With regard to lighting instruments there is a series of lights made by the Mole Richardson company that were given the name 'Baby Series' lamps.
During the (circa) 1930's through the 1980's Mole Richardson made a series of lights that held 10,000, 5,000, 2,000 and 1,000 watt lamps.
There are a number of uses of the term 'Baby' within the film industry.
With regard to lighting instruments there is a series of lights made by the Mole Richardson company that were given the name 'Baby Series' lamps. During the (circa) 1930's through the 1980's Mole Richardson made a series of lights that held 10,000, 5,000, 2,000 and 1,000 watt lamps. When the need and ability to manufacture smaller sized lamp housings came about, the larger lights were given a re-design and scaled down considerably to save on storage and transport size/weight as well as to ease operation of the previously unwieldy lights. The older lamps are still in use in many studios today and are referred to as Mole "Studio" series lamps. The new smaller series of lamps were dubbed with the name "Baby" because they resembled the appearance of their predecessors, but were considerably smaller. The Baby series lamps were also referred to as "Hot Baby" or "Hot" lamps. The smaller size of the lamp housing required that the reflector inside the lamp and the glass fresnel lens of the lamp be smaller as well. These changes to the Baby series design lamps caused the beam of light emitted to be brighter than their larger studio lamp predecessors. Another trade-off when comparing the 'studio' series and 'baby' series lamps is that the studio series lamp will have a wider beam when compared to the baby series equivalent. With regard to the amount of light emitted, a 1,000 watt studio lamp will emit less light than the same 1,000 watt globe (bulb) inside a "hot baby" series lamp. The Baby series of lights from Mole Richardson soon became the standard in incandescent film lamps that utilized tungsten filament bulbs that were needed to recreate the perfect Kelvin Temperature to correctly expose and render colors on tungsten based film emulsion or 3200K settings on digital cameras.
Another usage of the term 'Baby' in the film industry is in regard to Grip gear and/or Lighting Rigging equipment. There are basically two types of mounting pins that exist on the Bail of a lighting instrument or piece of grip equipment. The larger type is called a Junior mount and has an 1 1/4" pin that inserts into a mating hole in a stand or piece of rigging gear. The smaller type of mounting is called a Baby mount and is a 5/8" pin or hole that exists on a lighting instrument's bail or is affixed to a piece of grip equipment. The Baby pin is the male component of the baby mount and usually has a knurled recess machined near the tip of the mounting pin. This is a safety feature that is intended for the tightening knuckle of baby receiver hole to catch in the knurled slot. If the tightening knuckle was to become loose, after hanging or mounting, the lamp would remain caught in the knurled recess and would not fall to the ground or pop up off the stand or mount. A redundant safety feature in the very tip of many baby pins allows for insertion of a safety clip, pin, nail or wire that will physically prevent a baby receiver from sliding off of a baby pin. It is popular practice to take apart a C-47 clothespin and use the wire spring inserted in either end of the baby pin safety hole as a double safety for any lamp hung on a baby pin mount in an overhead or Underslung position. Lighting stands are generally referred to as Baby stands because they are normally exclusive to the lighting department. A baby stand is a three legged stand that may be very short (Premie Stand) or may have two risers or three risers. Baby Stands are also manufactured out of square or round tubing and may be all steel, all aluminum or even a mixture of both materials to save weight in some designs. The C-Stand also used the baby pin as it's main mount atop it's risers. The Gobo Head that slips onto the c-stand top riser has a baby pin sized 5/8" hole with a tightening knuckle and as part of the round gobo head itself there is a groove machined to accept the c-stand head/arm. The arm of the c-stand is also 5/8" diameter and a head/arm combo has an additional gobo head with an additional 5/8" groove machined for accepting other arms, baby pins or other 5/8" accessories.