Recently Browsing 0 members
No registered users viewing this page.
thought that I would post my activities over the last few days.
12 months ago I went from a 100 inch 16x9 to 130 inch scope screen with a mk3+c and now a mk4 aussiemorphic lens.
There a well know comprimises with A-lens, prisms (ie mke 3+c) will exhibit minor non uniformity and CA particularly at the left and right edges and cylindical (mk4) whilst providing clear and sharp focus across the whole image generally suffer minor pin cushioning. (note trying to start a war here just stating the facts and note I did say minor)
Anyway in my setup the pin cushining is approximately 25 to 30 mm (top and bottom) at the centre for approx 3100 mm screen width. Not a lot but like all these things when you know its there is bugs the hell out of you. You can see the impact on the attached image which is a grid pattern, the top and bottom lines drift off the screen half way between the centre and the edge of the screen.
On way of dealing with the pin cushioning is to curve the screen. I discussed this with Mark Techer for CAVX and Richard at OzTheatre about 6 to 8 months ago, and with a bit of spare time in the holidays thought I'd give it a go.
First work out how much to bend the screen, after much searching of the internet for maths formulaes to work it out (never lose that engineering approach) I fell back to Marks tried and simple method which is simply to use something (in my case a length of stiff paper) to measure and mark the height at the centre of the screen, then move to the edge and move the paper out from the screen until the image from the projector is the same as the distance measured in the middle. In my case the distance out from the screen was 100 mm.
So a quick sketch and off to bunnings to buy some supplies. I ended up deciding on using a 140mm width MDF to make a box which would then be attached to the wall.
Couple of photos of the construction showing
- the raw materials laid out on the floor
- frame made up and trial put together on the floor
- all painted up (blocks at the ends set to hold the ends of the screen 100mm out from the centre) and test of the curvature using some scraps of timber
So the next day into the theatre room and pull everything off the from wall and mount the frame to the wall.
Brace the back of the screen (good tip from Mark) as due to the cross sectional shape or profile of the screens frame, the screen will try to pinch in the middle as the pressure is put on the screen frame to force it to curve. I used 20x12x1.4mm aluminimum angle.
I drilled a hole through the screen frame at the centre and then used a tek screw to pull the centre of the screen back against the box mounted on the wall.
So after all that effort did it work?
In short yes I think so. The attached grid pattern shows that almost all of the image is now on the screen, there is a slight drift off in the top left corner but compared to the before shot much better.
Measurements of the grid rectangles using a tape measure are
1. width is 296mm at centre and 301mm at either side (1.7% increase)
2.height is 207/208mm at the centre and 210mm top and bottom
Issue/lessons learnt/things I'd do different
1. use heavyduty/mor bracing to the back of the screen, even with the bracing that I used the screen still pinces about 5 mm in the middle (note however that this is over a height of 1280mm so relatively minor) and
2. the screen material bows out towards the room in the centre (top to bottom) about 25mm due to the tension from each ends. I might need to look at more tension to the top and bottom and letting the edges go a bit on the left and right ends.
3. I now need to adjust the A-lens again to try and fix up the top left corner
4. the A-lens expansion ratio and the screen ratio are slightly different, on the finished product photo the top and bottom grid lines are right on the edge of the viewable area but the left and right sides still have about 50mm before the grid line hits the screen frame. Not much I can do about that except to overscan the image onto the frame top and bottom
5. It takes a reasonalbe push to curve the screen frame, it doesn't do it under its own weight that is for sure.
Anyway alls well to far, I might have a play around over the next couple of weeks and provide any updates.
Fs Crt Projector Runco 991 (Nec Xg75) With Hdmi +/- Faroudja Processor Scaler +/- Component To Rgbhv ConverterBy tacky
Long time reader, seldom poster
Looking to sell the following gear ASAP - make me an offer on anything. All located in Brisbane or Sunshine Coast, QLD. Everything boxed up and ready to go for postage or contact me for pick up.
My Converter on Fleabay with all the details:
My processor on fleabay with all the details:
MAIN item is my CRT Projector on fleabay:
Runco DTV991 (NEC XG75) CRT Projector with HDMI input
AMERICAN VOLTAGE 110V - AMERICAN VOLTAGE 110V - US VOLTAGE 110V
Specialised Item - please only bid if you know what this is and how to use it, thank you.
WORKING SET (see images in link below):
Approx build date 1999/2000. Minimal wear on tubes. NEW PSU installed ~3yrs ago by me at time of purchase. Hours unknown probably ~2000hours put on since unit purchased 3yrs ago.
Works well with HD 720p (60hz or 50hz) sources such as PS3, XBOX360, Popcorn Hour, FTA Digital TV STB, etc
N.B. set is 110V and will require ~1000W step down transformer (not included)
Obviously will require re-convergence once relocated.
ceiling mount (heavy steel post and plate with some but not all bolts)
serial control cable (for calibration with PC - useful!)
backlit full function IR remote for set
IR remote for moome HDMI card
batteries for remotes
I accept Paypal, Cash (only for pickup), and direct deposit
Available for pick up (preferred and cheapest option)
Current location = QLD, Brisbane, 4122
Item securely packaged to a pallet and ready for immediate dispatch if shipping required
Dimensions = 120 x 78 x 48 cm x ~60-70kg
Pallet delivery service required (most major couriers offer such a service)
High resolution images of set taken 2 Jan 2012:
Thanks to one and all for considering my items for sale
a post awhile back on Whirlpool, on getting some advice for buying a new projector.
I was very close to ordering a
BenQ W1100, but feel that I have not considered other projectors, and also a little worried that I am spending more than I need based on my requirements.
So, this new post is just to try and spark some comments/advice into alternate models or perhaps confirm that the W1100 is a good choice for my needs.
The other cheaper model I have just been considering, is the
BenQ W1060. I think this makes more sense, but seen less talk of this one. I see OfficeWorks have it for $999 which seems good (Which is another Q, wheres a good place to get one?)
- Do not currently have a TV, and do not have Foxtel.
- I DL typically 1-2 shows a day to watch in the evening on my 27' monitor.
- I DL 2 movies a week usually watched at weekend,
- I only watch DVDRips but will DL BluRayRips if a film.
- Im 30, with no kids but watch all the above with my gf.
- Also like the idea of having friends over to watch movies.
- Would use either my a Asus 1201N netbook (ION graphics/HDMI output) or my girlfriends iMac. May consider a HTPC build in the future.
- Not fussed about 3D or onboard sound, and will use my AudioEngine A5s for audio.
- Budget wise 1400 is really the top end. Because of bulbs, prob not going to be looking at 2nd hand.
- Bulb life scares me. I want something that lasts.
- I may watch some TV on it, therefore an aerial in would be nice (but not essential)
- Now the big one. I will mostly use it in my living room, but really like the idea of using it outdoors at night. I was thinking of having it on my window sill (will create a stand, but the projector remains indoors, window open) and then project out to a screen about 13-14ft away. This is still all under cover, and there is not too much lighting to interfere with picture.
So with all that said, what should I be looking at?
Was also looking at the
W1200 and something a bit cheaper a with the MX511
Are these along with the W1100 overkill? Ideally would be great to find a good model nearer the 1k mark, but one thats still bright and considered a HT-projector.
Would really appreciate your advice. I am not a video-phile, but still want something that will look good and last. N