Axiom Home Page Forums General Discussion Home Theater Screen size -- how big is too big ?

There are Horizontal and Vertical Stretch lens designs. Mine is a Horizontal design, so first my theatetek software vertically stretches the 2.35 image to get rid of the black bars, then I turn my knobs on the lens which horizontally reformats the image to fill the 2.35 screen. The nice thing about a Horizontal design is that you can get a pretty big image from a relatively shorter throw distance.

A vertical lens actualy squeezes the image down to form the same 2.35 image but the end result is a smaller size from the same throw distance. Most people with vertical lens have longer throw projectors.

I’m still trying to figure all this out myself, so I really don’t know squat. One thing that I continue to see referenced at AVS with these lenses is throw distance. Apparently, some lenses don’t do so hot with short throws under about 15 feet. You might want to do a little digging on the lens capabilities a bit before you commit yourself into incorporating one into your set up. The lenses recommended for short throws are pretty expensive I think. (above 3500 US).

When you get all this figured out John, let me know what you come up with eh? That way I can just copy what you do. My set up is about the same as yours (seating and throw distances).

Oh, you might as well start looking into video processors too. That seams to be the norm with folks who use anamorphic lenses.

You want to take your throw distance/width (width of original unstretched image) = ratio of compatiblity.



For the most part anything over 1.3 should work with small pincussion effect. In my case with a 13ft throw on my Z2 and 7.57ft width (16:9) gave me around a 1.7 ratio. Another important factor is that you want to place your projector so your using as little of zoom as possible to get your desired screensize. The less zoom you use the less artifacts.



Obviously a longer throw distance would end with a higher ratio, and potentially less distortion, but I can tell you my picture looks very nice and I have very little pincussion at 13ft with my short throw Z2.

Ahh... the width of the UNSTRETCHED image. That makes a big difference... and makes more sense now that I think about it. I'm probably going to end up with the projector 14 feet away and a 6 foot unstretched width, so should be solidly in the green.

My new Z4 projector has a "zoom" setting which, at first glance, seems to automatically expand a 2.35 movie to full height. Running it with a 480p input right now -- I know some projectors won't zoom a 720p input the same way they do with 480, and others won't zoom an HDMI input, but I'll see how far I can go without a video processor or HTPC.

Yes, Randy, I can see from my own typing that some time in the last couple of hours I gave in. Not gonna buy any more toys until I sell the old house though.

When I had my Z2 mated with the Panasonic S97S upconverting DVD player, I could use the Zoom button to cycle through the options. One of them would take the 480 image of the 2.35 movie and vertically stretch it to get rid of the black bars. The width was not changed so everything in the movie looked skinny. Then you would use the lens to make it look normal again. However, with the Z2 and S97S, I was unable to use this zoom option over DVD/HDMI, the signal was locked.

It is my understanding that the Z4 WILL stretch(scale) an incoming HDMI signal from either a upconverting DVD player or a HTPC that is running DVD software that does not have a built in stretch option like Theatertek.

I know at one point someone pointed me to the part in the manual where it talked about the additional ZOOM options on the Z4, that the Z3 or Z2 did not have.

The HTPC route would most likely cost more to build, but personally I think the scaling ability is much better as you can set your resolution to natively match that of the projector 1280 x 720. My HTPC has a Nvidia 6600GT which does a great job.

You may find it easier just to buy an OPPO or some other good upconverting DVD player. I'm not sure what will happen with these new HD DVD players in regards to 2.35 movies.

This stuff makes my head hurt.

Alright, I am starting to get confused here. I am planning on having a 16:9 screen, you guys are saying you are going to have a 2.35 screen? So what do you do when you have a full 16:9 image?

-Robb.

set the lens to "pass-through" and mask the sides of the 2.35 screen (using curtains etc...), like they do at the movies.

I have a 16:9 format screen and every time I watch a movie, I wish I had something to mask off the top and the bottom of the screen, but I haven't come up with a low cost, yet nice looking, way to do it. If I had a 2.35:1 screen, then the issue would be bars on the right and left side instead of the top and bottom like on my 16:9 screen. Those would be easier to just hang some sort of mask on each side (thanks to gravity) and adjust them as needed. SkyHawk is right on the mark. That is what movie theaters do.

For my 16:9 screen, I will have to find something rigid, yet light, to put over the top and bottom bars. Not that easy over a 8' span.

Randy,

AVS is having a power buy on the new panimorph lens. http://www.panamorph.com/UH350Program.html

I was tempted to buy one, but am leery if it will work in my situation very well. (12' seating distance and an 11.5' throw). What do you think???

In a 2.35 constant height setup, all Aspect Ratios keep the same height, the only thing that changes is the width, which is much easier to mask if you desire. At this point in time for 16:9 or 1.85 DVD's the side bars don't even bother me.

Another benefit of this setup using an anamorphic lens, is that you reclaim the 33% lost by the black bars, which in turns gives you upto 20%+ more brightness. When you watch 2.35 movies on a 16:9 screen, your giving up 33% of the pixels to the bars.