Can anyone Help

[Matt_Student]

hey im in search for the discription of the following things. if anyone can tell me where I can get info on what these are, or pass some knoledge through this forum it would be greatly apreciated.

 

Beamlights

Bifocal spot

Ellipsodal

Gate

Thyristor

Axial spot

 

sorry I dont know wat im really looking at, I know they are mainly lights accept 2 but wat are they.

 

all help apreciated

 

Thanks very much

 

matt

[Mush]

39 views and no replys Ill take a go on a couple;

 

Beamlights

 

Beamlight gives parralelll beam of light, a single `shaft` of light, Just uses a mirror no lenses

 

Bifocal spot

 

Er, not sure, not a common expression, possibly a zoom profile spotlight with variable beam width

 

Ellipsodal

 

U.S. expression for what U.K. people call a profile spot, light that has ability to project shapes, gobo, and have beam shaped with shutters, gives a circular cone shaped beam of light, ellipsodial refers to shape of mirror around lamp this type of light has lenses in it for focussing.

 

Gate

 

either part of profile/elipsoidial wher the shutters are mounted or bit of thyristor that switches it on, whats the context?

 

Thyristor

 

Power switching bit in a dimmer that actually controls the mains, Triacs similar and more common nowdays, but an internal part of a lighting dimmer anyway.

 

Axial spot

 

Way the lamp is mounted in a spot, Axial means the lamp is on axis with the mirror and lenses in a profile. If you look st that light side on, the lamp is mounted on its side and base is mounted on back of light

 

Context would help , guess your reading an American book on stage lighting?

[paulears]

bifocals go back to the sixties with the strand 264 - a pretty standard design profile but with two sets of shutters - one with hard edges like usual, and the other set vignetted - sort of large teeth, like in a wood saw. these are not at the point of focus and give a soft edge. really useful when you want a hard cut-off at one side, with a soft cut-off on the other. As far as I know, nobody else made them, and strand only carried it on for 3 generations - 264 - 764 - t-spot. A shame really, as they were very useful.

[gareth]

Beamlights

Lanterns that contain a lamp, a couple of reflectors, and no lenses. A small reflector in front of the lamp bounces all of the light backwards to a large parabolic reflector at the back of the unit (none of the light from the lamp is allowed to 'escape' directly from the lantern). The design of the parabolic reflector is such that a near-parallel beam comes out of the front of the lantern (although there is the possibility of minimal variation in beam angle by moving the lamp and little reflector in relation to the big reflector - this does tend to result in some unpleasant black holes in the beam if you're not careful, though).

Bifocal spot

See Paul's definition - I can't possibly add to that!

Ellipsodal

American term for profile.

Gate

The bit of a profile into which things like gobos and irises are placed - the 'optical centre' of the lantern, if you will ....

Thyristor

A semiconductor, kinda like a big chunky transistor, used to 'chop' the AC waveform in dimmers.

Axial spot

Profile lantern in which the lamp is mounted axially through the centre of the reflector (e.g. Source4), as opposed to being mounted base-down at the bottom of the reflector (e.g. Cantata). Has the advantage of getting more of the lamp's filament closer to the centre of the reflector.

[andy_s]

T64 is bifocal and fixed-beam angle - T84 only had one set of hard edged shutters, and is a zoom profile - variable beam width.

[gareth]

T64 is bifocal and fixed-beam angle - T84 only had one set of hard edged shutters, and is a zoom profile - variable beam width.

<{POST_SNAPBACK}>

Yup, no-one's arguing with that!! ;)

 

I guess when Paul mentioned T-spots as being bifocal, he was referring to the T54 and T64 which were the 'original' T-spots. The T84 was a later addition to the range.

[paulears]

I drew a line after the first ones started to fall apart - although in retrospect I dug one out in a panic the other day and it (a T64) held it's own against a cantata - bit dimmer, a little more colour around the gobo edges, but not too bad at all) I've never tried a zoom version, so can't comment on those at all.

 

One day, I'd really like to gatyer a collection of everybodies favourites together and do a proper 'shootout' - brightness, beam quality, sharpness etc and then produce a set of specs that would make sense. I've always thought that as soon as the next decades worth come out, anything old is forgotten about even when sometimes they possibly were better. I have no idea how to arrange this, but it would be interesting. Maybe a uni project for someone?

[andy_s]

T64 is bifocal and fixed-beam angle - T84 only had one set of hard edged shutters, and is a zoom profile - variable beam width.

<{POST_SNAPBACK}>

Yup, no-one's arguing with that!!

 

I guess when Paul mentioned T-spots as being bifocal, he was referring to the T54 and T64 which were the 'original' T-spots. The T84 was a later addition to the range.

<{POST_SNAPBACK}>

 

Gosh - even though I'm very old (certainly compared to most of the people around here) I've never seen a T54. I indirectly blame the T64 for my bad back - it was when the chief electrician decided they should all be replaced with cadenzas on the FOH bridges that I first had twinges - something to do with having to carry the cadenzas along the very restricted headroom lighting bridge while bent double. If the T64s had been any good, we wouldn't hve been replacing them.... slightly irrational, I realize....

[Stu]

Gosh - even though I'm very old (certainly compared to most of the people around here) I've never seen a T54.

I think I've come across the odd T54 in my time, but never a T84. Has anyone still got any?! They were on the market for 4-5 years (I think), with the Harmony being available for the last 2yrs of that, so I can't imagine they sold that well.

 

Does anyone know what changes were made in the T-spot 2 version? I can't tell the difference between ours... Can't find any mention of it on the Strand Archive.

 

Stu

[andy_s]

Gosh - even though I'm very old (certainly compared to most of the people around here) I've never seen a T54.

I think I've come across the odd T54 in my time, but never a T84. Has anyone still got any?! They were on the market for 4-5 years (I think), with the Harmony being available for the last 2yrs of that, so I can't imagine they sold that well.

 

Does anyone know what changes were made in the T-spot 2 version? I can't tell the difference between ours... Can't find any mention of it on the Strand Archive.

 

Stu

<{POST_SNAPBACK}>

used to have mainly T84s on the FOH bridge at the Brewhouse in Taunton in the 80s and 90s, I guess they're probably all gone now. Certainly came across plenty on the small/mid scale circuit in the 90s, although I guess CCT won the arms race with the sil 30 in that generation.

[Stu]

Talk of the devil..

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...3753161530&rd=1

 

Stu

[dave e]

My old school has six T-84 as FOH spots, and my uni had a couple kicking around the gods, but they may have gone into the other music performance spaces now.

 

They were quite good as baby follow spots on stands, i.e. they had a decent focussing handle at the back, the heat escaped out the top with little coming through the back vent and the focus knobs were big and chunky.

 

Quite a useful unit in a way.

 

Dave

[andy_s]

Nostalgia - it ain't what it used to be!

[Matt_Student]

does anyone know where I can get a internal layout diagram of a Beam Light??

and am I correct in saying that the only difference between a Fresnel and a PC is the lens?

 

cheers for all the help so far im really starting to understand all this now.

 

 

thanks matt

[andy_s]

does anyone know where I can get a internal layout diagram of a Beam Light??

and am I correct in saying that the only difference between a Fresnel and a PC is the lens?

 

cheers for all the help so far im really starting to understand all this now.

 

 

thanks matt

<{POST_SNAPBACK}>

 

Strand Lighting have a traditional beam light in their product range now, there may be diagrams on their website.

 

You're almost correct about PC and fresnels - there is often a difference in physical size of the unit, with the PC being longer (needs a longer focal length than a fresnel), and there is a difference in the quality of the light coming out of the front - fresnels tend to have a softer edge to the beam, but the basic construction is the same - lamphouse containing reflector, lampholder and lens, colour runners at the front to hold colourframes, and barndoors to shape beam / prevent light from hitting undesirable areas of the stage.