Saturday, November 28, 2009

Comparison: Color Shift from Reflectors - Why it pays to buy quality (take 2)

The last post dealt with color shift from light modifiers. This prompted me to conduct yet one more similar experiment, only this time using light bounced from my collection of various reflectors. suspicion that some of my reflectors are causing a color shift was fueled by the findings from testing umbrellas and softboxes. Since reflectors get used primarily for filling shadows and often in conjunction with a fill light, the color shift is often not particularly noticeable and therefore easy to overlook. However, when using a single light source and a reflector for fill, the color shift could be very dramatic, so if there is a problem with any reflector, it needs to be identified and eliminated.

As with other light modifiers, this important aspect of performance seldom gets any kind of attention. A mild performance issue may cause an image to not achieve its potential. In the extreme it could ruin an otherwise good photo (or cause significant Photoshop work to spot color correct).

Test Methodology
For this test, I am photographing the white side of a Lastolite 12” EZ Balance collapsible light balancing disk, which exactly matches the white patch on a QP Card. For each photo I have taken multiple readings from different areas on the disk and am documenting a representative RGB reading (the most commonly seen).

To ensure no color shift from changing flash power, the flash power was set once and left unchanged for all subsequent shots. To compensate for the efficiency of each modifier I changed the camera's aperture and moved the flash a few inches forward or back as needed for consistent light readings.

The reference shot was taken with direct light from the monolight fitted with a 7” reflector. All subsequent shots were the same light source bounced off of the reflective surface. I took two shots for each setup to ensure consistency, but this turned out to be unnecessary, as the lighting was very consistent between for the duplicated shots.

Test Results
White Balance Reference shot
(direct light from 7” reflector)

RGB Patch Reading
244, 244, 244

This is the reference to which all the other photos are compared. I performed a custom white balance based on this shot and used the settings from this shot (white balance, contrast, etc.) for all of the other shots. As you can see, it is a perfect white balance. For each of the following test shots, I have included a slice of this reference on the left side to make an easy visual comparison.

White Polyester Fleece
RGB Patch Readings
235, 242, 252

Not so long ago I set up a photo booth for a baby shower. I used this white polyester fleece for the backdrop and along one side for a reflective wall. What I noticed during processing is that when the lighting was properly balanced to achieve good skin tone, the backdrop took on a distinct blueish hue. That finding by itself was enough to warrant never again using this material, but since I was doing a controlled experiment it was logical to include this material. Even without the RGB reading you can plainly seen just how much this material shifts the color toward blue.

Amvona 22" white side of 5-in-1 reflector
RGB Patch Readings
245, 245, 245

Amvona are known for making inexpensive equipment that can actually do the job. In this case, they get an A+ for color correctness. Unfortunately, I would not give such a good grade for durability in this case, as the gold side of the reflector started flaking off a couple of years ago (after owning it for around two years). I recently replaced it with an eBay purchased reflector that was supposed to be a Photogenic, but turned out to be a cheap Chinese imitation. Read on to see how it performed.

eBay 22" white side of 5-in-1 reflector
RGB Patch Readings
245, 245, 245

Looks like another winner, it is perfectly neutral. Unfortunately, the wire rim of this 5-in-1 reflector was rather flimsy, so I swapped the scrim, which contains the rim, from the Amvona to combine the best from both reflectors.

eBay 32" white side of 5-in-1 reflector
RGB Patch Readings
233, 237, 248

When it comes to cheap equipment, sometimes you win and sometimes you loose. In this case the white surface is a total loss. This was the my last reflector purchase some time ago and is the last generic I will ever buy. Its performance came as somewhat of a surprise to me, not that it is imperfect, but just how bad it actually is. The silver side is just fine, but the white side is utterly useless.

eBay 42" white side of 5-in-1 reflector
RGB Patch Readings
234, 237, 244

This is my first and oldest reflector bought some years ago. It will be replaced in the not too distant future. It might be usable where color control is not critically important, but really does not belong in a proper studio.

eBay 60”x40” white side of 5-in-1 reflector
RGB Patch Readings
230, 234, 245

Oh my, this is getting expensive; my largest reflector needs replaced! I have had this a long time and have used the black surface more than anything else, but this white surface is simply terrible. Fortunately, the silver side is okay and the black surface is very useful too. However, this does exemplify that you often do get what you pay for.

20”x30” white foamcore
RGB Patch Readings
237, 236, 234

A big thumbs up! I have always heard that foamcore is essentially color neutral and makes a great reflector. Well, if this sheet of Elmer's foamcore art board is a representative sample for all white foamcore, then I am in full agreement. It is lit just a bit dimmer, but as you can see, the white balance is quite acceptable. It adds only a little bit of warmth. For the money, it is hard to beat, especially since this piece was on sale for a one dollar per sheet. I used this to create a set of V Flats, but that is something to talk about in a future posting.

Once again we can see that a bargain is not always a bargain. A couple of the inexpensive reflectors, 22” Amvona and 22” eBay, did very well, but the others did not. Those that didn't make the grade will be replaced, proving once again that it is better to buy good stuff once... lesson learned.

As always, feel free to derive whatever conclusions you wish. If you have done similar experiments, I am interested to know if your results agree with mine. If you find this posting useful, please leave me a comment.

Until next time...



  1. Many underestimate the value of good sheet of foamcore ;-)

  2. I'm curious how Joe McNally's bedsheet diffuser technique would hold up. ;)


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