Does Zoom use affect PQ? - AVS Forum
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post #1 of 15 Old 11-10-2002, 09:37 PM - Thread Starter
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Hi all! I am planning on purchasing the HS10, and following the excitement closely! Given that a nice person has posted throw ratios I am measuring my basement for placement. I have a 10' 3" wall to project on, so it appears largest dimension is 120" diagonally. It looks like it will be HUGE! I might want to vary it down to about 100" diagonal, possibly...time and testing will tell.

Here is my question: If I place the PJ approx. 15' 6" back, to get a 120" screen, will using the zoom at max affect the picture quality? Would I be better off with no zoom and a 100" screen? Or placing it at 18 or so feet back, no zoom, to acheive 120" that way? I am assuming that zoom increases the diagonal measurement, or am I all wet and it decreases it? I have not owned a PJ before, so much is new to me, but I have been researching for over a year, and finally it seems the right PJ is in ....almost....reach.

Any input from this wonderful forum is appreciated.
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post #2 of 15 Old 11-10-2002, 11:53 PM
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It all depends on the projector's lens quality. I have noticed when using these projectors that some will display a noticeably inferior image at maximum WIDE. Zoom in a little and the picture improves. Zoom decreases image size.
Something to check out before you purchase.

ziggy
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post #3 of 15 Old 11-11-2002, 06:12 AM
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There have been several posts/threads suggesting that zooming the picture to its smallest size is the best for eliminating/reducing pixelation in LCD projectors.
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post #4 of 15 Old 11-11-2002, 06:33 AM
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Mobius1,

I'm no optical engineer but common sense suggests that quality will go down as you get closer to the outer part of the lens. So keeping the beam as narrow as possible would be best. I have an ISCO II also and saw in a post sometime ago that keeping the beam narrow into this lens was best for the same reason. My experience has proven this to be good advice.

Good Luck!
Peter
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post #5 of 15 Old 11-11-2002, 07:45 AM
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Depends on the quality of the optics, but youre going to pay more to overcome the possible issues. You have more lenses and that can reduce light output somewhat as well. Its a nice feature to have though. You dont have to be so exact when mounting the pj. I got lucky and my non zoom LT150 happened to mount right where I needed it, but it would have been a pain if it didnt.

Funny, I used to think my 32" tv was big. Now my 92" screen is starting to look small !!
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post #6 of 15 Old 11-11-2002, 09:09 AM
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And then there is the perceived screendoor to take into account. On my friends Epson TW-100 we found that the picture looked more smooth and "film-like" when it was zoomed out max (widest picture).

When it was in the socalled sweet-spot, in the middle, it seemed to be much easier to see the pixels, and the allready existing MPEG artifects got exagerated.

Screendoor got less intrusive on when zoomed out.

Regards,
Tore K.
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post #7 of 15 Old 11-11-2002, 09:22 AM
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This all depends on the definition of PQ - do you want to accurately see what should be there or blur out/distort (especiall at the edges) what you would rather not see (screendoor and artifacts)? A decision, Mobius1, we each have to make for ourselves. Best advice is to play with this on some projectors.

Peter
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post #8 of 15 Old 11-12-2002, 10:16 PM - Thread Starter
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Thank you to all for your responses...for me this is still a good question and I undoubtedly will have to tweak. I wish I were in a location where I could play with other PJs but feel I am in a similar situation to my Canadian neighbors, still in the US but close to the border and, as with some, lacking in U.S. big city options. The trade off is the great scenery! As for PQ, I would of course like to optimize: no screen door and artifacts, but no blurring either. I will have to take my chances on the HS-10 sight unseen, there is no other way, so I am quite reliant on the good advice of more advanced members.

Mobius1
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post #9 of 15 Old 11-13-2002, 06:23 AM
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What do you mean by zoom out....Example. If I have a choice between 9-12 feet to mount the projector to get a 92 inch image, do i choose the 9 or the 12 feet?

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post #10 of 15 Old 11-13-2002, 10:35 AM
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Joe I think he means by zoomed out is that the zoom lens is set to its minimum (i.e no zoom) on the projector. Ive experiemented with 3 or 4 different XGA projectors and their zoom lenses and Ive found a significant reduction in screendoor when using no zoom on each of the projectors. It does mean though that the projector sometimes needs to be very far back from the screen but I personally think this helps the uniformity of the picture and also the blacks in a little way.

Most of my friends who have seen my projectors would roughly say that with mid zoom on a projector they see screendoor from about 8 feet and about 4 feet with no zoom (xga class projectors and 114" diag screen). Oh and I never mentioned this trick I found to any of my friends to see if they noticed and they pretty much all commented within the first 10 minutes of watching a film that screendoor had completely gone and the picture seemed more film like than digital.

YMMV
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post #11 of 15 Old 11-13-2002, 10:52 AM
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Quote:
Originally posted by jrwood
Joe I think he means by zoomed out is that the zoom lens is set to its minimum (i.e no zoom) on the projector. Ive experiemented with 3 or 4 different XGA projectors and their zoom lenses and Ive found a significant reduction in screendoor when using no zoom on each of the projectors. It does mean though that the projector sometimes needs to be very far back from the screen but I personally think this helps the uniformity of the picture and also the blacks in a little way.

YMMV
Well, it seems I misunderstood the use of the zoom. I thought of zoom as magnifying the size, hence placing the PJ closer to the screen. I'll also need to do a bit more experimenting before making the final decision what gives the best picture. IMHO at least, the middle setting did not seem to give the best result..

Regards,
Tore K.
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post #12 of 15 Old 11-13-2002, 08:33 PM
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Mercer, I think you have it right. Zoom will make the image larger, meaning that for a given screen size, you can place the projector closer. If you use minimum zoom as some suggest to minimize screen door, then you will have to move the projector farther back in order to get the size you want.
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post #13 of 15 Old 11-13-2002, 08:58 PM
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Yes from my experimentation Ive found that I see screendoor from about 8 to 10 feet on a grey screen with zoom set to the middle, with no zoom I see screendoor from about 4 feet (the projector is 20 feet from the screen - so this may help screendoor a lot ?, plus grey screen helps imho).

Mercer I think the term zoom is a bit confusing, as when you think about it when you have set the zoom to its minimum then your actually just using in theory the lens of the projector, when you start using the zoom lens then you are magnifying the projectors image somewhat (and in my opinion) making the gaps between pixels further apart and causing more screendoor.

YMMV
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post #14 of 15 Old 11-13-2002, 09:16 PM
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I've been corrected on this beforeand I think the generally accepted case for zoom is the opposite of what is intuitive to me, which is that increasing zoom makes the image bigger. Projectors are rated as having things like 2.1 to 2.6 zoom lenses. In that case, I believe the 2.6 would be the maximum zoom, which would make the distance from the screen be 2.6 times the image width. I think that is what people are used to with lenses and in that case increasing zoom actually makes the image smaller on the screen.

--Darin
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post #15 of 15 Old 11-14-2002, 12:50 AM
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I don't use the zoom feature.
I just don't zoom, move the projector back until I get the screen size that I want.
Voila, mount the projector in the ceiling.
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