Fluorescent tubes tests

M

max123

Member
Hi Everyone,

Since this forum has been a great source of info, I would like to give something back.
Going through the frustration of choosing the right equipment for a particular job, I decided to conduct some tests.

A little background: I work at McGill University as an Audio/Video Tech. In order to properly light whatever we will be filming around here, I had to get some gear: Too many options, too little detailed info, too many sales pitches.

So, this weekend, I will be conducting some tests to figure out how Fluo fixtures and Bulbs react. Here is a list of what I have. If any manufacturer is around (including Richard / Cool Lights, who seem to be very "Cool" himself :) and would like me to include their stuff in the test, drop me a line / lend me some samples.

1 12' X 20' room, 10' ceiling
1 Panasonic HVX 200
2 500W Tungsten Photo fixtures with umbrellas. I have photoflood bulbs in the white (3200) and blue (5600) kind
1 Kino Flo Diva Lite 400
1 Kino Flo Foto Flo 4X 4'
1 Chinese 6X55W fluo fixture (High Frequency, noise and flicker free)
4 Kino Flo K32 4' tubes for foto flo
6 Kino Flo K29 tubes for the diva lite
5 kino flo K55 tubes for the diva lite
12 Osram Dulux L 3200 tubes (But I think those are actually 2900 ish)
6 Osram Studioline 3200 tubes
1 DSC white / warm card
1 Xrite Color Chart
1 person who can act as a model.
1 9' white background (superior seamless studio paper)

Now, in order to save time, I will shoot using only one setup. Lights at the same distance from the subject, no diffusion, one lens aperture, one zoom setting

The test:

Would you like me to white balance at every tube change, or should we decide upon a "reference" and rate everything else against it?

How far / High do you want the light fixtures to be

Which lens aperture to use, or which exposure should I be reading using the built in spot meter of the camera.

Which zoom setting.

Which Matrix / Gamma / Setting on the HVX?

Anything else...?

Thanks,

Karle
514-398-6114
karle@ego.psych.mcgill.ca
 
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max123 said:
Now, in order to save time, I will shoot using only one setup. Lights at the same distance from the subject, no diffusion, one lens aperture, one zoom setting
Click to expand...

Sounds interesting - there's a problem with your one-setting idea though: your output from each fixture will be different, either radically or subtly. For a meaningful test, I'd think you'd want to at least go for optimum exposure. If you use the same shutter speed throughout, you can change the f-stop for optimum exposure and just note the setting with each test image, which would also give us a decent idea of comparitive light output. (Seeing two similar fixture tests, but one was shot at 2.8 and the other at f8 for instance, would tell us there's several stops difference in output between the two).

If you shoot everything at, say, f5.6, chances are you'll have a lot of blown out shots, a lot of murky shots, and really no useful data.

As for color balance, I'd consider shooting everything at daylight (if these are all daylight tubes). Though it would be nice to see one version daylight, and one white balanced to the specific fixture. That would tell us (A) how well they play with other daylight fixtures or locations, and (B) if there's an improvement "on their own".

I'm not trying to be picky with someone who is volunteering their time so generously, this is just my .02 - with my thanks in advance for testing & sharing! - MC
 
What are you testing for?

How bright the lights are, how even the spread, how energy efficient, how heavy, how robust, how easy to set up, how accurate the color temperature, how well skin tones are rendered, how much optional equipment is needed, etc.

What are your needs? Classroom settings? Video conference, ENG? EFP? lighting sports? narrative, etc.

If you are just going to test for one characteristic, what are you testing for?
 
I want to test for:

Light Output
Light Spread
Color Rendition

I am interested in the direct relationship between a tube / fixture combo and the overall picture quality.

Once the above 3 points are known, it is only a matter of choosing how many / which type of fixtures to get, and how portable we want the rig to be, etc.
 
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I will compare the foto flo 4' to the Diva Lite 400 to see if the 4' really offer a spread / coverage advantage and also to verify the quality of the light.

For my particular needs, I will be using the fixtures to film :

1-subjects running experiments (we are a psychology lab).
2-The Performances of bands playing at the university.
 
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Preliminary test results.

I put the tubes in a Diva lite 400 and put the light 6' away from the color chart (45 degrees to the right, center of light at the same height as the chart.

I white balanced to a DSC white card after each tube change (I let the tubes warm up for 5 minutes, because I noticed that the Studiolines take quite a while to reach full power). I just wanted to get a basic picture in order to get ideas on how to run the real test.

I used the HD norm preset on the HVX 200, and I set the camera to full auto. The marker was aiming right at the pink square for all the tubes. I took the files from the FS-100 and dragged those directly into after effects CS3. I then exported the layers to Photoshop.
The Tubes tested and exposure are written in the file.
you can download the file at:

http://132.206.108.126

username: dvxuser
password: colortest

I will run the test with a human subject this weekend, as I haven't received the Daylight tubes for the foto flo yet.

Please give me your impressions, suggestions, ideas.
 
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