Editing Slide projector (section)

===Light source and collimation===
[[File:Braun Camera-Werk Novamat M 330 - Philips halogen lamp-2203.jpg|thumb|left|[[Philips]] [[halogen lamp]] used in [[Carl Braun Camera-Werk]] Novamat M 330 slide projector]]
An [[incandescent lamp bulb]] is used to generate light, usually specially designed to have a small, bright [[Electrical filament|filament]] to produce a sharp and bright image. For example, the [[Ernst Leitz GmbH|Leitz]] Pradovit RC uses a special 24V 150W quartz lamp, with provision to center it, required for best performance. This projector had provision to reduce lamp power by 20% to double its life (50 hours at full brightness).<ref>{{Cite web|url=http://www.pradoseum.eu/Literatur/pradovit-rc-74.pdf|title=Pradovit RV-74 projector manual|publisher=Leitz|date=September 1972}}</ref>

Light from the bulb is modified from a point source by reflection and passing through condenser lens(es) to generate a [[collimated beam]], which is then directed through the slide. A flat piece of heat-absorbing glass is usually placed in the light path before the slide, to avoid damaging the latter. This glass transmits visible wavelengths but absorbs [[infrared]].<ref name=Kodak-E2>{{cite web |url=https://archive.org/details/kodak-ektagraphic-e-2-slide-projector-manual-1970s/ |title=Kodak Ektagraphic Slide Projector, Model E-2 |publisher=Eastman Kodak |date=May 1975 |access-date=30 August 2024}}</ref>{{rp|10}} Some slide projectors used bulbs that had an integral [[multifaceted reflector]], which were more expensive than bare bulbs, but were more convenient to use, as the reflector did not have to be adjusted after bulb changes.<ref name=PopPhoto-9010/>{{rp|43}}