Maximising image contrast - Part 2

afterall its your room and you will be sitting in it, not me, so its not important what I say or offer advice on :smashin:


There,there Allan:blush: you do have one or two golden nuggets to offer..here's one: Do it once, do it right:thumbsup:
 
:laugh:
Indeed we are cut from same cloth!
I said that in reference to Pecker and not you as I'm also looking to increase screen size too!

:D

There's a new Panasonic LED/Laser projector coming out. It might be a dog, but it potentially could be excellent. It's listed as being 3,000 lumens, which is probably just manufacturer talk. However, being LED/Laser, whatever it's calibrated lumens is, it'll pretty much stay there. If it's 1500 lumens caibrated, that'd be better than one that's 2,000 calibrated, but comes down to 1,000 after the first few hundred hours.

Interesting to see how it's reviewed, but I suspect it might be the sort of thing Jag would be looking for. Current 'word' is it'll be priced at £3k (£2.5k + VAT - but this is not confirmed, just informed rumour). A 4m wide screen with a gain of 2.4 that's anything like decent would set you back a lot of money, so...well, you can see where I'm coming from.

Steve W

ps. My new screen, coming next year, will be around 2.8m wide, so I'm just envious of Jag. :smashin:

SW
 
Side by side comparison in the same environment? Sensible idea:thumbsup:

Yep! The Sony is on paper brightest of the bunch. The 1000E is the benchmark. According to PJ central a 1.4 gain would be totally fine at 4 mtrs. You've got a gem of a PJ dude!

I've been quite lazy. Was supposed to paint in there last night but gave up on the idea. Same again tonight. Maybe a project for the weekend. ;)

Can we see some more pics of your project? Even a couple of screenshots would be great.
 
Getting back to lumens and screen size - unless you actually measure it, you'll be surprised at just how bright a dim image looks :)

One chap I did a calibration for had something like 3fL before the screen gain was calculated for IIRC (so 4fL total), and he was quite happy with that in his fully light controlled and black room (and it didn't look as dim as it measured). With DVD I actually prefer around 9fL and would use filters to get around 12fL with a new lamp so that with age and dimming I would still be happy until it reached 7fL and then remove the filters. To me it looks more cinematic as it matches closer to what we see in a commercial theatre (sad but true). With DVD, source artefacts would start to become noticeable after 12fL (if they were there) so that's what steered me in that direction. Of course with Blu Ray we can go brighter if we want to due to the improved compression but I prefer cinema levels. Joel Silver recommends 20fL for BD for example, and with todays higher contrast pjs, we can do that with smaller screens without sacrificing the black level too much (compared to lower on/off capable pjs of a few years back).

Unless you like a plasma like brightness most people would be happy with a dimmer image than they think, and visually the JVC with a newish lamp will probably look just fine on a 4m wide screen.

I'm a bit rusty at this, but IIRC if you want to work out the lumens you need, and know the reflectance level you think you want (unless you've measured before and have a preference), you just multiply the screen area (in square feet) by the fL you want, and that will give you the lumens you need. If the screen has gain, divide the lumens by the gain to give you the (lower) lumens needed for the same fL. If the screen has gain, divide the screen area by the gain then multiply by the required fL you want to achieve.

If you know what the lumens are, then divide the lumens by the screen area and multiply by the gain for the fL you will get.

So in theory, it sounds like it might not work, but it may look just fine when viewing. How long it may look just fine depends on the viewer and their preferences for image brightness, but dimming is gradual so may last longer than you expect.

Jagdeep, is your screen 16:9 or 2.35?

Gary
 
Jagdeep, is your screen 16:9 or 2.35?

Gary

Hi Gary, thanks for your very informative post on the subject. My screen is 2.35:1. Likely to be closer to 3.8mtrs rather than 4mtrs.. but if i can stretch to 4 i gladly will ;) The Sony has a plus point in that i can use an anamorphic to quite easily stretch to that sort of size. They JVC should manage it too as it has 2x zoom. The PJ distance will be 5 mtrs from the screen wall. Not quite sure how much pincushion i'd have with that.
 
With an A lens you calculate for the 2.35 screen whereas when zooming you calculate for 16:9. As you probably know though, depending on your throw you can lose lumens the further back the pj goes so although the calcs work OK you need to know the throw and actual lumens to get an accurate fL figure. From your comments I take it you'reusing a lens?

Your screen area for a 4m wide screen using an A lens is around 73.3 square feet which needs around 1200 lumens on a unity gain screen to give you 16fL, so plenty of dimming before you get to 8fL which you may find OK. If you zoom it's 97 square feet and you'll need around 1550 so quite a lot more light or a higher gain needed, depending on how you find the image when testing.

You will probably find that your wall is closer to unity and although some screens claim certain gains, it can vary. I've seen the same screen advertised as 1.3 then later 1.0 but actually measure at 1.25. 3 good coats of a decent matt white paint should be close to unity apparently.

A genuine 1.3 gain screen will probably be all you need but it will be interesting to see what you think when you actually demo on the wall. :)

If you want to get technical, you can buy a cheap light meter to measure full white at the screen to allow you to calculate what you really have in the way of lumens. The more expensive meters allow better dark readings for contrast measuring, so it depends on what you want to know. Sometimes a little knowledge can be a dangerous thing though - ignorance can be bliss sometimes ;)

There is a pincushion calculator over an AVS (search for Aussie Bob or Aussie Bob II) and that should give you a good idea of how much pincushion you'll get.

Gary
 
If you want to get technical, you can buy a cheap light meter to measure full white at the screen to allow you to calculate what you really have in the way of lumens. The more expensive meters allow better dark readings for contrast measuring, so it depends on what you want to know. Sometimes a little knowledge can be a dangerous thing though - ignorance can be bliss sometimes ;)

I was quite surprised how far out my cheap 'unnamed brand' meter read compared to another I could check against, unfortunately in the wrong direction.

(It was OK in natural day light)...So stick to a name brand, i.e Alphatek and you should be alright, you can pick these up for under £30.

I know the fl is very low on my screen, but I am more than happy with the results. I hope to check this on Friday with my D3.

Your right Gary, ignorance can be bliss!!
 
Kep an eye out for Robin RT24 or Tecpel 531 meters (see ebay item 251154220173). There are a few light meters that are pretty much identical but are different colours and under different brand names, but all are pretty accurate and give repeatable results. Mine came with a NIST calibration certificate so you can get it checked each year and recalibrated if you want.

It's a bit dearer but works well and the results I've had compare with some of the magazine reviews such as Greg Rogers from Widescreen Review which gives some confidence in their capability. I've compared the Robin to my American equivalent and it read pretty much the same. I think there's a small +or- percentage accuracy level (3%?) but they're good enough for what we want. Provided you place the meter close enough to the pj to get a good reading for black and not overload it for white, you can use them for on/off measurements too.

If you read around 100 lux at the screen facing the pj, you should be getting something like 9fL which is around 12fL with a 1.3 gain screen IIRC. This has been discussed a fair bit in the past so a search should find a few threads with these meters and how to do the measurements etc.

Gary
 
I use the same Tecpel 531 meter as recommended by Gary. I aim for 90-95lux on my 1.5 gain screen which gives approx 12-14fL depending on what value I take for the screen gain (1.5 might be slightly optimistic I think). I just use the 100% test pattern in my Lumagen and check every now and then. If the reading has dropped below 90 Lux, then I open the iris a click to get back to around 95 Lux again. I also measure the lux when I use my A lens, so I get the same fL for 2.35:1 as I do for 16:9, so the meter helps me set the iris for this other memory in the projector.

I also used my Tecpel meter to measure ANSI contrast in my room and when trying different room treatments such as my 'bat tent', black sheeting on the floor and dark throws on the sofa near the screen. It helped me to see which things gave the biggest improvement (the bat tent as it covered my white ceiling for those interested). I will also use it to see if with my extended pelmet/drop down curtain project meets (and hopefully exceeds) my previous highest reading of 230:1.

Whoops, nearly brought the thread back on topic there, sorry. ;):D
 
Long time lurker of this thread, finally done some changes at home that you might be interested in!

It started couple weekends ago, my housemate and I suddenly had the urge to rearrange the lounge. We span it round 90 degrees and implemented a poverty tiered seating system :D

w0DRLh.jpg


That's right, the back row is on pallets. 4x EUR Pallets to be precise, very sturdy, perfect fit and FREE!

rnk7S.jpg


So that's layout sorted, next we turned our attention to the screen.
It started like this last year.
20110916141655.jpg


We've added a second frame to the front basically, allowing a thicker border and an actually square image. It's bang on 2400mmx1000mm now so perfect for films.
H0s7Sl.jpg


Now we had to address the walls, always wanted to do it but never quite had the motivation but we were on a roll.

This is the fabric we used: http://www.minervacrafts.com/viscos...e-velvet-designer-dress-fabric-per-metre.html
This could be a great new alternative to Devore/Maplin/Whatever guys. It's pretty black and £6.99 (or less)p/m. I managed to get a Devore sample today and heres a few flashed shots to compare.

The Devore is the small patch with the white circle on.
CZL2X.jpg

cZwyA.jpg


Not the most scientific method I know, but you can see it's pretty dark stuff. At less than half the price it's a great alternative!

Here it is on the screen.
dhMpyh.jpg


And here's a few pics as everything is now. We intend to do the right hand wall asap, once we figure out something for the door. The far left wall (chimney breast) and behind the sofa was done with really cheap felt just for the sake of it really!

EqzFmh.jpg

fblSCh.jpg

WqQ08h.jpg


Bare in mind all of this is fairly bodged and temporary aswell, as it's a rented house we had to be quite inventive! We've a mixture of zip ties, picture hooks, fancy 3M adhesive strips & staples!
 
Can see some higher res pics here
Lounge - Imgur

I might get the proper camera out later try and get something better.
 
Great transformation! I like the Pallet idea too :thimbsup: you should go to idea and get a rug to hide the industrial look ;).
 
"This is the fabric we used: http://www.minervacrafts.com/viscose...per-metre.html
This could be a great new alternative to Devore/Maplin/Whatever guys. It's pretty black and £6.99 (or less)p/m. I managed to get a Devore sample today and heres a few flashed shots to compare."

Thanks Chris.

That material looks really good, and given it's 50" wide and UK delivery is only £2.99, or free for orders over £20, it also looks like a good saving over Devore. Ordered a sample (99p).
 
Good idea mcspongy, it's good stuff. Dare I say in the last pic it looks blacker than the Devore :p. Need a proper side by side with same size pieces really, but I'm very happy with it. It's a deeper pile though, if that matters to anyone.

I ordered 10m Thursday afternoon, so it was only £6.64 a meter and it turned up Friday morning with free delivery. Good stuff!

I'm not too concerned with hiding the pallets for now, they're mostly obscured by the front sofa anyway. I will however be getting a big black rug to lay between the front sofa and the center speaker etc, probably from Ikea. Might grab some remote control sockets while I'm at it.

2012-11-24%2014.jpg
 
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"This is the fabric we used: http://www.minervacrafts.com/viscose...per-metre.html
This could be a great new alternative to Devore/Maplin/Whatever guys. It's pretty black and £6.99 (or less)p/m. I managed to get a Devore sample today and heres a few flashed shots to compare."

Thanks Chris.

That material looks really good, and given it's 50" wide and UK delivery is only £2.99, or free for orders over £20, it also looks like a good saving over Devore. Ordered a sample (99p).


MMM Looks like a good find ....

Is it thinner than the devore ?

Does look like a good cheap option

I have some black cloth and I think thats doing a good job but the devore cost to upgrade has always made me think do I need to do it.

but at 6.99 its a lot better and would be a upgrade from what I have without the devore price

Richard
 
Yep! The Sony is on paper brightest of the bunch. The 1000E is the benchmark. According to PJ central a 1.4 gain would be totally fine at 4 mtrs. You've got a gem of a PJ dude!

I've been quite lazy. Was supposed to paint in there last night but gave up on the idea. Same again tonight. Maybe a project for the weekend. ;)

Can we see some more pics of your project? Even a couple of screenshots would be great.

Sorry, completely missed this. If you pm me your email, I'll send some pics over:smashin:
 
I think It's a slightly thicker pile, marginal. It also appears SLIGHTLY less opaque, but it's really hard to compare.

Here's a couple other pics, Devore is the small patch.
LuH0h.jpg


Devore on the right.
NON1D.jpg


It's pretty much impossible to capture it properly with pictures, but subjectively the Minerva stuff is very close. Perhaps it would be more obvious with larger pieces in a room.
 
what you have done is excellent Chris

when we moved in to our house i decided the spare room was going to be an AV room, that was 12 years ago and i am just doing it now. Keep us posted everyone on the devore / alt as i intend to do some of that at some point, painting the room black to start with (appreciate not ideal but its a start)
 
Morning Chris.

Rather annoyingly these two (vital) pics do not show up for me (pics 5 & 6):

The Devore is the small patch with the white circle on.
image

image

Neither do these two:

I think It's a slightly thicker pile, marginal. It also appears SLIGHTLY less opaque, but it's really hard to compare.

Here's a couple other pics, Devore is the small patch.
image


Devore on the right.
image


It's pretty much impossible to capture it properly with pictures, but subjectively the Minerva stuff is very close. Perhaps it would be more obvious with larger pieces in a room.

Can you help?

Cheers.

Steve W
 
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One more thing, I see you're covering the tops and sides of the speakers, but not the front. Is this because you've tried it and it's not acoustically transparent?

If not, could you give it a go?

Many thanks.

Steve W
 
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I know it's always difficult to get the truth from pics because the camera and path from camera can change things, and what people see on their monitors can differ too, but I thought I'd take the first pic from post 519 and use the colour picker tool in a paint program to tell me which one had the blackest pixels. What was weird was the (to my eye) dark patches of the Devore measure lighter than the lighter patches of the Devore. Overall the Minerva did seem to average slightly darker but it's not the most scientific test I have to say.

Not an entirely accurate conclusion IMHO but I they look very close. I think the best test is the old torch test to see which one absorbs the light the best. Would that be possible to do Chris?

Gary.
 
I know it's always difficult to get the truth from pics because the camera and path from camera can change things, and what people see on their monitors can differ too, but I thought I'd take the first pic from post 519 and use the colour picker tool in a paint program to tell me which one had the blackest pixels. What was weird was the (to my eye) dark patches of the Devore measure lighter than the lighter patches of the Devore. Overall the Minerva did seem to average slightly darker but it's not the most scientific test I have to say.

Not an entirely accurate conclusion IMHO but I they look very close. I think the best test is the old torch test to see which one absorbs the light the best. Would that be possible to do Chris?

Gary.


Looks to me like the flash has been used to take the pic's so this is much the same as the torch ?

I did some test with the other suff that was found a bit back the Chinese stuff ..

While it did look very close the cost was not that much cheaper at 12.95/Mtr after you had got to the 10m price on devore.

This does look good with it only been 6.99 or bit less ordering 10m to make me think it could be a good option.

What I did find with the other stuff was it was a lot thinner but as I now already have some black sheet around my frame I could just add this on top so it would no longer matter if it was thinner.


Think I am going to order a sample and this could be a weekend upgrade job I am already happy with the black sheets so this would be a cheap upgrade without the devore cost

Richard
 
I'm not sure I can really do the torch test with such a small piece of Devore? Not in terms of 'how much does the screen light up from this blob' like I did before (big difference even between the front and rear sofa lol!)

Pecker try these links:
http://db.tt/F8MzSbEG
http://db.tt/7zp2Iy9l
http://db.tt/JPprtp21
http://db.tt/181QHfJQ
http://db.tt/z81lwGGK
http://db.tt/YYvKzhED

http://db.tt/JF4MZGdy
http://db.tt/sH1QSPmv

I'm not sure I've a good enough ear to really test its acoustic properties, unless it's really obvious. The reason the speakers aren't dealt with yet is we haven't decided what to do with the left over Minerva material. The covering on the speakers is actually a cut up blanket we've had for ages :p, it's quite grey!

Other observations between the two, held up to the light Devore lets through less light. The backing of Devore is higher quality, and it's pretty much completely unstretchable. The slightly thicker pile of the Minerva means you can sort of crush it and create fingerprints etc. if your not careful, you can see one on the screen pic infact.
 
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