quote:

---

Sankor, cheap with relatively shorter life or Iscco and Schnider, expensive with relatively longer life

---

Lenses have a lifespan? That's news to me. Unless you fry it, scratch it, or drop it, it shouldn't change.

danny
 

---

Posted by Richard Fowler (Member # 893) on 04-04-2004, 01:03 PM:
 
Optical glass, like all vitreous material, is amorphous, which is neither solid or liquid. Stain glass over the centuries will vary in thickness due to gravity...and this glassy state allow you to score and cut glass by disturbing the surface. So if you want your projection lenses to last...remember to rotate them at least every 1/2 millenium
 

---

Posted by Scott Norwood (Member # 30) on 04-04-2004, 01:05 PM:
 
With old lenses, the glue that holds the glass elements in place disintegrates and discolors. This results in unsharp images due to "separation" issues. Look at old B&L CinemaScope lenses for an example of this; some of them will be perfectly clear and sharp, while others will not focus properly at all.

My understanding is that lensmaking technology has improved since the early 1980s and that the glue that is used now is much better and doesn't disintegrate like the old glues did. I'm sure that Steve G. or someone else will explain this fully.

I haven't seen the new Sankor lenses, but I agree with everyone else that new ISCO and Schneider lenses are top-notch. If you can possibly afford them, don't mess with anything less. If you can't, then you should probably buy good, used B&L (or similar) lenses and start saving cash to upgrade later.
 

---

Posted by Mark Gulbrandsen (Member # 72) on 04-04-2004, 01:30 PM:
 
Scott,
The cement used before the advent of modern UV curable adhesives was made from Canadian Balsam sap. This is because after it is refined it has very similar optical characteristics to good optical glass. In fact many of the finest optics ever made have element pairs cemented together with Balsam. The down side is that Balsam, like any sap, can actually burn and turn to a brownish color if subjected to high heat over long periods of time. The fact that most old projection optics are still usable is a good clue as to how good Balsam was as an optical cement.

Modern cements are optically clear and curable by subjecting it to an exposure of UV light. This is actually an advantage as it allows lens pairs to be re-cemented quite easily and you have quite a bit of time to achieve proper alignment of the pairs of glass. I've used this type of cement on a number of occasions to repair projection lenses in which the Balsam had burned to a brown color. Getting the pairs apart is not that hard either.... Sometimes baking them will soften the Balsam makong easy seperation of the pair, or soaking them in a solution of MEK will also work its way inside the pair by dissolving the Balsam.

As to the B&L scope lenses turning to a yellow color.... this is due to certain rare earth flourides that were mixed into the glass compound. On occasion you will still find one or two of these anamorphics that are still sharp as a tack. I had one once that was so sharp it even had the president of Schneider Optics fooled! Steve K. probably remembers this lens.

The new Sankors are still junk by comparison to anything Isco or Schneider turns out. The best way to ruin the performance of several hundred thousand dollars of nice projection equipment is to go ahead and install Sankors in them (I bet Gord disagrees though).

Mark
 

---

Posted by Frank Angel (Member # 248) on 04-07-2004, 05:22 AM:
 
Well, not to rain on the Schneider/ISCO parade, I specified ISCOs for a new install and the client's budget committee kicked it down to my second choice which were Schneiders. Then, to my shock and horror, I come to find out that they actually changed the order to Sankors and completely cut the lenses for two formats -- the scope anamorphots and the sphericals for 1.37. I threw a fit, which the budget guys just snickered at.

We still need to rent when we book scope or pre-1953 titles, but here's the strange, yet eye-opening and very surprising thing that I discovered: the Sankors looked damn good! Even I had to admit it. Yeah, yeah, I know...."good" compaired to what? and by what technical testing? Well, by no techical testing....I am only talking about a "subjective" evaluation....you know, the normal people (not us) standing around looking at various films and saying that the picture just looks good to the naked eye. What I mean is, I look at the picture, even as close as ten feet away and I don't see any color fringing, no halos around bright objects, as good contrast as I have seen with our spanking new Schneiders in another theatre. The test patterns look sharp. In other words, practically speaking, when the picture is on the screen, no one, not even me, says, gee, that picture sure looks bad. In fact, the client commented on how sharp and what a "good" picture the new lenses projected. I couldn't very well say, yeah, but you should see how bad they look under a microscope.

Unfortunately, this pretty much puts the kabash on my foot stomping, demand that they put aside funds to eventually buy ISCOs to replace the Sankors. They say, "You're just nit-picking -- the picture looks great; and besides, we can't afford your nit-picking."

Reluctantly I have to agree with them. Is it the BEST image that the best lenses could produce? Most likely not; but if the differenct between an ISCO and the Sankor can only be perceived under test conditions and not by an audience, then maybe the budget guys have a point. What I am finding is that the client as well as the audience sees a image that they find perfectly acceptable and meets their expectation of what a very good picture should look like. I have a hard time arguing that that is not good enough, especially since we still have to rent lenses for scope and flat 1.37. The one last bastion that I will stand firm on is that they get ISCO anamorphics (if there is a God, please let it be that Sankor does not make anamorphics).
 

---

Posted by Erick Akers (Member # 875) on 04-07-2004, 05:51 AM:
 
Frank,

Sankor makes anamorphics, so I guess you may be
outa luck!
 

---

Posted by Steve Guttag (Member # 268) on 04-07-2004, 06:55 AM:
 
Frank,
You go lucky...I've too seen the "modern" Sankors and one didn't need any microscope to perceive you could never really get them into focus. And, one would predict, the anamorphics (yes they make them...in different colors too) we notably worse.
So you found a couple of sizes that work...big deal...Sankors still suck...and the average person can actually still see the difference that Schneider/ISCO make.
The Schneider/ISCO thing did not come about by accident...there are tons of KOWAs and Sankors out there...and in isolated circumstances, one could say they are good enough but one shouldn't bet their reputation on them. On a recent installation (not by us)...the customer complained of their lack of sharp foucs with their lenses (looked like ISCO Ultra-Stars but were really Sankors). He gave us the focal lengths and we brought some ISCOs...even mere ISCO Ultras (we are talking 1970s, early 80s lenses)...it was like night and day. There were, however a couple of focal lengths that did indeed look fine with the Sankors but it wasn't the rule.
Steve
 

---

Posted by Steve Kraus (Member # 476) on 04-07-2004, 08:30 AM:
 
Maybe someone can lend Frank an ISCO or Schneider of matched focal length and a couple prints of a good looking trailer so he can run a split screen side by side comparison.
 

---

Posted by Ravindra Desai (Member # 2337) on 04-07-2004, 09:42 AM:
 
In continuation to this discussion, how much do screen, mirrors contribute to the picture quality?
When do we saty the light is good (to the nacked eye)? When the yellow turns white and when the blue is really brilliant.....what are the most common things one should notice?

Ravindra.
 

---

Posted by John Pytlak (Member # 331) on 04-07-2004, 10:00 AM:
 
Anything in the optical path between the film and the viewer's eyes can affect image quality: lens, port glass, any mirrors (periscope), and screen. Although most people only focus (pun intended) on resolution, image contrast and color are also very important.

Poor quality lenses and port glass often have significant flare, reducing image contrast. Dirty optics can likewise kill contrast:

Conquering Contrast Killers

Seven Deadly Sins of Projection

Screen Luminance

A stained or damaged screen is a constant distraction to the audience, and a dirty screen can waste light or change color temperature.
 

---

Posted by Randy Stankey (Member # 64) on 04-07-2004, 11:48 AM:
 
We just got new lenses. Some of you may remember the pictures I posted of our old ones:







When I priced out new lenses I didn't even mention to the boss that there were cheaper brands out there. I just told him, "These are the lenses we need."

Those old lenses were replaced with brand new ISCOs. Let me tell you! The difference is like night and day! If you have crummy, old lenses you should replace them. The money is WAY worth it!
 

---

Posted by Daryl C. W. O'Shea (Member # 1303) on 04-07-2004, 01:35 PM:
 
Is that an HBO clock?
 

---

Posted by Dan Lyons (Member # 1454) on 04-07-2004, 02:43 PM:
 
Randy...

Did you steal those lenses from my theatre?!

danny
 

---

Posted by Randy Stankey (Member # 64) on 04-07-2004, 03:39 PM:
 
I got the clock at a garage sale for 50¢. It never had a logo on it since I've had it. Somebody else could have removed it. As far as I know, it's that ubiquitous clock made from a 16 mm. film reel that you can find all over the internet. It very well could be that HBO clock.

Those lenses were the "El Cheapo" solution when the projector was first installed. I never liked them. It took me several years to even convince the boss to listen. It took me almost 6 months to get him to bite once I got him interested. We got a big money donation to the college. That's how we paid for them.

If you want your lenses back, Dan, I'll be glad to send them!

Seriously, though. We're going to keep them as paperweights. That's about all they're good for!

I've been talking to the boss about using them as "tokens of appreciation" for people who donate money to the college. We'll take them to the local trophy shop and have them engraved with a "Thank you" message. Then the donor can take one home and keep it on their mantel as a momento.

Either that or I sell them on Ebay. Some stupid idiot is bound to give me $50 for them!
 

---

Posted by Dan Lyons (Member # 1454) on 04-08-2004, 12:49 AM:
 

quote:

---

Either that or I sell them on Ebay. Some stupid idiot is bound to give me $50 for them!

---

I've seen several used equip. dealers ask 100 each for those old things!
 

---

Posted by Randy Stankey (Member # 64) on 04-08-2004, 08:46 AM:
 
Cripes! I would NEVER sell these junky things as usable equipment! They're paperweights!

The most I would ever think of doing would be to say, "Own a piece of cinematic history!"

...Because these lenses are HISTORY!
 

---