Projector Zoom Funtion

[rocketrazor]

Hi Guys,

When looking at projectors I'm trying to understand the throw distance and zoom funtions. I think I get throw distance, but what I am a little unsure of is the zoom. My understanding is there are two ways to make a projected image larger, increase the distance between the projector and screen or use the zoom funtion. When using the zoom function does it distort the image? For example if a projector is 3.5 mtrs from the screen and left on 'normal' zoom it could project a 100" image, using the zoom function this can be increased to 150". So is the quality the same on the 100" and 150" or by using the zoom have you compromised the image quality?

Cheers

Rocket

 

[spiny norman]

Really depends on the quality of the lens, but in general zoom lenses tend to get worse as they are zoomed out (ie to a shorter focal length) to give a larger image size for a given throw.

 

[rocketrazor]

right, so it would be better to have a longer throw then a greated zoom? ie move the projector to 4.5 mtrs for 150" and no zoom rather than 3.5 mtrs and zoom for 150". Or stick with 100" at 3.5 mtrs

 

[spiny norman]

right, so it would be better to have a longer throw then a greated zoom? ie move the projector to 4.5 mtrs for 150" and no zoom rather than 3.5 mtrs and zoom for 150". Or stick with 100" at 3.5 mtrs

It's always a compromise: longer throws mean greater light loss. Best by far to choose a projector/lens combination able to give the image size required at the given throw without having to zoom the lens right out.

 

[abacus]

Projectors have a very small zoom range; therefore, it would have to be a really rubbish lens to notice any difference between the minimum & maximum zoom, so I wouldn’t worry about it.

Hope this helps

Bill

 

[macdiddy]

my projector has a fairly short zoom range and I was lucky that when I mounted both it and the screen on the ceiling it only needed a small adjustment for the image to fit, to me there was no difference in image quality when zooming to fit.

*music2*

 

[spiny norman]

it would have to be a really rubbish lens

Past experience suggests that some are.

 

[Xanderzdad]

Most commonly any lens suffers at the extremes of it's zoom - whether zoomed in or out.

Aim to keep it somewhere in the middle. But in the real world even an average projector has such a short zoom (as mentioned earlier) that you would struggle to notice.

I only ever detected a difference on a projector with a particularly broad zoom 'range' - it went very, very slightly less clear at the extreme zoom.

The real enemy is digital zoom or digital lens shift (allowing for offset projector positions).

 

[spiny norman]

But in the real world even an average projector has such a short zoom (as mentioned earlier) that you would struggle to notice.

As I said, I was speaking from past experience – maybe lenses have got much better these days.

The real enemy is digital zoom or digital lens shift (allowing for offset projector positions).

Absolutely agreed!

 

[rocketrazor]

cheers guys