Halogen studio lights

What problems could I expect trying to use two 70 watt halogen bulbs as the light source for a simple portrait studio setup.

You'll need to think about colour balance. As regards the model, the bright lights will tend to make her (or him) squint and the pupils will close down. Portraits tend to look better with dilated pupils, hence the widespread use of flash.

The other thought is that the model will get quite hot and makeup may start to run.

Cold continuous light is available and seems a better alternative. However, for the reasons stated I would prefer studio flash.

1/ would bouncing the light off umbrellas resolve the squint issue?

2/ is the heat thing because the light is not powerful enough so you would have to place it very close to the model.

3/ is this what you call cold continuous lights link

If you use a flash set up, and mine would be AF540 type flashes not studio, is it not more difficult to achieve the right lighting and shadows? At least with continuous lighting you can see what you are getting.

That's true, Barrie, but with studio flash you get modelling lights. These are low intensity bulbs that show what the lighting will be like. They are not so bright as to dazzle the sitter. With small units that have no such luxury the only indicator will be to quickly review a test shot. At least with digital this does become possible.

Continuous lighting does have advantages as you have perceived, but also many disadvantages.

My lighting of choice would be natural daylight and in the right place this can be just magnificent. However, when studio lighting is needed I prefer flash. It also removes the need for a tripod as the shutter speed is effectively the flash duration.

If you want to put the effort in you can make modeling lights for your flashes. Simple lamp holders for light stands are cheap, or clip-on lights from IKEA are even cheaper. You'll need dimmers for each, and a bit of patience to adjust the relative brightness of the modeling lights versus each flash, but it's not hard. Used this setup quite a bit when I built it back in my earlier 35mm days, as it was cheaper and easier than polaroid (to check the exposure). I used 75 and 100w reflector bulbs IIRC which back then were quite large, but now are available in many smaller profiles. Just make sure that they are dim/dimmed enough to not have much/any effect on the actual lighting - or warming the model!

(Yes I know dimming alters the colour temp, but they take no part in the actual exposure.)

But building on John's alternate suggestion, invest in a cheap reflector (or car windscreen sunscreen - although those aren't that common in UK ) and combine with window light for a 2 light equivalent setup. One light really wants to be dimmer than the other anyway.

70 watts is about as useful as a spent match, professional halogen lamps are really intended for filming and are typically 500W, 1.2Kw, 2.5Kw and 5Kw. Because of the heat generated you cannot use any of the useful light modifiers you can use with studio flash, they would simply catch fire. Even the modelling lamps in my flash heads are 250W.

From experience a small 200 Watt/second flash head in a typical portrait session will, using a soft box, allow an aperture of around f6.7. I was shooting portraits yesterday (link)and a 500 Watt/second head with a soft box as my key light and was getting f8 even on 1/8th power. That would be f32 on full power, by comparison a 500W tungsten redhead would only give you f4/f5.6

Bowens and other manufacturers flash heads are built to standard way, way beyond Pentax's current models and at a fraction of the cost. A Bowens 200 Esprit Gemini, which can run on mains and battery is only around £180 but you would have to allow another £50 for the wide angle brolly reflector. The downside, of course, is that you cant stick it in your gadget bag!

Another option is to buy a device which allows a standard hotshoe flash to use Bowens mount light modifiers. link

Brollies have their uses but too often its a case of 'no skill, just fill'

With the K5 excellent high ISO can you not get away with a lower power lighting set up than was previously the case?

After doing some video with tungsten lights - man, they're hot. We were using 3 x 800W in a small flat and ended up with f4. And 35C. We overheated the 7D.

Bottom line? There is such a thing as too much power, but as soon as you increase the size of the object (for example to a car), then I see the real use case for 1000Ws and more.

Bret

You can now buy Daylight cold cathode full spectrum (or similar) lights that don't get HOT! OK and often preferred for still life's but for portraits flash is better.

This one type link

I frequently work with halogen lamps and have converted many inexpensive worklights for pro video uses..
they work... but for for portraits you will use a lot of power and make heat.. this can be worked around..(open a window and use a fan or two, shoot in the early morning when it's cooler) ). but have you considered florescent lights? easier on the circuit breakers, less heat... and you can make both strip lights and clamp lights on the cheap with one trip to the hardware store, and careful selection of bulbs for full spectrum and proper color balance... just keep your shutter speeds lower to avoid flicker...

be an available light shooter... shoot with any light that is available... don't be afraid to mix light sources...

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