Doubling projectors

[Drew]

In order to cut our budget on a charity show where profits are of upmost concern, I recently suggested using two projectors on the one screen. Does anyone have any experience with this?

 

The screens are 8ft x 6ft and the projectors are 3200 ansi lumens (I believe).

 

Any advice or information would be appreciated.

[Big Dave]

In what respect are you using the two projectors? - to make the image brighter are to diplay different sources?

[Wilf dLampy]

We've done the using two projectors on one screen to make a brighter image thing, by flying the projectors one directly under the other for This event. It worked very effectively, and also gives you a backup image if one projector fails for some reason. You need to make sure you have plenty of image adjustment features on the projector, and it's best to get them as close to each other as possible.

[MikeR]

If youre running two projectors at the same time you have to take care to get the registration accurate obviously. You should take the time to make up a projection pattern that you can project from one source through both machines simultaneously to help in this. As others have said get them vertically stacked as close to one another as possible. Either have one projector in the optimal position for the lens & projector and offset the other as little as possible or offset both by the same amount off the mean / optimal position - which works best for you will be probably be discovered through experimentation depending on your environment. Either way it is (obviously) vital that the registration is spot on. Bear in mind that cheaper lenses ( and those permanently mounted on cheaper projectors) will not be absolutely accurate in terms of focal length. In other words of two lenses claiming to be 0.8 s you will probably find that neither is exactly 0.8

[Drew]

To confirm, it is to make the image brighter as we're projecting outside.

 

It actually turns out that the projectors are only 2000 ansi lumens - so I'm even more keen to try this out.

 

Many thanks for your replies.

 

Drew

[MikeR]

Outside? If during daylight dont bother. LED walls etc are the best bet. Errr havent we had this conversation? at least without searching though the forum theres a very similar topic somewhere quite recent too.

[Drew]

haha, yes, we had this conversation. And it was started by me.

 

Anyway, these are for night time.

 

Drew

[MikeR]

Thought it rung a bell -

Night time :)! go fer yer life

[Pete McCrea]

It is possible to get a cunningly titled "Double Stacking frame", which fixes the two projectors one on top of the other, and allows for more accurate adjustment. I've used one for Sanyo 9005 projectors, whether it's made for the projectors your using I'm not sure.

 

The key is getting them to sit well, and allow for the adjustment. And a good Line Up screen to allow for accurate alignment. Always best to make sure they have the same lenses- I've done it before with the same projectors, different lenses and it was a .

[MikeR]

same projectors , different lenses ? Probably impossible to get a perfect result especially when you bear in mind that even lenses claiming to be x mm focal length probably aren't.

[Pete McCrea]

It did work. Not great, but passable- same focal lengths, but by different manufacturers. To get great results you need the same lenses as MikeR has said.

[MikeR]

Not just the same lenses but optically identical lenses which you wont get without hiring good, in "", lenses. 0.8, 0.79 & 0.81 are not the same alas.

[Jivemaster]

Give yourself the best start by getting the ambient light down as much as poss.

[MikeR]

Using a black stripe fresnel screen if possible may also help.