Cylindrical A-Lens Owner's Thread - Page 21

That is very impressive indeed.

There is nothing magic about the 1.25. I stand by what I said in the other thread, although I decided it wasn't good use of my time arguing there. The 1.25 will have the same geometry issues inherent with a 2 doublet A lens. I believe part of the reason he was seeing light drop off was he was vignetting and didn't know it. If the ray pencils are partially obscured at the lens it does not result in an image shadow on screen, but a light drop off as he described. As the 1.25 has less expansion, it will have less artifacts from expansion by definition. But those should be trivial and for the most part unmeasurable. Problem with that Sony and a IIIL is it has a fat beam at the physical exit point of the chassis. Someone that knows how to ensure no vignetting needs to check where it will, and will not fit.

And that alone is the only thing is has to offer IMO. $15K?

To be fair, it is substantially larger, so vignetting will be less of an issue and you could use it at shorter TRs. Of course it doesn't really cost that much, depending on where it comes from.

Can I assume there is an additional row to this theater? It would be a shame to put that kind of money into it and sit against the rear wall, where are the rear/side speakers?

-Sean

The other thing to consider too is that the ISCO III being 1.33x, was designed to work with HT projection where the ISCO 1.25x is really only made for the 2048 units used in D-Cinema. You could use a 1.25x in the home, but you would need custom scaling where the 1.33x lenses will work with the simple letterbox and 4 x 3 modes.

A massive PLUS ONE on that

A-lens or not decisions decisions........14`.2" throw 1.97 TR.

JVC RS65 (X90) 3m white 1.2 gain screen 108hours Calibration at 250hrs. Resized only.


Arts Sim HT5000 + A-Lens 4.25m screen

You could combine the JVC and anamorphic lens. I have an RS55 with an Isco 3 on a 135" wide 2.35:1 Enlightor 4K screen - my first row is at about .85 SW and I love the effect of the e-shift and anamorphic lens at that close distance. In my tests it seemed that the benefits of e-shift diminished once you reach 1-1.2SW depending on the quality of the source and the screen material.

Thanks for the reply Hogpilot
Your A-lens is giving you more lumens needed for your 3.4m screen which is good if needed but what else is the A-lens doing to improve the picture?
If extra lumens are not required, menus visible all good but is the picture quality something you can photograph to show A/B comparisons or is it more like a perceptual improvement?
The 6million odd e-shifted pixels and no SDE remaining without the A-lens and lower lumens degrade picture quality enough to buy the A-lens?

Just trying to understand, i can purchase an A-lens with a 2 week full refund if needed but to save the hassle hear i am, extra lumens would be nice as lamp ages but really asking about picture quality..

It's notoriously hard to appreciate the difference an A lens can make just using photographs (you need the full res available otherwise it's a waste of time), and usually only a demo can provide what's needed.

Gary

I'd say the lumens are the biggest contribution. I haven't had a chance to A/B with and without the lens in my final setup (zoom vs. lens). I have yet to notice any extra CA, but the Isco is about as good as they come in this respect so no surprise here. What's your viewing distance?


I would love to take some pics, but I'm currently deployed to the Middle East until July, so unfortunately my theater will be sitting and waiting unused until then Sorry I can't offer more help on this...


Only you can really answer that question, but I'll offer this up - when I was A/B'ing the Enlightor 4K screen material against the Seymour AV CenterStage XD, the 4K clearly had the edge in terms of lack of screen surface visibility, yet my eye was constantly drawn to the image on the XD because it was noticeably brighter. So I guess what I'm saying is not to underestimate the benefit that the extra brightness will give you. Whether or not it's worth the cost...everyone has a different answer as to how much money is "enough" - hence the rather heated debates on the subject in this forum


I would say that extra brightness contributes to PQ significantly. Since you have the 2-week grace period, I'd recommend you give the lens a shot and see if you like the result. If you don't, at least you're not out any money.

+1! Couldn't agree more...

Thanks for being there for us, Hog. Fly safe. May I use your Isco 3 while your away?

Thanks Hogpilot i do sit 1SW back, looks like i will have to see for myself. Prismasonic Finland must be confident giving 2 weeks grace if disappointed, i will check again though.

Sure, just fix the inop slide for me while you're at it and we'll call it even It's a re-branded Panamorph slide, which may be part of the problem...

Be sure and start a thread with your impressions, please. I'd sure like to hear them, and I'm sure others would.


Motorized, I presume.?

Yes indeed. And I didn't mean to insinuate that Panamorph makes sub-par equipment; quite the contrary, my personal opinion is that their stuff is by far the best bang for your buck in terms of price/performance ratio.

However I don't think that the slide was meant to handle the heavier weight of an Isco 3, hence my suspicion that the motor may be burnt out. However it may be more than that - the unit won't even turn on, so it may be something on one of the small circuit boards under the cover. I meant to send it away to a guy over on Curt Palme's forum so he could look at it before I left, but I ran out of time so it will have to wait until I get back. Or maybe I'll just trade up to a CineSlide...

With your JVC is there a need for a slide with these menu options?

Manual quotes
Anamorphic The video images are projected after being enlarged in the vertical direction of the panel
resolution. This setting is used when one uses the anamorphic lens to enlarge them in the
horizontal direction.
If a 3D signal is fed in when Anamorphic mode is set to A or B, Anamorphic mode is
automatically turned Off.
Settings: A, B, Off [Off]

A: Video with an aspect ratio of 2.35:1 is enlarged in the vertical direction of the panel resolution and then projected.

B: Video with an aspect ratio of 16:9 are displayed by reducing them in the horizontal direction, without changing their size in the vertical direction.

Off: Used when watching video images other than those with a 2.35:1 aspect ratio while using an anamorphic lens. 2.35:1 video images are projected without any changes. (Black bands appear on all sides)

I haven't personally played with that feature (my Lumagen Radiance does all the processing), but yes it sounds like you are correct, no need for a slide if you want to use the JVC's built-in scaling functions.

Am i right in thinking with an A-lens I leave my pic in 16:9 mode (mid zoom) let the A-Lens fill the screen gaining 12,500 on/off CR (X90) + 25% Lumens 425?

Cine4home table:
-------------Zoom IRIS Lumens X70 X90
High / D65 Max Closed 370 53000:1 80000:1
High / D65 Min Closed 310 69000:1 105,000:1

You'll maintain the CR, but you won't "gain" lumens - you'll still only have the quoted number of lumens, you just won't lose any to the overspill you'd have if you were zooming.

The only time you "gain" light output from using an anamorphic lens in numerical terms is when you're measuring light off the screen in foot-Lamberts, since that measures light per unit area.