Power Control For Tungsten FLood Lamps

[georgedingwall]

Hi all,

I have an old copy stand which has 4 X 100 watt tungsten flood lamps as part of the setup.

I'm working on adapting these lights, and their mounting arms, for use with my macro setup. Each light is separately switched but has no output control.

Can anyone suggest a suitable method of adding a variable output control for these lights. Is a simple domestic dimmer switch all that is needed?, or do I need something a little more sofisticated than that.

When I search on Google "Variable Reisistor", "Voltage Regulator" or "Rheostat", I tend to get mostly pages for circuit board based components rather than some sort of box that I can plug the lights into, and then have a control on the box to vary the output of the lights.

I have enough electrial knowledge to build something from components if I knew what components to use. ( I served in the Navy as an Air Weapons Electrician back in the sixties).

I'm a little concerned at the amount of heat generated by the lights. Should I consider making some sort of housing for them and then creating some sort of cooling sytem to extract the heat away from the specimen stage and camera.

I have had a look at fibre optic illuminators, but they cost a little more than I want to spend at the moment. Trying to save up for new Computer, Printer, TV, Washing Machine, Dryer, Lawn Mower, VR Lenses, Car, etc, etc, Maybe my lottery numbers will come up before Christmas.

Any suggestions are eagerly awaited.

Bye for now.

[DaveW]

Probably not so much a problem with digital George, but reducing power on Photofloods alters colour temperature. That used to be a problem with film because you did not have infinitely variable colour temperature filters. I presume the auto white balance on digital should take care of this though?

There did used to be devices for switching Photofloods in series from parallel I believe to dim them, but this was done to prolong bulb life when not actually exposing film rather than for variable output for taking shots, and of course altered colour temperature.

I have seen quartz halogen lights of the type used for floodlights on building sites used for photography and you can get cheap halogen spot lights from the DIY stores but I don't know if a dimmer switch on these would have the same effect as with Photofloods. Also I believe Video lights are useable for photography and maybe the small low voltage bulbs and reflectors that seem to be used for household mini spot lights would be weak enough for your purpose?

DaveW

[georgedingwall]

Hi Dave,

I presume the auto white balance on digital should take care of this though?

I shoot all my indooor macro in RAW format, and it doesn't matter what your camera is set to when you use this format, as you can choose any colour temperature you want when you are importing the files into Photoshop.

you can get cheap halogen spot lights from the DIY stores but I don't know if a dimmer switch on these would have the same effect as with Photofloods.

I'll be going into B&Q and Homebase in the next few days on another matter, I'll check out the lighting section to see what's available that might work for me.


Thanks for the input, Dave.

Bye for now.

[rjlittlefield]

Is a simple domestic dimmer switch all that is needed?

Domestic dimmer switch has always worked fine for me.

Now that I have a halogen fiber illuminator for main light, I still use an ordinary incandescent with domestic dimmer for backlight.

--Rik

[georgedingwall]

Hi Rik,

Domestic dimmer switch has always worked fine for me.

--Rik

Thanks for that info. I was hoping that the simple solution would be all that was needed. I have a tendancy to over-think things a bit.

Bye for now.

[puzzledpaul]

Not quite sure from your post whether you want individual control of each light or not - but if you want to stay 'non-electronic' ... I have some ex-equipment variacs knocking around somewhere.

From memory, they're either 2A or 5A at mains rating, so even the lower rating would do for your application.

Wiring up such a beast is simplicity itself, of course.

Let me know if interested and if so I'll check exactly what I have etc...

Cheers

pp

[georgedingwall]

Hi there,

Not quite sure from your post whether you want individual control of each light or not - but if you want to stay 'non-electronic' ... I have some ex-equipment variacs knocking around somewhere.

From memory, they're either 2A or 5A at mains rating, so even the lower rating would do for your application.

Wiring up such a beast is simplicity itself, of course.

Let me know if interested and if so I'll check exactly what I have etc...

Cheers

pp

I have 4 X 100 floods and would want to be able to vary each of them individually so that I can control the light and shadow falling on a subject.

If, as Rik has already said, a simple 4 gang dimmer switch will do the job, that seems the simplest way to go.

What do these "variacs" look like. The name is familiar, but I seem to remember that they were large transformer like things with a big wheel on the top that you turned to vary the voltage being output from the source.

Thanks for the info. Bye for now.

[puzzledpaul]

<< I have 4 X 100 floods and would want to be able to vary each of them individually so that I can control the light and shadow falling on a subject. >>

Yes - this seemed likely - but it's always better (imo) to know the exact nature of a problem before trying to find / offer a possible solution

I'd say these things are more like rather large wire-wound potentiometers than transformers, as there's no primary / secondary coils / windings.

Mains is applied between one end and a tap some distance in from the other end of the winding - which then allows the output to be greater than mains voltage (typically 270v from memory).
(there's no 'overdrive' facility with std solid-state dimmers afaik, btw)

When seen in (older) films, they tended to be quite > very large, often being operated by a white-coated mad prof applying juice to Frank's electrodes ... but the ones I have are somewhat more mundane - 4in dia x 5in long (maybe)

I've not seen any 4-ganged dimmers recently - but then again, I try to avoid B&Q / Wilkos like the plague as it generally means boring DIY stuff ... if available at reasonable cost, they sound a good option.

Good luck with the project

pp

[georgedingwall]

Hi Paul,

When seen in (older) films, they tended to be quite > very large, often being operated by a white-coated mad prof applying juice to Frank's electrodes ... but the ones I have are somewhat more mundane - 4in dia x 5in long (maybe)

I have a blue coat. Will that do

I've not seen any 4-ganged dimmers recently - but then again, I try to avoid B&Q / Wilkos like the plague as it generally means boring DIY stuff ... if available at reasonable cost, they sound a good option.

pp

The one I've seen is available at Screwfix

http://www.screwfix.com/app/sfd/cat/pro.jsp?id=29680

This one is rated at 250 watts, but I'm not sure if this means that each of the 4 switches can handle upto 250 watss, or that the total of all 4 switches should not exceed 250 watts. I'm trying to find out from Screwfix, but the first email I had back from them was ambiguous, so I've asked anohter question and am waiting for a reply.

Thanks for the info. Bye for now.

[PeglegOS]

Try this: http://www.smithvictor.com/products/det ... &nm=DC%2D1

[georgedingwall]

Hi pegleg,

I'm in the UK, so I'm afraid US style electrical components don't generally work over here. Wrong voltage and different plugs.

Thanks for the thoughts. Bye for now.

[Charles Krebs]

George...

I shoot all my indooor macro in RAW format, and it doesn't matter what your camera is set to when you use this format, as you can choose any colour temperature you want when you are importing the files into Photoshop.

This is true to some degree as long as all the lights are "outputting" at close to the same color. The ability to set your color when converting from raw files is a "global" setting. So for an extreme example: suppose you had a person illuminated on one side with a fluorescent bulb and on the other with a tungsten bulb and you shot raw. You can convert the raw file with correct colors for one side or the other, but not for both simultaneously. Mixed lighting can still be a problem even with raw conversion.

[puzzledpaul]

<< but the first email I had back from them was ambiguous >>

Yes, I can imagine - probably sent by the office cleaner just reading from the brochure / website and learning how to send emails

Looks fine, I suspect it's probably 250w / channel, otherwise at just over 60w / channel, it wouldn't make much sense, with ppl often using 100 or even 150's in individual holders (at least for those ppl who're not using low-energy bulbs) - or ceiling clusters of 3 or 4 x 60w.

Blue's fine, btw - hope you get some sense out of them

pp

[rjlittlefield]

...as long as all the lights are "outputting" at close to the same color...

halogen fiber illuminator for main light...incandescent with domestic dimmer for backlight

Charlie's point applies perfectly to my setup. I set color balance for the main light, typically by shooting the pingpong ball as if it were a gray card (with appropriately reduced exposure, of course). There can be drastic color differences between the main and the backlight, depending on how much each one is dimmed. This is usually no problem for what I'm doing, since my backlight is usually filtered to be colorful anyway. But if I wanted a nicely matched gray background, I would have a devil of a time getting it!

--Rik

[puzzledpaul]

George - Just had a quick shufties on Ebay - there appear to be some (new, BIN) options that might be worth checking out.

I entered '4 way dimmer' and '2 way dimmer' into the search engine, btw.

pp