Tease, new Prismasonic cylindrical lens and remote motorized sled. - Page 17

There should be clear point of focus.

That doesn't sound good. Is it too much one way and when you move it back the other it puts it too far as well? Try just barely moving the allen wrench (I think that's what is used to adjust focus on this lens) as you might just be over-turning it. I am curious to hear if anyone else is having this issue though.

-Sean

I wish some of you guys would post some screen shots

If anything I seem to need to turn the allen key a full 360 degrees to register any difference which isn't a problem at all. What I'm finding though is that was is in focus in the middle area of the screen leaves the outer extremities not as crisp. Is this normal? It's really only noticeable when I'm checking the grid lines from 6 inches but still curious.
I'm not sure screenshots will assist anyone having read some of the older threads and arguments that they seem to generate-and I'm no photographer but I could try.

Hmmm, that is interesting. I wonder if that has anything to do with the 1.35x stretch that the lens produces? Anssi said that it would allow the center to be closer to 1.33x but maybe that is at the cost of over-stretching the sides and somehow causing improper focus? I would like to hear if anyone else is having the same results or if maybe there is just something going on with yours that they can fix?

-Sean

As the throw ratio get's smaller there exist more non-idealities in the picture.
The geometrical- and grid distortion increases. Such happens also to focus non-uniformity.

Having said that, this is naturally depending on the lens design how well the focus uniformity in handled. Since the HD-6000 series has been designed to fit the beams for throw ratios down to 1.3, I guarantee that all effort in design has been put to find the best possible focus performance. According to the simulations and experiments, with 6000 lens the focus uniformity is more than ten times better than with the CORRECTED prism designs. (IMO the corrected prism design has already a very acceptable focus performance.) Also with a very thorough comparison experiments with the ISCO3, even if I'm biased to judge, I frankly have to say that HD-6000 handles better the side-to-side uniformity. I remember that Alan got a similar result as well..

I suppose bigjas has a pretty short throw setup, since he was surprised of pincushion distortion. If you can move further back with the projector in a room, and use less zoom, the performance will improve in all aspects. However, if you have to go to 6 inches from screen to see the focus imperfection in grid lines, it has to be close to perfect already.

EDIT: I forgot to mention that most projectors in themselves have already more or less non-uniform focus, especially LCD's which can be very fussy on the edges. It is also good to take this into consideration when testing the system, because lens attachment cannot correct the problem caused by the projector.

We have guaranteed to receive the aluminum parts for 100 pcs of mounts on around 15th of this month. Then the parts will be surface treated. It takes 1-2 weeks. So I would estimate that the mounts will ship in the first or second week in August.

The mounts will be shipped to customer directly from us. We will need to know the drop from ceiling to the projector's bottom, because the pipe length of mount will be customized according to customer's wish. We can also give a support in discussing which is the minimum recommendable drop with 'lift' lens models (HD-6000R and HD-6000RX).

The user manual is not finished yet, but we try to get the manual available as soon as possible. Some information can be found here.

http://www.prismasonic.com/english/d...on_cb500.shtml

Those who are worried about the compatibility issue with a projector; please rest assured. By utilizing the cad drawings of tens of latest HT projectors, we have not found a single which was not compatible with the mount, including the projectors with non-flat bottom or asymmetric optics position.

My throw ratio is 1.9 which while not brilliant is well within the acceptable range for this lens. My screen is not curved however so maybe that's a part of it too.

You'll also need to make sure the light path passes horizontally centered through the optics. Being off by even 1mm can be the difference between having pixel level clarity and not.

Does this mean that non expert user installs are unlikely to ever achieve the best results. 1mm is pretty daunting as I'm only doing this by eye. Any tips or tools that may assist? It looks like the light is passing through the middle of the exit lens but I'm by no means certain

I got my first cylindrical lens in 2009 and I'll admit, it was not until some time in 2010 I actually worked out how to get the best out of it. So no I don't expect anyone here to have it sorted right away.

For a time my lens was mounted to a manual slide and the difference between where the slide touches the rubber stops and locks was the difference between perfect focus and not quite there.

The interesting thing is, there are probably next to no movies that actually have much detail to the level of single pixel lines, so even when you don't have 100% alignment, the image will still look good.

As Asnsi said, the projector's lens itself may prevent you from obtaining corner to corner focus simply because of its own design faults or limitations, so don't lose sleep over it. I would suggest removing the anamorphic lens from the light path and focusing the image as best you can first, then add the A-Lens and do the astigmatism adjustment.

One of the best tips for checking alignment was originally posted by Aussie Bob which involves sliding a piece of paper between the Projector's lens and the anamorphic adapter. This way you can see the rectangle of light and its position on the glass with out blinding yourself by having to look into the raw light beam.

Of course, you can also see the effect this has when looking at the screen and being able to slide the lens left or right whilst projecting a test pattern of similar high detailed image.

That's very interesting. Thank you. The paper tip sounds good as I had been sliding it left and right as you also suggested.
The image does indeed look good when actually watching film content so to put anyone else's mind at rest, we are talking very close scrutiny of grid lines only. I didn't know that about the whole single pixel thing.
When you say remove the lens and achieve PJ focus first and then place lens to adjust for astigmatism- do you mean the focus or the tilt adjustment?

I re-aligned mine tonight before watching a film. I am currently typing this whilst using my projector as the monitor. When the anamorphic lens is set up right, you will be able to see pixel structure on text. If not, don't discount the projector and keep playing with the adjustments on your lens so you get an understanding to what it is doing.


This is from my Blog for my lens, but works for all Anamorphic Lenses.

1. Start with the Anamorphic Lens out of the light path and project an image that has single display pixel lines running in both horizontal and vertical directions.
2. Focus the projector to be as sharp as possible with the lens out of the light path.
3. Add the Anamorphic Lens ensuring that it is centered in the light path.
4. Adjust the Astigmatism Correction [by turning the cap screw with the Allen key provided]. DO NOT rock the projector's focus at any time during this adjustment.

Once you have completed these four steps, you can adjust tilt to even up the pincushion top/bottom.

1,2 and 3 all done.
Sorry for being a bit dense but
4. Astigmatism Correction - does this mean the lens focus?
If so this could be where I went wrong as I adjusted the tilt before the lens focus and you seem to be saying focus the lens first (after 1-3 above) and then adjust the tilt after. Thanks again

Your can make this after the tilt if you like. Astigmatism correction on your lens is made with the hex head socket bolt. This is focus of the lens and because the thread is small, you may find even partial turns can be the difference between being 100% in focus and not.

What are you using for a text pattern?

You've seen or are knowledgable of Annsi's astigmatism thread pitch? Just curious, you seem very familiar with it. Are you making them for Prismasonic?

FWIW, the Isco's are very insensitive to any lateral offest. Certaintly not to any 1mm level. Perhaps it's the plano (flat) glass surfaces that the Isco's don't have internally that fix that anomaly. My personal lens wil focus perfectly regardless of horizontal offset from center.

No, not at all. I used M6 bolts for this exact purpose on my own Mk4 from 2009.


PLANO on the ISCO III? The last ISCO IIIL I saw had curved front and rear glass on the outside as well as the inside. I know some of the older ISCO 2x lenses from real cinemas had PLANO (flat surfaces) on the out side as do mine.

What is the size of the rear lens on an ISCO IIIL?

AB made a post about it some time ago and I played with my own lens and confirmed what he said. I discovered that I could get 100% corner to corner by simply sliding the lens to the left or right by such a small distance. I am simply passing on what my own experiences in a hope that these guys will find joy from these new lenses and not write them off as a bad experience because they couldn't get the image as good as others claim it can be.

10-4. But I think you misunderstood the comment "the [plano surfaces that] Isco's don't have internally".

So nevermind, just sounded like you had some interesting inside info.

Cheers,
Scott

Yeah sorry I misunderstood that. They should have 4 curved surfaces - two external and two internal.


Nothing I haven't found here.

Well I pretty much got my hush box built this weekend (with nice extension for the Prismasonic lens):





Those of you looking closely at the pics will see that there is no a-lens in place! The Primsmasonic lens looks really nice, but I am having my fair share of problems. First it was a dead remote control, now after mounting and running the lens up and down a couple of times, one of the drive motors looks like it stripped a thread.

I had made a mount that would allowed the lens to be suspended directly from my ceiling (roof of hush box) -- the HD-6000R is designed to be mounted on a shelf or with custom attachment to the projector mount. It seems to me that it would be a good idea if Prismasonic supplied mounts similar to mine with the base unit -- they would be extremely cheap to produce.



Anyway, after a couple of lifts up and down I was about to set up the focus when I heard a crunch and the lens froze. Back and forth movement would not free it so having just mounted everything I tore it all down and dismantled the lens. You can see the one side where the motor no longer can hold the weight of the lens.



I've pinged Anssi at Prismasonic to see how he wants to handle this, but I'm really bummed right now since I'm back to 16:9 and cannot zoom anymore since the hush box porthole is not big enough. I'll review the lens and mount just as soon as I can, but at this point I would say that the lens looks solid but I'm not so sure about the lift...

There is more information about my hush box in my build thread (see sig).

Cheers.

Nice. Your hush box looks nicer than my entire theater.

Thanks very much, it's been a LONG two year journey!

Update on my lens: Anssi asked that I ship it back for repair. He promised a fast turn around and I'm hopeful that I'll be enjoying 2.4:1 movies very soon...

Fascinating build! I need to spend more time looking at the thread of your entire journey. But +1 on what I've seen so far.
I think Anssi should have direct shipped a replacement lift along with an RMA for the defective one. But what do I know? And I'm doing my own sled for the lens and God Only Knows how that will turn out.

Hi Steve,

I'm not bothered with the repair vs. replacement. It's not like these units are being cranked off the factory floor. Anssi is going to simply replace the motor drive. The only pain is that the motor is "not end user replaceable" and thus requires the whole lens module to be returned. The motor consists of a coiled spring that would uncoil if detached so I understand the need to return. Anssi at Prismasonic has been very responsive and easy to work with.

I did give a lot of thought to building my own sled. However, given that I've built every other aspect of my HT including curved screen and automated masking system I was reaching the point of exhaustion. I liked the vertical travel and price of the Prismasonic lift so I hit the EASY button. At least I thought I had.

Looks like I will have the lens back in my hands next week...

I hear ya! And my sled? I may have wished I'd gone to the EASY button too. But my vertical travel is limited; It would have meant the lens being lifted into the ceiling. And I had originally planned that. But somewhere along the line I thought "I can build one!". Yeah, we'll just see about that. Lens is supposed to be here today. Sled is still nowhere near done. Still working on soft and firmware.
Addition: My lens arrived today. It is no wonder your lift got a hernia; this lens is BEEFY!

installed the prismasonic and the one thing i can say right away is it's sharper than the panamorph 480 i had. pixel lines are much clearer.. don't like the motorsled..no auto stops..you have to pay attention to where you want it to end up.. pincusion is vg also..the motorized focus would have been nice also

Anssi/Others,

Any reason why hard stops couldn't be secured to the two shafts of the lift to set the IN position so you wouldn't have to guess at the stopping point in the light beam's path? Seems like it would work to me and allow one to have an exact stopping point. You'd still want to stop the motors when it got there, but it would at least provide precision to the lift.

yes this will work. As for balance reason both poles should have the stop at the same level.. And those really have to be stops not breaks. We are working on this issue as well.

Without the stops, IMO, it is still pretty easy to stop the lens just watching the screen. >1.5 throw ratios there is much margin in optics height so that there is an area instead of precise spot in where the lens fits the beam, thus allowing a small time period to stop the lens.

Sorry. I meant to add in their that I would have one each shaft. I was thinking that if you included two rings to the right diameter with set screws it would be great. Then again a perfect set up for most here I would think would be to also have a set in and out position that required just a single remote button press. Short of that, adding stops will be a big help.

Thanks for the quick reply.

Stops in the IN position would be safe given that the motors do not stall in this position. Given my issue with one of my motors I would not do this in the OUT position. Instead, since the motors look like simple DC geared motors you could add a couple of, normally closed, limit switches. Add a reverse power diode in parallel to still allow motor reversal and thus exit off the limits...