Re: Lighting question

From: Juerg Steiger (
Date: Mon Dec 20 1999 - 01:09:17 PST

Date: Mon, 20 Dec 1999 11:09:17 +0200
From: Juerg Steiger <>
Message-Id: <aabcdefg4205$foo@default>
Subject: Re: Lighting question

Hi Andrew

>Has anyone got any experiences to share with either Metal Halide or
>High Pressure Sodium lighting with CP's?

Plants evolution has developed for millions of years in the sunlight
('daylight') spectrum. It is well kown today that specific parts of the
daylight spectrum are more important than others for specific biological
functions as assimilation, growth, flowering. Therefore many different
light sources were created to emitting spectrum parts which increase
specific biological functions (e.g. FLUORA lamps).

In case of generally poor daylight conditions (within appartements etc.) it
is by far the best to chose a light source which emitts a daylight-like
spectrum, of which the market offers two product groups:

(1) Light sources giving daylight-like impression based on a
discontinuous spectrum with sharp single peaks as e.g. lamps of the
type Lumilux color 11, Metal Halide lamps of the types HQL de Luxe,
HQL-R de Luxe, HWL-R etc.

(2) Light sources which emitt a more continuous daylight-like spectrum.
The physically most daylight-like spectrum of all artificial light sources
are emitted by metal halide lamps of t type 'Powerstar HQI-TS...NDL' and
'Powerstar HQI-TS...D'. (I personally use these lamp types).

See e.g. <www.OSRAM/>

Kind regards Juerg

Juerg F. Steiger M.D.
Institute for Medical Education IAWF
Master of Medical Education Program
University of Bern, Faculty of Medicine
Inselspital 37a
CH-3010 Bern, Switzerland
Phone: +41 (0)31 632 98 87
Fax: +41 (0)31 632 98 71

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