Sunday, October 15, 2006

Lesson 403, Jewelry - Some Easy Hints

In the previous post you see the fourth and loose "lamp" clipped to the tripod with a piece of duffusion material attached in the shape of a triangle, but here it's "down and dirty" with aluminum foil wrapped (carefully) around it and the old man trying to get the subject to give up some "sparkles".

In the third right photo, an easy and cheap way to get the tripod out and over the jewelry - simply extend one tripod leg and use a soft weight from your nearest running or aerobic training supply to create a counter weight on the forward leaning camera and tripod. Or tape a one pint or one liter water bottle to one extended leg. ARROW is pointing at the "training" weight bag.

Lesson 402, Jewelry - Sparkles

Jewelry can be the hardest of all photographic subjects - you have high contrasts - bright silver surfaces and dark black leathers or velvets, you have "gems" that must reveal polished surfaces but you must also show their transperancy and depth with some sexy sparkle here and there.

The usual, but not 100% solution is to create a broad light source with graduated brightness - a single even light source will not reveal the curved surfaces of your subject. In the example above we have removed one of the lamps from the EGO closest to us - so EGO ONE, full brightness, EGO TWO, half brightness, but brighter on the side nearest EGO ONE - then a the white card to complete the "circle" of broad light around our varied subject.

Compare the photo on the left with the one in the middle. To add some "sparkle" we have placed the light bulb we stole from EGO TWO into a clipon socket very near the camera lens and, then carefully watch where it "pops" open the reflective metal and glass and stone surfaces. See close up photo on the next post.

Lesson 401, Jewelry - Gold, Silver

Simple silver with gold belt buckle. First, this is were the 5500Kelvin color output makes EGO "shines". As explained in the earlier post, the Digital technology is weak in the blue and very strong in infrared (hence, night vision goggles) - try get good looking silver and gold with Tungstun - dont believe yet - here's a FREE no cost test.

Get a silver (metal) wrist watch and set it on a moveable card with a color reference chart. Photograph your setup with a digital camera under tungsten light - any household Edison lamp will serve - these lamps are about 2700 Kelving. Then carry your card with watch and color reference outside to an shaded side of your building - open shade will be about 10 to 30,000 Kelvin - may several more digital exposures. Now compare in Photoshop or similar - which light source resulted in the best silvers and golds?

SETUP Above: Here are two EGOS with two reflector cards arranged to create a full "spherical" tent. The belt buckle photo on the left is with the "roof" reflector in place and, the photo in the middle, the "roof" has been removed. Note the difference.

Why is the light from EGO better than anything else?

As the concept designer of EGO, I forget that the very special lamps used by the EGO are nearly 10 years in the making especially for digital and video capture. They have four important features - small and compact; "photo" daylight balanced 5500Kelvin; high color rendering (92CRI+)for visual and film use without filters; and no IR (infrared) to distort digital. Together with the illustrations above, here's a quick primer about light - REMEMBER light meters read ONLY GREEN of photopic vision and not blue or red - in the top chart, the meter would be reading the same, that is, both 2700K and 6500K have the same quantity of green - so a lot of tungsten light does not translate into a lot of light on the meter, but especially not a lot of light on the digital chip - read why.

First, a Quick Primer in Continuous Light- O.K., boys and girls, keep those pencils sharp. What is the first thing that comes to your mind, when you think the words, "Continuous lighting?" By chance, is it, "Tungsten Light"? (aka: quartz halogen, incandescent)? Certainly, tungsten light was the first and last thought in the "minds" of many photo salespersons. But tungsten light matched with digital imaging is the worse possible continuous light source - the HOT devil incarnate. (You will be tested!) Why?

REASON One: No blue! and no blue. If good color balance (neutral silvers and grays0 is important to your image, then you must match the weaknesses and strengths of the sensitivity of your media (digital) to the weaknesses and strengths of the output of the light. Tungsten light at 3000K has less than 10% of its total visual output with in the blue [400 - 500nm](5500K is B33%, G33%, R33%). This could and should be at least EQUAL RGB (5500K) for digital capture meaning at least 33% in the blue (400-500nm), or as it is with 6500K- the color of overcast sky - a little extra blue (chart top). On the same count, Digital (CCD) sensitivity has the similar input problems -less than 10% sensitivity of the chip to blue (see above bottom). S0 -No Blue and No Blue. Junk in, junk out and no amount of PhotoShop magic will create color that was never there on two counts.

Now compare CCD sensitivity. Go to Kodak's great resource on this subject- and print out any of their color CCD PDF files that strike your fancy, but especially the sensitivity curves of Kodak's so called "extra-blue" CCDs (fourth chart above). Also, if possible, note sensitivity curves with and without the IR blocking filters. Which brings us to-

REASON Two: The invisible HEAT of tungsten distorts CCD imaging. The CCD is 10 times more sensitive to Infrared (aka: heat) than visual light. Tungsten visual spectrum is only 7% of the supplied energy, and the balance of the 93% is anti-imaging infrared (aka: heat) that travels out to the subject with the visual spectrum. Take a look at the IR in tungsten output at:

Carefully compare the Kodak CCD PDFs (as example, the lower charts above compare daylight film with an "extra blue" CCD chip) you downloaded above for CCD sensitivity with and without the IR blocking filters - heat is a big problem. IR filters help somewhat, if properly designed, but IR "cut-off" filters also cut out tungsten's already overrich visual spectrum in the far red.

From the book "Lighting Technology" by Brian Fitt, Focus Press, 1997 - "The tungsten lamp is a heat generator from which we can get a little light. The conversion of total electrical energy produces only 6.5% light and 93.5% wasted heat." The author further notes that that heat travels with the spectral makeup of the light to the subject and back to the camera. Heat entering a digital camera distorts the entire RGB visual response (study the Kodak charts) but especially in the already weaken blue channel - hence, shadow noise, bad dark greens, grays and silvers without balanced RGB.