Screen Size and Zoom

[swdude12]

Im building a screen and i have a distance of 12 ft from the lens to the wall. I have the IN72. I did the calculator and they give me a min and a max. Is the max with the zoom all the way up? My question is should i build the screen to the Min? what is going to give me the best picture? does the zoom all the way give a worse picture?

[wbassett]

When you use zoom the fL drop, usually a lot the higher the zoom setting is.

[swdude12]

So by making the screen at no zoom the quality of the picture will be greater?

[wbassett]

Well it will be brighter. I use my zoom some, probably somewhere around half and the picture is plenty bright enough. Just keep in mind that zoom does change the fL is all I was saying... if you have lower lumens it can drop off a lot at max zoom...

[bud16415]

The amount you loose will vary dependent on what projector you are using and also the range of the zoom. Most of the DLP’s have a pretty small zoom range and you wont notice much if any drop. It’s a good idea to try and stay someplace in the center with a projector like this as you will need some of the adjustment to get the image to fit your screen. Also some projectors when fully zoomed will produce slight distortions when fully zoomed.

Along with projector model you need to think about placement based around seating etc. in my case the projector ended up straight over head and that’s not a problem. I’m not sure if there would be a distraction if it was mounted ahead of my seating area or not. But something to think about and if you have the range maybe factor in.

[swdude12]

Oh sweet thanks for the input i will start building my screen asap.

[caddy-shak`]

I'm looking at buying the panny AX100U
According to the calculator, to get a 126" diaganol picture, my throw range is between 12 - 25'.
If I'm reading it correctly, with no zoom (1x) I need to mount at 25'. If I move the projector closer to the screen, I will need to zoom to achieve the same picture size?

So, is it better to zoom or not to zoom? What are the pros and cons?

[stevem911]

Im building a screen and i have a distance of 12 ft from the lens to the wall. I have the IN72. I did the calculator and they give me a min and a max. Is the max with the zoom all the way up? My question is should i build the screen to the Min? what is going to give me the best picture? does the zoom all the way give a worse picture?

I also have the IN72, 17 feet back with full zoom to make it bigger.(120") I zoom it in and out and dont notice any picture loss in terms of brightness or just overall quality of the pic. Im sure if i used fancy tech tools one might say there is brightness loss i suppose. But thats the same theory that some speakers are more "true" on the sound.....but my ears cant hear it so who cares.....ZOOM AWAY...in my opinion.

[Wet1]

So, is it better to zoom or not to zoom? What are the pros and cons?
If you want to only consider one screen size @ min vs max throw... Generally speaking: at min throw you'll get a brighter image, at max throw you'll get better CR.


Regarding the original question, yes... smaller pictures usually mean better PQ. The picture looks sharper, brighter, and defects are not as noticeable on the smaller image. But, a smaller screen certainly has it's downsides as well as they are generally not as enticing as larger screens.

:)

[graffixjones]

I'm looking at buying the panny AX100U
According to the calculator, to get a 126" diaganol picture, my throw range is between 12 - 25'.
If I'm reading it correctly, with no zoom (1x) I need to mount at 25'. If I move the projector closer to the screen, I will need to zoom to achieve the same picture size?

So, is it better to zoom or not to zoom? What are the pros and cons?

The thing to keep in mind too is that you're going to lose fL no matter whether or not you zoom or locate the projector further away and use less zoom. The key to fL is the square footage covered by light, and the larger your projected image, the less lamberts you have per square foot, and thus it will appear dimmer.

I've noticed no difference in picture quality in using the zoom versus locating my InFocus IN72 further from the wall (I didn't see the change in brightness vs. CR as mentioned by Wet1). The fact that the light travels through all the zoom lens elements whether or not you're actually 'zooming' means that you can expect the same picture quality unzoomed as you would when zoomed (except possibly at the maximum zoom where the picture can get a bit soft at the limits of the lens' mechanics).

The only time you'd notice a difference in the quality of the projected picture would be using a fixed focal length lens (non zoom) and accurately positioning the projector at a fixed distance from the wall to get the desired picture size. A fixed focal length lens has fewer elements (i.e. internal glass lenses) and thus there is less abberation in the enlarged image, and less light fall-off due to the light traveling through the inner lens surfaces.

However, this would not be ideal, because, as you've discovered, with a fixed focal length lens you'd have to have the projector 25' from the screen, and for the majority of households, this isn't practical. Most probably have a 10' to 15' limit on distance, so adding a zoom lens to the projector addresses this problem.

So, your best bet is to locate your projector somewhere between the maximum distance, and 3/4 of the way to the minimum distance. In your case that would be somewhere between 15'4" and 25'. Or you could always settle for a bit smaller screen size, but who wants to do that? ;)

So really, the only 'pros and cons' you have to worry about are screen size vs. picture dimness, rather than the pros and cons of zoomed vs. unzoomed pictures. One is a very real tradeoff, whereas the other is fairly negligible in the overall picture, IMO.

[jimwhite]

"However, this would not be ideal, because, as you've discovered, with a fixed focal length lens you'd have to have the projector 25' from the screen, and for the majority of households, this isn't practical. Most probably have a 10' to 15' limit on distance, so adding a zoom lens to the projector addresses this problem."

what I wouldn't give for a projector like my HD1000u with a 25' throw!!!.... my room is 25' across and it would be PERECT!... too bad I can't start popping out lenses :D

:cool: