Tease, new Prismasonic cylindrical lens and remote motorized sled. - Page 15

Ron, thanks. Yes, Anssi is absolutely taking care of me. Replacement parts have already left Finland, arrived and departed Sweden and are on there way for Thursday delivery!! I'll save the full story for later this week but thus far I'd have to say this is the best service I've ever encountered.


I would suggest that the single mounting hole would be fine if attached to a flat plate and well tightened. You could also fashion something to clamp onto the non linear motion (15mm) support. In my case I'm going to create an elongated 'U' mount that attaches directly to the ceiling and mount the lift inside. This way I can keep the weight off the projector mount.

Sean:

I have the manual stand, so no moving parts. I had to take down the projector and attachment plate (AK-5 from panamorph), which attaches to the chief mount. I lined up the lens to the projector and then did an outline of the stand top with tape on the attachment plate. Then I cut the stand top out of paper with the corresponding two slots/holes on the stand top. I then placed that "paper version of the stand top" within the tape outline on the attachment plate and marked the two slots/holes on the attachment plate (for the metal shop to drill the slots/holes). A pair of bolts, nuts and washers and I can attach the stand to the attachment plate.

I would recommend using the two slots/holes for attaching the stand to ______________ in your set up. I like the fact that the slots allow for some give and take when maneuvering and attaching the stand ...a hole requires exactness. And the other reason being stability.

Ron

The 6000R series lenses cannot be mounted upside down, and if the CB-500 mount with grips to the stand rails is not used, perhaps the only way to ceiling mount the lens is to use the two mounting holes with 6mm screw threads (red circles) on a motor plate, and some kind of U brackets to the ceiling. I suppose Moggie is planning to do something like this.

One idea is to have only one u-bracket, which attaches both screw threads and goes up from sides of motor box (from between the stand rails). This may be the cleaner, since the brackets don't go in front of the IR windows.



The 6000F series with fixed stand can be mounted upside down. The following drawing shows the hole positions.

http://www.prismasonic.com/images/drawings/HD-6000F.pdf

... Or make or purchase (sold separately by Prismasonic ) grips that the owner can affix to their existing PJ mount, similar to how they work for the CB-500 mount, or on the bottom of their mount. Admittedly not a perfect option since it throws of the the balance of the mount/PJ combo. But may be preferable where a separate ceiling mounted lens lift is not feasible.

The slot holes on the attachment worked perfectly with the prismasonic stand. I was able to use two screws, nuts and two washers per screw to attach the stand to the plate. I've adjusted the geom. and took a stab at sharpness (but I'm not satisfied there). I popped in a couple of blu rays, but could only spend about 20 mins, so certainly not enough time to get an impression of the lens.

What I did notice was an increase in detail. We watched "Get Low" over the weekend. Watching scenes last night, the fibers on the jackets stood out and the stripes in Murray's dark suite were noticable. I also noticed an increase in sharpness on the edges of the image. Another positive was the ease of setting up the geom. with this lens.

Two other observations:

1) Autofocus would be great feature to have vs my manual. Turning the wrench and stepping up to the screen each time to verify the results is a pain. But, once it's set, it's set.

2) Keep in mind, I have 2000 hours on my lamp...but I noticed that I had to go from econ to standard on the lamp to get the associated pop that I felt was missing vs my prev. lens. Again, it's not fair to say that it could be my eyes playing tricks on me, but image did seem a tad dim. A simple excercise would be to take the lens out of the path by loosening it and sliding it up....but I just got it into place and the last thing I wanted to do was that exercise.

Again, those are my initial observations with only 20 mins of playtime and still some tweaking to do. I know everyone is interested in some real world usage, so I wanted to get at least some thoughts on AVS for those interested.

Ron

Update: So replacement parts arrived today exactly when they were scheduled and the lift is now working perfectly. It turned out that my original remote wasn't working -- strange because feedback LED and IR LEDs are transmitting something.

Anssi, thanks for your help!

It is very hard to estimate the brightness differences otherwise than with the light meter. I have found that even by doing the A-B test by switching the lens, your brains can have any opinion due to the lack of reference, especially if the difference is marginal.

According to our brightness comparison measurement between the ISCOIII and HD-6000, the ISCO III had around 1% better absolute value (lux) in brightness. However, taking into account that HD-6000 expands the picture 1.35 x (versus 1.33x expand of isco), the lumen (lux * m^2) value is close to exactly even.

I've built my screen to be 2.37:1- so how will the 1.35 expansion compare with a 1.33 expansion ( which I thought this new lens was also)?

1.35 expansion converts 1.78:1 to 2.40:1. Compared to 2.37:1 the difference is only 1.3 % (few centimeters in 3 meter wide picture) , and can well be masked away from sides.

Ditto. I've done the math for my 115" wide scope screen and the difference between my 2.35 AR and a higher AR is easily lost in the side mask/frame, esp. since you're splitting that difference by absorbing the overshoot on both sides. For 2.40 that's 1.22" spill on each side.

What is the vertical stretch produced by our electronics (be it a scaler, projector, blu-ray player, etc.)? I was under the impression it was a vertical stretch of 1.33x, will this not produce improper geometry if the vertical stretch doesn't equal the horizontal? Or would it be so marginal that you wouldn't notice?

-Sean

1.33,

That's what I was getting at really but got mixed up with aspect ratio (thanks for the reassurance though).
What about the geometry issues?

I watched a 1.85:1 BR last night with the lens in place...perfect geometry...no curvature on either side of the image. I have not watched a film with a 1.33 aspect ratio, but will pop one in this weekend to see that image with the lens.

The more I use the lens, the more I become enamoured with it's performance. Again, the advantages of the cylandrical lens vs a prism lens are shining through for me. Hats off to Prismasonic for breaking the price point on a cylandrical lens.

Ron

Thanks Ron. The BR you mention-you're talking about a lack of pincushion right? The geometry issues ( if any ) will be where the 1.33 vertical stretch employed by the PJ is not quite compensated for with the different ( 1.35 horizontal stretch) employed by the lens? Right? I don't know if my dangerously limited knowledge has a grasp of this and whether the image will be slightly too tall or too wide - and more importantly, if it's noticeable or not.

Yes, pincushion is correct. Just to clarify for everyone my set up. I'm using an SMX curved 2.35:1 screen, planar DLP 8150 projector and my previous lens was a prism (panamoroh UH 480-terrific prism lens).

In my previous configuration, I would have noticeable pincushion on 1.85:1 material. Less so on scope material (because one could mask the difference with the frames light absorption).

Pincushion is on top and bottom not sides. No cylindrical lens should cause any substantial curvature on sides.

Can anyone please comment on the geometry question asked by bigjas and 230-SEAN?

My bad-stand corrected on the proper terms.

No? My ISCOII does. It's more notable at the top and bottom since they're longer but there's definitely a curvature on the sides as well.

Thats because the old isco 2 had spherical elements New ones are all cylindrical Don't see it on mine (3L). Insubstantial if there. Figured Ron meant top and bottom.

I can't say that I ever saw any side curvature on my ISCO II, though perhaps that was because it of the masking.

Gary

Moving away from the pincushion discussion again for a minute...
I can't think why anyone would build a lens with a 1.35 widening ability when most if not all PJ's, scalers etc employ a 1.33 vertical stretch.
A full screen image would appear to thus be wider / fatter by a couple of inches across a 115" wide screen(trying to now employ some logical thought) using this new lens thus the geometry is "out". Whether this is noticeable or not is the real question as this fattening occurs across the whole screen and cannot be hidden by cropping or borders etc
Anyone who actually has the lens care to comment? I can't see it being a huge problem for me but for others who look for these things-it could be.

Designing for a 1.35 stretch is somewhat of a head-scratcher. I too assumed this lens, as I think all others do, would use a 1.33 stretch and therefore ordered a 2.37:1 screen to get the right fit when using the lens without using any zoom. My screen is 54.85" x 130". If my calculations are correct, the difference in stretch between 1.33 and 1.35 on this screen will be 1.95" or 1.5% of the screen width. It would seem that indicates a 1.5% distortion in the picture. The question remains how noticeable will this distortion be in that size picture.

In addition, it now appears that zooming will probably be required when switching aspect ratios and using/not using the lens. This will not be a deal killer for me, but is an inconvenience I wasn't planning on.


I certainly don't know enough to know if there are some physical limitations in the design of this lens that required a 1.35 stretch but it would seem that these problems could have easily been avoided when the lens was designed.

Hopefully Anssi can chime in when he has some time.

Let me also mention that I had a problem with my lens from shipping damage. Anssi and AVS have been fantastic in dealing with the problem and my lens should be back to me on Tuesday. Tremendous customer service. I am anxious to give it a try and do a subjective evaluation of the stretch issue.

Is it possible that a 1.35x lens was cheaper to manufacture (the glass), allowing cost to be lowered, which in turn allowed the lens to be sold at a lower price point? Just a thought.

-Sean

It is not the price issue.

1.35 * expand has been designed due to very rational reason. Every anamorphic lens has a non - linear expand from center to sides. This linearity is dependent on the throw ratio. Lets take throw ratio of around 2 as an example which may be a pretty common value at HTs. With a 1.33 x lens around 50% of the area at the horizontal center of picture has not 1.33x expand but rather average 1.31x. With 1.35x lens this center area is very close to 1.33x (average). So this is a matter of taste wheter you want center of the picture having a correct expand or the sides. We preferred center in our design.

Other reason is that this 1.35x supports our 2.4:1 screens.

..and those who are worrying about seeing 1.5% distortion; no-one can see this in blind tests.

Some worse than others. Some almost none.

Thanks for the clarification. I wish I'd known this before I'd made my screen to be 2.37:1... Doh...
I don't mind a touch of zoom here and there presuming I'll still get constant image height and won't have to also adjust the lens shift?

Thanks for the explanation Anssi. It sure makes sense to have the proportions more correct in the center of the screen.

I also might have ordered a different screen ratio but agree that some minor zooming won't be much of an issue as long as we don't have to shift.