Need some bulb advice

[Chris Strobel]

Hi guys, I've got a 32" light tent, and three light stands with 12" reflectors coming from B&H.The lights come with 500w tungsten bulbs, and I ordered 3 250w tungsten's as well since they were only a few bucks.Now my qustion is concerning Compact Fluorescent bulbs, I found this at full spectrum solutions:

65w Compact Fluorescent Lamp

# Replaces: 300w bulb
# Dimensions: 8 1/2"l x 4 1/8"w
# Wattage: 65 watts
# CRI: 91+
# Kelvin: 5500
# Lumens: 4100
# Life: 8,000 hours [?]
# Not for use with dimmer switches

And this at at the Table Top studio store:

55 Watt Trumpet Top Daylight Balanced Bulb


# 5000k daylight color temperature
# Very high output 3,600 lumens
# 10,000 Hrs. of use
# CRI > 85
# Normally requires 12" or larger reflectors

As well as this also from Table Top:

30 Watt Trumpet Top Bulb

# 5000k daylight color temperature
# Cool
# 10,000 Hrs. of use
# Lumens 2100
# CRI >84

And lastly this from Garvin:

85W, 5500K High-Output Compact Fluorescent Light Bulb

* Watts: 85
* Equiv. Incan. (W): 400
* Operating Voltage: 120
* Style: Spiral
* Lumens: 5,500
* Color Temp: 5500K
* Base Type: E26 MED
* Overall Length: 8-1/2”

Which of these bulbs would be the best route for my setup.I want to shoot florals in my light tent and don't want to fry my orchids with the tungsten lamps.I use 4x5 and 8x10 view cameras with both b&w and chromes, and also have a Canon 20d that I'd like to play with as well.This is my first foray into table top work.Thanks much!
Chris

[Michael S. Briggs]

The first lamp looks better than the second and third. It outputs more lumens so that it will be brighter. It has a color temperature (5500) that will be good for for daylight film. It has a higher Color Rendering Index (CRI), so its light output is a good approximation of a black body spectrum and so the specctrum won't have color casts that are unexpected from the color temperature. The full comparison can't be done for the fourth lamp because the CRI value isn't listed. The fourth has more lumens. The question is color accuracy when you use color film.

[Helen Bach]

As a general rule, anything with a CRI of 90 or over should be OK for photography, but it is difficult to know what is acceptable in a particular case for particular criteria. The CRI is determined from only eight colour samples, all of which are fairly light and not particularly saturated.

As you are doing still-life, I'd be inclined to try the 250 W lamps, or even lower wattage lamps, first. When I do florals in a light tent I use 100 W tungsten lamps with Portra 100T film. The long-ish exposures aren't a problem, and the slightly low colour temperature can be corrected when printing.

Best,
Helen

[Chris Strobel]

Thanks Michael and Helen.I did find the fourth bulb only has a cri of 88 so I ordered three of the first.I already have some lower watt cri 91+ bulbs hangin around so I can play with those too.Guess I have lots of experimenting to do.

Chris