Soundman, you are completely right in all ways with your description.
The only possible exception to this would be to use a converging beam
PAR or R-Lamp such as a MR-16 type EPN where the beam of light focuses upon a specific
point in this case 9mm from the
lens, than reverses itself. As with a
Leko, this is the
point that a
pattern is placed as it is one source of light at that
point given there is actually two sources of light otherwise on a
Leko or
Par lamp or anything with a
reflector. The first source is the
filament, the second is the light reflected off the
reflector. Different sources of light equal differnt patterns projected off them thus a really bad projection. Also the larger the
filament or
point source of light, the larger the dispersion or fuzzyness of the beam projected.
All that said, if you study into the concept of a scene
projector or more properly called, a Linnenbach
projector, even a "Go Fres" presented in 1991
USITT Theatre Technology Exhibit Section 15, you will find a way to do this with the equipment you have. In the most basic sense, if you take the above description of how a
Leko projects a
pattern from it's focal center - that place in which all light beams converge in hitting the
pattern, than this is fairly easy to reproduce in any single source of light
fixture. All you need is that origional source of light without any secondary
reflection sources or wide random/soft dispersion lenses. In the case of a
Fresnel, it's a
fixture without
lens or
reflector. In the case of a Plano
Convex, it's without the
reflector and possibly without the
lens. In the case of a
scoop or
PAR fixture, it's a done deal as long as there is no
reflector being used. Place a
clear A-type normal household or better lamp without a
reflector into the
fixture and it now has a single source of light projecting
thru the
pattern. You don't need to have a converging beam of light, just one that's parallel and directly coming from a single location. Not it plus bouncing off a
reflector.
As a goal to work around, the larger the
filament area, the more diffused the beam it will have since light is coming from a greater surface area of light and angles from it projecting onto the
pattern will
effect how graphic or defined it is. The most graphic source of light to project a
pattern is a pin prick mini-source of light. The larger the source, the more angles and fuzzyness. A FLK lamp is probably going to be a better
point source than a EHG for patterns. A GLC lamp is going to be better than a FLK for this same
filament area idea. A
HPL should be about the same as the GLC with a HPR best yet for it's own unique design reasons given the efficiency of the
reflector and it's lenses on a
fixture also plays a factor. This is on Lekos, for projectors Lekos have nothing on a
stage and studio grade arc lamp having down to 4mm dia a light source as opposed to a 6.35x11.68mm
filament on a HPR, 9x8mm on a GLC or 13x8.5mm
filament on a
HPL lamp.
This possibly would be much of the reason why some have observed a
Strand SL
line of
Leko is a better
pattern projector than a
ETC S-4
fixture.
In the case of a
PAR 30
fixture, were you to install a normal screw
bulb in it instead of the
PAR lamp, such as an A-Lamp being a general term for any household
bulb in shape, you would have that
point source of light projecting on the
image, it's just a question of output and
filament size. Output because this lamp no longer has
reflection to collect up and re-direct the light in a general direction, and
filament size in making a useful beam of light projected. The above Linnenbach projectors or Go Fres's in projecting scenery don't need as graphic an
image as a Nike
logo on the way to their corporate event. Some execuitive would be really pissed with a fuzzy
logo. That fuzzy
image however is a design style most desired in projected scenery as in a whole back wall of a set that's a projected
image. To that you frequently will even add a
scrim to further disperse the
image.
For a
PAR 30
Fixture on a "B" sized
pattern, assuming you want a fairly graphic
image, we have to take as a given a maximum A-Lamp
bulb length of say 4.11/16" for a
PAR 30 long - given it would fit into a
PAR 30 can. Otherwise our
MOL as it's called for maximum overall length is 3.5/8" which is fairly short to try and match up a high wattage A-Lamp to.
This is important the more wattage when balanced with compact
filament, the better the
image will be. This is all taking it for a given that the
bulb has to physically fit into the
fixture both in dia. and length.
If your
fixture can take a long
PAR 30 instead of the normal short ones, than it's possible to go up to a 500w T-4 lamp in wattage given the length of the screw based lamp will fit into the
fixture. Such lamps as the GE owned EYE brand JD500w/E2 or Bulbrite Q500CL/E26 would work well for this given a cc-8
filament is fairly small in are instead of being linear as if a
RSC double ended type lamp which is also possible.
You could reasonably expect that the
intensity of the
image on the wall would be similar to that of a 200w lamp at the same distance. Should be decently bright above normal lighting, but not a huge amount of punch to it. Short of changing your lamp
base and adding a higher wattage lamp with a possibly larger
filament it's hard to
beat this in output. One key factor to figure on is not only
filament size and type but it's orientation. You could mount a very good BTR lamp into the
fixture given a change of lamp
base, but since it's
filament is perpendicular to the axis of the lamp, this in a
PAR type
fixture would not be very bright. With the above 500w T-4 lamps, it probably is very similar to a double ended lamp with a long
filament stretched between two supports instead of a compact
filament as per on a
Leko lamp.
The next best source given the above 500w lamps are long filaments, or at least one of interest would be a 400G/FL lamp such as you would find used in a 10"
scoop. Cheap lamp to get, bright, but it's
filament is not very compact meaning your
image would be fuzzy. Next best lamps that might fit are 250w even 150 and 100
watt more normal lamps. Given they are not too long and that's a specification thing, they should also work if
clear not frosted. A frosted lamp becomes a huge
filament because the light projects out in all directions from the frosted surface. It's as if there is one huge
filament. Not good for a
pattern projector.
Store bought lamps would probably limit you to about a 60w lamp in
clear, perhaps 100w. This will project an
image, but only figure on about 1/3 of it's total light coming out of the front - the rest is wasted.
Reflection is efficiency, remove that
reflection and the light just turns into heat. Expect that your
PAR 30
fixture might suffer from heat problems.
All said, you can make a
PAR 30
fixture into a
pattern projector. How well it's going to work with the
image of a B-size
pattern is a guess, but it would project as long as you went with a lamp lacking a
reflector.
Give it a shot, might work well enough, but chances are you are going to need either some type of
Leko or to modify a
fixture that has the axis of the lamp perpendicular to the opening it's shining out of.