Question CIW v CIH v CA for my room?

Discussion in 'Projectors, Screens & Video Processors' started by mattkhan, Mar 31, 2018.

  1. mattkhan

    mattkhan
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    I currently have a JVC X3 with a 92" electric 16:9 screen with throw & seating distance at ~10ft, scope content is played in a CIW style so that means you get ~87" diagonal for such content and screen height goes down ~45" to ~33".

    For various reasons I want to build a wall, put a fixed frame AT screen on it and the speakers behind. What I wanted to achieve (maintain existing 16:9 size, go big for scope, bring screen down a bit, put speakers behind screen) doesn't seem possible hence this thread to see if I'm missing something and/or to help choose between the options.

    Any comments/opinions are welcome. I'll start with my current conclusion, details for each option are further down the thread.

    Which one works best in my case?
    The details behind this are further down the thread.

    It seems like the following ranking makes sense ignoring budget.

    1) Anamorphic CIH
    2) CIW
    3) CA
    4) Zoomed CIH

    The rationale being that anamorphic CIH and CIW is the only ones that really deliver what I was after, i.e. go big for scope. I imagine CIW is the practical choice though as I assume the lens required will cost a serious amount of money.

    CA is seems not enough of an improvement over today while zoomed CIH seems like way too much of a compromise as I don't have the throw/zoom available to make that work.

    Current Setup

    A picture tells the story so this is the current setup except for the projector type (which is the sort of pj I intend to buy as part of this upgrade)

    i.e. screen diagonals of about 92" 16:9 and ~87" scope

    upload_2018-3-31_10-23-8.png

    Usage is probably 50:50 16:9 vs scope content btw, I don't really want to sacrifice one for the other but if I had to choose then 16:9 will lose out.

    Constraints
    * bottom of the screen can be no less than 30" from the floor
    * minimum screen height (i.e. unmasked) has to be at least 90cm (~35") though the more the merrier (I have relatively big speakers)

    CIW
    Leaving everything as is except shifting the image more and max'ing the zoom looks like it gives me ~101" 16:9 and ~96" scope

    The scope screen will be ~37" high

    Screen area is ~20% bigger than the current setup

    upload_2018-3-31_10-38-23.png


    Zoomed CIH

    This gives ~96" diagonal scope but only ~75" diagonal 16:9
    screen position is slightly higher than the CIW version (bottom of scope screen will be ~3" higher,
    bottom of 16:9 screen will be ~9" higher) though both at still lower than the existing setup

    upload_2018-3-31_10-42-52.png

    Anamorphic CIH

    This gives ~128" diagonal scope and ~101" diagonal 16:9, i.e. same size 16:9 as the CIW option but a markedly bigger scope screen

    screen position is on target

    upload_2018-3-31_10-45-28.png

    CA

    I'm not 100% sure this is the accurate way to calculate it as I can't just plug the numbers into a calculator but I think the maximum 2.05 image size available is ~86x43", masking the sides for 16:9 yields about 86" diagonal while masking top/bottom for scope yields ~93" diagonal for scope. This is about 2 sq m screen area in each case.

    This is about 15% smaller than today for 16:9 and about 15% bigger for scope.
     
  2. Peter Parker

    Peter Parker
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    I prefer using an A lens over zooming, even with UHD disks. If you leave the lens in place at all times it can allow quicker and easier switching to 16:9 using the pjs own controls - you lose some horizontal res, (it scales the width from scope to 1.85) but with 4K or fauK you only lose out on 16:9 UHD movies. Zooming often isn't mm accurate and focus can drift as well. An external scaler could also be useful. Scope should be the largest format other than IMAX so i would always try and maximise that presentation over the smaller formats.

    A lenses are expensive if you buy new but can be a lot cheaper if you can find one used, but that is the route I would go if you can't get a big enough scope image using the zoom due to throw limitations.

    I'm using an A lens and I'm not far from you, so if you wanted to pop round and have a look, drop me a PM. I'd also be interested in your speaker choices etc. I'm also running a baffle wall if that's what you intended to do.
     
  3. KelvinS1965

    KelvinS1965
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    Peter Parker beat me to it, but I did just want to add a comment: Given that you must be using quite a bit of zoom in the projector to start with, then you will likely suffer more pin cushion effect than I used to when I had my Isco II (same model as PP). You may even have issues with vignetting with something like an Isco II as I found when I tested mine at a shorter throw for a forum member. You might need a bigger lens such as an Isco III which is serious money.

    Even then you may need a curved screen for that throw distance unless you can live with over-spilling into the screen borders to hide the curved corners of the image.

    I used a lens, but then compared my old X35 with the lens against my X500 (both calibrated via my Lumagen) and felt that I didn't gain anything through using the lens. This was partly because I'm at a very long throw, which is good from a pincushion point of view, but also means that I gained back the light output when I zoomed, so the lens only gave me an extra 1% light output compared to zooming.

    PP has tried his lens on his Epson and has a different end result. So it is really one of those things that you need to see for yourself, which is handy given PP's offer to visit.

    I take it that you used the X790 screen calculator because it should be the same as your X30, rather than because you're looking at getting one?
     
  4. jfinnie

    jfinnie
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    You could keep as big a 16:9 screen as possible, and improve your vertical viewing angle for scope content using a video processor such as a Lumagen (shameless plug!) to shift the scope image area to the bottom of the screen. Then drop a top mask over the top of the screen, which is easier than doing top and bottom masks. With the mask down you can instantly zoom out the image for bluray menus etc using a remote button (again via the Lumagen). There is autoaspect stuff in the Lumagen but it isn't perfect.

    This is what I do at the moment at home and it works well.

    Edit: in fact, adding a Lumagen would also be of benefit with the CIH option as again you can shift the active image area to the bottom of the projector's panels (instead of it having to be in the centre), which helps with the lens shift range it seems you have issue with.
     
    Last edited: Mar 31, 2018
  5. mattkhan

    mattkhan
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    I am HTPC using jriver/madvr so I think I can do anything I need to here

    this intuitively feels right to me and is why I'm wary of going the bigger CIW route, it might just be because I'm used to it but the current 16:9 size feels about right to me.

    Your post also led me to find some earlier threads

    Too short a room for Anamorphic and/or CIH?
    Answered - Max width over 3m throw

    which also seem helpful

    thanks for the offer, I'll take you up on that as I am also planning a wall.

    I did some initial research into lens this afternoon and they all seem to recommend a bigger throw ratio then my max zoom ratio (which comes to about 1.33), more like 2-2.5 seems recommended though ~1.5-1.6 sounds like it should be ok.

    Some questions I had on this

    - am I right in thinking that the quoted throw ratio for various lenses is talking about the no lens ratio? i.e. throw / 16:9 image width?
    - any issues using vertical shift with an a lens? this occurred to me as a possible issue but couldn't find any commentary on it so I guess it is ok

    I intend to upgrade and it seems like a 7x00 would be the model I'd probably go for hence the choice in the calculator.

    Upgrade is because I find my current x3 is a bit dark really so I doubt it would cope with a bigger screen and it tends to lose it a bit too much as the bulb ages. I have all the kit to recalibrate as it ages so that's not a problem in itself but we put about 100hrs a month on the bulb these days (no TV) so a bulb is currently lasting ~15 months before I think "probably need to change this" (so add 3-4months before I get round to it cursing every time I watch a film that's has lots of night time content!).

    thanks, I am pretty sure my PC can do all this, will doublecheck that.
     
  6. mattkhan

    mattkhan
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    overall it seems like the option that delivers what I want, and which also obeys the laws of physics, is keeping approximately the current zoom (means throw ratio of about 1.5) so as to maintain the current 16:9 image then adding an a lens to produce the scope image

    if so, next step is to research a lenses...
     
  7. Peter Parker

    Peter Parker
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    Even better IMHO - I used to run an HTPC when I first started with pjs and I think it's a great solution for many reasons, though not for everyone.

    If your current 16:9 seems perfectly fine, then scope is just wider and more immersive which is the intent of the format.

    I take it you'll be building your own speakers - compression drivers and waveguides?

    Yes, use the 16:9 image as the one you base the throw on. Longer throws are better as they give less pincushion, but that can usually be hidden in the black borders of the screen.

    You can use lens shift (I am), you just have to angle the A lens down to match the beam of the projected image, it's not that difficult.

    Another much cheaper option is to use a simple camera add on zoom lens. There are some threads about them here, and I think RickyJ is looking at supplying them too. They zoom both horizontally and vertically just like the zoom on your pj so can increase the size of the image further if the pj is limited due to throw. That can give you the option of CIH+IMAX, using the HTPC (shrink method) for the CIH part, and then remove the top and bottom masking (16:9 screen) for the IMAX movies. I think that the bottom of your image and your screen height means that won't be that practical though, so won't work that well.
     
  8. mattkhan

    mattkhan
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    built, see AE TD10H/BMS4550/SEOS10 Build for details though the thread title is wrong and it's a bit of a long thread :) I currently have 3 ways at the front with a seos12/bms4550 and a pair of ae td12m under them, surrounds are based on a radian 5208 coax.

    I'm going to try out a synergy horn this year though using a tymphany cd on a seos15 with a celestion tf0410 mid firing into the horn and a pair of 6" faitalpro woofers arrayed underneath. This will be underpinned by a bms 15n840 to allow it to play down to 40Hz at HT levels while sharing the LFE load. I can then use it to smooth things out along with the main subs (NF and FF). Some details on the synergy in A MEH for 2018 (haven't really got anywhere with this yet, weather is not conducive to building stuff in my shed). The main sub is the one that puts the limit on the screen bottom as it is intended to go in the middle under the screen and is ~700mm tall (details in Rebuild time)
     
  9. Peter Parker

    Peter Parker
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    I like the DIYSoundgroup stuff and wish it was easier to get the designs here. I'd also like to do what you're doing with regards to designing and building my own speakers as it looks quite satisfying getting it all working just right etc.

    I've just built myself some mini ewaves based on a design by Zilch from a few years back. It's only a two way with an 18 sound XD125 CD and WG and Eminence beta 8A woofer, but I do like the sound they produce over domes. The tweeter response is pretty flat but getting the woofer measurements seems to depend a lot on where in the room I measure it and how close to the floor it is. My problem is understanding crossover design to try and build my own or tweak what is there. It's a great hobby but rocket science is easier :)

    Do you use software to help model the crossover?
     
  10. mattkhan

    mattkhan
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    I now use vituixcad (Software), possibly the main advantage is that it puts directivity right in front of you during design. You can see some examples in this one I designed recently - 3 Way BMS4550 SEOS 10/ BMS 5N160/ Faital Pro 8PR200 - it's a really powerful piece of software (and free, which is nice)
     
  11. mattkhan

    mattkhan
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    so it seems like a lens like the navitar hdssw065 (1.5x zoom) will work, screen ends up slightly higher than I'd like though as it is barely any lower than it is today.

    Anyone know how much these cost? avscience (in the US) is the only place I've seen a price for these (3000USD) so still not cheap but I get the impression that's a fair bit less than a new a lens.

    upload_2018-4-1_13-47-16.png
     
  12. Peter Parker

    Peter Parker
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    I think people here have been getting them very cheaply second hand from ebay, but that relies on waiting for one to come up for sale at the right price. You could have a word with RickyJ and see what lenses he has etc - he had some of them with him when I was at his last demo day. I don't remember them being that expensive when it was discussed on here in the past, so maybe there are some other cheaper lenses that do much the same thing.

    For $3000 you can get a good used anamorphic lens like the Panamorph 480 and even some ISCO lenses if you look around. But again, you have to wait for them to become available. I wonder if AVS has some B stock lenses available.
     
  13. mattkhan

    mattkhan
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    I'm not doing this upgrade til next year so plenty of time to keep an eye on the 2nd hand market as I can't say I'm particularly keen to drop 3k on a lens :)

    Are there any particular sites where this sort of thing comes up other than the classified here and ebay?
     
  14. Peter Parker

    Peter Parker
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    I got my used lens from AVS but you usually have to pay duty and vat on top, so unless it's a good price I'd stick with here and ebay. I did get a used ISCO II at a good price from the classifieds here so it's worth keeping your eye out. KBarnes had an ISCO II for sale a while back but I think that may be a bit small for your needs.
     
  15. KelvinS1965

    KelvinS1965
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    I might be imagining it, but I thought I saw an Isco III sell on here for £2k recently, which seemed cheap to me. The thread might have been archived now, but would at least confirm the details.
     
  16. Peter Parker

    Peter Parker
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    That's true - I think it was with a cineslide or similar but the seller may split them IIRC. It might have been archived but could be worth PMing the seller to see if he still has it and can relist it maybe.
     
  17. KelvinS1965

    KelvinS1965
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  18. mattkhan

    mattkhan
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    I have trawled the archives for sale threads. One thing that struck me is how bad (or good depending on your perspective) 2nd hand values are, seems as bad as projectors themselves which is seems surprising given that it is a lens and a lens shouldn't degrade over time in the way a projector becomes obsolete.
     
  19. KelvinS1965

    KelvinS1965
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    I kept mine about 5 years and in the end sold it for slightly more than I paid for it (ignore my archived sale thread if you came across it as the buyer pulled out, I sold it elsewhere). I think if you could get an Isco III for £2k with a slide, then I would think it would hold that value for a good while.

    With HDR if you can gain some extra light output using a lens, then that's a good bonus. I think this is helping revive interest in lenses, which would preserve values better. I suspect in your shorter throw set up you'd be more likely gain light output than I was too.

    I sold mine when 4K/Faux 4K was coming out on less high end projectors, but without HDR, so it seemed more about the pixel density/visibility which isn't such an issue once above 1080p IMHO. It was a hard sell at that time due to limited buyers and to be fair will probably always be a niche market.

    Of course if you try to sell on here later, then you'll get the usual low ball offers, or in my case the buyer wasn't happy that prices had gone up since I bought mine (they were going for quite a bit more elsewhere than I was asking).
     
  20. mattkhan

    mattkhan
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    2nd hand value certainly seems pretty stable (which is good if buying 2nd hand), my point was more that brand new prices are 3-4x that much so the hit to buying new seems surprisingly large (for a mechanical device).
     
  21. mattkhan

    mattkhan
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  22. Peter Parker

    Peter Parker
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    A zoomed 4K/fauK pixel is smaller than a 1080 pixel with an A lens so zooming works just fine and I think that's why they're not so popular now and have dropped in value on the used market. I just found I prefer the image using the extra pixels so kept my lens (pixels are smaller still), plus the added convenience of a quick aspect ratio change if needed for menu's etc. For IMAX stuff I still need to remove the lens though, but as it's pretty rare to be watching one of those, it doesn't get moved very often - at least not yet since I installed the lens. I'd had it since around 2004 so figured I'd try it and see if I wanted to keep it or not.

    There does seem to be a move to the vertical squish lenses now though - you zoom the image to scope which can give more lumens, and then by adding the VS lens you can gain as much as 38% more light, which is useful for those who want more for HDR. If you want full res for 16:9 you still have to remove the lens, but you can still use the pjs own aspect control if you want to leave it in place and scale 16:9 content. That may mean more people moving on their horizontal expansion lenses.
     
  23. mattkhan

    mattkhan
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    I think this sums up the possibilities, going from left to right

    - a 1.5x width wide angle converter lens (e.g. navitar hdssw065) at max zoom
    - a 1.33x anamorphic lens with a 1.5x throw ratio (am assuming this is the bare minimum though this might be pushing it)
    - current (CIW) state (but with the screen moved down)
    - max zoom CIW

    pros/cons

    1.5x converter at max zoom
    - probably a bit big so would have to reduce the zoom == screen rises upward == not ideal but not the end of the world
    - screen at max zoom is big enough to accommodate speakers in the 2.4 wings or (just about) inside the 16:9 screen, might be tricky to accommodate as the zoom reduces
    - need to examine speaker fit in more detail

    1.33x anamorphic
    - 16:9 screen is a bit small
    - speakers don't really fit
    - i.e. throw ratio constraint suggests this option is unworkable

    Max Zoom CIW
    - 16:9 screen is rather large, 2.4 screen is a nice size though a bit high
    - speakers will fit outside the screen

    upload_2018-4-2_15-49-25.png

    initial conclusion is that an a lens doesn't work in this work unless I accept that 16:9 screen size has to reduce from current state, seems a reasonable conclusion or am I missing sometihng?
     
  24. Peter Parker

    Peter Parker
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    Bigger is usually better provided your seating distance and vertical viewing angle is still OK. Height is more of an issue than width.

    In my last set up (a loft with sloping ceilings), I started with a 7ft wide 16:9 screen but never really liked it that scope was smaller and had less impact than 1.85. I'd grown up with proper CinemaScope theatres so wanted the same at home.

    To do that, I experimented with CIA and CIH and found I could get an 8ft wide CIH screen in, but 16:9 was smaller than it was. Scope looked so much better and satisfying though. To fix the 16:9 presentation all I did was move my seats a little closer so that I was again at the same seating distance to height ratio that I had before - with the 7ft wide 16:9 screen I was 3 x the screen height back (approx 12 feet). By moving the seats forward to a little over 10 feet, I was again 3xSH back and the 16:9 image was now visually the same as it was before, and scope was even more immersive. So just by adjusting my seating forward a little I gained a better viewing experience. That's not always possible in a lounge though, but sometimes there is some flexibility so could be worth trying. As pj and source res improved I moved my seating closer still, and now I'm at 2xSH. Closer than THXs optimal recommended seating distance but I like it there, and 1.85 doesn't look small.
     
  25. mattkhan

    mattkhan
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    the wide angle converter lens looks like the (only viable) way to go to me

    - ~2.35xSH
    - vertical viewing angle is markedly better than today (about +22 degrees vs +30 degrees max)
    - screen size change is a proper upgrade (not far from wall to wall admittedly) and scope is now bigger than 16:9
    - screen is big enough to fit the speakers inside the 16:9 screen without being tragically close together

    any known downsides to those lens?
     
  26. Neil Davidson

    Neil Davidson
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    You can use this calculator to experiment with your viewing angles

    https://vac.cinema-tools.com/#!/

    The recommended angle is my own formula and based on the aspect ratio of the screen.

    If done well an ISCO can be an option at low throws as you can get good sharpness due to the astigmatism correction but you will always have pin cushion to deal with. I can’t accept the lenses without any astigmatism adjustment.

    There is a healthy supply of second hand iscos and cineslides available in the US as people upgrade and give them up.
     
  27. Peter Parker

    Peter Parker
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    Hi Neil,

    Nice tool :p

    For vertical viewing angles I've been using a simple on-line angle calculator, but this tool is a bit easier to use and gives you a professional looking pdf with the results. I'll be using this in future. :)

    Cheers.
     
  28. Peter Parker

    Peter Parker
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    I think the preferred left and right speaker location is outside of the 16:9 screen but within the 2.35 screen (page 2):

    https://www.dolby.com/us/en/technologies/dolby-atmos/dolby-atmos-specifications.pdf

    Nothing stopping you putting them where you like of course, but I'd assume the mastering was done with the speakers in those locations.

    I've not used or seen the wide angle lenses except a simple test at Ricky's, so I don't know the downsides - a small drop in ANSI and maybe on/off CR just like with a normal use of the zoom perhaps. There maybe some image distortion if the lens is used at its extremes, but that's just a guess.
     
  29. mattkhan

    mattkhan
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    I don't think that is a big concern at these screen sizes and in an acoustically small room as the speakers themselves and their interaction with the room will determine the perceived sound (e.g. apparent width), in my case the wider the better without getting *too* close to the walls is what I'm aiming for. Not that I have any choice anyway as whether to mask (for 16:9) or not is going to dictate where the speakers go :facepalm:

    Seeing your setup was enough to end thoughts of going with another CIW approach so I spent more time reading about lenses. It does seem like ~1.5x throw is doable, even if it's not ideal, with a decent lens. The inevitable pincushioning seems an acceptable tradeoff to me (and I don't have the depth for a curved screen to counteract it anyway)

    I revisited my previous diagrams to check what this would produce and it seems this yields ~ 2.6SH and a 3m wide screen. If I back this off to 1.6x TR then it's ~2.7SH and ~2.8m wide screen.

    upload_2018-4-6_14-24-30.png

    I don't see any way to accommodate this screen and my speakers and masking for 16:9 but then I don't mask for scope today and that doesn't bother me so that doesn't seem like a problem as such.

    The 1.6TR would leave the speakers a shade narrower than they are today, the 1.5TR would allow me to move them slightly wider. I don't think that will make an audible difference either way though.

    Now I just need to find a lens at an acceptable price o_O Anyone know what prices are like atm for the current prismasonic (PRISMASONIC - Ultra Wide Home Cinema Concept) offering? and whether they're actually good lens? seems hard to find current information on them (which actually seems true for most manufacturers, they all seem to have changed the available models in the last year or two).

    I also need work out how to mount such a thing onto a projector on a pole. It feels like that will need an upgrade (some sort of enclosure attached to multiple poles perhaps? Does such a thing exist or would it be a custom build?
     
  30. mattkhan

    mattkhan
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