Originally Posted by tibia
I have been reading this thread with interest. Not because I am in the market for a new projector but rather because I was Product Engineer for the SP8602 until I left InFocus last October after 13 years working there. Now with Art Feierman's review just published I would like to share with you how some things got the way they are. I've got to hand it to Art. Some of his comments are spot on. Like he knew what we were thinking. I've never met Art but did have some correspondence with him after he received an early pre-production unit for his initial evaluation.
SP8602 was intended to be every bit as bright as IN83 but with SP8602's smaller 0.65 inch DMD compared to the 0.95 inch device in IN83 we knew that goal was probably not going to be achieved. Furthermore IN83 allowed a little more yellow to sneak into its Rec. 709 green in its quest for maximum lumens which was noted by some reviewers.
As a young school boy I developed an interest in motion picture projection and, for a time as a young adult, operated two movie theaters and designed the projection booth in one of them. Long before the term home theater was coined I was working with CRT projectors fitted with 3 tubes, barely able to make 100 lumens on a good day, in my home and disco night club starting around 1977. Movies and the projection of them have always been of great interest to me since I saw my first projection booth in 1947. To be able to faithfully reproduce the vivid colors of three -strip Technicolor movies is the cat's meow I thought.
I took a stubborn, single minded approach to SP8602 in that at all costs it must deliver the best possible color fidelity and image quality from a bluray 1080p24 film based HDMI source when installed in a well designed, light controlled environment. Video based material and sporting events had to also look good, but for me it was always about movies. I love movies.
With this background I jumped when given the chance to have an influence on the design of SP8602. My goal was first and foremost to get the color right. The eye is far more sensitive to color variation than lumens variation. Even at the cost of losing lumens color had to be right. Furthermore it had to be right across the entire dynamic range to the full extent afforded by DLP technology. I drove the SP8602 designers in Taiwan and China to the point of being a royal p.i.t.a. in an effort to get the sequence code right followed by lamp pulse to get the good dynamic gray scale tracking and lifelike color Art liked.
There are two critical design parameters in DLP projectors that aren't often mentioned or even well understood by most people outside of projector design and manufacturing. They are sequence, or sequence code, and lamp pulsing. This is the root code that determines how DMD mirrors will flip their on/off states based on color wheel segment size in conjunction with lamp spectral power distribution referenced to a certain RGB bit level.
Art mentioned some SP8602 gammas seemed a little unusual. Maybe it is because we placed so much emphasis on getting the sequence code right and let gamma fall where it may.
In its original design SP8602 would have been a little brighter when the lamp was in high power mode compared to the default low power mode. It seems the lamp's manufacturer was having some life and thermal problems when running the lamp at its specified full 280W power. In order to avoid another huge production delay waiting for a new lamp design we agreed to slightly reduce the lamp's power to 260W when in the high power mode. This is why there is not a great lumens difference between default normal 230W power and high power lamp modes.
Yes, SP8602's case is rather large and boxy. Part of this is a result of InFocus's new design language but does allow for better air circulation using a larger size lamp cooling fan but spinning at slower speeds. Another factor is that we said there could be no light leakage or venting from the projector's front surface. Everything is vented out the side and rear with extra baffles to prevent any direct light escapement.
SP8602 was supposed to have been released last summer. Its electrical, mechanical and optical designs were complete by that time but its firmware has been huge undertaking because InFocus' manufacturing partner for this product didn't have much experience in going beyond standard Texas Instruments reference designs. Such are the perils when dealing with the Chinese. SP8602 makes extensive use of Pixelworks devices for front end processing as well as image enhancement and motion smoothing, frame interpolation.
Although I am no longer with the company I still maintain close ties, do occasional contract work and have been kept current with firmware. The unit I have is pre-production and has the 68th version of firmware which is two weeks old. I suspect there are even newer versions now. So you see this has been a long struggle and, at times, frustrating for everyone.
InFocus has tried very hard to fully test SP8602 firmware to confirm it meets all design goals and features offered before releasing it to full manufacturing status. There are many more features than Art mentioned in his review. So many times it was one step forward and two backwards. This is why it has taken so long to bring this product to market but the delays have surely resulted in a better product.
As I read Art Feierman's review I picked up on his not too favorable impression of SP8602's dynamic aperture. There are two ways to activate a dynamic aperture, stepper motor or voice coil. Each method has their pros and cons. SP8602 uses a stepper motor. Perhaps more and smaller steps could be incorporated at the low end of the aperture's range.
Another thing is the color temperatures Art measured. Every SP8602 is supposed to be individually color calibrated to D65 in Video mode with a Minolta CL-200 chroma meter but Art's out-of-the-box measurements were slightly higher. The algorithm that does this is normally quite accurate so I am a bit puzzled. Knowing InFocus as I do I am sure there will be much discussion about this.
I wrote this post in an effort to give SP8602 owners and potential owners some idea of how much effort and thought has gone into this product. I am not a spokesman for InFocus so what I've written are my own recollections of events. I don't think it appropriate for me to say anything more but I'm sure SP8605's project manager, Ben Joy, who just joined AVS Forum as InFocus-Ben will keep you all informed.