Hey everyone,

Been following this page for a few months now. I've designed my PJ in my head and partially on paper. I have a very limited building window, as I am moving out and will lose use of my dad's power tools

Anyways, I am in the sourcing part of my PJ, and am looking for lighting equipment. I want to go with the M59 coil and cap ballast, since it is far cheaper, and i'm on a tight budget.

However, looking at the s51 HPS bulb being sold in the LL store, all the M59 bulbs have a much lower CRI. How important is the CRI? It seems pretty important to me, since I want a crisp and vibrant image. However, I have no experience with any of this...

Also, regarding color temp. Based on what I've read, anywhere from 4000-5500 seems OK. Am I correct in this? What is the boundary of acceptable color temp for good projection? Also is there a specific sweet spot?

Finally, has anyone found any m59 bulbs with a higher CRI than 65, becasue I've been searching all over the net for two days with little luck (I found one 70).

Thanks guys! I'm looking forward to getting this project underway ASAP!

My CRI is 65 and the colors look good to me. The only time I see a slight difference is when I put my TV next to the projector and directly compare colors. Even then the difference is only minimal. A good experiment for you to try is to go to best buy or Sam's Club or any other store with a lot of TVs on and compare there colors to each other. What I found was that the the color variance among commercial TVs were much greater than the difference between my projector and my TV at home. So the fact that my projector had a slightly different shade here and there than my Tv did not mean anything, since any other brand TV would show the same result when directly compared.

I would consider CRI the least important parameter in the lighting setup. I would recommend going with a pulse start bulb since it is essentially the same price and is brighter. I would also pay close attention to the physical size of the bulb and the distance to center gas packet of the bulb. Many people (including myself) don't realize that these bulbs can be overly huge and disproportionate in size if they pick the wrong formfactor.

CRI is totally useless to us in our PJs ....

The CRI rating reflects how things look under the light ..... For example a humans face under a MH bulb would be discolored naturally due to the color emmitted from a bulb, a bulb with a higher CRI will be closer to a natural look for objects under the light ....

Since nothing is under the light from our bulb, and the light passes through the LCD than the CRI doesnt matter to us.

Im sure the insides of your projector will look more natural with a higher CRI bulb, but ..... that doesnt matter ....

To sum up what I just said ...... do not pay any attention to the CRI when choosing your bulb ....

Sweet!

That's what I like to hear. One less thing to worry about.

If you want to see my designs, I just started my PLOG, which is where all future questions and such will be.

Thanks!

well, the lcd is the light hitting element. A 90 CRI lamp will show more real image on the LCD than the 64 CRI one. But I wouldn´t say it is the most important spec we need to check... take care of the color temp, this is more importnt for us.

I wouldn't say that CRI isn't important all other things near equal I'd consider higher CRI better than lower. CRI isn't a truely meaningful index, but it is an indication of how equal the Red, green and blue brightness are. Some people like warmer (lower CCT) and others like cooler (higher CCT). HPS bulbs have CRI numbers of 20-30 which is bad, 65 isn't bad and if I could find good brightness with a high CRI I'd jump on it. But brightness and CRI seem to be opposites, high CRI bulbs tend to be less bright than low/mid CRI bulbs.

I wouldnt notice it in our PJs .... CRI reflects how things appear under the lamp directly .....

retails stores that need to show off things on display closer to natural sunlight use high CRI lamps. clothing stores, car show rooms ect will want higher CRI lamps because they want to mimic natural light as best as possible

Since the light passes through the LCD the CRI term is completly and totally moot and irrelevant in every way for our Projectors.

Higher CRIs are typically associated with the with the whiter (mid color temp) bulbs ... I.E. the S400DD has a higher CRI than the EYE and PS lamps .... This is because the lamp falls into a whiter color temp, therefor things under the lamp directly will appear more natural.

The light passes through filters on the LCD so you end up with a band of Red, Green and Blue if these aren't ballanced it will make the image look colored. CRI isn't the best meassure of a balanced spectrum but its all we have so should atleast consider that a higher CRI is better. I would agree that brightness should be our first consideration but if the bulb is heavily red or yellow or blue then that will effect the IQ. So I can't agree that CRI is moot, it is a factor, looking at the spectrium is a better way to eveluate a bulb but this is avilable less than 30% of the time.

are you sure the a high CRI is a perfect balanced spectrum of RGB?? ..... For example a 4000K bulb that may have a high CRI (if they exist) ...... that wouldnt be a balanced RGB ....

I agree with what you said about the RGB balance, but I think the proper balance of RGB falls into the color temp and not the CRI ....

the definition from ventures website, says the ability of a source to render color relative to 100 .... Not a very good description ... but what I understand of it is ...... how good the color of the bulb is, in retrospect to its rated color temp .....

for example a bulb that has a color temp of 4000K ... could have a CRI of lets say 20 ... when said bulb is lit it could measure a color temp of 3800K or something .... while another 4000K temp bulb that has a CRI of 95 .... may measure out to be 4050K or something like that ..... I understood it to be, the lamps ability to render color closer to its rated spec ...... I could be wrong though ....

CRI isnt all that important since the LCD filters only let through narrow bands of colour (Red, Green and Blue), which are mainly detirmined by colour temperature, not CRI.

I'm not sure how CRI is calculated but a bulb with a few spectral spikes that generates "white" light can give a good color temp but if you look at bulbs with a high CRI they have a more even and less spiky spectrium. This is not to say that CRI is measuring flatness of spectrum but bulbs with higher CRIs tend to have a more even spectrum.

From my looking at MH bulbs it seems that the cheaper bulbs that just provide light have color temps of 3K, better bulbs have color temps of 4K as not to look too yellow, but the highest quality bulbs to make clothing, food, jewelry etc.. look better have color temps of 4500-6500K and have more even spectra as that appears better to the eye. So higher color temps and CRI often go together because those bulbs are designed for color reproduction rather than the cheapest way to light a warehouse. I don't think that CRI is the best indication of evenness of spectrum but all we generally get in specs is color temp and CRI if they do provide a spectrum ignore CRI. So I think you could have two bulbs with 4K color temps but one with a lower CRI and one with a higher and I would expect a more even spectrum on the higher CRI.

CRI = 70
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CRI = 90
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CRI = 19 (HPS)
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yes, i agree with you pagerman.

"Since the light passes through the LCD the CRI term is completly and totally moot and irrelevant in every way for our Projectors"

this is wrong. Although I believe it is not very important a very high CRI, it is more inportant and relevant the color temp value.

example; Tungstene lamps have very high CRI, but the color temp is too warm for us.