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Post by gjaky on Mar 11, 2018 16:56:27 GMT -5
Uh, that COULD be something other than the C element. It could even be the lenses. I have some of the Elcan made (last generation) HD-10L lenses made for VDC after 3M shut down the lens shop, and my Elcans do exhibit a small but (in some scenes) noticeable reflection issue. The reflection appears 180 degrees across the screen from the source part of the image. It has to be a bright object and a dark background to be seen. Scratches in the C element should do nothing but ever so slightly reduce your overall contrast ratio. I would really not expect to see your symptom being caused by the C element. I am evaluating the Elcan HD-10L lens against a "vintage" USPL HD-10GT17 lens as to which one to use. And so far I found the Elcan lens to be better as far optical build quality is conserned. Can you explain further how to test this reflection thing? |
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nidi
Junior Member
Posts: 72
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Post by nidi on Mar 13, 2018 17:11:27 GMT -5
I observed the same optical problem on my HFQ900 lenses. you basically take a black background with white titles (like the end credits of Star Wars)
I had inverted faint scrolling of the end credits in the opposite direction.
since the black powder coating of the inside of the housings that's gone (or I haven't noticed it again since)
Michael
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Post by stridsvognen on Mar 15, 2018 5:12:01 GMT -5
Personally i prefer the 3M build HD10l lenses over the Elcan ones. The older lenses dont perform better contrast wise than the Elcan, i got a set of 3M HD10L with me back home from the states last time, wich ill put on my projector when i get the time. Rey measure light output on green only with 2 different lenses, and see how it compares, i had 0,6fl more out of a Elcan lens, than on my 1997 GT17 set, and the impression watching the immage is that the extra light is scattered light, washing out the image. I think that any off the matte black 3M lenses performs as good as it gets, so its just to pick the one for the screen size your running.
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Post by gjaky on Mar 15, 2018 15:11:32 GMT -5
My GT17 is a shiny black one, probably from '97-98, without a sticker, as it was on a Runco machine.
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Post by stridsvognen on Mar 15, 2018 15:39:08 GMT -5
Can you snap a pic, i have 2 different type og GT17 the oldest one 1996/1997 from my Vidikron Vision One
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Post by gjaky on Mar 16, 2018 2:04:12 GMT -5
 This is it. |
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Post by stridsvognen on Mar 16, 2018 8:20:39 GMT -5
look like the 1999 set i have here, if so they should be verry nice lenses.
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Post by stridsvognen on Mar 16, 2018 8:33:33 GMT -5
 This is a 2005 HD10L, very nice lens, will work better on a normal HT screen size than a HD10E / HDQ 900, but they will bothe have focus uniformity issues as none of them is made for the 90-110" screens most of us is running, the HD10L can resolve the tubeface on screen, the HD10E cant. Greg was running Elcan HD10L on his Marquee 9518, and we swapped those to a 3M set, wich was a very nice improvement in contrast, Focus wise they are the same. |
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Post by gjaky on Mar 16, 2018 16:46:25 GMT -5
I just gave the GT 17 to friend for testing, he has a more mature setup than me, but he using a plain HD-10 lens now, so I will be curious what he finds out.
As for testing on my side. I wrote somewhere here already these test. but I do it again. I have a friend who designs astronomical telescopes, and he showed me a few tricks on testing the lenses.
1.) put up a dot pattern and stand in the plane of the screen, so an individual dot would fill the whole area of the lens as you watch directly to the lens. Then observe the surface of the glass of the lens, also by moving slowly in different directions see how the dot is moving out of the glass.
2.) Get a paper sheet and play in front of the screen, before the focal point.
We did these test originally on my XG 135 LC's lens, the HD-18, and my friend was not impressed at all by the optical build quality of that lens.
Now I revisited these with the two lenses. For test 1.) the GT17 showed clear signs of concentrical disturbances in glass and the distribution of the light was uneven. While the Elcan lens showed rather smooth glass surface here, with only a few random "scratches" in the center area, and the light distribution was as good as it should.
For test 2.) the results were similar, paper sheet before the focal point showed light uniformity issues in the blob with the GT17 lens, the outer edge beeing "lighter" as a sign of spherical aberration in the lens, while the Elcan lens showed smooth, even result again.
Interestingly I found the GT17 lens results very similar to the HD-18 results back then, and the Elcan lenses showed clear superiority in these regards. But of course light scattering still could be an issue which is not covered by these tests.
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Post by stridsvognen on Mar 17, 2018 4:24:26 GMT -5
The Elcan lenses seems sharp to me, only isue i had was the contrast, it should not hold uniform focus across a 100" screen, think the specs state up to 80", its a small screen lens, most likely perfect for a 70" screen, the GT17 lineup at the 90-110" screen size, and then comes the HD10E for extremely big screens. I would like to try out a 2005 build set of GT17, as i think they would be the perfect compromise for our aplications.
I did test a brand new set of 1996 build GT17 lenses against the 2005 build HD10L lenses on a 110" screen, and we kept the HD10L lenses on that projector, and it was originally mounted with Elcan HD10L
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