High CRI and its significance

McGizmo

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Some technical problems. Putting yourself where the subject is may not be trivial but probably orienting yourself to the sun as the subject is oriented to the sun might be good enough. But in the case of a 8" dome port with a FishEye lens behind it, you would be hard pressed to cover the field of view with the ExpoDisc external to the housing!! My new D300 and Subal housing do provide quick access to white balance adjustment and I might experiment some with this but I suspect that conditions change to rapidly and not knowing in advance what it is that I am going to shoot or where it might be, relative to me and the sun....
 

Stillphoto

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Don, just bring a titanium light down there...it's gray enough to base a white balance on...or at least get a general baseline lol.
 

yaesumofo

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Some technical problems. Putting yourself where the subject is may not be trivial but probably orienting yourself to the sun as the subject is oriented to the sun might be good enough. But in the case of a 8" dome port with a FishEye lens behind it, you would be hard pressed to cover the field of view with the ExpoDisc external to the housing!! My new D300 and Subal housing do provide quick access to white balance adjustment and I might experiment some with this but I suspect that conditions change to rapidly and not knowing in advance what it is that I am going to shoot or where it might be, relative to me and the sun....



Call me crazy but if you are using Photoshop to do corrections and because it is difficult to white balance under water
a very simple solution might be to take one of those small plastic calibrated color charts down with you.
Then you shoot it under the same lighting conditions that you are shooting your images with.

You have a standard color chart to color the shot to later in photo shop.
You might even be able to create an "action" that gets your images real close maybe even close enough. These calibrated color charts are used often in the Film industry and in stills for the very propose of making a consistent color in the end product regardless of the media or lighting.
A good example of this is the curious case of benjamin buttons. They shot using several different digital cameras as well as different film cameras and stocks. combine this with different lights HMI, Tungsten, daylight, florescent, the film was color corrected PERFECTLY. they were able to MATCH all of these elements. One of the tools which make the process is use of calibrated color charts.

All you need is a small one of these placed in the corner of an image, No need to fill the frame. it is for reference only. Anyway I have to think that shooting a color chart under water has got to be easier than doing an underwater white balance.

As an aside I am seeing more and more references to CRI in lighting equipment literature related to the film industry. It is like they have discovered a new spec...

Until recently most DP's (director of photography) were pretty hazy about what CRI is and how important it is. The introduction of LED lighting and the associated problems has brought it forward as an important specification.
Yaesumofo
 

McGizmo

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Hi Yaesumofo! :wave:

Yeah, I thought about picking up one of the small color checkers to do just what you suggested but candidly, with PhotoShop CS4 I am satisfied with tweaking the color temp and tint in "Camera Raw".

A white card under water is not white anyway. It is typically slightly green or slightly blue/ cyan depending on the depth and water clarity. Unless you are shooting macro, you typically are using a very wide angle lens if not full on fisheye lens. You have already distorted the image relative to what the naked eye sees. When I used to shoot film, the lab that did the processing had their own adjustments they would do to partially compensate for the heavy blue and lack of red and the results were reasonable but not close to what you actually saw, color wise. Now that I am shooting digital and have software that allows me to do my own adjustments and indeed enhancments, that is what I attempt to do. In most cases, I try to get the colors to represent what I saw but in some cases I will attempt to get the colors to what I would have seen had the conditions been pristine. :shrug:

By experimenting with some of the images that do contain a white surface (underside of a ray's wing or the white on a humpback whale) I now have a sense of the corrections required but to render these white surfaces white, in most cases, you dial in so much red that you get some red flares and artifacts elsewhere in the image which detract from the image on one hand and they certainly were not seen at the time the pic was taken.

Historically, the professional UW photographers would bring their own light sources to the shoot and flood the scene as much as possible with artificial, full spectrum light. Stunning images resulted but images you never saw in person!! Red is a common color adapted by much of the underwater creatures because it is a color that is not present in their habitat and as I understand it, many under water creatures don't even have vision in the reds because it is not light encountered down there.

Here is perhaps a good example of color rendering and how it might fit in. I missed out because nobody told me but last year, there was a rare Hawaiian Sea Horse residing outside of the reef I usually swim. It was down at ~ 30' so I would have needed to use scuba to visit it. At any rate, in the weed field it hung out in, it appeared to the naked eye as the same dark and dull color as the weeds. In reality, it was a really pretty red! It was first spotted by divers who had some dive lights with them. With a bright dive light, the Sea Horse would pop right out of the green/brown seaweed. A diver I see at the beach all the time who takes tourists out on dives showed me some of his pictures and I gave him some grief for not telling me about the Sea Horse. In his defense, at the time it was there, He and i would just nod heads at each other as we had never had any dialog.

So I guess the point is that without artificial light of adequate intensity (in the reds), one was likely to miss seeing this fish to start with. If you did happen upon it, would you want a photo of it as it appeared to the naked eye which was a dark non colored animal or would you want a shot showing its bright red as it would appear, say at the surface? I would think the latter.
 

fisk-king

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To the subject of High CRI and its significance, right or wrong, good chef or bad chef, I really wanted to improve on the illumination over my BBQ as the Cree LED's provided more than ample light but the meats and vegetables on the grill were not rendered well in color, IMHO.

To wit:

DSC_0012.jpg


The solid copper bar was milled with a pocket to receive a 3x 083 High Cri MCPCB as well as a piece of half round optic.

I used some really slick Viega copper crimp connectors and a length of copper tubing to complete the fixture. The optic is bedded in a clear UV cure epoxy and the Viega fittings are plumbing fittings so the LEDs are well sealed from the elements:

DSC_0013.jpg


DSC_0014.jpg


I contemplated taking a shot of the color checker on the grill under daylight as well as at night under the Nichias but I couldn't find the motivation energy required. :eek:

The optic is great at concentrating the light on the BBQ and its immediate surrounds.


wow! I was sitting here thinking about tomorrows evening at the grill (mmm, 1" ribeye's
eat.gif
) wondering if a couple of High cri Nichias would be better than these blasted *bug light* incan's that I have. Of course it would
cloud9.gif
:twothumbs

Now I just have to find someone who does this type of work:whistle:
suntan.gif



:D
 
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McGizmo

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Hi guys,
I just received some new info from Nichia and in the presentation were a number of charts and graphs on their High CRI versions as well as a new Moderate CRI grouping/ option to some of their LEDs. I hope they don't mind but I am sharing a couple of the pages below.

First is a bar graph showing how, at least for Nichia, they rate their LED's in regards to the High CRI VS CCT.

CCT-CRI.jpg


The second page I think is quite informative because not only does it show the spectrum of a High CRI LED but it illustrates the break down of the various CRI indexes and shows the colors being indexed. The blue line although not explained on this particular page represents a "typical" white LED.

NichiaLED-CRI-Info.jpg


I find it promising that a number of the pages in their presentation address High CRI and now a Moderate CRI LED. Perhaps they have identified a niche in the lighting market they can focus on or perhaps the industry at large is becoming more focused on color rendering in addition to flux and color temperature considerations.

Now that efficacy has improved to the present levels we enjoy, hopefully we will see more options where the quality of light is addressed even though it be at the expense of quantity of light.

Now these graphs are based on Nichia's product line as far as I can tell and I don't know if their "typical" white LED applies to any significant degree with the LED's of other manufacturers or not.
 

Tally-ho

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I find it promising that a number of the pages in their presentation address High CRI and now a Moderate CRI LED. Perhaps they have identified a niche in the lighting market they can focus on or perhaps the industry at large is becoming more focused on color rendering in addition to flux and color temperature considerations.
There is no niche for high cri in the lighting market because high cri light sources are already widely used (filament bulbs).
I am sure that every LEDs manufacturers would like to know how to make LEDs with high brightness and high cri. Since our birth we get used to high cri lights (sun, filaments) and we all tend to prefer high cri because it provides more informations to our brain through visual perceptions. Well, in fact we prefer high brightness first vs. high cri because it allows to perceive a lot of details that our brain needs to evaluate distances, shapes etc.
High cri give only additionnal details due to better light "quality" (nuances of colors, ...), but details that our brain needs, to interpret the more completely and accurately what we are seeing.

Low/moderate cri light sources are just a compromise when someone has to choose a light source considering brightness and power consumption. Those light sources are widely used in industries or for street lights for example, but if a manufacturer would propose a high cri LEDs alternative to this, he would beat all his competitors.
Manufacturers are improving brightness first because there is no use for very dim lights for general uses.
 
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fyrstormer

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There is no niche for high cri in the lighting market because high cri light sources are already widely used (filament bulbs).
That is a very confident statement. Not terribly accurate, but very confident at least. :rolleyes:

I don't know what the laws in Europe are like, but in the USA, filament bulbs are going to be phased out over the next few years, so there is definitely a market niche for Hi-CRI LEDs.
 

Bullzeyebill

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That is a very confident statement. Not terribly accurate, but very confident at least. :rolleyes:

I don't know what the laws in Europe are like, but in the USA, filament bulbs are going to be phased out over the next few years, so there is definitely a market niche for Hi-CRI LEDs.

They may will be phased out over time but not without some fuss from the public. Not easy to phase out anything in the US.

Bill
 

Tally-ho

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That is a very confident statement. Not terribly accurate, but very confident at least. :rolleyes:

I don't know what the laws in Europe are like, but in the USA, filament bulbs are going to be phased out over the next few years, so there is definitely a market niche for Hi-CRI LEDs.

The actual alternative to filament is compact fluorescent bulb: light that flickering, that needs time to heat up to full power, that has limited cri, that has to be recycled.
People don't like it much...but it is the "only widely available" alternative in stores and supermarkets, so they buy it.

Yes a big part of the world is phasing out filament lights. Think of this market size in term of potential. Market niche ?

There will be a market niche demand for high cri LEDs if their price is way to high compared to fluorescent lights but, if the prices are comparable (I mean "price divided by longevity" is comparable) ...the market demand for high cri LEDs will be huge !

BTW: A couple of years ago, Ikea started to sell a nice little (stand ?) light with Seoul P4 (don't know if it's high cri)

jansjo.png


Yeah i know that ikea will not fulfill the market with this light but it is interesting to see that a mass market manufacturer is taking interest into LEDs.
I bought one about 2 years ago, its LED temp color is too high (cool white) but now it is 3000K.
I will probably mod mine with warm white high cri P4 :D
 
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jellydonut

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That is a very confident statement. Not terribly accurate, but very confident at least. :rolleyes:

I don't know what the laws in Europe are like, but in the USA, filament bulbs are going to be phased out over the next few years, so there is definitely a market niche for Hi-CRI LEDs.
They may will be phased out over time but not without some fuss from the public. Not easy to phase out anything in the US.

Bill

Hello,

The EU has ALREADY banned incandescent bulbs. They are on their way out as we speak and are being replaced by disgusting compact fluorescent bulbs.:barf:

Which means I'm looking for good LED based bulbs that fit in ordinary sockets.;) They make them, of course, but they usually consist of dozens of 5mm white LEDs and that does not inspire any confidence.
 

jellydonut

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My grandparents have one of these bulbs in their bathroom and the light is actually pretty white, not blue or green, and plenty bright. Behind some kind of diffusing screen it would be quite okay. I would of course prefer something more yellow..

On the other hand I suspect if I buy more than one of these bulbs I'll be playing high stakes tint lottery.
 

Kiessling

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Forget it, color temp sucks and i don't know anybody who gave it a try that was not disappointed by the very weak light.


I just bought one ... 60 3mm LEDs ... 3000K warm ... they claim 200 lumens. There is not that much light emitted, but for the intended application (bathroom mirror) it is just fine.

I'd guess over time LEDs will surpass the fluorescent bulbs as they suck for more than one reason and as incans will be banned. I hoarded a boatload of them, of course, to bridge the time untill LED is there, especially power-wise.

The light emitted by the modern High-CRI LEDs is rather pleasant and not sickly yellow or blue. I love the McGizmo SunDrop, but to light up my room it would need to grow up a little :D

bernie
 

fyrstormer

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I buy fluorescents online and most of them I like quite well. The trick is to avoid the cheap brands and stick to OSRAM, Westinghouse, etc. I suppose their CRI aren't as good as incandescents, but low color temperatures give me headaches, so for me to use incandescents I have to use 75W or higher in each bulb. Needless to say, switching to fluorescents gives me as much light if not more, at a pleasant "soft white" color temperature, for much less electricity. Since converting almost all the lights in my house to fluorescent, my electric bill has dropped by ~20%. That is significant to me.

I look forward to the day when I can have Hi-CRI LED lighting everywhere in my house, but LEDs require special heat-dissipating fixtures that are not well-suited to retrofitting into incandescent sockets, so I'm going to wait until the market offers a reasonable number of PnP purpose-made LED fixtures for me to choose from.

That's a good quote in your signature, Kiessling. I just noticed it now.
 
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