viewing light to check color of products

<p>Anyone recommend a viewing or proofing light system to check the color of a product? Anyone use proofing station made by a company called GTI? I'm just using a lamp with daylight balanced bulbs in it to check the color of products shot at the studio--to make sure the final photoshopped image matches as closely as possible...<br>

Anything more sophisticated out there that doesn't cost a fortune??<br>

Thanks!<br>

Cathy</p>

<p>Hi, Cathy. I use a regular desk lamp with a regular daylight <em>fluorescent </em>bulb. The results are as good as the expensive ($100 and up) daylight bulbs you can buy (I don't remember the name of the expensive ones). </p>

<p>Solux bulbs in any fixture that will accept an MR16 type of bulb.</p>

<p>You don't really need a fancy, expensive proofing station. The bulb(s) you use are the key. And you have to either reduce the ambient light or shield the subject from it. Just be sure to choose a <em>stable full-spectrum</em> daylight bulb, as some of the fluorescent types have spectrum gaps which can depict certain colors incorrectly. Major manufactures of lighting like Philips, GE, Fujitsu and Seimens all make premium, full spectrum daylight bulbs that will work well.</p>

<p>Howard has nailed it. There's nothing for proofing colors like a SoLux. Near perfect 98 CRI (color rendition index).</p>

<p>Think of the CRI as the average percentage of "rightness" of the colors. Basically, the 98 CRI that means that once your eye adjusts to the "white", colors are an average of 2% off. Some colors won't be off at all, others could be a lot more than 2%, depending on the location of those "spectrum gaps" that Rick referred to. (actually, "spikes" are more of a problem than "gaps"). Incandescent lights like SoLux really don't have spikes and gaps, their spectrum is smoother, with just gentle rolling hills and valleys. ;)</p>

<blockquote>

<p>I'm just using a lamp with daylight balanced bulbs in it to check the color of products shot at the studio</p>

</blockquote>

<p>Even the so-called "full spectrum" compact fluorescent lights have, at most, a 93 CRI, and 85 CRI is much more common (most of the bulbs that are advertised as "high CRI" are 85). The "expensive ones" that Diane mentioned are most likely the "Ott-Lite" bulbs. In my opinion, Ott put a lot more effort into their advertising campaign than their product, because I've seen independent measurements of the Ott-Lite at CRI anywhere from 79-85, never near the 90-09 claimed by Ott.</p>

<p>The problem with SoLux lamps is the low efficiency and the high heat generation in a fixture you'd use for proofing. SoLux works by taking a standard halogen (about 3200K, way warmer than daylight 5500K) and putting it in a reflector that reflects more blue light and less red light towards the subject, allowing a lot of red, orange, and yellow light to escape out the back of the reflector. That energy has to go somewhere, and a proofing fixture simply "absorbs" it, getting hot.</p>

<p>There are such things as "real" high CRI fluorescents, but not in "compact" forms. Philips makes a line of CRI 98 fluorescent bulbs that really do look good on the spectrometer. But they're big: T8 (1 inch diameter, 25mm) straight tubes in 2, 3, and 4 foot lenghts, and T5 (5/8 inch, 16mm) bent tubes.</p>

<p>So...which do you think is a better light source? Solux bulbs....or the Phillips fluorescent bulbs? Appreciate it!<br>

Thanks Joseph...<br>

CAthy</p>

<p>The listed threads below have images created and edited to accurately show what these types of lights do to color:</p>

<p>

<p>http://www.photo.net/digital-darkroom-forum/00ULME</p>

<p>http://www.photo.net/photography-lighting-equipment-techniques-forum/00SN3Y</p>

<p>http://www.photo.net/digital-darkroom-forum/00Rr6Y</p>

<p>http://www.photo.net/casual-conversations-forum/00Skps</p>

<p>http://www.photo.net/beginner-photography-questions-forum/00VEJG</p>

</p>

<p>Solux no question. </p>

<p>As for CRI, its not at all useful and more a marketing aid for Fluorescent light manufacturers than anything else. Eight tiles are used to compare the light under versus a reference light source. That's too small a set of tiles. The manufacturers pick the tiles. That make it easy to create a spectrum that will render the 8 tiles and doesn't tell us that the light source is full spectrum. It doesn't tell us how the other colors will render. My understanding is there are two reference sources; Tungsten for warm bulbs and D50 for cool ones. That means that a normal tungsten bulb and perfect daylight both have a CRI of 100! As such, a high CRI is a decent gauge of how well a light will preform in your home but not such a great indicator of how well it will work for photography and proofing. Both a Solux 48 and a "full spectrum" tube from home depot may have a CRI of 97. I can assure you the Home Depot bulb has a giant mercury spike and some spectral dead spots. </p>

 

<p>Andy, you keep saying "the manufacturers pick the tiles".</p>

<p>I've checked the CIE 1995 standard, twice, and it specifices quite clearly which 8 BCRA tiles are to be used for Ra (the CRI value given by most lamp manufacturers) and what is to be done with the other 7 (saturated colors and flesh tones). The other standard (R96a) for use with a ColorChecker instead of BCRA, also specifices which 10squares are to be used.</p>

<p>It doesn't appear that the lamp manufacturer ever gets to "pick the tiles".</p>

Ottlite. No need for regulation, and the results are excellent.

<p>Solux, $8 per bulb. That sums up for me the deciding criteria among (between, actually) the available choices. The results are excellent also. It's silly to presume there is only one product that can produce satisfactory results. That's playing into their marketing and sales hype.</p>

<p>Solux has a cogent explanation on their website of why museums choose Solux at 3500K, something to do with how the rods and cones interact at the lower light level indoors and the perceived spectra compared to bright daylight outdoors. D65 and 4700K works for my environment and equipment.</p>

<p>Even if they don’t pick the tiles, they are designed to make Fluorescent lighting report far better than they really are and 8 tiles are far too few to define an illuminant. Again, I strongly believe the spec is nearly useless for consumers who want to really know what the light can produce. As I said, nearly all Fluorescent lights have really bad spectral spikes, easy to see when you view their SPD’s (something you can do, and I could illustrate using EyeOne Share and an EyeOne Pro Spectrophotometer). That a Solux and a home depot light can share the same CRI value is telling after you view the SPD. If you’re working with papers with OBA’s, Fluorescent can be very problematic and show significant metameric failure. OTT lights (all Fluorescents) fall into this camp.</p>

<p>The CRI spec is much like the Lumens spec for projectors. Consumers look at these values and think its an indicator of quality or performance and that’s far from the case. There are projectors with far lower lumens spec’s with far better image quality (and higher values using a newer and better reporting spec called Color Light Output) that blow the doors off units having higher values specified with this old and mostly manufacturer defined metric (see http://www.lumita.com/site_media/work/whitepapers/files/New_IEC-proposal_1207.pdf). </p>

<blockquote>

<p>That a Solux and a home depot light can share the same CRI value is telling after you view the SPD.</p>

</blockquote>

<p>I don't recall mentioning anything about "Home Depot". AFAIK, they don't sell anything with a CRI higher than 85, but that is not the issue, it is diversion on your part.</p>

<p>Andy, I find the rest of your comments are also too far into the rhetoric that you often repeat, but doesn't really seem supportable. Saying that CRI is bad because some other measure of some other unrelated parameter is bad is a non sequitur. I also disagree with your comments about 8 tiles (24 vectors into tristimulus values) being insufficient to define an illuminant, considering that 16 vectors are often used for color profiling. Neither your logic nor your math checks out.</p>

<blockquote>

<p>Andy, I find the rest of your comments are also too far into the rhetoric that you often repeat, but doesn't really seem supportable.</p>

</blockquote>

<p>Well I’m not trying to address this solely to you for obvious reasons. But for others, this piece does provide a SPD (spectral power distribution) map of a Fluorescent light and daylight:</p>

<p>http://www.ppmag.com/reviews/200604_rodneycm.pdf</p>

<p>The Solux SPD is very similar in terms of the flat curve<strong>. </strong></p>

 

<blockquote>

<p>I also disagree with your comments about 8 tiles (24 vectors into tristimulus values) being insufficient to define an illuminant, considering that 16 vectors are often used for color profiling. Neither your logic nor your math checks out<strong>.</strong></p>

</blockquote>

<p>The SPD provides the proof, the CRI doesn’t. End of story.<br>

<strong><br /></strong></p>

<p>Cathy, I have a very nice GTI box and love it but I don’t find the Fluorescent lighting to be close to ideal for the reasons I mentioned. I use it because I work with prepress and labs that use the same booth. The ultimate (ideal) illuminate, especially for photo content where papers with OBAs might result is the Solux due to its spectrum. The main downside is heat and control. If the viewing conditions are too bright, unlike the GTI I have with digital dimmer, the only way to fix this is to move the light closer or father from the print. But from strictly an illuminate perspectives, the Solux build is so far, the closest man made lighting you and I can afford that simulates daylight. </p>

<p>For those of y’all who don’t have a spectrophotometer laying around and would

like to get an idea of why fluorescent lights are so bad for photographic purposes, there’s a

trivial experiment you can do.</p>

 

<p>First, get a silver-colored CD (or DVD or whatever). Take it outside and tilt it around until you

see a rainbow on the shiny side. Look critically at the rainbow, and pay attention to the relative

brightnesses of the colors an the transitions between the colors.</p>

 

<p>Now, go indoors to wherever there’s some fluorescent light. Make the same observation

with the disc. See all those dark spots and abrupt transitions, plus some narrow bands of certain

colors that are especially bright?</p>

 

<p>Of course, the <em>real</em> problem is that our prints aren’t always — indeed,

rarely — displayed under good light. The good news is that, with a spectrophotometer and the

right software, you can create a custom ICC profile for your printer that will compensate for a

particular lighting condition and produce much better prints. The bad news…is that such a print

will look bad when viewed in different light.</p>

 

<p>Even with good lighting, you still get optimal prints from such a custom profile. As an added

benefit, if the lighting really is decent, then the print will still look okay in different lighting conditions;

just not quite as good. If you’re making prints to be displayed as part of an exhibition or for a

high-end client, it’s a good thing to do if at all possible.</p>

 

<p>Cheers,</p>

 

<p>b&</p>