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Quote:
Originally Posted by rlhjr34 /forum/post/16904600


WOW! with the equivalent of a 20x Color wheel I should hope there is no RBE! If someone claims there is they have to be making it up!

There is no visible RBE. Not even when you look directly in the lightpath.


Regards,

Ekkehart
 

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The manual for the unit looks pretty much the same as the manual for the Planar 8150. i think the manual needs some additions specific for the LED nature of the machine. The manual has very little info on the dynamic black functions, referring to it as a dynamic iris.The Planar has a Dynamic iris. This machine does not. From the cine4home review and posts by Ekkehart, the Dymaic Iris has been omitted from the light engine whereas it is present on the Planar. To me it is very clear the Dynamic Black functions are implemented by LED dimming. One could expect this function to be refined and improved over time. Like the planar, the optics will perform optimally if the machine is mounted with lens center at screen center though good performance should be obtainable with the lens kept between screen top and bottom. 20% above and below are possible but there will be some noticeable CA by such extreme lens shift.
 

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Quote:
Originally Posted by Cine4Home /forum/post/16906337


There is no visible RBE. Not even when you look directly in the lightpath.

Ekkehart after he spend too much time looking directly into the light path
 

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Bob H. said optimum CR without bad optical degradation would be at screen top or bottom for the lens position. This would be due to the black inside of the lens barrel absorbing some of the reflected light. A compromise trading off some optimal optical degradation for improved CR. Bob had no hard data just the designer`s gut feel for overal projector optimization. In this case, a position to be respected.


From the Planar manual, lens sweet spot would be at no lens shift, the lens center positioned at screen center. This would result in lens optimal optical performance. Optimal performance of the projector involves trade offs with the individual choosing the balance


My statement regarding optical performance of the lens is valid. Hope this helps. Take care.
 

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Bob`s position once again was theoretical. How much CR would be improved probably would be slight. I don`t know and neither did Bob. You can with the machine view CA increasing and edge focus decreasing as one uses large amounts of lens shift. Certainly the degradation is tolerable between top and botton of the screen. To me, once you go above it is not tolerable but that is an individual choice.


Hope this helps. Take care.
 

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Quote:
Originally Posted by mark haflich /forum/post/16907383


You can with the machine view CA increasing and edge focus decreasing as one uses large amounts of lens shift. To me, once you go above it is not tolerable but that is an individual choice.

Last year I believe you said that you would accept 2 to 3 pixels of misconvergence near the edges of the screen with a 3 chip DLP if the projector cost less than $30k. How much CA and loss of edge focus are you talking about here that you consider intolerable?


--Darin
 

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I don`t remember saying that but if I did my position has changed. I`d like to maximize sharpness edge to edge as well as the appearance of misconvergence because with a one chipper there is no misconvergence. Once again all this is my own priorities. I don`t like seeing any bleed on text crals which are usually at the bottom of my screen. Also I notice a loss of sharpness there with extreme lens shift. Tome, given what I get with close to screen center placement, the detrioration is not tolerable. I haven`t measured it. If I notice it, to me its not tolerable.
 

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"wrong, Planar actually recommends optimal performance is WITH Lens shift as it increases on/off contrast."


Actually it's ANSI, not on/off.


"How much CR would be improved probably would be slight."


Darin, didn't you find ~50% increase w/a JVC?
 

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Thank you Noah. Do you mean 50% short throw to long for on\\off or do you mean with lens shift ANSI? Obviously if lens shift gained that much ANSI we are talking significant re the JVC. Then lens shift might be very tolereable if good convergence before lens shift. The JVC is not all that sarp to begin with and some decrease in sharpness might not be that big of deal and outweighed by the ANSI increase.
 

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"Do you mean 50% short throw to long for on\\off or do you mean with lens shift ANSI?"


The latter; IIRC from centered lens to even with top of screen.


It makes perfect sense; it would take lenses w/perfect AR (antireflective) coatings to stop reflections stop from bouncing back and forth between lenses.


This will happen maximally with the lens centered where the central area of the lenses can reflect the most light straight down the axis and to the screen.
 

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Quote:
Originally Posted by noah katz /forum/post/16907826


"How much CR would be improved probably would be slight."


Darin, didn't you find ~50% increase w/a JVC?

Something like that, but I don't recall what iris position this was for. I suspect that JVC might be using a lighter colored back side of the iris in order to reduce heat issues with it since the ANSI CR goes down from iris open to iris closed down. I'm just guessing as to the reason there, but I plan to ask them at CEDIA whether any new projectors will have this issue of the ANSI CR going down with more closed iris positions fixed. On the Sharp 20k I measured the ANSI CR was higher with the irises shut down than opened.


--Darin
 

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Darin. I think the thread had morphed to a discussion as to whether image positioning within a lens had a significant affect on ANSI contrast, not whether iris settings had such an effect. Now I do realize that a smaller iris might mean moving the image extemes further from the side wall but my question here would be using lens shift say with the iris fully open and shifting the image to say the top of the image being much closer to the inside of the lens barrel. I can`t imaging ANSI would signicantly increase by doing so. What do you think? Thanks
 
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