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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Mon Jan 26, 2009 11:02 pm Post subject: Lens Flapping Move the Lens or the Tube |
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Which works better and why. Ampros seem to move the lens while others do not. Is there a difference??
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Zebu Fellenz
Joined: 21 Dec 2006
Posts: 2567
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| Posted: Mon Jan 26, 2009 11:07 pm Post subject: |
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I don't think either method is "better" as they both create the same geometric distortion side to side and top to bottom. I've never seen an Ampro though, does anyone have a picture of the mechanism?
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Tue Jan 27, 2009 12:44 am Post subject: |
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One of the reasons I ask this is that I read in another thread that an Ampro owner was moving away from the Ampro lensflapping to the Marquee. In other words he was going to the trouble of converting his projector.
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Tue Jan 27, 2009 12:46 am Post subject: |
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Ohh that's Chip. He get's board and ties one hand behind his back then figures out someway to make all his bit's and pieces of equipment play nice together  
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Tue Jan 27, 2009 1:21 am Post subject: |
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Sony moves the tube. (Continuously variable on the fly = awesome.)
Nec moves the lens. (Have to undo screws to adjust = annoying.)
Ampro doesn't move the C element, which is not as good.
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CRT_Ben
Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia
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| Posted: Tue Jan 27, 2009 1:23 am Post subject: |
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You probably read my post in the other thread. Something I want to clear up - flapping never moves the tube itself. Toe-in moves the tube, during the physical alignment of the guns.
Flapping on the other hand, either moves the lens only (in the case of air coupled PJs or liquid coupled Ampros), or it moves the lens and C element (in the case of all liquid coupled PJs besides Ampros). For liquid coupled PJs, it is pretty well accepted that moving the lens and C element together results in better focus. For air coupled PJs, the only option is to move the lens only, because there is no C element.
Edit: Mark - are you sure the Sonys move the tubes?? The whole point of flapping is to angle the lens so the plane of the tubeface optically matches the plane of the screen. I would think that angling the tube face (essentially toe-in) would unnecessarily affect the mechanical setup?
Last edited by CRT_Ben on Tue Jan 27, 2009 1:29 am; edited 1 time in total
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Tue Jan 27, 2009 1:28 am Post subject: Re: Lens Flapping Move the Lens or the Tube |
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| km987654 wrote: | | Which works better and why. Ampros seem to move the lens while others do not. Is there a difference?? |
There is a difference. Ideally the "C" element should be parallel/perpendicular to the lens. That means the liquid chamber has to be flexible for sheimpflug to work. Ampro went the cheap way and designed the liquid chamber with the "C" element fixed to the tube instead of the lens. Unless the projector is mounted perpendicular to the screen there is an angle between "C" element and lens that causes a slight loss of focus performance at the top of screen for table mounted projectors or less than perfect focus at the bottom of screen for ceiling mounted set-ups. Ceiling mounted is not really a problem.
Scott
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Tue Jan 27, 2009 1:34 am Post subject: |
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| CRT_Ben wrote: |
Edit: Mark - are you sure the Sonys move the tubes?? The whole point of flapping is to angle the lens so the plane of the tubeface optically matches the plane of the screen. I would think that angling the tube face (essentially toe-in) would unnecessarily affect the mechanical setup? |
100% certain. Go and look at a G series Sony.
The result is the same either way. Maybe you would need to correct the toe-in in theory on a Sony, but not in practice. Toe-in is coarse, Flapping is very fine.
The real issue is Ampro didn't move the C element - refer to Scott's post above.
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Tue Jan 27, 2009 5:55 am Post subject: |
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So would the consensus be that moving the C element (or perhaps the tube) is better and if so is it that much better that you would modify a projector from the moving the lens to moving the C element??
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CRT_Ben
Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia
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| Posted: Tue Jan 27, 2009 6:02 am Post subject: |
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| km987654 wrote: | | So would the consensus be that moving the C element (or perhaps the tube) is better and if so is it that much better that you would modify a projector from the moving the lens to moving the C element?? |
The real issue here is simply keeping the C element in proper position relative to the lens. However that happens is largely irrelevant. Why do you need a consensus? Unless you're designing your own projector, Ampro is the only mass produced projector that I know of that has the stated focus flaw.
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CRT_Ben
Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia
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| Posted: Tue Jan 27, 2009 6:08 am Post subject: |
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I see from your profile that you have a Barco 1100. I don't know what kind of flapping that PJ has, but if you're thinking of converting it somehow, I wouldn't bother. Even though it's a 9" set it's electrostatic focusing and your money and time is probably better spent elsewhere.
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Tue Jan 27, 2009 8:25 am Post subject: |
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Well I was thinking of adding lens flapping since I have all the parts. I actually like my PJ even though it is an ES focus set. Barco 1100s have no adjustable lens flapping. I have enjoyed modifying it and its really a hybrid of many different Barco sets.
I am not sure why people seem to dismiss ES sets as something inferior to EM set. I understand the difference in focus ability between the two but I have to say after reading a lot of threads ES sets don't seem to suffer from some of the ailments of EM sets like lines down the left side of the screen etc again though its just what you like.
I don't need a consensus but since I was asking I thought I might try and get some agreement. As with most things though it would seem that there are different points of view depending on who you ask and thats OK of course.
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CRT_Ben
Joined: 28 Aug 2006
Posts: 1684
Location: Northern Virginia
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| Posted: Tue Jan 27, 2009 3:22 pm Post subject: |
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| km987654 wrote: | Well I was thinking of adding lens flapping since I have all the parts. I actually like my PJ even though it is an ES focus set. Barco 1100s have no adjustable lens flapping. I have enjoyed modifying it and its really a hybrid of many different Barco sets.
I am not sure why people seem to dismiss ES sets as something inferior to EM set. I understand the difference in focus ability between the two but I have to say after reading a lot of threads ES sets don't seem to suffer from some of the ailments of EM sets like lines down the left side of the screen etc again though its just what you like.
I don't need a consensus but since I was asking I thought I might try and get some agreement. As with most things though it would seem that there are different points of view depending on who you ask and thats OK of course. |
I apologize, I didn't mean to bash your set. However, unless you are planning to do the simplest flapping conversion (putting springs on the lens screws or similar, to achieve lens-only flapping), I still wouldn't go through with it. Even if you have all the parts (this means you would have three new LC housings, and some way of mounting them to your PJ), you still have to unmount your tubes and silicone them into the new housings which is a fair bit of work. Not to mention that you could probably sell those LC housings for a few hundred.
Prices are such these days that most people can afford an EM set. Therefore, ES sets which were the norm at one time are now a bit looked down upon. Is this fair? Probably not, because the ES sets aren't any worse, people just have better sets now. However the differences are real. I went from a Sony 1271 (8" ES) to a Marquee 8500 (8" EM) and it was night and day. I expect that 9" ES to EM would yield the same benefits.
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Wed Jan 28, 2009 12:50 am Post subject: |
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No offence taken. A lot of what you say makes sense and at some time I am sure I will buy an EM set. I managed to buy a number of tubes from an Ampro set that uses the same tubes as my Barco. So all my tubes are in Ampro LC housings I would have to remove them and place them in Barco LC housings so I was thinking I might just as well build a frame for the Ampro LC housings and get Lens Flapping thrown in but I take your point about the differences.
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zGman
Joined: 22 May 2006
Posts: 599
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| Posted: Wed Jan 28, 2009 5:53 am Post subject: lens flapping - aka - schliemphlug adjustments |
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On every late model LC machine I have seen (marquee, sony, barco) the lens and c-element
always stay in position while the tube angle changes. The entire assembly (tube+lens+housing)
only moves together for "toe-in". If you go moving the lens all about for schliemphlug, what
is that going to do to your centering and geometry?? I think there would be endless chasing
about to dial everything in....
G
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