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Maximising image contrast - Part 2

Discussion in 'Projectors' started by jacked, Feb 22, 2012.

  1. sammy the squid

    sammy the squid Active Member

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    Magic, if you have it by Thursday, could you possibly bring a small sample over please? Curious as to how it compares to the devore, thanks:thumbsup:
  2. Wull

    Wull Active Member

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    Thanks Faffer. :smashin:

    I hope so, I've been gradually improving my masking over the last few years which has been pretty tricky I've found. The price of this material which is matched by the quality should/will/has inspired me.

    My layout is a little awkward, 'IB in the ceiling with down lights & folding projector screen on a counter balance system' so it won't happen over night I know, yet I am looking forward to the challenge.

    I will post pics once done :)
  3. sammy the squid

    sammy the squid Active Member

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    The counter balanced and folding projector screen is a feat of engineering-ive seen it first hand:thumbsup:
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  4. Wull

    Wull Active Member

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    Not a problem mate, I have a sample which I will bring along, if not more by then :smashin:

    Looking forward to the second visit Asif, I'm sure I will be as impressed as I was last time, but this time amongst friends :)
  5. sammy the squid

    sammy the squid Active Member

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    That's excellent mate, thankyou:smashin: yes it should be fun, looking forward to having you chaps over again and Dave as well:thumbsup:
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  6. Wull

    Wull Active Member

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    Dave and yourself both have very inspirational rooms Asif, hence the order ;)

    The quality of the Devore, dare I say is lush, it really gives that polished look, this is not taking anything away from your paneling, I can see this being key.

    I made my first new ceiling frame/panel this morning, my plan is to install this before making the next, that way I hope to avoid discrepancies, well that's the plan. :rolleyes:
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  7. soupdragon

    soupdragon Active Member

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    Logical approach - no room or walls are truly square. I found this to my cost in early attempts at floor tiling :)

    I wonder who will be the 1st to send some devore to a tailor to make them a black viewing suit :devil:
    (shell suits are banned from my movie room)
  8. s_inman

    s_inman Active Member

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    Shell suits are banned from my house ;).
    Last edited: Dec 8, 2012
  9. Ideal AV

    Ideal AV Active Member Assured Advertiser

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    Depends who built the house ;)

    been their done that :D

    and whats wrong with a Devore shell suit, very comfty :rotfl:

    even Devore ones Stu :lease:
    Last edited: Dec 8, 2012
  10. Faffer

    Faffer Member

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    How about a jml snuggie should be easy enough to do and one size fits all

    Easy for guest to put on over what they have on
  11. soupdragon

    soupdragon Active Member

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    Well I'm sticking by my theory as it surely couldn't be anything to do with my tiling skills ;)
  12. bravogolf

    bravogolf Member

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    I miss my cinema room :( My partner is off for two weeks and she'd much rather sit down stairs in front of the fire rather than watch something upstairs!
  13. flyinmunky1

    flyinmunky1 Member

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    I was thinking of goin the devore route and making awesome panals etc, then i remembered how rubbish i am at DIY.

    So i ended up painting my dedicated room (all walls, ceiling, door) with Laurence Llewelyn-Bowen black cat paint lol. All they had in B&Q.

    Took a few coats but its actually pretty decent matte finish. You can pretty much only see the screen when projector on so was very happy.

    Heres a old pic before screen went up...the plug socket has been replaced and covered now.
    [​IMG]

    And below you can see it done. You can just make out my one speaker at this angle but when watching from straight on you cant see them.
    [​IMG][/url]
    Last edited: Dec 15, 2012
  14. soupdragon

    soupdragon Active Member

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    The thumbnails at the end are from a little test I did tonight. 1st time I've used my new lux meter and I wanted to measure my ansi contrast and overall contrast. Currently running a Sony VW85. Not sure how good my lux meter is, not very expensive and only measures in 1 lux increments (i.e., no decimals). This has hindered my somewhat and I'm not sure how valid my workaround is.

    But anyway, its given me some interesting results and how my white door might be effecting my ansi contrast. I've posted some pics below to show my room to give you an idea of what its like. The screen area and sloped ceiling above it, along with left and right walls a couple of feet out, are all covered in black stuff :D
    Then the left wall (left as I sit and view the screen) is well blacked out with black and red stuff. The right on the other hand, has still some work left. Not pictured, but I've since put up more black and red from the floor to about 3ft up on the right side as well. But, the door remains white.

    So the 1st test was ansi contrast, and you can sort of see in the checker board pic that the right side blacks are brighter than the left side. I used the flash on my mobile but hopefully you can see the difference. I also snapped my result which I wrote on the page. So, my overall ANSI is 160, and the left side ANSI is 195 and the right side ANSI is 137. So can I assume that the left side has nearly 50% better ANSI than the right simply because of this door? I'm sort of thinking that the door may even still be impacting the left ANSI too and that once I sort the door out, the variance will be even bigger?

    To get these results, I had the sensor about 3-4ft away from the projector, but pointed at the projector. But my other question is this - why if I'm pointed it at the projector is there variances in the number as surely the room effects should be removed this way and each square should measure the same? I tried to do it at the screen but because my sensor only measure 1 lux, I got zero lux for each black square.

    So then I did the overall contrast, and pointed at the projector about 6 inches from the lens. I got 9900:1 from a 100% white of 19800 and black of 2. I'm assuming to get contrast you divide 1 by the other? For ANSI, I added all the white and all the black readings together and devided them into each other - I'm thinking this is right?

    So in summary, my 1st time with this meter and I would like some confirmation if I've measured this correctly or whether I just need to get another meter and change my approach?

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Attached Files:

    Last edited: Dec 20, 2012
  15. pRot3us

    pRot3us Active Member

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    I can't comment on the sensor readings (yet to get myself a meter), but that door would do my nut in, I'd be covering it asap.
  16. Jazz Monkey Jr

    Jazz Monkey Jr Active Member

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    What lux meters are recommended?
  17. soupdragon

    soupdragon Active Member

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    I bought this one - its well reviewed but I'm not sure if its actually up to the task of home cinema measuring...

    Light Meter LX1010B, 50, 000 Lux Luxmeter with lcd display - Amazon.com

    And yes, pRot3us, I will be getting that door sorted out as it also annoys the hell out of me. Just need to decide on black paint our if I'll use the black material to cover it. Painting is easy but even black paint in a satin finish reflects a bit which mights still annoy me...

    Edit: and the white table is for the scrapheap sometime soon as well - don't know what the hell I was thinking when I bought that :eek:
  18. Faffer

    Faffer Member

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    Use black Meterial its much better.
  19. pRot3us

    pRot3us Active Member

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    It's a slippery slope :D

    The door must be throwing light back onto the screen, but it's the immersion factor that it'll be having a bigger negative effect on.

    I have a fridge just to the left and slightly forward of the seat to my left that I cover with black speaker cloth. If someone even puts a glass on top it annoys me to the point that they may as well be shining a torch in my face. Thankfully that's rare as all usual visitors have been instructed not to and thankfully I can point them to this thread if they question my sanity. :D
  20. Scifi

    Scifi Member

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    I would just stapel some devore on the door as quicker and easier to reverse than painting and will work better, ive just finshed covering polystyrene sheets with devore and sticking them to the ceiling and walls. Ive done about 1/3 of the room plus around the screen, it looks great but im wondering if I need to paint the remainder of the ceiling as its white, although it is only just visible when seated will this still have a bad effect on the picture?
  21. Ideal AV

    Ideal AV Active Member Assured Advertiser

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    do the ceiling do the ceiling do the ceiling :smashin:
  22. soupdragon

    soupdragon Active Member

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    Yeah, I was thinking of attaching it straight onto the door - might staple some on temporarily to see how it looks and also re-measure my contrast to understand the benefit :D

    For your white ceiling, yes, it will be impacting but you've got by the screen done which is good and you've got to draw the line somewhere? Or, we can always just black everything and ensure we wear dark clothing and that we have no reflective surfaces? Your eyeballs for example can be a very reflective surface - not a good idea to keep your eyes closed during the movie though so maybe just refuse to blink and with less blinking, the lubrication will dry up resulting in less reflection and better contrast - makes sense :laugh:
  23. Scifi

    Scifi Member

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    Ok I will do the ceiling!! A nice dark grey, matt if I can find some, should work good with the dark purple walls at least then Ive done everything I can.

    Was so worth coming to see your room Allan although I may be cursing you if I ever move and have to paint the ceiling white again :)

    Do they do matt black contact lenses?
  24. Ideal AV

    Ideal AV Active Member Assured Advertiser

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    yes I have some active shutter matt black lenses in all the time, they work a treat and 3d really has improved no end, light reflection is zero and they are acoustically transparent as well so I can hear the doorbell :devil:
  25. KelvinS1965

    KelvinS1965 Well-Known Member

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    Just a couple of points:

    You should take the ANSI contrast reading at the screen with the meter facing back towards the projector. If the meter won't measure below 1 Lux, then I recommend getting the Tecpel 531 meter that I have which was only about £60 IIRC. Taking readings near the projector are mostly going to show you the projector's ANSI contrast (though could still be effected by the room if there are reflections at the back of the room perhaps).

    You should be able to measure the on/off contrast using the method you state. Averaging all the ANSI measurements (ie all the white averaged then divided by all the black measurements averged) is what I did. I found I got slightly lower readings on the outsides of the screen IIRC (this was when I had my 'bat tent' set up).

    Your post is a good example of why very few reviewers measure ANSI contrast, because it is very easy to get different results according to method and the meter. At least if you measure in your own room then you can see if things improve so that you know what gives the best improvement for example: I found that covering my white ceiling (unsurprisingly) gave the biggest 'bang for buck' and my floor made the least difference. I measured 75:1 in my room untreated and got 230:1 with all my bat tent set up and black sheets and throws covering cream leather sofa and the floor with my old HD350. This measurement is only any use for me though, but it will help when I start on improving the room after Christmas, plus it might show me if the X35 gives any more ANSI contrast in the same set up, so I might try this over the break to see if it's any higher than 75:1 in the untreated room (I have a feeling it will be as it looks like it might be).
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  26. Pecker

    Pecker Well-Known Member

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    Regarding the white door - you could put a curtain rail over it, and pull the curtain when watching a film.

    Because the curtain will never be seen it could be made of anything as long as its black.

    Steve W
  27. soupdragon

    soupdragon Active Member

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    Makes sense, good idea, I think that's what I'll do.
  28. soupdragon

    soupdragon Active Member

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    Many thanks for the tips Kelvin. When I 1st broke the sensor out and realised it didn't go below 1 lux I though I might be limited and yes, I can't measure black at the screen as it is just reading zero :(
  29. Faffer

    Faffer Member

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    Thanks for the tip on the meter Kelvin,


    The main thing I see with the room upgrades are how the screen is my only bright thing to look at ..the black still seam the same but a meter would show me more.


    Might get one after xmas and have a look ,.. while I see the £60 would be better spent in the room on some more room upgrades I will never know just how much or what works better as an upgrade as I have no way to test before and after if I dont have a meter


    Richard
  30. Gary Lightfoot

    Gary Lightfoot Active Member

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    There are a few meters out there that are pretty much the same meter, but in a different colour body under a different manufacturer. Other than the Tecpel that kelvin has, there is the Robin RT24, Extech 431025 and the Wavetek Meterman LM631 (discontinued and replaced with Amprobe LM631A). The AVS favourite is the (visibly different) AEMC CA813.

    I believe they all use CIE photopic correction curves which matches the Human eyes daylight adapted response levels down to mesopic/scotopic/ dark adapted levels (where the human eye adapts; cones to rods), so you just make sure you have the light meter close to the pj get a high value for your black readings but not so close that you overload it for white (when measuring for on/off contrast, ANSI hopefully shouldn't be a problem). 0.001 for black would also allow for a large error as it's at the extreme of the meter, but something like 0.15 would be better for example.

    Some light meters out there may be more for other uses such as camera/photography, and have a different response curve so could give different and comparably inaccurate readings.

    Gary

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