I wonder, do other brands of 16mm projectors, Eiki, Elmo, etc, have so much light coming out of the lamphouse as the B&Hs. The room is never really dark, and some people place a piece of card over the case to make the room darker. It doesn't bother me as I still get a good picture, but I wondered what other brands are like?

All of the Elmo 8mm projectors I have used are brilliant at illuminating our ceilings Robert! 😂

Nicely patterned too! 😂

I don't believe placing card to restrict the venting and exhaust lamp heat is the answer Robert personally, but I much prefer any machine which vents the lamp heat through ducting to the rear of the machine rather than partially vertically at the lamp house.

Some have metal heat shields inside the lamp house to protect the body of the machine and reduce the heat to the touch at the lamp house cover so really, there was never really a need or an excuse to send this heat vertically through an open grill at the lamp house cover.

Even double louvres on top of a lamp house cover eliminates this stray light vertically, and then without any need to illuminate the ceiling area directly above the projector.

Today's video projectors generally use far more powerful lamps than our cine projectors use yet none I've seen have a need to disperse the lamp light power to any great extent anywhere other than out through the lens.

I don't interfere with it Andrew; films are to precious to take risks with.

No quite right Robert, it needs to exhaust the heat in the manner it is doing if that's how it is designed.

I was only questioning the necessity for this concept from a design engineer's perspective and from what I've seen alternatively, I don't believe there is one.

The Elf NT1 i use is very good, no light through the top, or at least hardly any, just a bit through the side which doesn't cause a problem,
As for the elmo 8mm machine, this is what i do,
there's a little groove in the carrying handle, an old post card folded in half slots into this perfectly, it is high up enough so as not to prevent or interfere with the air flow out and it doesn't block the light out but it does stop it flooding the ceiling. you can position it to suit your own needs, if you feel you want to let out more air just move it forward or back with the handle. I tend to use this only when i view films with a lot of night scenes. Marathon man is a good example, if you try this start the film without it, then, as your viewing, put it on, take it off then put it back on a see how much a better contrast you get when you block the light to the ceiling.
I have been doing this for over 20 years, never had a problem yet, its too far up from the slots to act as a block for the air flow.
i assume i am not the only person to do this.

There are others doing this. Not sure I understood Andrew, or maybe he didn't understand me. I leave the projector as it is Andrew , with the light shining upwards. There is a lot of heat coming out of that grill. Toast anyone?

Yes Robert, I understood you perfectly which is why I replied that it is quite right to leave the vents uncovered and illuminating the ceiling if that is how the machine is designed to keep it cool.

I equally understood that you said it wasn't yourself covering up the lamp house grill but that you understand others do by placing some kind of box around the machine in some way or another.

Covering the entire machine can never be a good thing as temperature inside would only ever get far higher than the machine should ordinarily get to, even if the box contained some ventilation in a different area to where the lamp house grill is situated.

I certainly would never completely cover the machine or lay anything over the vents in any way, what i do here doesn't interfere with the cooling process at all, all it does is greatly reduce the amount the room gets lit up.
I have heard that other people, (no one in the hobby in a serious way as anyone on here is), have actually used big boxes that almost cover the entire projector. Thats a no no.

Wise words Tom.

A deflector, say a good few inches away, acting purely as a baffle to divert the heat and stray light in a different direction, can do no harm at all.