BetterPhoto Q&A
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Photos taken with SONY having green cast!

I thought maybe I had accidentally touched other buttons thus triggering other settings during photographigng, but then ruled that out by double-checking all camera settings.

To see if the problem would persist in a different lighting condition, I brought the camera outdoor to try. No green cast shooting outdoor.

I brought it back to the home studio setting. There're only two lights in this studio setting. One is the main light, positioned just to the right of the suject. The other is the overhead light, just above the subject. The green cast persisted when I shot with both the main light and overhead light on. I then shot several photos with only the overhead light on, http://i10.photobucket.com/albums/a147/ ... erhead.jpg all w/o green cast. I tried with the main light on only, and guess what, there was real noticeable shift in color from http://i10.photobucket.com/albums/a147/ ... C-432S.jpg this first shot to http://i10.photobucket.com/albums/a147/ ... C-433S.jpg this.

At this point I wasn't sure if the SONY MVC-FD87 or the main light was the real culprit.

So I retested under the studio setting with a SONY DSC-W7
And I got more confused because the photos taken with DSC-W7 turn out to be way darker than those taken with MVC-FD87. Both the DSC-W7 and MVC-FD87 have the same setting: WB is auto, EV is 1.0

Please help! I've been testing and retesting the whole weekend. I must figure out what the real problem is!!

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May 14, 2006

Mark

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May 14, 2006

The 'AUTO' WB setting on most cameras don't do too well with settings other than natural daylight. And if you have a mixture of two different types of light, say tungsten and flourescent lighting, the camera will usually balance itself for the more predominent one. Yet, you will still see the color cast from the other light source.
As Mark stated, I would check to make sure that when shooting in the studio, there are no other light sources turned on during the shoot that might upset the WB and give you little green men.

Bob

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May 14, 2006

I am 100% positive there was no other house lights around. Only the two studio lights are turned on. The main light is fitted with 4 daylight balanced 5500K 23W spiral light bulbs. The overhead light is fitted with 3 of the exact same type of light bulbs.

When I occassionally shoot during daytime, I turned off all house lights and blocked out ambient lights from the window.

Help!

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May 14, 2006

Bob

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May 15, 2006

First understand that florescent lights are hollow tubes filled with mercury gas. An electric charge travels from one end to the other using the mercury as the conductor. The mercury gets excited by the flow of electrons. Excited mercury glows with UV light. The UV hits the inside walls of the tube which is coated with phosphorus. The phosphor, struck by the UV, glows with visible light. The visible light is a continuous spectrum but it is not uniform. If you could see it diagramed on graph paper you would see spikes that are not good. You can get so-called daylight fluorescents but consider the following.

Lamp voltage caused huge changes (with incandescent also).
Over time the phosphorus burns in and changes color (same type of material on inside of TV picture tube. Phosphors change with time.

I advise getting rid of the florescent lamps.
Consider investing in a good set of strobes.

Also:
The main should be high and off to the side.
The fill should be somewhere on a line drawn between camera and subject. You are filling from the cameras prospective not from the prospective of an off-axis observer.
The fill should present to the subject, ½ the illumination level as the main. This provides a 3:1 lighting ratio presumably best for saleable portraits. 3:1 because the frontal areas of the subject are illumined by light from both the main and the fill. Say 100 units from the main and 50 units from the fill for a total of 150 units. The shadows only receive light from the fill which is 50 units only as shadows do not receive light from the main. Now the ratio is 150:50 or 3:1. Anything goes if you aren’t trying to make money.

Alan Marcus
ammarcus@earthlink.net

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May 15, 2006

Here's what the main light looks like.
http://i10.photobucket.com/albums/a147/bemyhost/main_sellit.jpg

And this is the overhead light.
http://i10.photobucket.com/albums/a147/bemyhost/overhead_kphoto.jpg

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May 15, 2006

I stand by my suggestion to relocate the lamps. Your fill should be placed close to the camera lens. The main should be off to the side and high and twice as bright.

The exposure is based on a reading taken with main turned off. Set camera for this exposure; turn on the main back on for exposure. Follow this advice, you will get a 3:1 ratio, the image will have more contrast and your product will look more attractive and thus more sellable.

Alan Marcus
ammarcus@earthlink.net

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May 15, 2006

I tried exactly that, and the green cast is pretty much all gone (not quite as you'll soon see).

After I had the WB on "HOLD", I took many many shots with both the main and overhead on. The first few shots after WB is set to "HOLD"
http://i10.photobucket.com/albums/a147/ ... sthold.jpg
differ slightly in color from the later ones.
http://i10.photobucket.com/albums/a147/ ... vc575S.jpg

It's like the color really wants to get back to green from normal even when the WB is set to "HOLD".

But if I change the WB from "HOLD" back to "AUTO" as shooting is going on, the picture immediately has a visible green cast.

What's the real story behind the green cast? I'm really upset because these are relatively new and I've spent a great chunk of time and energy (and money spent too) trying to make my photos pop.

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May 16, 2006

Real lighting for Real photographers !!! ;>)

Mark
==============================
If you're gonna photograph with the BIG DOGS, you gotta get off the porch !!

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May 16, 2006

I think I may have caught the real culprit! In all my previous attempts to figure out what caused the green cast, I never thought of exchanging the light bulbs in the main light with those that are inside the overhead. (We later all know something's wrong with light from the main.)

This is what I just tried: I took out all four bulbs inside the main and put back the three bulbs that was originally insdie the overhead. I took a shot with the main only, and guess what..green all over. I thought that was weird. So I randomly selected three of four bulbs originally from the main, and I put them in the overhead. I took a shot with the overhead only, no green cast/perfect.

This is really strange. The main light is only 6 months old and had rarely been used (except I don't know about that one time I let a friend borrow it). Anyone has a theory?

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May 17, 2006

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May 18, 2006

Over the years I paid lots of attention to photographic light sources especially lamps used in projection printers (enlargers – photofinishing printers), and studio strobes. There are many factors to take into account, some are not obvious.

All artificial light sources have enormous stability issues.
All artificial lamps shift in color and intensity as line voltage fluctuates.
Line voltage is good about maintaining frequency (50 – 60 cycles per second county dependent) voltage fluctuates 8% or more. In-house wiring causes fluctuations too, motors turning off / on like refrigerators and air conditioners etc., and the lights dim.

Studio strobes shift in color and intensity as the lamp, lamp coating, plastic lens, and electronics age. Most designs signal ready before the capacitors are fully charged. Umbrella materials change over time. However they are hands down, the most desirable artificial source.

Standard and photo grade tungsten lamps shift brighter and bluer as they age.
Tungsten halogen lamps have the best longevity curve.
All tungsten lamps drift blue as lamp voltage increases – red as it drops.
Fluorescent lamps suffer from color variations due to types of phosphors. They appear white to the human eye but do not have a continuous spectrum so they photograph white with difficulty. Phosphors shift in output and color with age. Heretofore, florescent tubs were too big for most studios however they had a following in the mass portrait business (black & white)as banks of tubes produce a very broad forgiving light. These banks of “broads” were the inspiration for the umbrella diffusing system so popular today.

From a manufactures standpoint Fluorescents are attractive:
Fluorescents run cool and have lower power requirements (good selling points)
New compact tubes allow a design similar to tungsten lamps.
Mostly standard metal work with standard lamp industry wiring, no complicated electronics or engineering thus inexpensive to make.
Makers probably have little photographic background, design based on lamp maker’s claims.

However:
New tubes and phosphors available most every day – maybe a breakthrough has occurred.
Future designs will probably be LED (light emitting diode) or something wonderful.

Glad I was able to help,

Alan Marcus
ammarcus@earthlink.net

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May 18, 2006