What Projector/Screen for a school hall?

[alawil]

Hi

 

I'm looking for some guidance please, we are a primary school for around 315 pupils with a large school hall which fits all the children in. We currently have a 4:3 Electric Sapphire screen (RS232 controlled) which is 3.3m * 2.5m (W:H) and a Panasonic Pt-ew540L projector - the lamp has around 1600 hours use and the image is looking rather washed out. The projector is mounted at the back of the hall, with the screen at the front and the distance between them is ~13m. We have a SY control panel controlling the screen (up/down) and the projector via RS232.

 

 

Firstly we would like to upgrade to a 16:10 screen, the thought is to get a 4m * 2.5m Electric Sapphire screen (same height just wider), couple of questions:

 

 

1) Will the RS232 control box that we have on the current screen be transferrable to the new screen?

2) Should we consider a fixed frame screen instead?

3) would you agree with the proposed screen size?

 

 

In terms of the projector I've calculated that we need a ~8000 lumen one, I understand that the lens that we have currently will be transferable to the Panasonic pt-mz770l projector, couple of questions:

 

 

4) would you agree 8000 lumen is the right brightness? - the hall has windows on one side which is north facing so whilst its light its not bright sunlight.

5) would this seem a good choice of projector? or would you strongly recommend something else?

6) should we seriously consider relocating the projector instead of having it 13m away?

 

 

Any other inputs would be welcomed, we really want to make the right choices and your help would be amazing.

[MarkPAman]

If you can use your existing lens on a new projector, then there's real optical no advantage in moving it any closer. And if appropriate cables go there already, even better.

[Bryson]

1) Will the RS232 control box that we have on the current screen be transferrable to the new screen?

2) Should we consider a fixed frame screen instead?

3) would you agree with the proposed screen size?

 

1: Should be, but someone will likely need to take a look at it to be sure.

2: I wouldn't. Retractable is good for keeping screens away from errant screen damage.

3: Theres a complicated calculation in the DISCAS spec, which give *almost* exactly the same answers at any sensible screen size as the old 4/6/8 rule, so I will ignore the complicated stuff and use 4/6/8 instead. (https://www.avixa.org/standards/discas-calculators/discas if you feel like getting into the fun stuff!)

Screen height is 2.5m, most distant viewer is at 13m. That's 5.2 times the screen height which puts it squarely between the analytical and basic decision making. Seems fine to me.

 

4) would you agree 8000 lumen is the right brightness? - the hall has windows on one side which is north facing so whilst its light its not bright sunlight.

5) would this seem a good choice of projector? or would you strongly recommend something else?

6) should we seriously consider relocating the projector instead of having it 13m away?

 

4: Using the ET-ELT22 Lens, that gets you +200nits on the screen with a 8k Lumen projector. That'll do nicely. https://www.projectorcentral.com/Panasonic-PT-MZ770WU-projection-calculator-pro.htm

5: Those Panasonics are nice projectors, and if it saves you buying a lens, then that's great.

6: But wait, the new screen is wider, so that probably means the same lens won't do the job from the same distance, unless it's inside the zoom range, maybe? What lens do you have?

 

 

Playing with the calculator, the 5k should still be OK. Maybe all you really need is a new lamp? EDIT: Expected lamp life is 4000 hours, so, probably not. Must be excessive ambient light from the windows that's the issue.

[alawil]

thank you, that is really helpful!

 

So 4m * 2.5m screen it is - we will check the RS232 box on the current screen with Sapphire to make sure its transferrable, hopefully it should be as it was added in the last couple of years.

 

In terms of the projector, I think we need to double check exactly what lens we have by taking the lens out and verifying.

 

But, I'm beginning to wonder if the lens is the ET-ELT20 which apparently is NOT compatible with the MZ770 projector (https://panasonic.net/cns/projector/products/mz670/accessories/) but is with the MZ570 and MZ670, with that in mind it seems that in our situation the MZ670 with the ELT20 lens would give 205nits vs the MZ770 with ELT22 211nits

 

What would the suggestion be in this case? (our existing combination of Pt-ew540L and ELT20 gives 145nits) - is the extra ££ for the 8K projector worth it vs the 6.5K projector?

Is there a way of calculating how many nits we should be aiming for?

(it seems the existing lens should be ok for the proposed screen size)

Once again thank you for all your help so far

[Dicky]

The big difference here is the pt-mz770l is a laser source projector, and the big difference between that and a lamp based projector is that the light levels don't deteriorate anything like they do as with lamps.

On some of the 10k panasonic lasers that I service, I'm seeing negligible difference in light output after 4000 hours of runtime, which is incredible compared to the lamp based units.

 

I've had lots of good information and help from AV partsmaster, who stock a wide range of projectors, they might be able to help with the lens questions. There is also a Panasonic lens calculator Here which may help you out.

 

These projectors do need a good clean every so often, even if they're sold as 'maintenance free' the fans do clog up with dust, so worth making sure it's taken down once a year and hoover the dust out!

 

Dicky

[TomHoward]

Can you comment on laser vs lamp? Are lasers a given choice these days?

Although not a reduction at 4000h, what's the overall life of a projector like?

 

(In same boat but unfortunately very much at the pricing stage only).

[timsabre]

Apart from the fact that laser sources don't lose brightness (much) over their life, laser projectors also tend to have sealed optics meaning no problems with dust and smoke fluid getting into the optical path because they don't run as hot as a normal lamp.

 

We installed a couple of Optoma UHZ65 (which I think are the cheapest laser projector currently) in meeting rooms at my church, they've been great so far. A bit small for the OP's task though.

[alawil]

I did briefly speak with Jordan at avpartsmaster and he indicated that as a rule of thumb the lumens required was twice+ the width of the screen. In our case we are looking at a 4m wide screen so we should be looking at 8K+ lumen output projector.

 

He suggested the Epson EB-L1490U (9K) but suggested I send across full details and some photos to make an exact recommendation which I will be doing.

[TomHoward]

Apart from the fact that laser sources don't lose brightness (much) over their life, laser projectors also tend to have sealed optics meaning no problems with dust and smoke fluid getting into the optical path because they don't run as hot as a normal lamp.

Does that mean the also tend to run quieter then? Or is that overly hopeful?

Is there any advantage of still installing lamp projectors? Is it purely cost driven?

[timsabre]

The Optoma ones are pretty much silent. Don't know about others.

[Dicky]

The Panasonic RZ970s have lots of fans to keep the lasers cool, and the noise is similar to a lamp based projector. This is a few years old now and the technology does change all the time, so worth getting all the info you need. most manufacturers should give a dB rating for how loud they are.

 

 

It's true that lasers are more optically sealed, I can only speak about Panasonics, and yes, there is a lot less dust inside the optical path on a laser than on a lamp based projector.

 

The Optoma ones are pretty much silent. Don't know about others.