lighting bar


Postby gordo52 » Tue Apr 30, 2013 2:25 pm

Hi first post on what looks a brilliant forum.

I am setting up a small photo studio. trying to do as cheaply as I can without cutting on safety.

I want to make a lighting bar for hanging from the ceiling I plan to use dimmable GU10, mainly becuase I have been given 10 holders and 10 bulbs.

I want these wired to a 1000wat dimmer, they will be worked via 13amp plug and 3 or 5amp fuse.

A 2.6inch to 3ft piece of wood will be used to attach the lights to and suspended on chain or something suitably man enough to take the weight.

what is the best method of wiring ? like an old fashioned daisy chain (probably wrong way of describing)

Wire to the first and continue from the first to the second and so on.. ?

any help advice etc appreciated
gordo52
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Joined: Tue Apr 30, 2013 2:11 pm

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Postby ericmark » Wed May 01, 2013 11:29 am

I also love photography in the main out doors and in woodlands and I have also had lighting problems. I use two flash guns one on hot shoe and one auto triggered off that but down to trial and error so using a constant light source has advantages. I have a LED light bar I use for macro which works well. The LED colour temperature is very good and does not vary as the batteries discharge.

Using GU10 LED lamps would likely work well, but they may be flashing at 1/100 second or may have a capacitor to give a constant light and until you try you will not know. The tungsten will not flash but if you try to dim the colour temperature will change and likely to be rather hot.

The compact florescent or cold cathode has problems with colour. If you get a CD and angle it at the light it will split the light into the spectrum. Look at LED light and it is even through the spectrum but with compact florescent or cold cathode you get distinct bands of colour clearly not wanted.

Since you say 1000W dimmer I would guess your looking at tungsten. Maybe you want to be able to adjust colour temperature but likely you will also need some air conditioning unit to remove the heat.

Dichroic lamps have a special reflector which allows heat to pass through the reflector and only reflects the light. Still hot but not as hot. Clearly free air required behind them to keep them at correct temperature.

In theory you should not dim quartz tungsten lamps. They are designed so the quartz is that hot the tungsten will not be deposited on it but will return to the element. Over time the element thickness will vary and in the end they will blow but if you run them cool the tungsten will be deposited on the quartz turning it black and causing it to fail well before it's expected life.

Yes I know you can adjust the colour temperature in photoshop while converting from the RAW file but in that case it would be better to use LED and not fry the model.
ericmark
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Location: Mold, North Wales.


Postby gordo52 » Thu May 02, 2013 2:13 pm

Many thanks for the post, a lot to mull over in there my friend. I have decided to hang back a little, and do some more thinking, pondering (like a good ponder) and research.

I just made two soft boxes out of plastic adverting board, sticky back plastic and gaffer tape. using at the moment cotton white sheet in the front, but will be experimenting with other material for different moods etc.

So far have been working with a good Bridge camera as couldn't afford the outlay for DLSR. (after Camoron had his way with my disability benefit) But have got just enough saved up to get an entry level looking at canon EOS 1100D .

But thread is way off topic now. Thanks again
gordo52
Posts: 2
Joined: Tue Apr 30, 2013 2:11 pm


Postby ericmark » Thu May 02, 2013 10:05 pm

As well as being an electrician I am also keen on photography and I have looked many times at the problem with lighting. Today Photoshop has a host of tools to correct colours. I select the white balance eye drop tool and try to select a true grey area to correct the colour in my RAW images as a matter of course. Even with CS5 I still some times fail and resort to monochrome. I am lucky got CS5 while studying of "A" level photography so got on student licence. The "Open in RAW" works with Jpeg as well as RAW and I do find it good at correcting colours but also with jpeg you can use the in camera software to correct.

There is no need to have a D-SLR to get RAW images in fact with the 4/3 cameras you have many advantages in getting rid of the mirror. I see no real advantage in the mirror in fact the reverse. The mirror pushes the lens away from the CCD so results in a far bigger lens to do the same job. OK I will admit size of CCD matters and a Nikon D700 will produce better results than my Nikon D7000 but that's down to CCD size not having a mirror in fact both have mirrors. The R of SLR means it has a reflex mirror it is nothing to do with being able to change lenses in fact changing lens often means dust gets in so the 18 - 270 mm Tamron lens on my D7000 is never removed.

The camera being high speck is not as important as one may first think. My K10D Pentex is my preferred camera it is simpler to use but with that one I can't lock up mirror so I have to use the D7000 for some shots and also the D7000 has a better ISO range. The Pentax can still use lenses made in 1980 so is also a cheaper option when I want a 400mm (35mm rating) lens.

The cheaper software options GIMP and UFRAW will do most of what Photoshop will do but not as easy. With Picturenaut (HDR) and Hugin (Panorama) you can do most things for free but not as easy.

Returning to lighting Photoshop in RAW conversion mode has two correction areas. The first is two sliders one marked colour temperature the other red - green but there is also a second with 8 sliders where you can enhance of suppress a colour.

So even with poor colour lighting one can to some extent correct but one must ask why would you want to go to all that work where with LED lighting it is not required.

To do on the cheap don't rule out the old methods. As well as the tripod for camera frames to stop the subject moving can really help.

The real problem is speed. I go into the woodland with flash guns and LED lighting bars and can spend 20 minutes getting the shot right. The bluebell does not object. But ask a model to hang around for twenty minutes where you experiment is something else.

I would select a doll or teddy bear and experiment first. It also means you can view the subject when you work out settings required.

There are special tools to calibrate your screen. My camera club has one and the advanced members borrow it and set up their screens. I am a beginner and I do not really worry if a little out. Also I don't print all mine are used for web pages and to get correct colours the viewer would also need a calibrated screen and be using firefox which has best colour rendering of all web browsers.

However I have talked only about technical aspect and the artist bit is far more important.
ericmark
Posts: 1165
Joined: Fri Oct 02, 2009 8:49 pm
Location: Mold, North Wales.


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