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MSR, MSD etc differences


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MSR = Medium Source Rare-Earth

Philips designation for a medium arc length metal halide arc lamp using dysprosium iodide as the halide fill. These are all double-ended discharge tubes mounted in single-ended envelopes and bases.


Power variants available (depending on range) tend to be 125W, 200W, 250W, 400W, 575W, 700W, 1200W, 2500W, 4000W, 6000W, 12kW and 18kW.


The variants above 1200W are rare in theatrical use, mainly being seen on film sets.


Remember the 18kW lamp puts out nearly 1.75 megalumens. This is equivalent to something like 150 500W tungsten halogen lights.


HSR = Osram equivalent part


CSR = GE Equivalent part


/2 variants have higher colour temperature (7200K instead of 5900K).


HR types have hot-restrike capability (usually requires base with better insulation to cope with the >10kV restrike voltages- so 575/HR is only available in G22 base, not GX9.5)


These usually have a lifetime around 750-1000 hours although some low wattage lamps like the MSR 200/HR hace a lifetime of only 200h.


CRI around 70-90. Film types can have a CRI around 90-95.


MSD lamps - slightly different gas fill, mainly for architectural purposes.

Arcs are slightly longer than the MSR type.

Colour temperature is around 6000K, although Philips offers /2 variants for some power ratings with 8500K colour temperature for these as well.


Generally the very high-wattage (above 1200W) variants aren't available with MSD fill.


Spectral peaks tend to be much sharper- the overall spectrum appears less balanced than that of the MSR lamp.


The main advantage of the MSD lamp is the significantly longer lifetime at 2000-3000 hours.


MSD lamps are also rather more expensive than the equivalent MSR types.


Electrically the MSR and MSD lamps of a given wattage appear to be interchangeable. Mac500s and 600s support both, for instance.


The different manufacturer's lamps variants appear to be electrically and physically equivalent, but have some variation in CRI and lifetime.


Interestingly, GE (CSR) and Ushio (USR) MSR equivalent types are not listed as 'approved' by Martin. I have no idea why.

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I'd just like to add a bit more information, to add to any confusion you may have experienced:


Firstly, Philips does sell double-ended screw terminal unjacketed MSR lamps in the style of the Osram HMI, so not all lamps designated MSR have single-ended bases.


The pupose of the glass envelope on MSR lamps appears to be to improve the surface temperature uniformity of the arc tube, reducing hot spots that reduce lamp life.


MSR lamps come with several different base styles, and it is important to be aware when replacing lamps with a different manufacturer's equivalent that some wattages are available with more than one base type.


Smaller lamps below 400w tend to use either a g12 or gy9.5 base, but the hot-restrike variants come with interesting assorted bases of type gzx9.5/gzy9.5/gzz9.5 which are slotted between pins to improve insulation.


From 400-1200w you tend to see gx9.5 (non-hot-restrike) or g22 bases (there are also 1200w HR lamps with g38 bases).


Above that you have g38 or the enormous g51 (2") for the 18k lamp.


There are also MSR SA (short arc) lamps which don't have an envelope but still use a single-ended base. These are not direct substitutes for standard MSR lamps and must be run with a suitable digital ballast. Bases used are gy9.5 and the unusual gy22. They are used by various High End Systems and Vari*lite spot fixtures, where the short arc provides a better point light source and contributes to a higher beam intensity. Colour temperature is around 5600-6000k and CRI around 70-80.


Philips seems to have convinced a few manufacturers (Coemar, at least) to adopt its new 'FastFit' base for MSR lamps as well.

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I second that, or make sticky/add to FAQ?



(Compact Source Iodide) A high intensity discharge lamp. Most often used in followspots, because it has a colour temperature (approx. 4000K) close to that of the tungsten halogen lamps.

(source: Theatrecrafts.com)



(Compact Iodide Daylight) A high intensity discharge lamp that produces a light similar in colour temperature to daylight approx. 5500K). A 1000W CID lamp produces 2.5 times more light than a 2000W tungsten halogen source.

(source: Theatrecrafts.com)



(Hydrargyrum medium-arc iodide) A mercury-halide gas discharge medium arc-length lamp with a multi-line spectra emission. Hydrargyrum = Mercury (Hg). 6000K. Single or double-ended. Single end has outer bulb. Hot restrike.

(source: Osram/wikipedia)


HTI: 4300-7500K. Single or double-ended. No outer bulb. Double-ended can have hot restrike.

(source: Osram)


HMP: A variation of HMI, specifically for OHP's. Features might include dim/boost.

(source: Osram)


HSD: 150-1200W. 6000-8000K. Single-ended.

(source: Osram)


HCD: 35/70/150W. 3000-4200K. Sinlge-ended. Includes UV filter in outer bulb.

(source: Osram)



I'm not sure how useful all that is but maybe if people can add we can compile/refine into a vary useful reference? I'm struggling to find definitions for most of the Osram variants although I realise they are, for the most part, just registered names.

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