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post #1 of 37 Old 03-26-2012, 03:08 AM - Thread Starter
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I have a Panamorph FVX200 lens and the dust collecting on this thing is killing me. I clean both side and the projector lens constantly. When I look at the lens it always seems to be dusty. It looks like there may also be dust inside the lens. I really don't notice it on the screen but it drives me crazy seeing it on the lens. Is this normal?
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post #2 of 37 Old 03-26-2012, 03:32 PM
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Quote:
Originally Posted by chambers1517 View Post

I have a Panamorph FVX200 lens and the dust collecting on this thing is killing me. I clean both side and the projector lens constantly. When I look at the lens it always seems to be dusty. It looks like there may also be dust inside the lens. I really don't notice it on the screen but it drives me crazy seeing it on the lens. Is this normal?

The scary part is that about 80% of dust is actually human skin flakes
Dust on the surface of the lens looks terrible, but the reality is, that unless there is so much that you can write your name in it, it is virtually transparent for the light passing through it. I'm sure there is a way to measure the light loss and I am sure the anti-A-Lens brigade would have ideas for this, so get yourself a can of compressed air or you build a bench top wind tunnel like I have that allows cleaning of the optics in a space that prevents dust (static) from reattaching itself. Of course, that does not stop airborne particles settling on the surface once the lens is in use.

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post #3 of 37 Old 03-26-2012, 07:25 PM
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The scary part is that about 80% of dust is actually human skin flakes
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post #4 of 37 Old 03-26-2012, 09:22 PM
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Your forgot the at the end

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post #5 of 37 Old 03-27-2012, 12:30 AM
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You should see what most cinema lenses and projection port glass looks like, been there done that Ha!
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post #6 of 37 Old 03-27-2012, 09:18 AM
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The main problem of dust on the lens is not so much soft focus but light scatter, which can reduce contrast considerably. So dust on the lens is definately to be avoided.
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post #7 of 37 Old 03-27-2012, 09:55 AM
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Quote:
Originally Posted by chambers1517 View Post

It looks like there may also be dust inside the lens. I really don't notice it on the screen but it drives me crazy seeing it on the lens. Is this normal?

I have noticed the lenses in my PJ have defects which look like "dust" but afaik are not dust.

Unless you are suffering softness as taffman mentioned IMO you should just ignore this (don't look at the lens when it is lit!).
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post #8 of 37 Old 04-03-2012, 04:34 AM
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Quote:
Originally Posted by CAVX View Post

The scary part is that about 80% of dust is actually human skin flakes
Dust on the surface of the lens looks terrible, but the reality is, that unless there is so much that you can write your name in it, it is virtually transparent for the light passing through it. I'm sure there is a way to measure the light loss and I am sure the anti-A-Lens brigade would have ideas for this, so get yourself a can of compressed air or you build a bench top wind tunnel like I have that allows cleaning of the optics in a space that prevents dust (static) from reattaching itself. Of course, that does not stop airborne particles settling on the surface once the lens is in use.

I don't touch my lens knowing my luck I'll end up doing something wrong.

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post #9 of 37 Old 04-03-2012, 10:23 AM - Thread Starter
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I clean mine and a day later dust again.
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post #10 of 37 Old 04-04-2012, 01:48 PM
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Quote:
Originally Posted by Harlow58 View Post

I have a Panamorph FVX200 lens and the dust collecting on this thing is killing me.

What is it about these A-lenses that attract so much dust? If its as bad as these users describe I would have thought that they would have given up and gone back to zooming.
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post #11 of 37 Old 04-04-2012, 04:13 PM
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Quote:
Originally Posted by taffman View Post

What is it about these A-lenses that attract so much dust? If its as bad as these users describe I would have thought that they would have given up and gone back to zooming.

A lens is a lens, they all collect dust.

An "A" lens collects no more dust than a prime lens, it just looks like it has more since the glass surface is six times larger than the prime lens.

Just don't worry about it! My image looks no better after I clean the dust off my "A" lens, with or without dust it still looks the same, GREAT!
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post #12 of 37 Old 04-04-2012, 04:29 PM
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Originally Posted by RapalloAV View Post


Just don't worry about it! My image looks no better after I clean the dust off my "A" lens, with or without dust it still looks the same, GREAT!

That's good to know.

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post #13 of 37 Old 04-04-2012, 07:19 PM
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[quote=Franin;21868878]That's good to know.[/

I clean mine every 6 - 12 months when I pull projector down for filter cleaning. No measurable light loss before or after. It has been mentioned before that the dust doesn't effect the picture due to focus distance much like dust doesn't effect picture when on lens.
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post #14 of 37 Old 04-05-2012, 04:22 AM
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You've cleaned the filter have you ever cleaned your 'A' lens coolrda ?

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post #15 of 37 Old 04-05-2012, 04:43 PM
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Quote:
Originally Posted by Franin View Post

You've cleaned the filter have you ever cleaned your 'A' lens coolrda ?

Thinks he means he cleans his lens and filter at the same time.

Find a way to neturalise the static on the lens that may assist in dust minimisation. The zerostat comes to mind(used for LP's) used just after cleaning. The cleaning action alone will create static.

Dust will reduce light and image detail, MTF........unavoidable.

http://www.turntableneedles.com/Zero...un_p_3822.html

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post #16 of 37 Old 04-06-2012, 05:35 AM
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Originally Posted by Highjinx View Post


Thinks he means he cleans his lens and filter at the same time.



Oh ok thanks.

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post #17 of 37 Old 04-06-2012, 05:56 AM
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I measured the ANSI through my ISCO II lens a few years back, and despite the image going through a lens with dust on it, the ANSI was much the same as the pj when measured without the lens.

I think it's a bit of a myth IMHO.

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post #18 of 37 Old 04-06-2012, 06:06 AM
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Originally Posted by Gary Lightfoot View Post

I measured the ANSI through my ISCO II lens a few years back, and despite the image going through a lens with dust on it, the ANSI was much the same as the pj when measured without the lens.

I think it's a bit of a myth IMHO.

Gary

I know when we did an ISF calibration with and without the lens it was all indentical. I couldn't tell you how much dust was on the lens though

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post #19 of 37 Old 04-06-2012, 08:33 AM
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Franko Aaron used to clean the lenses on front projectors as part of the sevice before ISF calibration, did he ever clean your optics?
or perhaps they were pretty clean to justify doing it ..
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post #20 of 37 Old 04-06-2012, 09:45 AM
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Originally Posted by cinema mad View Post

Franko Aaron used to clean the lenses on front projectors as part of the sevice before ISF calibration, did he ever clean your optics?
or perhaps they were pretty clean to justify doing it ..

Hey Jase, he didn't. But he did a calibration without the lens first and then with to see if the results were different and they were not. I can tell you i was happy as he charged by the hour so that saved me alot of time and money. Actually I've found and another calibrator here where i live looking forward in trying him out soon. I've recently replaced my lamp so i will need to get another calibration done.

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post #21 of 37 Old 04-06-2012, 06:40 PM
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I measured the ANSI through my ISCO II lens a few years back, and despite the image going through a lens with dust on it, the ANSI was much the same as the pj when measured without the lens.

I think it's a bit of a myth IMHO.

Glass is not 100% transparent, granted better glass is more transparent than ones of lesser quality, dust is a light blocker altogether(dirty sunglasses/reading glasses anyone?)thus light passing through will be affected to varing degrees in reaching it's destination.

Measured results depends on the quality and sensitivity of the measuring instrument.

UMR(Jeff Meier) uses some SOTA measuring gear:

http://homecinemaguru.com/?p=698

"I recently aided a test with a Prismasonic H-FE1500R and a JVC DLA-RS35. The projector was mounted at a 2.0 throw ratio. Using lens zoom to fill a 10 ft wide 2.35 screen the ANSI contrast was measured at 250:1. With the anamorphic lens the ANSI contrast fell to 112:1."

and that is just the A-lens.........I would think dust would have a significant effect on light scatter and a decrease in ANSI and light transmission further.

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post #22 of 37 Old 04-06-2012, 09:28 PM
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Quote:
Originally Posted by Highjinx View Post


Glass is not 100% transparent, granted better glass is more transparent than ones of lesser quality, dust is a light blocker altogether(dirty sunglasses/reading glasses anyone?)thus light passing through will be affected to varing degrees in reaching it's destination.

Measured results depends on the quality and sensitivity of the measuring instrument.

UMR(Jeff Meier) uses some SOTA measuring gear:

http://homecinemaguru.com/?p=698

"I recently aided a test with a Prismasonic H-FE1500R and a JVC DLA-RS35. The projector was mounted at a 2.0 throw ratio. Using lens zoom to fill a 10 ft wide 2.35 screen the ANSI contrast was measured at 250:1. With the anamorphic lens the ANSI contrast fell to 112:1."

and that is just the A-lens.........I would think dust would have a significant effect on light scatter and a decrease in ANSI and light transmission further.

Thanks for that Highjinx. When i get an ISF calibration done soon im going to ask to measure the ANSI contrast just for curiosity.

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post #23 of 37 Old 04-07-2012, 01:35 AM
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Originally Posted by Franin View Post

Thanks for that Highjinx. When i get an ISF calibration done soon im going to ask to measure the ANSI contrast just for curiosity.

Also the fact that the lens in question was a prism based one. It will be interesting to see the results of a cylindrical A-Lens.

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post #24 of 37 Old 04-07-2012, 01:42 AM
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Originally Posted by CAVX View Post

Also the fact that the lens in question was a prism based one. It will be interesting to see the results of a cylindrical A-Lens.

I'm sure the ANSI loss will be off set by whatever the gains are for the individual......no free lunch and of course there is the lack of on/off CR losses compared to zooming.

Agree a good cylindrical A-Lens with good glass will have less losses, keen to see the results of a dusty lens vs a clean lens however.

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post #25 of 37 Old 04-07-2012, 01:47 AM
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Originally Posted by Highjinx View Post

keen to see the results of a dusty lens vs a clean lens however.

No doubt there would be a difference, but is that difference noticeable to the eye?

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post #26 of 37 Old 04-07-2012, 04:27 AM
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Originally Posted by Highjinx View Post


Agree a good cylindrical A-Lens with good glass will have less losses, keen to see the results of a dusty lens vs a clean lens however.

i would be interested to see the results of that also.

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post #27 of 37 Old 04-07-2012, 04:40 AM
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Originally Posted by CAVX View Post

but is that difference noticeable to the eye?

I have dust on my lens i have to admit pic looks good.

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post #28 of 37 Old 04-07-2012, 04:18 PM
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Quote:
Originally Posted by CAVX View Post

No doubt there would be a difference, but is that difference noticeable to the eye?

Once I've cleaned my reading glasses the difference is quite noticeable...

Actually when my projector lens is cleaned(I use lens cloth/solution and a zerostat to neutralise static) the image appears crisper/sharper.

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post #29 of 37 Old 04-07-2012, 04:22 PM
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Quote:
Originally Posted by Highjinx View Post

Once I've cleaned my reading glasses the difference is quite noticeable...

Yeah I have to agree there. Though more than dust seems to find its way on the optics of a set of glasses.

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Actually when my projector lens is cleaned(I use lens cloth/solution and a zerostat to neutralise static) the image appears crisper/sharper.

And one reason why I ran my A-Lens through the "wind tube". I like how when you look at the optics (projector not running) and you can't actually see the glass.

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post #30 of 37 Old 04-07-2012, 05:10 PM
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Quote:
Originally Posted by CAVX View Post

Yeah I have to agree there. Though more than dust seems to find its way on the optics of a set of glasses.



And one reason why I ran my A-Lens through the "wind tube". I like how when you look at the optics (projector not running) and you can't actually see the glass.

What's the wind tube?

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I like how when you look at the optics (projector not running) and you can't actually see the glass.

Now that's a lens with great transparency!

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