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Discussion in 'Home Theater Projects' started by DFurr, Jan 3, 2015.
And hot spots on a silver screen are brutally obvious.
My new 3D lens arrived today and preliminary test are telling me that I can in fact show polarized 3D movies on a white screen. These are the lens that had the linear filters removed and Dolby 3D filters installed. I'll have to increase the bulb output or install a 1.4 gain screen (or maybe both) because the Dolby system requires more light than linear. A real pleasant surprise is that I've noticed that some of the know ghosting issues on my Friday the 13th 3D print have actually disappeared. I intend to run the entire print tonight to see if other ghosting issues are with gone or less noticeable than with the linear filters. I suspect that Dolby's use of the color spectrum is more efficient than the technology of the older linear 80's style 3D lens.
For any forum members that have an interest in this experiment I'm doing with 3D lens I promise to update this thread as I do more tests and learn how all of this is going to work out. Thus far I'm pretty happy with the results.
I have screened both Friday the 13th 3D and Final Destination 5 3D with the new modified lens. One thing for sure.....whatever ghosting issues that I've seen with the older lens is GONE with the Dolby filtered lens.
There is one problem that has surfaced. The lens is producing a very light glare on the screen that is somewhat distracting. It only appears in very dark scenes and undetectable in lighter scenes. I've sent a communications to the seller about this issue and awaiting his response and ideas concerning the glare. It appears at the exact same spot each time, lower left portion of the screen. Focus is very good, 3D effects are really super but the light glare is a bit worrisome. At this point I'm suspecting a flaw in the modification of the lens. We'll see!!
This is on your Technicoat screen, right? I notice the tensioning of the fabric isn't 100%, and I'm spitballing here, but wondering if that has something to do with the glare, which sounds similar to a "hot spot".
That's a good point Stephen. I'll be sure to check that on my next test run although the spot where the glare is pretty much flat but it will be checked. Thanks for the excellent idea.
I checked the possibility of a hot spot but that doesn't seem to be the case. I also thought that since my travel curtain was open behind the Technicoat screen, I surmised since the white screen was a mini-perf the light was hitting the silver screen and shinning back through. I closed the curtain but the spot still appears.
I've reset the 3D lens for another spacing and tomorrow I'll run a reel of a different spacing to see if that has any effect. Moving the small split lens in the rear to change the spacing requirement might make a difference.
I'm having a GREAT day. I discovered this morning that the issue with the glare on the screen was being caused by a defective rear split lens. Good news is I had two other 2.0 Sirius lens so I replaced the entire rear assembly with one of mine. The glare has disappeared!!! Upon very close examination of the modified lens I received I discovered not only were the rear split lens cloudy but one side was scratched as well. Problem solved.
I have sent a message to the seller of those lens asking for compensation!
Now on with the task of replacing my silver screen with a larger matt white.
So, the seller of the defective lens offered several options for compensation.
Next phase of the project is underway. I've got three lens on the way to verify the size of the new screen. Aspect ratios will be 1:33, 1:85 and 2:39, all based on constant height. I'm pretty confident that my Epson projector will zoom to fit all three formats. Luckily the Epson seems to be formatted for constant height images. We'll see.
New shipment of format lens arriving tomorrow afternoon. The first try proved to be the wrong focal length as all three formats were too large for the room/new screen. We've recalculated the lens sizes so I'm hoping we're right on the money this time. One inch here or there won't matter but a foot too wide or too high just won't work!!
Still hoping to end up with a 2.35 picture 11' by 4' 8" and a 1.85 picture 8' 8" by 4' 8". I'll be happy with anything that's really close.
My Epson 5010 will zoom out to almost 11' wide so if the new lens comes in at 10' 10" or 10' 11" that will be perfect for the Epson and the 35mm picture. That would make me very happy. A letterbox picture would NOT make me happy.
New set of lens arrived. Finally have the correct focal length for a new larger screen in our HT. New screen ordered today.....Harkness 11’ 2” x 5’ 4” 1.4 gain Perlux 140.
First order of business awaiting the screen.....modify the screen frame for the larger size. I've decided on a 3/4" tubular metal frame attached to the current wood frame. That will allow me to either use springs or "string" the screen with a light rope material.
So now the work begins. Pictures to follow once the screen as arrived.
New screen is still scheduled for delivery around the 17th of this month.
I've built and installed the new tubular screen frame as well a the adjustable top and bottom masking rods.
I was concerned that the Epson 5010 zoomed to the maximum picture size might be a couple of inches shy of my new larger picture size so I installed a small magnifier lens in front of the Epson lens so now I can increase the picture will will actually project of both side walls. I was determined to NOT have any letterbox picture on the new screen. The new picture size should be about 11' X 4' 10". At least now the Epson can keep up with the 35mm picture aspect ratio.
The old silver screen has been removed, new springs to mount the new screen which is being delivered tomorrow are hung on the new tubular screen frame. (Tuesday). I'm anxious to get this party started!
New screen is hung. Working on masking panels now. This is really tedious work!! Whew! It's got to be perfect.
That's coming along great, like a miniature version of a well-appointed neighborhood art house.
How will the side making operate? Are they on curtain track or did you come up with another way?
Peter the side masking panels are operated by a pair of actuators which move the panels which are mounted on two tracks each in and out to preset limits. The actuators are activated by the automation system and are tied to the lens turret. When the automation calls for a 2:35 format and actuators pull the panels out and just the opposite for 1:85.
We're finishing the black felt on the side panels tonight. I'm glad this job is about finished!! I'm ready to watch some movies again!
Very slick - can you post a picture of the mechanism? I keep saying I want to motorize my side (and top/bottom) masking one of these days.
Here you go Peter. This picture is with the actuator extended in the 1:85 mode. These operate @12VDC.
Here is a pic of the type actuator I'm using.
Thanks Don. I did some YouTube watching last night seeing how people use those for masking projects. I see I can get them inexpensively from Ebay, etc., I might have to get one and experiment with my side curtains. I have an idea of how I could use one of them with pulleys, wire rope, and bungees to open and close them. Cheaper than a motorized curtain rod.
I agree Peter. I'm using a Tom Thumb masking motor for my travel curtain but decided on the actuators for the masking. Tom Thumbs can run as high as 500-600 bucks. I've got a spare just in case something happens to the other one. My actuators were ordered to travel 13 1/2 inches but I think you can buy units that can be adjusted to the travel distance you require. I suspect they cost more than the "one" distance model. These motors are very strong so moving a masking curtain would be almost a no-load on these units.
Decided tonight to screen our 35mm print of Friday the 13th Part 3 (3D) since the new matte white screen and masking panels have all been installed.
Very happy with the new larger screen and especially thrilled with the quality of the 3D on my white screen. There's no doubt that Dolby 3D filters for use on a white screen project a superior picture. With the older linear filters there were many flaws causing ghosting issues. For some unexplained reason those ghosting problems has disappeared. Full disclosure, there were no 3D movies in the 80's that were perfect including Friday the 13th but it looks much better using the Dolby system.
Blew off the dust and gave another watch to "Flesh For Frankenstein" 1973. This Space Vision 3D print was difficult to watch the last time we screened it but once again, with my converted 3D lens with Dolby filters installed we could see a huge difference. Unfortunately the lens didn't improve the acting and didn't lessen the blood and guts of this title but some of the 3D shots are very interesting and most effective.
I understand from another thread that a 2D Blu Ray is available but it wouldn't be the same movie without the 3D "bonus"!