Running Solux lights at 13.5 volts. How?

Hi

 

I'm currently printing on an Epson 2400, and I'm using a daylight balanced fluorescent

lamp as a viewing light next to my monitor. It's way better than the blue 'daylight'

tungsten light I was using previously, but my prints still look slightly different when

viewed in daylight.

 

I've just done a bit of research on print viewing lights, and I would like to give Solux a go.

I'm going to buy a couple of their bulbs and a track system with two fixtures.

 

I've read that when the lamps are fed the standard 12 volts they will run at 4700k.

 

However if they're supplied with 13.5 volts they will run at 5000K (D50).

 

This dramatically shortens their life (and no doubt increases the heat in the fixture to a

dangerous level), but I'm nevertheless interested in trying it.

 

How do I go about getting 13.5 volts of electricity?

 

All standard lighting transformers seem to supply just 12 volts (and from what I've read

often less than that, thus causing the lights to run at a warmer colour temperature).

 

I'm based in the UK, so I'm trying to convert 240 volts AC current to 13.5 volts DC.

 

I plan on running two 50W lights.

 

Thanks for any advice

 

Elliot

The difference between 4700K and 5000K is imperceptibly small, about 12 mireds to be exact. Instead of changing the voltage, how about just putting a correction gel filter under the lamp? A 1/8 CTB gel gives about a -18 to -20 mired shift, which brings you to about 5100K...and 1/8 CTB is the smallest increment they make.

I know 5000K is a standard many seem to adhere to, but it's not daylight. Try 6000 to 6500

for daylight balanced prints. I don't think your prints will look right in daylight if you are

printing them for 5000K.

I just installed two 50W Solux 4700K lamps, and found a new problem.

 

All transformers / voltage converters available in normal lamp shops in Sweden are rated 11.5V - 11.7V. The one I bought was 11.5V, and that is not enought to give 4700K.

 

My CRT is calibrated for 5000K and my walls are neutral grey. When they were illuminated with the lamps I saw very clearly that they have a much warmer (lower temperature) color than the 5000K of the screen.

 

I took a picture of the wall and white balanced it in Acrobat RAW. The value I got was about 4300K, way too low. So my first step would be to find a transformer that really gives 12.0V!

 

Where do I find it?

 

Jakob

Barry,

 

Daylight can be anything from 4500K or lower to 15000K or higher.

 

The most important thing is to have the environment of the room and the screen calibrated to the same standard. If you have, you can have the image displayed on your screen and compare it to a print you are holding just at the side. They should look exactly the same.

 

If the environment light is different from the screen calibration, you can never compare prints and screen side by side, which can be useful if you want to make further adjustments to a test print.

 

Of course, there are other things to consider as well when choosing the color temperature. One is that the inks may show metamerism, i.e. behave differently at different kinds of light. For me, that is one reason for why D50 (5000K) is better than D65 (6500K). You are closer to indoor light which is usually used when viewing images.

 

Jakob

 

http://www.fotoverkstan.se

I feel that I've successfully used Kar Wai's approach. The desk lamp I got at Office Depot for $35 takes the Solux lamps, so my total outlay was pretty cheap. I got some gel filter scraps from a videographer buddy of mine - 1/8 CTB, 1/4 CTB, and couple of densities of ND and some frosted scraps too. I simply held up combinations of the filters until the white on my screen matched the white of my most-used printing paper, both in color and in brightness. The filters fade over time and have to be replaced, but it's my feeling that I've got a very close match between screen colors and print.

One other thing, I can't help being a bit afraid of the possibility to overheat the lamp fixture. If I go above the standard voltage, how do I assure something doesn't melt or catch fire? I think it is important to have lamp fixtures that are built for the high power dissipation of 50W lamps on 13.5V.

 

Jakob

Hi

 

The reason I'm after a power supply that can be turned up to 13.5 volts, is because I've

read that most 12 volts transformers do not actually give out 12 volts.

 

4700K I can work with (I can always adjust my monitor to match) but 4300K or 4400K is

too warm for me.

 

Does anyone know where I can get an adjustable transformer? Or is this the sort of thing

that can only be found in a science lab?

 

Jakob, what type of fixtures are you using for your lights?

 

From what I've read it's important to have a fixture that is closed at the back - the Solux

bulbs spill a lot of warm light from the back and you want to have this absorbed by the

fixture.

 

Also, I've read that Solux lamps produce a circle of light with a warm halo on the outside.

To eliminate this halo, it is desirable to use a fixture where the lamp is recessed somewhat

(thereby masking off the halo).

 

If you are concerned about heat, then the lamps can be mounted on wire tracks instead of

in fixtues. Air can then freely circulate around the lamps. You can purchase shields that fit

directly round the back of the lamp to eliminate the warm light spilling out of the back.

You will still have the problem with the warm halo. This can be eliminated by using

diffusers on the front of the lamp, but this will mix the halo with the main light, thus

warming everything up.

 

Elliot

 

(There is a lot info on Solux lamps at the forums on robgalbraith.com)

Elliot,

 

I bought "Mini Par Spot". Google for them, and you will see. They where the most affordable I could find locally (less than USD 30). THey are not very high quality, and it was difficult to insert the lamp without destroying it.

 

The electronic transformer I bought, "Osram Halotronic", incidentally quit working one hour ago, after just a month. I guess I will get a new one at the shop. Really good professional stabilized electronic power units, like this one from a Swedish distributor

 

http://www.elfa.se/elfa-bin/dyndok.pl?lang=se&vat=0&dok=5015.htm

 

would probably be the best but they are not so cheap. SEK 2154.00 equals USD 300. But it delivers 13.2V, 10A = 130W which would be satisfying for two 50W lamps.

 

My lamps at 11.5V did seem to deliver quite dim light. I am surprised that I did not get more light out of two 50W lamps than I did. Is this the experience of others, as well?

 

I will check your link in detail.

 

Jakob

Hi Jakob

 

I found this transformer here in the UK which I think would fit the bill. I think it does a

similar job to the one you posted(?). It is also expensive - about 215 US dollars:

 

http://www.maplin.co.uk/module.aspx?ModuleNo=30391&doy=

 

The lamp fixture for Solux lamps that is often recommended on the internet is this one by

Halo:

 

http://www.northshorelighting.com/browseproducts/L2770-LOW-VOLTAGE-MICRO-

STYLE-WITH-INTEGRAL-12V-ELECTRONIC-TRANSFORMER.HTML

 

Again, not cheap. I'm thinking of possibly buying a couple of these (+ tracks etc) from the

US, and then buying a transformer here in UK, to knock our mains power (240V) down to

US levels.

 

However I'd be worried that with two cheap transformers in the system, supplied voltage

might be less than 12V. And anyway, US suppliers in general seem wary of shipping

outside of their country...

 

Last night I was looking at this UK site - http://www.altima.co.uk/ - the only site I could

find that had (possibly) appropriate fixtures (I think they're called 'Professional'). (Hmm,

the site seems to be offline at the moment.)

 

So maybe one 'Professional' fixture (the one that give a 24 degree beam of light), plus 1

metre of track, plus the expensive transformer to give 13.5 volts. I'm not sure how bright

the Solux lamps are at 13.5volts, but I'm hoping that one lamp, about 6 foot from my

print, will give an illuminated area about 30 inches in diameter, and enough light to match

my monitor at 140 cd/m2.

 

(I knew that the trigonometry I learnt at school would one day come in useful!)

 

Cheers

 

Elliot

 

(- it looks like photonet might insert a space in that second link)

I recently put some solux bulbs up in my GF's office, and even though they provide pretty light for general viewing, I prefer my 5000k compact fls for reference viewing.

 

While I can adapt to either for color reference purposes, the 5000k compact fluorescents can run in any standard fixture, aren't fussy about voltage, are much brighter, and last much longer. Biggest reason I prefer them is I simply don't like point light sources like the Solux for reference viewing prints.

 

I have the Solux bulbs on track goosenecks so I can bounce them off the ceiling, which I feel provides easier lighting to work with, but also introduces the variable of the pigments used in your ceiling paint.

Try a GE Reveal light bulb. Its cheap, and it is pretty neutral.

 

My office walls are neutral gray, carefully chosen with a Pantone swatch and matched. It's high end paint. The paint was evaluated under three light sources prior to purchase in a light box at the paint store (Sherwin Williams). Metamerism was minimal. The walls still REFLECT light, and they will slightly warm and cool depending on the light source. Metamerism and its causes are manyfold. In any event, the paint isn't too metameric. I used to make automotive paints, and believe me, metamerism can be pretty embarrasing when a person drives his Mercedes into a parking lot at night and sees a pink retouch spot on a red car!

 

They grey warms up with overhead tungsten as expected, and I use this light when guests come in. Its more appealing. When I use fluorescent, they are somewhat blue, and when I use GE Reveal, they snap to neutral grey. Neutral grey isn't that attractive, but it works for work mode.

 

I found that my color eye was drifting toward a cooler or bluer grey as "neutral", so I painted my office in the neutral.

One way to get a specific voltage for the lamps is to use a variable transformer. This is an auto-transformer with a rotatable knob that allows for infinitely variable output voltage. They have an internal contact that slides over exposed turns on the transformer.

An example is the US made "Powerstat" by Superior Electric (WWW.Superiorelectric.com). They probably have UK distribution, and there probably is a UK manufacturer of similar units.

 

The advantage of these is that it allows you to adjust it (you'll need an AC voltmeter) to give any desired voltage, and see the results, or to adjust the voltage until you reach (visually) a color temporature that you like.

 

Before using any method of raising the lamp's voltage, consult with the lamp manufacturer for a source of industrial quality sockets or fixtures for the lamp. These will have a much larger temterature safety factor.

 

Good luck.