New photo lights for shooting turnings

[john lucas]

I got the new FLD photo lights this week and finally had time to run them through a test. man to they tell tall tales about these things.
Here is what I got. this one is a 70watt FLD in a softbox.
http://www.adorama.com/FPSSB.html
This one is 3 45 watt FLD lamps in a 12" reflector. comes with a diffuser, umbrella and a stand.
http://www.adorama.com/LTO210.html

Because I didn't believe the power ratings and knowing that the type of reflector, soft box, etc will drastically change the output, I put them in a plain socket with no reflector whatsoever.
I had two standards. A 100 watt incandescant bulb, and 500 watt EBW blue photoflood. I used a 70 watt FLD and one 45 watt FLD.
The 70 watt FLD claims to be equivalent to 350 watts. Interesting because it read 2/3's of a f stop less light than the 100 watt lamp.
The 45 watt lamp came out to be equal to about a 35 watt lamp, 1.4 stops less than the 100 watt lamp.

color wise, they are supposed to be 5500 K. they actually read more like 6300, the 45 watts are more like 6170K. shooting with them on the daylight setting they are extremely close color wise. They are very slightly green. Less than most people's computers would show. My computer at work is color corrected.

Here are some sample photos. I will try to put together a video on how I would suggest using them. This system costs a little more than I would like. Tax shipping and all I have about $170 dollars in it. That doesn't count one light stand I already had. I'm going to do another test with some plain hardware store reflectors. That and the lamps should cut the cost down to $50 not counting stands but you can make what we call "stick in a can" stands very cheap. I'll show those also later.

for those interested the shots were done at 1/4 second at F8, 200 ISO, on the Daylight white balance. No corrections were done in the software, these are straight out of my Nikon D700 using an 80-200/2.8 lens.
don't laugh at the turning. That was one I did about 25 years ago when all I knew was gluing dry wood together. We've had it in the office for all those years.
I'll be doing a demo at the OHIO symposium in September and wanted to update my lighting. The quartz lights I've been using are good but they are very hot and dangerous. These lights will require a longer exposure by about 3 stops so you need a darkened room to shoot in. I did some reciprocity tests on long exposures on 2 of our cameras and noticed only a very slight difference in exposure, no color shifts. Your camera may be different but if not you should be able to shoot at f22 at about 2 seconds for this kind of photo. With the hot quartz lights it would have been about 1/4 second. Still need a tripod of course.

 

[Bill Boehme]

John,

Thanks for the great evaluation. I think that part of the problem regarding comparison of CFL's to tungsten lights is that different kinds of standards are being used for rating the lights depending on whether the goal is photography or for interior lighting. I think that the CRI number is geared towards human perception of light, so a CFL with a high CRI rating would put out the greatest portion of its light in the part of the spectrum where our sensitivity is the greatest (the peak sensitivity occurs around yellowish-green) while at the same time providing an overall average color temperature that we could recognize as being white. The Kelvin temperatures that you measured would fit that requirement. Cameras perceive light quite differently than our eyes do and as your measurements indicate, the light level is closer to the true wattage and not the human equivalent value.

One other test that would be worthwhile is to photograph a 24 patch Gretag-Macbeth Color Checker (now x-rite) using these fluorescent lights and compare the results to the chart photographed in mid-day daylight conditions. If, after normalizing the white balance to the same color temperature, the results look satisfactory then that is what really matters. I suspect there may be some of the color patches that don't look quite "right" under the fluorescent lights.

I still use the 500W EBW blue lights, but they are short lived, expensive, and hot. I had one where the glass melted! I would love something better, but studio strobes or even speedlights are sort of pricey. Jamie Donaldson uses the 500W halogen work lights that you get at Lowe's and Home Depot. They seems to be perfectly acceptable and aren't very expensive.

 

[john lucas]

Bill I also use the cheap Quartz lights but they have several problems. They are really really hot and dangerous. You have to be extremely careful if you put any kind of diffusers or filters near it. Since the reflectors are so small you do have to diffuse them or like Jamie does bounce them off of a white panel. They do hold their color temperature really well. I've used a set in our copy room for 2 or 3 years. Many many hours of use on these and they still shoot the same as day one.
The reflectors are also hard to add barn doors and don't even think about using cardboard for a barn door.
The FLD bulbs although not any where near as bright are very cool. I turned the 100 watt bulb on for about 8 seconds to take the exposure meeting. Then I burned my finger removing the bulb. The FLD's on the other hand are just warm to the touch. I didn't feel even remotely uncomfortable putting a cardboard gobo next to them. I think barn doors would only get slightly warm. It still may be hard to add barn doors to the round lights but they stay so cool I think you could easily tape cardboard or foil to the reflector to block light without it catching fire.

 

[Bill Boehme]

..... and don't even think about using cardboard for a barn door.

I sense an untold story here. 😀

 

[Bill Boehme]

BTW, if you are shooting digital then reciprocity would not be applicable if you are talking about the non-linear characteristic of film that requires you to compensate the exposure time for long exposures.

 

[Robert Manning]

I have been using daylight fluorescents for studio photography for two years. I went this route because I liked the idea of them being cool and safe with a 10,000 hour life. OSH had clamp lights with aluminum reflectors and fifteen foot cords so I bought four of them. I got a four-pack of 23 watt 6500K daylight CFL's at Lowes. I also bought three different brands of CFL's and checked each light individually by shining onto a white wall and examining the light visually. There was color variation between brands and between lights out of the same box. Keep in mind that you need to allow these lamps to warm up for a minute to get full intensity.

John, I like your fixture with the triple sockets in one reflector.

My five year old digital camera had trouble with white balance. Even with three different fluorescent settings, I could not get neutral whites and considered switching to photo floods, but my new camera has the ability to measure my graduated background and balance the color with CFL's. This is done with the lighting setup in a dark room with no other light contaminating my shot. With the PRE white balance setting, this quickly measures the reflected light on my neutral background with 100 percent accuracy, even with these hardware store fluorescents. This is a big advantage over color film photography which requires lighting balanced for a given film . Once I get my whites and grays neutral, I have found that minor exposure adjustment will give me accurate color right out of the camera.

I use AUTO white balance for most outdoor shots and that works well.

I shoot basic jpeg for everything and like the fact that I can get over 3,000 images on a 4GB card. Some people have encouraged me to shoot RAW and do a bunch of post processing and some people say it isn't 2006 anymore. I can't imagine going through the gymnastics of RAW photography if you can get the shot right in the camera. My D5000 and other generation 2 Nikons automatically correct color fringing and lens distortion every time you click the shutter with Nikkor lenses. The lens distortion feature works great if you have straight lines at the edge of your frame and I haven't seen much fringing.

The following shot is right out of the camera and the only software adjustment was a one degree alignment rotation. It's shot at 1/13 second @ f16 with a +2/3 stop exposure bias, ISO 200, in aperture priority mode (my lights are very close to the subject). The lens is an 18-55mm set at 55mm (82mm equiv.) The background is graduated from snow white to jet black and I use a ten pound tripod. I have a Hoya multicoated UV filter protecting the lens. The wood is Black Oak from the Sierra foothills near Sequoia National Park.

 

[Bill Boehme]

I have been using daylight fluorescents for studio photography for two years.

I shoot basic jpeg for everything and like the fact that I can get over 3,000 images on a 4GB card. Some people have encouraged me to shoot RAW and do a bunch of post processing and some people say it isn't 2006 anymore.

The following shot is right out of the camera and the only software adjustment was a one degree alignment rotation. It's shot at 1/13 second @ f16 with a +2/3 stop exposure bias, ISO 200, in aperture priority mode (my lights are very close to the subject). The lens is an 18-55mm set at 55mm (82mm equiv.) The background is graduated from snow white to jet black and I use a ten pound tripod. I have a Hoya multicoated UV filter protecting the lens. The wood is Black Oak from the Sierra foothills near Sequoia National Park.

Very nice bowl and very nice photography, Robert. The CFLs seem to be working quite well for you. It looks like you are using a graduated background that is the same as one that I use (Studio Gray).

While your friends are right that it is not 2006, I agree with you that it is not necessary to shoot raw images if you can do what you want by getting a proper exposure in the camera. Raw and jpg both have their advantages. I mainly shoot raw mostly because I frequently do creative image processing that can't be done in the camera. To a limited extent, raw can also be used to "fix" a less than perfect exposure. One nice thing about raw that is often useful is the ability to apply white balance after the fact. Since raw images are unprocessed data, it means that they do not have a white balance or shooting style (Nikon calls it "scene style") in the sense that jpg images do. Something that you might consider to appease your friends: I noticed that the D5000 has some limited in-camera editing and raw conversion capability which means that you could shoot raw, do minor in-camera editing if needed and then have the camera process the raw files into jpg images.

If you can get 3000 images on a 4 Gig card, it means that you are probably saving your images as small compressed jpgs since they average about 1.33 Meg in size. For posting on the web that is fine, but if you are thinking about printing any of your images or sending any of them to a gallery or show, it would be much better to use a large jpg. Having more than a couple hundred images on a CF card is sort of moot unless you never delete any of them after uploading them to your computer.

I also wanted to comment on the color profile of your image because I saw a potential problem. For posting images on the web, the defacto standard is to use sRGB since it roughly matches what most computer monitors can display. Sometimes, people post images without an attached color profile in which case the web browser will simply assign sRGB to fill in for the missing profile and that usually works just fine (assuming, of course, that the image color profile really was sRGB before it was saved without a profile). But, somehow your image wound up with a hardware dependent color profile (camera RGB, which I presume means it is related to your D5000). I have set up my web browser to be color-aware (meaning that it reads the embedded image color profile and is able to use that data to correctly display the colors) so I am probably seeing the correct colors in your image, but otherwise there is a possibility that what someone sees on their web browser might be way off from the correct colors.

I have shifted towards using a much darker background (Thunder Gray) for photographing most of my turnings unless the wood is very dark, in which case I would use the studio gray. The reason has to do with light reflecting from the light background onto my turning and causing a somewhat washed out appearance. Additionally, something else that John Lucas pointed out to me was that the lower exterior of my bowls wound up being very light while the interior was much darker. This is backwards from what it ought to be. The darker background also helps with that problem, but I also use a bit more light from above to help with this. I haven't tried it yet, but I could probably use some gobos with my lighter background to get the lighting to be more natural looking.

 

[john lucas]

I started shooting in RAW a few years ago. It has huge advantages. One of the best is for shooting this kind of artwork. Sometimes it's very hard to get the shadows under pieces just right. I can do it of course with lots of light tricks but that can take another 20 or 30 minutes of setting up mirrors or reflectors or even a spot light(I'd have to explain how I use that, I call it invisible light)
In light room or photo shop I can lighten just the shadow area with a click of the button. There are other simple tricks as well for some images. Another example is we often use large soft lights to produce softer shadows but the highlights can be ugly. I will shrink the size of the spot to make it less obnoxious. Again I have the skills to get rid of this while shooting but it often takes a while and when I'm shooting 10 pieces of glass that time really adds up.
In JPG every single thing you do the image reduces the file size. If you spot dust specks, or sharpen, or change the contrast a little. Each one reduces the file size. When I compare final images there is a notable difference in the contrast and fine detail of the piece.
I use light room to download the images. Then I'll use light room to make a folder of JPG, TIFF, small JPG or all 3. this makes it very easy to use RAW.

 

[Robert Manning]

Thanks Bill,

My background is pure black at the top which is out of the frame. It's a Flotone. Also, I think this photo could be sharper. The images I get are 4288 × 2848 which is large basic jpg. Basic is for maximum jpg compression. I can't tell any difference between basic, normal, and fine. Some images are 4mb and some are in the 500k range with most images falling somewhere in the middle. Sometimes I get a sharp enough image to enlarge the equivalent of six feet wide on my laptop.

I suspect the fluorescents have some limits or missing parts of the spectrum. I had some trouble reproducing the tan color on Indian Summer while keeping the background completely neutral, but overall they work pretty well.

That is interesting about sRGB. I might need to know more about this.

John,

I have a shadow slider in iPhoto which I brighten sometimes to get more detail in the shadows. This works very well and can be adjusted a large amount. There are a couple other adjustments I use sometimes, but if you adjust too much it looks unnatural. If I make the adjustments in camera, I seem to get higher quality.


I enjoy landscape photography and recently scouted out several new locations where I took some shots and now I'm working out what time of day and year I want to shoot these scenes. In the meantime, I got some nice shots and enjoy it greatly.

Here are a couple more shots in this bowl sequence with subtle differences in the exposure and lighting. You might like one of them better.

 

[Steve Worcester]

That is interesting about sRGB. I might need to know more about this....

Interesting that as I went to look more into it, as usual you get opposing viewpoints. I didn't read through and dissect them, but for your viewing pleasure

http://www.cambridgeincolour.com/tutorials/sRGB-AdobeRGB1998.htm

http://www.kenrockwell.com/tech/adobe-rgb.htm

 

[Robert Manning]

Bill,
I just checked Color Space in my shooting menu and there are two choices:

sRGB and Adobe RGB

The camera has always been set on sRGB. I wonder if your 'puter is detecting something from iPhoto. In the iPhoto preferences under importing there is a choice to embed ColorSync profile. This option is enabled as the default.

Thanks for the links, Steve. I originally set up my camera with Ken's setup guide for the D5000. I changed some of the settings to match my shooting style, but it was a great starting point to become familiar with the equipment. One of the reasons I went with Nikon over Canon was the detailed and current information Ken has made available on Nikon cameras and glass.

Best regards,

 

[Bill Boehme]

Also, I think this photo could be sharper.

They probably were sharper before being saved as a highly compressed minimum file-size jpg and also there is not much chance of having sharper images with this level of compression. Most people do not readily notice the various jpg compression artifacts unless they are really bad. Since I know what to look for, I can see the artifacts created when your image was compressed to the small file size. Two of the most readily noticed things are color smearing and a "grainy" look around what would ordinarily be sharp edges. I can also see the tell-tale jpg "pattern".

The images I get are 4288 × 2848 which is large basic jpg. Basic is for maximum jpg compression. I can't tell any difference between basic, normal, and fine. Some images are 4mb and some are in the 500k range with most images falling somewhere in the middle. Sometimes I get a sharp enough image to enlarge the equivalent of six feet wide on my laptop.

Many laptops use basic TN displays that aren't always capable of revealing the differences because they may only be able to display six bits of image data and have a color gamut that is smaller than sRGB (which itself is a rather small color space). The lower quality jpg images are generally just fine for online viewing. However, they don't fare well if you need to edit them (change brightness or color tint or contrast). The highest quality jpg images (fine, in Nikon speak) can withstand moderate editing without taking too much of a hit in image quality.

That is interesting about sRGB. I might need to know more about this.

The subject of color spaces and profiles is rather involved, but sRGB was developed as a device-independent profile through a joint venture between Microsoft and Hewlett-Packard, I believe in the 1980's. The purpose was to have a standard color space that most CRT computer color monitors could display and also have a standardized profile that could be attached to images that would tell the monitors how to translate the image colors to monitor color so that the image could be displayed with reasonable accuracy.

The gamut of colors defined by sRGB is rather small compared to the range of colors that we are capable of seeing. However, that is the best that low cost CRT computer monitors were able to do. When LCD displays came along, the possible range of colors that they could display was even smaller. Fortunately, there have been improvements in LCD displays to the point that some of the high-end ($$$$) units can even display most of the gamut of Adobe RGB, a very large color space. To get an idea of how various color spaces compare, you can download the Microsoft Color Management Module which is a Control Panel App. It gives a 3D graphical representation of any ICC color profile that you have stored on your computer. The app is also very useful for anyone who works in a color managed environment when processing images, which is a very good idea.

I have attached a screen shot of the Adobe sRGB profile being modeled by the app.

If I make the adjustments in camera, I seem to get higher quality.

That is because the in-camera adjustments are being applied to the raw image data before it is converted to the jpg format. Something important to know about jpg is that it is a lossy format. With jpg images, file size is more important than preserving image details.

Interesting that as I went to look more into it, as usual you get opposing viewpoints. I didn't read through and dissect them, but for your viewing pleasure

http://www.cambridgeincolour.com/tutorials/sRGB-AdobeRGB1998.htm

http://www.kenrockwell.com/tech/adobe-rgb.htm

I regard whatever Ken Rockwell says with a jaundiced eye especially if it is of a technical nature although he has occasionally surprised folks and said something that made sense. Regardless of his lack of technical expertise, he does have a following on his blog which in turn attracts advertising to his site. Now, I suppose that I should follow the link to see what he says about color spaces and profiles.

Now, you have piqued my curiosity with the statement about opposing viewpoints and I will have to read both articles. Color spaces and device profiles (as well as device-independent profiles) are simply definitions of the gamut of color that is contained within any given color space. I suppose that one could argue about the perceived goodness or usefulness or shortcomings of a particular color space for a particular application.

One would not suspect that so much could be written about so little, but I have several voluminous texts on the subject of color. Interest in the subject has grown immensely with the advent of electronic means of capturing and displaying color images.

 

[Bill Boehme]

OK, I read both articles and as I suspected KR seems to mostly be promoting himself and not much else. He does have some useful caveats for those not versed in color management about using AdobeRGB vs. sRGB especially if the web is the image destination. However, it is clear that he doesn't fully comprehend the subject when he says things like "assign" a color profile to an image to see if there is any difference. An image can't magically have a wider gamut simply by assigning a different profile. For that matter, one should never "assign" a profile except for specific conditions that doesn't include his suggestion. His example "dull looking" AdobeRGB image had the profile assigned and then he is displaying the result on a medium that can only display sRGB. Duh!

Color profiles of photo images should be "converted" and also it is important to note that conversions from a large color space to a smaller one are non-linear and out of gamut colors are clipped to the nearest in-gamut neighbor. This means that the reverse conversion can't restore clipped colors back to their previous values.

 

[Steve Worcester]

Color profiles of photo images should be "converted" and also it is important to note that conversions from a large color space to a smaller one are non-linear and out of gamut colors are clipped to the nearest in-gamut neighbor. This means that the reverse conversion can't restore clipped colors back to their previous values.

On this subject I am admittedly non-technical. But knowing that a RAW file posses the amount of color that the camera sensor is capable of gathering, say 16 bit (although I think 14 is what my camera can do, but the math was easier in 16 bit).

16 bit is 65536 colors, and with my 18MP Canon can take a photo of 5184 x 3456 or 17,915,904 pixels. Far less than the color space.

Is the difference between them what spectrum of color they can represent?

I don't buy his special software needed argument, many cameras today will shoot in either and most decent photo software , even the RAW converters that come with the cameras, can use either. And his arguments were too subjective.

 

[Bill Boehme]

On this subject I am admittedly non-technical. But knowing that a RAW file posses the amount of color that the camera sensor is capable of gathering, say 16 bit (although I think 14 is what my camera can do, but the math was easier in 16 bit).

16 bit is 65536 colors, and with my 18MP Canon can take a photo of 5184 x 3456 or 17,915,904 pixels. Far less than the color space.

Is the difference between them what spectrum of color they can represent?

I don't buy his special software needed argument, many cameras today will shoot in either and most decent photo software , even the RAW converters that come with the cameras, can use either. And his arguments were too subjective.

Actually the bit depth doesn't have anything to do with the gamut of colors that can be captured by the camera. The bit depth determines the "fineness" of incremental brightness steps. If we were to compare the output of a 10-bit camera to a 14-bit camera where everything else was equal, they would both capture the same maximum and minimum brightness levels (i.e., the ISO sensitivity would be the same) and the color gamuts would be equal, however the difference would be in the resolution of discrete steps in brightness. This becomes important in the darkest parts of a captured image because a sufficient number of incremental brightness levels are necessary in order to reasonably resolve image details. A practical minimum exposure zone is reached (if you are familiar with the "zone" system of exposure developed by Ansel Adams then this is easier to visualize) when there are insufficient levels of luminance to resolve details. Therefore, the bit depth is the main factor that accounts for the possible dynamic range of a digital camera.

"Number of colors" is most likely the brainchild of some depraved marketing type and doesn't convey any information about what is really going on ... not to mention that it is an outright lie. The description is most often used with display devices such as computer monitors to intentionally mislead consumers with its implication of a rich color gamut. The thing that determines the color gamut of a device (camera, scanner, display, or printer) are the color filters (camera sensor, scanner, or LCD display), phosphors (CRT display), or inks (printer) used by these devices. Capture devices such as digital SLR cameras do not actually have a defined color gamut because unlike other devices, cameras do not operate with a fixed illuminant. It turns out that DSLR cameras have the ability to capture colors within a gamut that is larger than even the huge ProPhotoRGB color space. The catch, however, is that for any given situation, the gamut of available output colors is dependent upon the light source du jour. If the light source being used has a wimpy spectral content, then an image with wimpy colors will be the result. Therefore, two things determine the gamut of colors actually captured by a digital camera:

1. the red, blue, and green filters on individual photodiodes on the sensor and ...
2. the light source

BTW, the pixel dimensions of the images produced by your camera has nothing to do with either the color gamut nor the bit depth. Also, the 14- bit per channel image data gets written into 16-bit words, but it is still 14 bits of sensor data per channel. Another bit of trivia: digital cameras have only one capture mode -- RAW. JPG images are just the product of processing these RAW files in-camera with some predetermined conditions applied during the conversion.

 

[Bill Boehme]

Bill,
I just checked Color Space in my shooting menu and there are two choices:

sRGB and Adobe RGB

The camera has always been set on sRGB. I wonder if your 'puter is detecting something from iPhoto. In the iPhoto preferences under importing there is a choice to embed ColorSync profile. This option is enabled as the default.

OK, that makes sense. What has happened is that iPhoto is converting your image profiles from sRGB to something else. ColorSync is an Apple color management module (CMM) and if I am not mistaken there is also a color profile (or possibly group of profiles) under that name or something similar. Anyway, what I saw on my computer was the image profile that was embedded within the file when I opened it in Adobe Bridge (a utility program that integrates all of the various Adobe applications). For any image has a color profile, it will be in the file metadata (part of the file housekeeping data before the actual image data) that tells applications like Photoshop useful information about the image.

Apparently, it seems that you may have ColorSync set up as the CMM and possibly as the working space for iPhoto on your computer. It is not necessary to convert the image profile to ColorSync from whatever profile the camera had assigned to the image, but neither is it a bad thing to do so. The important thing, however, for any of your images that you plan to later post on the web is to convert them to sRGB before they are saved. Some programs may do this automatically if you do a "Save for the web", but if you are not sure about the software that you are using, it would be best to explicitly do this and eliminate any doubt.

I used AdobeRGB as the working space for images, but typically I do not convert image profiles to AdobeRGB even though Photoshop asks me every time if I would like to do so. For images that I plan to print, I eventually convert them to AdobeRGB before they are saved. For images whose destination is the web, I convert them to sRGB. Since I mainly shoot images in RAW which does not have an associated color profile, I initially process them in the largest color profile that is available in Photoshop -- ProPhotoRGB.

One thing that KR said that is valid is to stick with sRGB if you either are not familiar with or decide not to use color management throughout your image processing workflow.

 

[Robert Manning]

Thanks Bill.

I have a question.

These images which I uploaded here of my black oak bowl appear to have a perfectly neutral gray background on my laptop. Is everyone else here seeing my background with no color cast?

I also see John's photos in this thread as very slightly green, which he mentioned in his first post. Is everyone seeing those as we are?

 

[Bill Boehme]

Thanks Bill.

I have a question.

These images which I uploaded here of my black oak bowl appear to have a perfectly neutral gray background on my laptop. Is everyone else here seeing my background with no color cast?

I also see John's photos in this thread as very slightly green, which he mentioned in his first post. Is everyone seeing those as we are?

The background in your image number 1410 is slightly closer to neutral gray than it is in image 1408. However, it is plenty close enough to neutral for all practical purposes. I have attached a copy of your image 1410 where I did some color sampling so that you can see the results. The measurement numbers across the top correspond to the numbered sample points. Each sample point consists of an average reading from an area of 5 X 5 image pixels.



Whenever an object that has any color is placed on a pure neutral background, it is going to scatter light having the same color as the object. This is essentially the same as shining a colored light onto the neutral background. You can see that the color of the sample points on the background near the bottom of the bowl have picked up some color from the bowl. There are some other points that are not picking up as much reflected light from the bowl and the background is closer to truly neutral. Of course, none of this is a problem because it is perfectly natural and what we would expect to see. In fact, things would look a bit odd if there were not any blending of colors from objects in close proximity.

I do not trust my Flotone backgrounds enough to use them as a color reference except in cases where I forgot to bring my white balance reference card with me. I think that the Flotone background has a hint of blue in the gray. Of course, you can force it to be a neutral reference by creating custom white balance in which case everything will have a very slight color bias from what it "truly" should be, but the difference is really picking at nits and nothing to get excited about.

So to be technically nit-picky, neither your background nor its photo are not perfectly neutral, but neither is any other background. For all reasonable and practical purposes, you can say that it is a neutral background (without the "perfectly"). Engineers tend to shy away from using absolutes like exactly and perfectly because they don't leave any wiggle room for the uncertainty inherent in measurements.

 

[john lucas]

Robert They appear quite neutral on my work computer. I don't have my new home computer set up yet but don't have monitor calibration software for it yet either.

 

[Robert Manning]

That's a nice screen shot, Bill. I do notice a very slight yellow cast in the bowl compared to my original uploaded image.

In your screen shot, sample #7 indicates:

R 102
G 102
B 102

I'm assuming this means equal amounts of Red, Green and Blue light.

Would this make sample #7 neutral in theory?



In addition, I might as well mention how I set the white balance. I usually measure the white balance by the light reflected off the white portion of my graduated background. This means that I zoom-in and take a close-up picture of the white area after setting the camera to receive this information in the PRE mode. When I measure white balance, I use the same lighting set up I use for the shot except the bowl is not there to reflect unwanted colors of light.

 

[Bill Boehme]

Yes, a color is neutral if R = G = B. Pure black is when R, G, and B are each equal to 0. White is when they each equal 255. Middle gray is 128.

Your Flotone graduated background is neutral because you have defined it to be so, however, it would still be very close to neutral even if your reference for setting the camera white balance were a calibrated reference card.

Just for grins, try using a sheet of plain copier paper for your white balance reference. Make sure that it is not inkjet paper because that type of paper often contains UV brighteners, especially if it says something like "Bright White Inkjet Paper" on the package. The plain cheap copier paper is surprisingly accurate for setting white balance and it would be worth comparing to the Flotone background. I have used a WhiBal card and an x-rite white balance reference as well as a sheet of copier paper and they all indicate a very slight blue bias in my Flotone background, but not anything noticeable to the eye. Besides, when anything is placed on the background, it will lead to localized color shifts in the background.

 

[Bill Boehme]

I forgot to mention that I am not too surprised that the color of the image looks a bit different to you after making a round trip from your computer to the web to my computer back to the web and then back to your computer. At least part of the reason is that the image on the web did not have an EXIF color profile. I made a "best guess" on assigning a color profile after trying out several options. Next, I "saved for the web" which is likely to introduce some additional color shift. The version that I posted also looked to me like it ws a bit more yellow than the original, but I did not really worry about the difference since the intent was only to answer your question about the background being neutral.

 

[Robert Manning]

Hi Bill,

Does 255 equate to 2.55 density on a densitometer?

 

[AlanZ]

255 has no relationship to densitometry.

In html, any given pixel primarly color has a value of 0 to 255 (hex 00 to FF)
The color of any given pixel is expressed by its primarly RBG value (Red, Green, Blue)

So,
255, 0, 0 is pure red
0, 255, 0 is pure blue
0, 0, 255 is pure green
255, 255, 0 is pure yellow


255, 255, 255 is white
128, 128, 128 is middle grey
0, 0, 0 is black

Make sense?

http://www.w3schools.com/html/html_colors.asp

 

[Bill Boehme]

Hi Bill,

Does 255 equate to 2.55 density on a densitometer?

255 has no relationship to densitometry.

In html, any given pixel primarly color has a value of 0 to 255 (hex 00 to FF)
The color of any given pixel is expressed by its primarly RBG value (Red, Green, Blue)

So,
255, 0, 0 is pure red
0, 255, 0 is pure blue
0, 0, 255 is pure green
255, 255, 0 is pure yellow


255, 255, 255 is white
128, 128, 128 is middle grey
0, 0, 0 is black

Make sense?

http://www.w3schools.com/html/html_colors.asp

Robert, Alan is correct about what the RGB numbers mean, but there is one minor inadvertent error caused by the somewhat misleading article -- it has nothing to do with HTML (hypertext markup language) which is a text formatting language that has been adopted as a standard for formatting text layout on web pages. One of its main features is linking images and text and connecting to other web pages. The author of the article is confusing two unrelated things. There was a set of "web safe" colors, but that is basically ancient history and isn't related to HTML, anyway.

Back in the early days of the web when computer processors were only 8 or 16 bits and web images were GIF format (a format developed by CompuServe), there was a limited set of colors that could be recognized by web browsers. A GIF image could only display 256 discrete colors because the data packets that computers used consisted of 8-bit bytes (and a 16-bit "word" consisted of two 8-bit bytes). In binary integer arithmetic, an 8-bit byte could have a value from 0 to 255 (denoted as 00 to FF in hexadecimal). A 16-bit word could have an integer value between 0 and 65535 (or 0000 to FFFF in hexadecimal notation).

Regarding 16 million colors, that is another fantasy. While it would be possible for the computer to send 16,777,216 different color values to the display, only a small fraction of those values could actually be displayed because of the rather severe limitation imposed by the color phosphors (CRT) or color filters (LCD). Even my wide gamut display doesn't come anywhere close to being able to display all of those discrete color values.

Here is a brief Wikipedia article about densiometry as it pertains to photographic images.

http://en.wikipedia.org/wiki/Densitometry

One is most likely to encounter references to it if scanning photographic images, especially transparencies. If you have a scanner, you will probably see references to its capability to record a range of image density. There is also densiometry in the medical field that relates to measuring bone density.

 

[mfoster]

profiles

OK,
You guys are a little over my head, but you now have me wondering about my color profile choices. I need to check my camera to see if I have options there, and what profile they assign when storing jpeg's. I do use iPhoto for storing all of my photos, yet export them to Photoshop for editing. I have the working space set for sRGB there and it always prompts me to convert to the working space profile when editing out of iPhoto. The iPhoto settings are to embed the color profile when importing. Am I losing data/color info. with these settings? Any help would really be appreciated.

Mike

 

[john lucas]

I had time to do a test on lamp warm up times yesterday. Both the 45 and 70 watt lamps need about 30 to 45 seconds to reach the stable exposure and color temperature. I checked them after 30 seconds, 1 minute, 5, 10 and 15. They stayed stable after a minute. I then turned them off for a minute and turned them back on. Did this several times because I though you might do this occasionally during shooting. They stayed stable. After cooling down for 15 minutes it did take the usual 30 to 45 seconds to again reach the optimum color.
The 45 watt lamp reads really close to 5500. The 70 still reads close to 6000. I'm going to buy a couple more of the 45's to see if I can make a really inexpensive set up using cheap store bought reflectors and the 45 watt lights. I think it will work pretty well with good color accuracy but you will have to shoot in a darkened room. They claim these are equivalent to about 200 watts but in my tests they actually come closer to about 45 watts when compared to standard household incandescent lights.
My goal of course is to create an easy to use set up for you average woodturner. Since these things are daylight balance or at least close if you use a camera set on full auto you should get closer to a decent photo.
I also want to find a little more sophisticated set up for the serious photographers and think the 2 lights I have now will do that with a little modification. I'm working on designing some barn doors for the reflector light and may build a grid for the soft box light. Then you will have a lot more control.
I hope to have the basic system put together by Monday and then I will start shooting some videos on photographing your work. My boss got my MAC computer running yesterday and it has Imovie so maybe I will finally be able to produce some videos and do it on a more timely basis.

 

[Bill Boehme]

OK,
You guys are a little over my head, but you now have me wondering about my color profile choices. I need to check my camera to see if I have options there, and what profile they assign when storing jpeg's. I do use iPhoto for storing all of my photos, yet export them to Photoshop for editing. I have the working space set for sRGB there and it always prompts me to convert to the working space profile when editing out of iPhoto. The iPhoto settings are to embed the color profile when importing. Am I losing data/color info. with these settings? Any help would really be appreciated.

Mike

The recommendation for anyone who is not technically up to snuff on all the things that need to be done to have a color managed work flow is to stick with sRGB on everything -- camera color profile, software working space, output file color profile, etc. The other recommendation is to simply turn off color management on the software.

While it is OK to start off with a color profile that has a large gamut of colors (such as AdobeRGB) and then later convert the profile to sRGB, it does not work going the other way. For all practical purposes, sRGB is fine because the average monitor can't display much more than sRGB anyway and most printers can't print much more than sRGB.

 

[Bill Boehme]

I had time to do a test on lamp warm up times yesterday. Both the 45 and 70 watt lamps need about 30 to 45 seconds to reach the stable exposure and color temperature. I checked them after 30 seconds, 1 minute, 5, 10 and 15. They stayed stable after a minute. I then turned them off for a minute and turned them back on. Did this several times because I though you might do this occasionally during shooting. They stayed stable. After cooling down for 15 minutes it did take the usual 30 to 45 seconds to again reach the optimum color.
The 45 watt lamp reads really close to 5500. The 70 still reads close to 6000. I'm going to buy a couple more of the 45's to see if I can make a really inexpensive set up using cheap store bought reflectors and the 45 watt lights. I think it will work pretty well with good color accuracy but you will have to shoot in a darkened room. They claim these are equivalent to about 200 watts but in my tests they actually come closer to about 45 watts when compared to standard household incandescent lights.
My goal of course is to create an easy to use set up for you average woodturner. Since these things are daylight balance or at least close if you use a camera set on full auto you should get closer to a decent photo.
I also want to find a little more sophisticated set up for the serious photographers and think the 2 lights I have now will do that with a little modification. I'm working on designing some barn doors for the reflector light and may build a grid for the soft box light. Then you will have a lot more control.
I hope to have the basic system put together by Monday and then I will start shooting some videos on photographing your work. My boss got my MAC computer running yesterday and it has Imovie so maybe I will finally be able to produce some videos and do it on a more timely basis.

Thanks so much for all of the great work that you are doing, John. I am very interested in seeing your videos.

Since my current camera can shoot full 1080p HD movies, I considered getting the Adobe Creative Suite Master Collection which included Premier Pro, but the price tag was much too rich for my blood.

 

[Robert Manning]

Hi John,

What device are you using to measure the Kelvin and intensity of your lamps?

Bill,

When would one use a color gamut other than sRGB for color photography?

 

[john lucas]

I'm using Minolta color temperature meter and Minolta Flash meter that reads ambient light.
I did a test on one of the cheap departments store 35watt bulbs this morning. It said it was equal to 100 watts. It took about 2 minutes to warm up and get bright but it was exactly the same brightness as my 100 watt incandescent. Now why my expensive photo lamps don't measure that bright I don't know.

 

[Bill Boehme]

Bill,

When would one use a color gamut other than sRGB for color photography

Mainly, a larger color space would be used if you have a color printer that is capable of reproducing a wider range of colors than what sRGB contains. However, this also requires your equipment to be profiled to have a color managed system. For the printer this entails creating a profile for each combination of inks and paper. I stick with Canon ink and use Ilford, Red River, and sometimes Canon paper. Also a different profile is needed for each brand of paper depending on type of finish such as glossy, satin, or matte. The average desktop inkjet printer that uses CMYK inks (cyan, magenta, yellow, and black) can't completely reproduce all of the colors in the sRGB color space. I have a Canon i9900 that uses eight dye based ink colors and does a respectable job of reproducing most of the colors within the AdobeRGB color space. For my "hero" images, I will use AdobeRGB or ProPhotoRGB for my images. For the ones that will be displayed on my web gallery pages I use sRGB. My printer is considered "outdated" now and some of the newer ones use the new micro-pigment inks that have greater longevity than dyes. Also, some of them have ten or even twelve different colors, however most of the additional colors are various types of black and gray.

.... Now why my expensive photo lamps don't measure that bright I don't know.

I wonder if it could be the portions of the spectrum being sampled by the sensors. How bright do the fluorescent lights appear to be visually when compared to incandescent lights? Don't look at the bulbs, but look at the subject being illuminated. Something else to consider is that while one f-stop in brightness doesn't visually appear to be a very large change when viewing already bright objects, the difference in light energy is a factor of two. For example, a brightly lit room that has a fixture containing three 100 watt bulbs would appear brighter if a second fixture containing three 100 watt bulbs were added, but it would not appear to be twice as bright.

 

[john lucas]

Bill it might not appear to be twice as bright but it would be. I do a lot of shooting where we use 2 lights to double our power or increase the exposure by 1 stop over 1 light. It takes 4 lights to double it again. I measured the lights with my minolta meter from 8 feet away using an white dome to read incendent light.

 

[Bill Boehme]

Since you are measuring incident light, the design of the reflector would have a significant effect on how the light is directed towards the subject. It might be spread over a wider angle or have a different fall off than the incandescent lighting. Of course, with photo lights you only care about the light on the subject. Stray light from the source doesn't serve any useful purpose.

 

[john lucas]

Very true, that's why I did the test in a socket with no reflector, in a dark room with the meter mounted on a tripod 8 feet away.
I spent the better part of my free time last week on the computer trying to find cheap reflectors for the FLD's to keep the cost down on the over all lighting. I finally found some and ordered them. They should be in early next week. I've spent way too much money on this endeavor but I'll have fun with it and hopefully it well help someone get better photos to share or to enter shows.
I'm going to put together several photography video's. One will be the simplest least expensive way to go. Then next will include adding slightly more powerful lighting with the softbox and reflector light. Then I may try one for really glossy pieces although the PDF I put together is probably more useful for this because it's an involved topic that takes time to absorb. I may do one that is just tricks and tips for solving lighting problems. Most of the problem with lighting your own work is problem solving. Hopefully some of the tricks will help (some of which are just lighting theory explained a little easier)

 

[Robert Manning]

John,

These CFLs are spring-like in their design. This is very different from the single filament inside a globe incandescent. I wonder if the top coil might actually shade the lower coils of the CFL causing a lower reading.

 

[john lucas]

I think that is possible. I may be able to try the same test in my small reflector. The problem is the bulbs extend out differently which would mean the reflector might not be as efficient with one lamp vs the other. Still it won't take but a minute to do. My new lamps I ordered come with reflectors. They are still 45 watt. It will be interesting to see if the reflectors designed for the lamps are more efficient.

 

[Bill Boehme]

John,

These CFLs are spring-like in their design. This is very different from the single filament inside a globe incandescent. I wonder if the top coil might actually shade the lower coils of the CFL causing a lower reading.

That is exactly what I was thinking. Most of the light from a CFL may be spread laterally and not straight out the top. An incandescent light is probably much more omnidirectional. It would be worthwhile to get readings from various directions to get an idea of the radiation pattern.

 

[Robert Manning]

I visually inspected a CFL and without instrumentation, I found it was brightest near a forty-five degree angle.