Focusing

[Tecnical Bradders]

Hi all

 

 

 

Now a bit of a debate I have been having with a friend and wonder what other people think/ carry out.

 

I have always been taught to focus at 70% and still use this method in my professional career, as it dramatically lowers the risk of the bulb blowing when the luminaire is been moved; therefore increasing the bulbs life.

 

This friend have been studying a lighting course at university and again like me has always been taught to focus at 70%, but during one of his first focusing sessions at uni realised they were focusing at 100%, when he challenged his tutor about the 70% theory she had never heard of anyone focusing at 70% and it is always carried out at 100% but allowing sufficient time for the lamp to warm up first.

 

This again is properly differences of opinion and techniques used between different technicians, but I wonder what other people think of the situation and practice themselves?

 

 

 

Bradley

[gyro_gearloose]

I've never heard of focussing with the lamps at 70%. I imagine it makes focussing saturated colours harder than it needs to be.

 

I've always been under the impression that its the thermal shock created when first powering up a lamp that causes most failures. Wherever possible I like to put the whole rig at 20 percent for a few minutes before focussing as this warms the lamps and helps prevent premature failures.

 

Another cause of premature lamp failure is overvolting. This document from Philips shows that lamp life drops off dramatically if the voltage rises only a few percent above what the lamp is rated to.

[Big Jay]

Never ever heard of this until now and as far as I'm aware it's not common practice in the 'real world'

 

What is common practice is putting a lantern at 'check' (different for some people but I have my check set @ 30%) then when the electrician is ready to focus the unit, take it to full. As your profile says you work at the WYP, surly you would know if it's common practice or not as it is quite a busy receiving and producing house with many different designers?

 

J

[niclights]

I try to keep as low as possible, purely for the consideration of the person focusing.

[Kopy]

Do whatever the lighting designer tells you.

[andy_s]

it's not unusual to take saturated colour out to focus and pop it back in before moving to the next unit. Of course this needs to be done carefully to avoid upsetting the LD by moving the light again...

[Tecnical Bradders]

Yes there is definitely the problem of focusing saturated colours, but as most people are properly aware a sharp jolt or any unsmooth movement of a lantern can cause the bulb to blow and bringing the percentage down does lower the risk of this issue. Obviously if the person focusing is struggling to see the saturated colours there no issue in raising the percentage.

 

I agree its down to the lighting designers, board operator and the person focusing decision at what percentage to focus on. I also agree that many people do focus at a high percentage and it is advisable to warm the grid up before any kind of movement. But the way I was always taught was to focus at 70% obviously saturated colours need that higher percentage but I personally think lowing the percentage lowers the risk of the bulb blowing.

 

Again its another technique, another way of working another opinion and I wouldn’t say there is any set percentage or way of focusing, its down to the discretion of the people there. Interesting to hear peoples views and opinions.

[tommulliner]

I usually warm the lamps (@ 20%) and then focus at full or half, dependent of the complaints of the person focusing!!

[Just Some Bloke]

I have always been taught to focus at 70% and still use this method in my professional career, as it dramatically lowers the risk of the bulb blowing when the luminaire is been moved; therefore increasing the bulbs life.

[snip]

 

I wonder what other people think of the situation

 

1. Personally I don't know of it being common practice to focus at 70%

2. Though I do know that it is common practice to talk about a "lamp" rather than a "bulb"

 

[/pedant]

[paulears]

I suspect much of this is just somebodies own preference, and because of it, everyone follows.

 

Like all of us, I've popped many a lamp when the focus slide suddenly gives - and have just accepted it as a fact of life. The only benefit I've ever really found is keeping them off until needed for focusing, simply to keep the fixture 'nicer' to touch - but when I focus, I want it bright, and re-focusing with saturated colour is difficult enough without having it even more dim!

 

In a house where they focus at whatever they choose, other than full - I go along with it, because it's their kit - but otherwise, it'd done on full. I don't pre-heat them - with full being measured by temperature anyway, after a few seconds the envelope is already at working temperature - making a warm up period a bit pointless.

 

Over the years I can't say I could produce any quantifiable evidence one way or the other, but what's certain is that 70% is NOT a standard of any kind.

[gyro_gearloose]

The idea of focussing at 70% may have arisen because certain types of lamp are notoriously fragile. I've managed to blow all three lamps in some hired-in Selecon Pacifics because I knocked them while focussing, and I understand that CP77 lamps as used in Lekos are also quite fragile. Maybe focussing them at 70 percent makes the filaments less likely to break?

[gareth]

Never come across this before. I, and everyone I've worked with over the years (and that's a lot of people! ) focus a lantern at 100%.

 

70% or 100%, doesn't matter - if the filament is hot, it's fragile enough to blow if you knock it unduly. Far better to be smooth and gentle when focussing. And if something gets a bit stuck (the lamp centering on CCT Freedoms being a constant example of this in my experience!) don't attempt to free it up with the lantern powered up - unplug it, do what you need to do to get the stuck bit moving freely again, and plug it back in.

[Bryson]

I've seen people do this.....and then go back and "tweak" the lantern the first time they see it at full!

 

Focus at full is the norm.

[no1lampyman]

Worked in a receiving house for 4 years.

 

As mentioned above their is NO Standard. and usualy you just go with whatever the LD says as its his rig.

 

Personally im with the majority of having a rig test of all lamps at 20% but again once you come to focus all lamps need to be off, so if you have more than a few to focus they will have cooled again so pretty pointless. Focus @ Full and be as gentle as possible. Lamps Blow "fact".

[Trunker]

I always rough focus at 80% and then final focus at 100%. Don't care if it right or not its what I do and as long as I get the desired effect, who cares?

 

Yes you read right, I normally focus twice (time permitting (I make time permit!!!!)).