CRI, 75 vs 85 vs 90 vs 95 ?

[Gints Klimanis]

Hi,

Will I be able to see a huge difference between 75 and 85 CRI ?
How about between 75 and 90 CRI ?

I'm thinking about upgrading some older 75 CRI, 3500K , T8 48" fluorescent bulbs. I'm able to get some 85 CRI replacements
for about $3.35 / bulb, whereas the my existing bulbs at 75 CRI go for about $1.50 . Is the extra cost worth it ? I can also get 90 CRI for about $10 each . I need 25-30 bulbs.

All pricing info from :

http://www.goodmart.com/products/bulb_fluorescent_tube_t8_octron_4_foot.htm

The True Match (kino flo) and MovieTone bulbs are quite expensive and offer 95 CRI. The MovieTone bulbs cost around $16/bulb, single quantity.

Thanks for your opinions,

Gints

[John Jackman]

Go for the highest you can afford (that's always a factor). I would go for the 90 CRI, but the 85 will be substantially better than the cheapies. The cheap ones lack spectrum and have a strong green spike so people look really sickly.

You don't need to get the really expensive ones.

[Gints Klimanis]

Thank you, Mr. Jackman. I learned a LOT from your book on lighting for digital video.

[Mark Sasahara]

Funny, I was just telling someone about GE's Cinema Lamps. CRI 95 for the 3200, 96 for the 5500K. You would do best to buy a case, if you need 20-30. They come in 30 per case, but some come 15 per case double check. There may be other brands, Osram, etc. that have similar offerings. The highest CRI that you can afford is best.

[Gints Klimanis]

Thanks for the tip. Here is the product brochure link. I Googled
for a source, but I haven't found anything other than press releases.

http://www.gelighting.com/na/business_lighting/education_resources/literature_library/catalogs/lamp_catalog/downloads/cat_stage_studio.pdf

[Gints Klimanis]

Also, I'm looking for bulbs in the 5400-5600K range, 30W, T8.
The best deal I can find are the 5000K Sylvania Octrons with a CRI of 90. A case of 30 sells for $150 .

The GE Cinema lamps look great, but I can't find an on-line source.
Given the buzz, I'm hoping they are not too expensive.

[Mark Sasahara]

You'll also want to be sure that you are using high frequency electronic ballasts. Check with GE, or the other manufacturers to see what they suggest.

CRI 90 or more is always better.

The Sylvania Design 50 tubes are high CRI, but they still have a pretty nasty green spike. The new GE Cinema tubes apparently don't. I have not used them, so I am going by what GE says.

[Gints Klimanis]

Here's another that's 96 CRI:

http://www.naturallighting.com/show_product.cfm?&product_id=402

Studio Supreme Day Light PL 55 watt
Studio Supreme Day Light PL 55 watt. 5500K, 96 CRI (no green phosphor). Similar to Kino Flo PL 55 watt day light. This lamp will operate with 40 to 55 watt PL type ballasts.

[Carlos E. Martinez]

Where can I get some information on CRI standards? What does the CRI number exactly mean? Light intensity, light spectrum, color temperature?


Carlos

[Mark Sasahara]

This is from GE's site:
http://www.gelighting.com/na/busines..._rendering.htm

This is my highly simplified explanation:
CRI-Color Rendering Index-CRI is a mathematical way to compare how eight specific colors appear under different light sources with the CRI value of 100 being ideal. However, there are two reference sources: daylight and incadescent lamps, both of which are considered to be nearly perfect. Interestingly, I cannot find anyone saying exactly what value they have but we'll say for argument's sake that it's 100. Note that both references have their deficiencies: daylight is strong in blue, so it suffers from weak reds and incandescent is strong in red and has weak blues. They aren't perfect, but that's the standard we have. You can also do a search for "color rendering index".

[Carlos E. Martinez]

<<<-- Originally posted by Mark Sasahara : This is from GE's site:
http://www.gelighting.com/na/busines..._rendering.htm
-->>>

So it was color spectrum after all, which is how we called it in film.

Color temperature I am quite familiar about, as in film you don't have a white balance button. You have to correct on camera, on the lights or on the lab. Usually on the three of them.

Until recently fluorescents were a serious problem in film shooting, because you got flicker. But modern fluos are high-frequency so you can use them on 50 and 60Hz countries, with almost any shutter angle you want, and get away with it.

The problem with fluorescents was that their light spectrum was quite nonlinear, which made it hard to filter them. When you did you cut a lot of their light, which was not that great either. A tough one that was.


Carlos

[Mark Sasahara]

That's why I love Kino Flo and that's why Frieder Hochheim is probably a millionare. One fixure and I can swap out the tubes with tungsten or daylight, or mix 'em up.

Back in the 80's I tried playing around with fluorescents, but there wasn't really anything to use, Design 50's. Vita-Lites came along and they're okay, but still a bit green.

The Kino Flo 4Bank System is great. I own some and use them a lot. I use them "nude" and tape them to walls or ceilings. Get their catalog, it's very informative. The website doesn't have as many on set pix, some of the links seem to be down. http://www.kinoflo.com .

When I was a newspaper photographer, we shot negative and put a Plus Green filter from the Rosco swatch book on our Vivitar 283's and then corrected the green in Photoshop after we scanned them. Before that we shot chromes and had to light everything.

[Carlos E. Martinez]

<<<-- Originally posted by Mark Sasahara : That's why I love Kino Flo and that's why Frieder Hochheim is probably a millionare. One fixure and I can swap out the tubes with tungsten or daylight, or mix 'em up.

Back in the 80's I tried playing around with fluorescents, but there wasn't really anything to use, Design 50's. Vita-Lites came along and they're okay, but still a bit green.

The Kino Flo 4Bank System is great. I own some and use them a lot. I use them "nude" and tape them to walls or ceilings. Get their catalog, it's very informative. The website doesn't have as many on set pix, some of the links seem to be down. http://www.kinoflo.com .

When I was a newspaper photographer, we shot negative and put a Plus Green filter from the Rosco swatch book on our Vivitar 283's and then corrected the green in Photoshop after we scanned them. Before that we shot chromes and had to light everything. -->>>


The problem with Kino Flo products is that they are too expensive.

It depends on what you are planning to do, but for documentaries something like the Lowel Caselite or Desisti flo kit, using that 55w U-shaped bulb, look very attractive. There are 55w bulbs that are more reasonably priced and are very close in spectrum to the higher priced flos. They need little correction, output a lot and are flicker-less.

As I commented on other thread here, I am looking for ways to DIY a system for myself or find some lower priced alternatives. Down here in South America, where I live, there seem to be some locally made heads, using 2 and 4 bulbs, that might do the job and cost less.

BTW: do you know if the 55w U-shaped lamps all use the same socket standard? AHSupply sells a kit, used in aquariums, that uses a 55w lamp that needs a 2G11 base (four pins in a row). AH claims is unique to their lamps, but I think they are wrong. Their 4 lamp kit has excellent individual reflectors that might make a very good lamp head.

Carlos


Carlos

[Mark Sasahara]

That's a 2G11 compact fluorescent mount (four pins in a row). 2G11 is an industry standard mount. GE calls their tubes "Biax", Osram's are "Dulux". The tube shape is T-55. Other manufacturers have other names.

Below is some info on the new GE Cinema Lamps. I have written about them and I will buy some soon and check them out. Apparently the 3200K tubes have a CRI of 95 and the 5500K tubes have a CRI of 96. Buy some bases and ballasts go into your basement or garage and have a DIY party.

GE's (Fabulous) "Showbiz" brochure.
http://www.gelighting.com/na/busines..._covrguard.pdf

Stage and Studio Catalog. Info on Pages: 6-5, 6-6, listings on P 6-10
http://www.gelighting.com/na/busines...age_studio.pdf

I may try and make my own as well. The Biax are a bit more specular/contrasty and have a slightly higher output than the regular T-12 shape, G-13 medium BiPin tubes.

[Gints Klimanis]

Mark,

Please post a source for a case of these bulbs. I would like
to try to use them in my existing T8 fixtures.

Thanks !