 1/60th, f/2.8 on ISO 200 at 5 feet away." Ergo, the Reflector Factor = GN² / (0.005 × Lumens × shutter time × ISO) = (5 × 2.8)² / (0.005 × 10,000 × 1/60 × 200) = 1.176.

Assuming we wanted to shoot at ISO 400 for a 1/60s exposure at f/8, with the soft-box positioned 5 ft away from the subject, here's how many Lumens we'd need:


Lumens = GN² / (0.005 x shutter time x Reflector Factor x ISO)
Lumens = (5 × 8)² / (0.005 × 1/60 × 1.176 × 400)
Lumens = 40,816

Hence, how I figure that I'd need 24 of the TL950 2000 lumen 5000K T8 bulbs, split into 3 soft-boxes with 8 tubes each.

[vinny]

You should be using shiny aluminum for reflector material, especially since you seem to be obsessed with cri graphs and maximum output.

[dh003i]

vinny,

Can you explain the suggestion for aluminum for reflector material? From what Behr told me when I called them, their ultra premium flat paint is 95% reflective, which is pretty good. A source online (now no longer up, but still cached (http://webcache.googleusercontent.com/search?q=cache:B2O0WQRuoMUJ:www.rollitup.org/indoor-growing/177656-mylar-foylon-vs-aluminum-foil.html+reflectivity+materials+aluminum+mylar&cd=2&hl=en&ct=clnk&gl=us)...maybe because the poster made a not-so-subtle reference re "sleeping easier at night" if they had a certain reflective material, because it is 90% IR proof):


Aluminum Foil:

Aluminum foil is no more than 55% reflective - if used, make sure that the dull side is the one that is used to reflect the light. When it becomes creased its reflectivity is even lower (around 35%.) It is also very dangerous to use because it creates hotspots easily, is electrically conductive, and is a fire hazard when it is in close contact with HID lighting. Attaching this to walls is a pain and usually using aluminum tape or glue is the best way. This should only be used as a last resort, and even then its usefulness is questionable.

[vinny]

Nearly all continuous lighting sources us aluminum reflectors (including every fluorescent light). Higher output and no introduced color shift. Does behr make lights for the still or motion picture industry? No, they make paint.

[dh003i]

Nearly all continuous lighting sources us aluminum reflectors (including every fluorescent light). Higher output and no introduced color shift. Does behr make lights for the still or motion picture industry? No, they make paint.

Point taken about aluminum reflectors being a sure bet, but that doesn't mean flat white paint would do poorly...95% reflective, and color shift is just up to a matter of testing out. A test I found shows mylar (http://www.flickr.com/photos/nickwheeleroz/2519958990/) coming ahead of regular flat white paint and aluminum foil on a DIY design...but that's foil, not polished aluminum (and although it may not be a concern with CFLs, mylar is a fire-hazard).

In any event, I'll look into some of those aquarium hobbyist reflectors.

[vinny]

Mylar will melt w/o good ventilation but it's your best bet if u can't find aluminum. Attach w/ super77 spray.

[erie patsellis]

dh,
You're shooting film or instant capture digital, right? Are you aware that 1600+ w/s pack head systems go for next to nothing these days? Especially the older ones with limited adjustability. I have a different situation, I have to use continuous light due to the use of a scan back.

Wiring a ballast is simple, the wiring diagram is on the ballast, the same socket is used for both T8 and T12 bulbs as well. No offense meant, but if you are having trouble figuring out the wiring diagram, you may want to reconsider the DIY approach.

As far as reflector material, you can buy thinner aluminum sheets fairly inexpensively, .025 to .032 3003 cuts pretty easily with hand shears, and can be pop riveted (or using aircraft style bucked rivets), which makes a rather rigid box.

Out of curiosity, what work are you doing that requires such a methodical, calculated approach? You can obtain soft lighting with nothing more than a silk (white ripstop) on a frame between the light source and subject, very inexpensive, versatile and no reflectors needed.

[Bruce Watson]

Re the 150W CMH bulbs and Philips 575MR bulbs used in HMI lights (I've been unable to find the 575MR bulbs), these are less efficient, hotter running bulbs than the fluorescents, right? (also, the 150W CMH lists a CRI of 85 (http://www.coollights.biz/cl15054-150w-5400k-quartz-metal-halide-single-bulb-p-74.html), although I'm not sure that means it is worse than the Philips TL950, because it may have a smoother spectral distribution without spikes).

It's my understanding that all arc lights, regardless of their "presentation mechanism" (direct, fluorescence, whatever) have spikes in their output. HMI's, like fluorescents, are kinds of arc lamps. The spikes may differ in frequency and size, but they'll be there. Which is why HMIs top out around CRI of 85 or so.

[Bruce Watson]

I found yet another bulb for you to consider. RPImaging sells the GTI bulbs (http://www.rpimaging.com/store/PID666). Supposedly seven phosphors (as opposed to two or three in the vast majority of the so-called "cinema bulbs". Closest thing to true D50 or D65 illumination that I've found, but the spectral power curve (http://www.rpimaging.com/store/PID666&pdetails=1#TOC)still shows some sizable spikes. And these bulbs aren't cheap.

[dh003i]

dh,
You're shooting film or instant capture digital, right? Are you aware that 1600+ w/s pack head systems go for next to nothing these days? Especially the older ones with limited adjustability. I have a different situation, I have to use continuous light due to the use of a scan back.

I shoot 4x5 film and an Olympus E-3 (4/3rds, the smallest DSLR sensor size format). Yea, I know that there are plentiful flashes available that produce lots of power, but I rather like continuous lighting to start out with. i.e., my 3 softbox idea will allow me to position things around and see how that changes the effect of the lighting, WYSIWYG. I am just starting out with lighting, and I've seen many (such as Frank Petronio, who introduced me to LF a few years ago) recommend continuous lighting to start out (and I figure fluorescent to keep things cool for me and the subject).

Frank Petronio recommend Dynalites for Flash. I've seen the Dynalite L2040 and 1836 sell for $118 - $150 used on eBay. What do you recommend and what is you definition of "next to nothing"?


Wiring a ballast is simple, the wiring diagram is on the ballast, the same socket is used for both T8 and T12 bulbs as well. No offense meant, but if you are having trouble figuring out the wiring diagram, you may want to reconsider the DIY approach.

LOL, well, I haven't actually looked at any of them yet. I am just trying to figure out what is needed to make a portable softbox unit that plugs into the wall outlet (ya know, 3-prong plug). So-far, I've found TL950 lights, electronics ballasts (http://www.1000bulbs.com/compare/?compare=+387+2213+3181+2215), medium bi-pin socket lampholder (http://www.elightbulbs.com/catalog_product.cfm?source=GoogleBaseCSE&prod=LW05900). Ok, so I don't see anything there that is going into a plug which goes into an outlet. This is what I'm trying to figure out.

I want to know exactly what I need to do before I go off like a loose cannon and start buying stuff.


As far as reflector material, you can buy thinner aluminum sheets fairly inexpensively, .025 to .032 3003 cuts pretty easily with hand shears, and can be pop riveted (or using aircraft style bucked rivets), which makes a rather rigid box.

Thanks.


Out of curiosity, what work are you doing that requires such a methodical, calculated approach?

Will be taking portrait shots of friends, as well as a sports photo shoot for a friend's portfolio to showcase his work. Being methodical and calculating is just in my nature. I like to have a solid idea of precisely what I need to do before I go out and do it. I'm not one for just trying stuff an experimenting...unless the experiment costs around $10.


You can obtain soft lighting with nothing more than a silk (white ripstop) on a frame between the light source and subject, very inexpensive, versatile and no reflectors needed.

Well, without the reflecting material behind the tubes, I'd be wasting half of their lumen output, right?

[dh003i]

I found yet another bulb for you to consider. RPImaging sells the GTI bulbs (http://www.rpimaging.com/store/PID666). Supposedly seven phosphors (as opposed to two or three in the vast majority of the so-called "cinema bulbs". Closest thing to true D50 or D65 illumination that I've found, but the spectral power curve (http://www.rpimaging.com/store/PID666&pdetails=1#TOC)still shows some sizable spikes. And these bulbs aren't cheap.

Yea, they definitely aren't cheap! The GTI D50 48inch F32T8/GL50 bulbs are $675 for a case of 30 ($22.5/bulb) vs. $102 for 25 TL950s ($4.08/bulb). As expected, they're better than the cheaper TL950 bulbs. The spectral distribution charts from this site (http://www.stevekim.com/2009/06/lights.html):

GTI D50 Spectral Power Curve: two major peaks
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Philips TL950 Spectral Power Curve: 3 major peaks, 1 more gradual peak
44693

But alas, I think the GTI bulbs are a little too pricey for me at this point. But I'll keep them in mind. From talking with the kind GTI representative, the their T8 48" F32T8/GL50 bulbs have a lumen-output of 1787, as measured under their conditions (vs. 2000 for Philips TL950s). He also reiterated to me that as spikes are smoothed out, lumen output decreases because that energy output is lost. This makes sense. They seem like great fluorescent bulbs.

[Bruce Watson]

How about something like this fixture from Lithonia Lighting (http://www.acuitybrandslighting.com/library/LL/documents/SpecSheets/Z8ASR-Z8SMR.pdf)? Got ballast built in, got reflectors already made. Stack as many together as you want.

Won't be as nice as a Kino Flow or Cool Lights biax unit. Doesn't have the light stand mechanicals built in. But you can use bi-pin bulbs and get the higher CRI you're after.