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Discussion Starter · #1 ·
Bob,


you've always been very forthright in your answers on this forum, so I want to thank you in advance for taking the time to clarify a couple points about the IF7205 versus the IF7200:


1/ HD2+ dimple fix - is the main effect of this technology upgrade to improve brightness, CR, black-level or "filmlike appearance" (or any combination of these)?


2/ Fill-factor / screen-door - is there any difference in the fill factor of the pixels between HD2+ and HD2? This is another change that could account for the improvements in "filmlike appearance" that TI has announced, but I have heard conflicting reports over whether there is any change in pixel fill factor between HD2+ and HD2 - thanks to clarify this for me


3/ 7-segment wheel - I've understood the advantages this improved color wheel provides in terms of reduced dithering and "dark scene performance". My suspicision is that the improved brightness delivered by reducing the dimple and/or increasing the fill factor resulted in a projector which could provide greater brightness with the same lamp/wheel/optics, or a projector which could provide equivalent brightness with the same lamp/optics but using only ~90% or so of the color wheel, resulting in some "space" to put a new dark/green-neutral segment of improved dark scene greyscale performance. Can you confirm if the improvement from "10- bit pixel depth" arises only from the use of this new 7-segment wheel and that the effective pixel depth for "all the rest of the pixels" which are using the brighter colors from the rest of the wheel are essentially getting the same pixel depth between the 7205 and the 7200?


4/ optics - I think I read somewhere that the 7205 has new optics that completely eliminate the "barrel distortion" or "pincushioning" which was evident on the 7200. Can you confirm this - are the optics on the 7205 different from those on the 7200? Is the distortion really "GONE"??


Thanks again for your answers. I am one of the countless people who is deciding between "buying HD2 now or buying HD2+ later" and getting some clear answers on these technical points from someone like you who is in the know will be an important factor in influencing my decision.



-fafrd
 

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Quote:
Originally posted by fafrd
1/ HD2+ dimple fix - is the main effect of this technology upgrade to improve brightness, CR, black-level or "filmlike appearance" (or any combination of these)?
The main effect from the reduced via (aka "dimple) geometry is improved contrast. This is achieved due to reduced diffraction from the via gemometry. There is also a reduction in the visible pixel geometry due to the fact that the via is much more difficult to see than before.

Quote:
2/ Fill-factor / screen-door - is there any difference in the fill factor of the pixels between HD2+ and HD2? This is another change that could account for the improvements in "filmlike appearance" that TI has announced, but I have heard conflicting reports over whether there is any change in pixel fill factor between HD2+ and HD2 - thanks to clarify this for me
As far as I know there has been no change to the fill factor of the pixels. The mirrors have improved reflectivity due to a new manufacturing process which accounts for the higher lumens, but I have not heard of any change to the fill factor (and I think I would have).

Quote:
3/ 7-segment wheel - I've understood the advantages this improved color wheel provides in terms of reduced dithering and "dark scene performance". My suspicision is that the improved brightness delivered by reducing the dimple and/or increasing the fill factor resulted in a projector which could provide greater brightness with the same lamp/wheel/optics, or a projector which could provide equivalent brightness with the same lamp/optics but using only ~90% or so of the color wheel, resulting in some "space" to put a new dark/green-neutral segment of improved dark scene greyscale performance. Can you confirm if the improvement from "10- bit pixel depth" arises only from the use of this new 7-segment wheel and that the effective pixel depth for "all the rest of the pixels" which are using the brighter colors from the rest of the wheel are essentially getting the same pixel depth between the 7205 and the 7200?
The 7-segment wheel has no substantial effect on the projector brightness. However, the bit depth in the green channel has been increased by 2 bits due to the addition of the 7th dark green segment. This is important because most of the luminance information of a video signal is in the green channel, therefore this channel has the largest impact on overall bit depth. Depending on how the color wheel is implemented the total number of bits available in each color varies. This is also complicated by the fact that DLP is a linear device, but video is gamma corrected to match the non-linear performance of CRTs. For a linear device to re-create perfectly an 8-bit video image designed for a CRT it would need 12-14 bits. DLP, even with a 7-segment wheel has only about 10 bits, so the remaining bits are dithered.

Quote:
4/ optics - I think I read somewhere that the 7205 has new optics that completely eliminate the "barrel distortion" or "pincushioning" which was evident on the 7200. Can you confirm this - are the optics on the 7205 different from those on the 7200? Is the distortion really "GONE"??
The projection lens for the 7205 is a new optical design, and has tighter geometrical distortion tolerances than the one on the 7200. There is no lens in the world that has zero distortion, but we believe this new lens will satisfy nearly everyone with its distortion characteristics. It is still an all-glass Carl Zeiss lens, and the only engineering tradeoff we made was to reduce the zoom ratio from 1.4:1 to 1.3:1.
 

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Thank you Bob.
Quote:
Originally posted by Bob Williams
As far as I know there has been no change to the fill factor of the pixels. The mirrors have improved reflectivity due to a new manufacturing process which accounts for the higher lumens, but I have not heard of any change to the fill factor (and I think I would have).
Here is an exact quote from TI (4th time I post it)
Quote:
The difference between HD2 and HD2+ is a new manufacturing process that enables the mirrors to be spaced more closely to each other and that enables the 'via' - the small 'hole' in the middle of each mirror - to be smaller. This provides a slightly larger reflective surface area to deliver more brightness, and reduces the opportunity for light to reflect from mirror edges, thus increasing contrast
Doesn't "mirrors being spaced more closely to each other" imply a better fill factor?
 

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Quote:
Originally posted by glenned
Are the brightness uniformity and focus uniformity of the new lense the same as the lense on the SP7200, or are those specs improved as well.
Both have the same basic specification as the current lens.
 

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Discussion Starter · #7 ·
Bob,


thanks for taking the time to answer my laundry list of questions. I think I understand most of what I was curious about. Just one more question for you:

Quote:
The 7-segment wheel has no substantial effect on the projector brightness. However, the bit depth in the green channel has been increased by 2 bits due to the addition of the 7th dark green segment.
Does this mean that the extra two bits of green is really the result of the 7th segment alone? In other words, if you were to black out the 7th segment, you'd be back to 8 bits per color, but by having some light through a green segment which is roughly 1/4 as bright as the "standard" green segment, the green resolution alone is expanded to 10 bits (and the other colors remain at 8)?


The reason I'm asking is to understand whether, other than the modified color wheel, if the only changes required for this expanded reolution are in the driver (ie: all data busses, etc remain as before - no hard changes to the chip).


If this is true, it would also mean that anyone staying with the 6 segment wheel could not claim 10 bit pixel depth.


I also undestand about the need for 14 bits to properly handle gamma correction - so the "old" 8 bit 6-segment wheels used dithering for the 6lsbs, where the new 7 segment wheel allows green to only dither the 4lsbs which should be much less noticable.


Complicated stuff - thanks again for your answers,


-fafrd


p.d. on screen door, there's a debate about whether the mirrors a spaced closer together or not. What matters most to me if is there is any apparent difference in screen door between the 7200 and the 7205 - have you ever had them up side-by-side, and what it your impression on this question?
 

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I did not buy an InFocus projector

(Though I've talked my friend into the 5700.


Even though I think the 7200 is as good as any DLP


That said, we are so lucky to have Bob as part of this forum

When will other manufacturers realize that

people like Bob get our (my) total respect.


Rob
 

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Ceiling mount direct swap 7205> 7200?


Since the 7205 has a different lens than the 7200-


is there a new calculation spreadsheet or other info to allow me to select a ceiling installation distance point that will work for BOTH the 7200 and the 7205 with my 130.5: Diagonal Screen?


Thank you in advance this regard.



Murray Kerdman
 

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Bob - do you think it will be possibly in the future for DLP to move from 10 bit color processing into the 12-14 range like CRT offers? And how much of a noticable difference would that make? Thanks.
 

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Lovingdvd,

Obviously Bob can respond on his own, but my guess is that the chip itself is limiting the dynamic range of the system. In other words, it wouldn't do them any good to move to 12-14 bit processing because the DLP chip itself couldn't handle that. The story would be different for a 3-chip design, though...
 

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Hi Bob ,


Two questions , has there been any change in the 7205's ability to "dial-in" the HD CIE x-y co-ordinates (such as the Yamaha DPX-1000 seems to be able to do through software) ? Is there anything you can post showing the CIE colourspace that the 7205 can reproduce ?


...and two , is the current draw still 4Amps like the 7200 ? (looking to sum up the load for a Power Conditioner)


Thanks much ,


Scott........................:)
 
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