Standard bulb Vs. PAR Flood Light
The above image shows the two lamps used in this comparison. On the left is a 72 watt halogen in a standard bulb shape capable of 1490 lumens; price - $1.25. On the right is a PAR30 60 watt Halogen Wide Flood that will produce 1070 lumens; price - $7.50. The PAR stands for "Parabolic Aluminized Reflector". The glass envelope diameter of a light is measured in eighths of an inch. So this PAR30 measures in at 30 eighths of an inch or 3.75". Both these lights are perfectly acceptable in the studio but it does make a difference what you choose.
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The standard bulb will emit light in all directions equally around itself. Normally this isn't necessary or ideal, so a reflector (like on the clamp-on light to the right) is used to project the light forward. This works really well if you need a wide spread to light a subject. However, if you need to light a painting, you may want to consider a PAR lamp.
Below is the result of the standard bulb with a reflector (left) and the PAR30 flood light (right) illuminating a white wall from 4 feet way. The amount of wall space photographed in the images is about 2 feet by 3 feet. The placement and exposure on the camera stayed the same for both photos. f/5.6 at 1/15 sec., ISO 100.
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Keep in mind, the 72 watt standard bulb produces 1490 lumens and the 60 watt flood light 1070 lumens. The 72 watt standard bulb actually emits about 28% more light than the 60 watt flood. So why does the flood light shine brighter?
The PAR light is brighter because it is directional. It can tightly focus a beam of light, the standard bulb cannot - even with a reflector. While the standard bulb in this comparison is brighter, the reflector allows the light to spread nearly 180 degrees. The PAR light, in this case, focuses its light in a 50 degree beam which means there is a concentration of light in a smaller area. This is great for paintings because often you want to illuminate only the painting and not the entire space around it. Of course the flood light costs more money, but this allows you to use less lights at lower wattages to achieve the same amount of light on your painting. Overtime the cost to operate the lesser amount of lower watt floods should pay off. Another benefit is less heat in your studio if you are using halogen lights. PAR lights are also available in fluorescent and LED versions, although I have not tried any of them. If you decide to use these light types, make sure the CRI is above 90 for good light quality.
Also available are BR lights. The BR stands for "Bulge Reflector". These deliver a spread of light softer than PARs, but tighter than a standard bulb with a reflector.
Floods lights come in a few different beam angles. For example, in the Sylvania PAR range, 10 degrees is a spot light, 25 degrees is a narrow flood, and 50 degrees is a wide flood. For my set up, I've found the 50 degree wide floods work well to illuminate my painting on the easel. I usually use two or three depending on the size of the painting.
Also available are BR lights. The BR stands for "Bulge Reflector". These deliver a spread of light softer than PARs, but tighter than a standard bulb with a reflector.
Floods lights come in a few different beam angles. For example, in the Sylvania PAR range, 10 degrees is a spot light, 25 degrees is a narrow flood, and 50 degrees is a wide flood. For my set up, I've found the 50 degree wide floods work well to illuminate my painting on the easel. I usually use two or three depending on the size of the painting.
See how to light a painting here.
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