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Manual zoom, 1.30x projector (vs smaller image): CIH too much of a hassle?

1636 Views 12 Replies 5 Participants Last post by ScottAvery, May 26, 2021

smania

Discussion Starter · May 21, 2021

I'm trying to get as much info as I can before buying my first projector. I see the point of CIH: maximize height for the seating distance and always use that height no matter the aspect ratio.

How much of a hassle is doing CIH with a projector with manual zoom AND a that can't totally go 1.78 -> 2.35 (I would miss a couple of centimeters vertically going 1.78)? (I think I'm going to get a Benq ht3550)

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bud16415

· #2 · May 21, 2021

With ceiling mounted it gets old fast and when you are close to the extreme ends of the range placement is hard to get right.

I made a rig that slides the projector on the ceiling and inclined track. the slide gives me zoom and the incline offset. The focus comes along for the ride as the DOF is adequate over the range I move it. I also counterbalanced the whole thing so it moves really easy. I can zoom well past CIH+IMAX and the move only takes about 10 seconds to do manually.
Climbing up and down to make projector adjustments isn’t good.

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Josh Z

· #3 · May 21, 2021

smania said:
How much of a hassle is doing CIH with a projector with manual zoom AND a that can't totally go 1.78 -> 2.35 (I would miss a couple of centimeters vertically going 1.78)? (I think I'm going to get a Benq ht3550)

That BenQ is a DLP model. In addition to limited zoom range, you should expect it to have a very high angle image offset. Meaning, if you table-mount it, the image will be projected high on the wall. And if you ceiling-mount it upset down, the image will be low. Although the HT3550 claims "vertical lens shift," I would not expect it to move the image much, maybe an inch or two. (In fact, the Projector Central review confirms as much.) This makes placement options difficult in general, though workable if using a static aspect ratio once you find the right mounting angle and throw distance. But the combination of these factors makes CIH with zoom virtually impossible.

If possible, the best solution for this projector would be to let it fill the width of a 2.35:1 screen at all times (spilling letterbox bars over the top and bottom) and use either an OPPO UHD player or Lumagen video processor to scale 16:9 content down into the middle of the frame. Unfortunately, that's an expensive solution. The OPPO player is long out of production and Lumagen processors are big bucks. The added expense to do that would negate any savings from buying this inexpensive projector. You'd be better off investing in a better projector with more (and automated) zoom range and lens shift.

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jsmith967

· #4 · May 21, 2021

smania said:
I'm trying to get as much info as I can before buying my first projector. I see the point of CIH: maximize height for the seating distance and always use that height no matter the aspect ratio.

How much of a hassle is doing CIH with a projector with manual zoom AND a that can't totally go 1.78 -> 2.35 (I would miss a couple of centimeters vertically going 1.78)? (I think I'm going to get a Benq ht3550)

One of my first projectors was a situation like this. It was a Sharp DLP (3000 something). On 16:9, it was a little too big, just as you describe.

My .02: do it. even thought 16:9 was a little overscanned, the black velvet of the screen absorbed it. Then when I zoomed out to 2:35, it was amazing. Notice that this is a good deal less complicated that Bud's solution, as I didn't have to build any track. However, it did come with the caveat of some overscan. The negative of the overscan is far outweighed by the positive of the scope screen experience.

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smania

Discussion Starter · #5 · May 21, 2021

Thank you everyone for the replies.
I didn't think about the implications of vertical centering. I assumed that once the image was centered there would be no re-centering while zooming. Is that not the case then?

The reason I'm thinking about that projector (ht3550) is that I only have a 326cm length available. Viewing distance 270cm (roughly).
Something with lens memory (5050ub) is much bigger and longer throw. So I would end up with a smaller image, say 95" (if I can make a hole in the wall on the projector side...) vs 105" or even more on the ht3550.

Would you go with the smaller image CIH vs bigger CIW?

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Josh Z

· #6 · May 21, 2021

smania said:
I didn't think about the implications of vertical centering. I assumed that once the image was centered there would be no re-centering while zooming. Is that not the case then?

That's not the case if the projector has a high offset. When you change the zoom, the image will move vertically.

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bud16415

· #7 · May 21, 2021

You need both zoom, vertical offset and focus every time you make a change. The specs on the projector you are looking at are quite similar to mine. Even doing manual you will be short on zoom as you know and also short on offset.

Like you I wish there were more short throw projectors that will give you scope and IMAX immersion in a smaller room with single row seating and the projector roughly directly overhead.

I also wish they built this type projector with built in scaling and digital image shifting. I know it is possible because my first projector 20 years ago had these features.

With 4k now I don’t see scaling as being much of an issue. I look at it this way if the pixel density and unit brightness is good enough for scope and IMAX then using the center of the image field will have the same pixel density and same unit brightness so what is not to like.

I experimented doing variable presentation using my projector and a HTPC approach. I was processing my video thru my laptop and using some free media players to scale the images and also frame what wasn’t used in 0,0,0 black. It worked great other than my laptop was older and had trouble with HD media. I considered building a PC to do it all when I came up with the idea of the ceiling inclined slide married with a DIY stealth painted screen wall. The idea of a stealth screen wall is there is no AR and no boarder and also no screen size. So I can easily follow CIH+IMAX conventions or deviate to CIA constant image area or any method in between. Self masking allowed my slide device to not have to be so accurate.

As a side note even though I don’t need to use the vertical offset on the projector I still do use it. I have my slide height set for being on the low end of the offset for normal seated viewing. When I’m feeling lazy and switch to full reclined I take the projector offset and lift the image higher. Not having a frame around the image lets you do that.
I wish the projector makers would figure out what people really want.

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smania

Discussion Starter · #8 · May 22, 2021

Again thank you for the replies.
What about my last question:

Would you go with the smaller image CIH vs bigger CIW?

I think the difference would be something like 95" vs 105" (could go even bigger) at 8'-9' viewing distance

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ScottAvery

· #9 · May 25, 2021

Your last question is really a personal, almost religious question. Most regulars in this forum are here because CIH is important to us, and we are willing to go through all the hassle necessary to make it work. Automation is VERY helpful for this. It can be done manually but unless you set up a slide like Bud, you are looking at a lot of time every time you change aspect ratio.

There are plenty of people who cannot understand the desire to have a CIH implementation and will argue until they are blue in the face that they we are wrong for making 16x9 so small! Well, only you can decide which side of the fence you are on.

CIW is easy, it takes no work at all unless you want top/bottom masking, or you want ratios smaller than 1.78 to be zoomed up. CIH takes effort, and committing yourself to doing it without automation may just ruin the experience for you. I would bet you can find an Epson or JVC that will meet your needs at a price you can afford. They both have motorized zoom/focus/shift models that are sold used or refurbed.

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bud16415

· #10 · May 26, 2021

ScottAvery said:
Your last question is really a personal, almost religious question. Most regulars in this forum are here because CIH is important to us, and we are willing to go through all the hassle necessary to make it work. Automation is VERY helpful for this. It can be done manually but unless you set up a slide like Bud, you are looking at a lot of time every time you change aspect ratio.

There are plenty of people who cannot understand the desire to have a CIH implementation and will argue until they are blue in the face that they we are wrong for making 16x9 so small! Well, only you can decide which side of the fence you are on.

CIW is easy, it takes no work at all unless you want top/bottom masking, or you want ratios smaller than 1.78 to be zoomed up. CIH takes effort, and committing yourself to doing it without automation may just ruin the experience for you. I would bet you can find an Epson or JVC that will meet your needs at a price you can afford. They both have motorized zoom/focus/shift models that are sold used or refurbed.

I haven’t looked at all the projectors with programmable features and what ones will provide the size image needed with a short throw also. It is a problem the market really hasn’t addressed very well. Scaling or moving the projector is the two best methods I have tried. It would be great if scaling was built into the projector just like keystone is.

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ScottAvery

· #11 · May 26, 2021

smania said:
The reason I'm thinking about that projector (ht3550) is that I only have a 326cm length available. Viewing distance 270cm (roughly).
Something with lens memory (5050ub) is much bigger and longer throw. So I would end up with a smaller image, say 95" (if I can make a hole in the wall on the projector side...) vs 105" or even more on the ht3550.

The throw limitation you have is why I went with a horizontal expansion anamorphic lens. It lets me do scope at exactly the same throw as the 16x9. The lens makes the image wider than the projector can do alone. Without using a lens you can consider using a mirror to create additional throw length.

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bud16415

· #12 · May 26, 2021

I started off with a mirror setup along with a level slide. If you do a mirror and a lens you will be looking at both some DIY construction and time along with an expense of the lens.

When I had the mirror and slide I found with making the mirror angle an adjustable feature it would work perfect as a vertical offset adjustment for the amount needed.

I have never used an A-lens but I thought short throw projectors didn’t work as well with them.

In a nut shell the makers of shorter throw projectors are selling them as large TV replacements for smaller rooms and don’t think anyone will be doing anything other than CIW or TV like presentation. Like I said I had a projector almost 20 years ago the Sharp XR-10X that allowed CIH projection with a scaling feature. Why they don’t offer it on these projectors is a mystery to me.
Moving the projector in the end was the best and easiest way for me and it uses the most pixels it can without a lens and more importantly when I zoom down of 16:9 TV the brightness goes up and that counteracts some ambient light we like for TV viewing.

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ScottAvery

· #13 · May 26, 2021

bud16415 said:
I have never used an A-lens but I thought short throw projectors didn’t work as well with them.

You are correct. I mentioned it because he said he would consider an epson/jvc with memory if it wasn't such long throw. Adding a lens let me use a JVC 25% closer.

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