Diffferent Lenses

That's really impossible to answer since everyone's definition of "major" is different depending on a number of factors.

I replaced a Panamorph P752 with a Prismasonic HD5000. IMO the difference was "significant", and worth the cost of the HD5000. That said, I don't think anyone who's seen my setup made a comment about the difference. So does that make it "major" because I think it was significant, or "not major" because no one else noticed? I can't say/don't know.

I will say I think as you take each setup up the lens chain from trophy prisms, to optical prisms, to coated prisms, to coated prisms with correction lenses, to full blown cylindricals the differences decrease while the price delta remains the same or probably increases. Where your price/performance threshold lies on that, well nobody can answer but you.

A couple wrenches I'll throw, or food for thought:

A top end lens is a buy once, use forever proposition* If you buy cheaper, you may well end up wishing you had, or at least wanting to upgrade later. This is how I was, I got the Panamorph used at a good price but eventually upgraded, and I'd still sort of like to upgrade to an ISCO/Xeit/etc.

I think there's definitely something to be said for buying a lens that's "price complementary" to your projector, what I mean is I don't think it makes a lot of sense to buy a $6k lens and pair it with a $1k projector over say a $4k projector and a $2k lens.

Consider 4K, it's getting close, when you get a 4K projector are you going to want to use the same lens, will you need to upgrade to something that can better resolve 4K, or will you just do away with the lens since 4K is high enough resolution anyway? If you're not going to use the lens in a couple years with a 4K projector does it make sense to get top end lens now? Likewise if you'd use the lens, does it make sense to pay more now so you don't have to upgrade again later...

Personally, if I could justify the price (read, if I didn't have other more "important" projects to spend that much money on) I would seriously consider a 4K "capable" lens now so when a great 4k machine comes out in a year or two you'd be ready to go.

how does a "4k capable" lens differ from the current lenses? This is a serious question, not a jab.

And one I don't really have a good answer to. And really, I think it's not really a definitive term, in that there's no objective published specification you can point to and say "hey, it's 4k capable". I've seen the comment made a couple times, and I'd like to hear what those folks think it is.

Nebulously, I'd say it's a lens that has artifacts much smaller than the size of a 4k pixel. So it would have CA less than 1 pixel width, it would be able to maintain focus down to that sized pixel, etc. My "assumption" based on the impression I get that there aren't "4k" lenses out there is that we're talking ISCO III, maybe Xeit class lenses. In contrast while my HD5000R is a good lens and works well for 1080p, I can "see" (no pun intended) how with a 4k projector you might be better off without it.

Not true about specifications.

www.xeitoptics.com/specifications/

(scroll down to "Astigmatism Performance" specification).

Well nobody else does

So is that for 1920x1080, when it says 0.25 pixels? Know of anyone using your lens with a 4K projector like the Sony VW1000?

Well, that's kinda my point, actually.

Yes, that's for 1920 x 1080. Double that "0.25" pixels to "0.5" pixels wherever it occurs.

The benchmark for Nyquist is 70% of energy within 0.5 pixels. Even the worst case in the list above is 75%, so it's "OK for 4K" with the following caveat:

Everything, and I mean EVERYTHING has to be perfectly aligned - lens centered, tilt perfect, perfect projector focus across the field (hard to achieve even WITHOUT an anamorphic in the way at typical low f-numbers of projection lenses, around f2, which the Sony 4K uses).

How often do installers achieve this kind of perfection in alignment? Not often.

In a way, it's harder to get digital projector optics perfect so that the hard-headed "focus freaks" accept them. This is because with a film projection lens you can't tell if there are pixel gaps because there are no pixels to see. Film is continuous tone. What you can't see - pixels - won't sent you into conniptions.

But with a digital projector there's always someone up at the screen with a magnifying glass trying to get individual pixels, or even pixel tiling (about 8 times pixel frequency!!!). They couldn't possibly tell whether a projector projecting continuous film tonality was sharp or not, but pixels in a digital projector give you a ready measuring tool.

To give you an idea of what we're talking about, a Sony 4K pixel on a 120" scope screen is 0.8mm wide, and a pixel tiling gap is 0.1mm wide. That's microscopic.

Yes, one of my CM-5E lenses replaced an Isco recently in a demo theater in Australia. Another is planned to be combined with the Sony 4K in the new year in one of those "million dollar" movie star Home cinemas.

To tell you the truth, I was disappointed in the 4K, simply because there wasn't any 4K material available to show on it. I'm sure there are 4K test reels around, but I haven't been privileged to see one yet. To tell any difference at all with Blu-Ray material I had to get REAL close to the screen, and I'm someone who knows what to look for. Your Average Joe wouldn't know the difference, even from a couple of feet away. That's my opinion, anyway.

Thanks for the info as always.

Well there is grain which is what I used to focus on when I used to project film way back when and I'm sure an old photog like yooself once had a darkroom with the little thingamajig that magnified grain so that you could focus precisely the grain under your enlarger. Then to be softened with nose-grease of course once you encountered a scratch in your negative.

td

Heh, I've still got one! Haven't used it for 20 years, though. It's sitting in my "Hoarding" cupboard right now begging me not to throw it out. They were a fantastic invention. Then I'd stop the enlarger down to f16 to ensure perfection.

Nowadays, I use a "video microscope" to focus and rotate my lenses when I'm calibrating them. You get a 16x12 array of pixels on the monitor which does allow focus right down to full and official "Anal-Retentive" standard.