Dust with Lens - Page 2 - AVS | Home Theater Discussions And Reviews
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post #31 of 37 Old 04-07-2012, 07:21 PM
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Originally Posted by Highjinx View Post


What's the wind tube?

I agree what's the wind tube?

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post #32 of 37 Old 04-08-2012, 03:01 AM
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Originally Posted by Franin View Post

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

Hi Franin. Yes. I clean the A lens every six months when I clean the filters. I've measured my ANSI and CR on/off with no change using an eye one LT & hcfr.
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post #33 of 37 Old 04-08-2012, 06:07 AM
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Originally Posted by coolrda View Post

Hi Franin. Yes. I clean the A lens every six months when I clean the filters.

May i enquire how you clean your lens? Is it an easy process? Im yet to do mine.

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I've measured my ANSI and CR on/off with no change using an eye one LT & hcfr.

That's very good to know thank you.

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post #34 of 37 Old 04-08-2012, 12:25 PM
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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.

Have you done much (any?) measuring of your own? It's around 1%.

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Originally Posted by Highjinx View Post

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

UMR(Jeff Meier) uses some SOTA measuring gear:

Lol. You're showing your ignorance - you don't need 'SOTA' equipment to take basic contrast measurements.

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Originally Posted by Highjinx View Post

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 if you continue to read further down you will see he has this to say in reply to someone who is questioning his methods:

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Originally Posted by W. Jeff Meier View Post

I have also measured many quality lenses that do not affect ANSI much as well. This is the worst I have seen. I suspect it is the fact it is a prism and not just a lens.

Seems you want to use one unusual result as a metric to which all others should be judged by.

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Originally Posted by Highjinx View Post

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.

Like I said, the effects (measured or otherwise), are inconsequential in real terms.

Gary

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Originally Posted by elmalloc
Who says Cameron is "right" and why do we care about him so much - lol!

I trust Gary Lightfoot more than James Cameron.
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post #35 of 37 Old 04-08-2012, 12:30 PM
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Originally Posted by coolrda View Post

Hi Franin. Yes. I clean the A lens every six months when I clean the filters. I've measured my ANSI and CR on/off with no change using an eye one LT & hcfr.

I used to measure mine with a dedicated light meter with the same results.

Seems pretty conclusive to me.

Gary

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Who says Cameron is "right" and why do we care about him so much - lol!

I trust Gary Lightfoot more than James Cameron.
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post #36 of 37 Old 04-08-2012, 07:20 PM
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Originally Posted by Highjinx View Post

What's the wind tube?

The wind tube is a DIY cleaning station 400mm long x 250mm dia piece of PVC pipe. A round desk fan with an OD of 250mm is mounted to one end blowing into the pipe. I simply stretch a stocking with finest denier (weave) I can find over the fan and back of the wind tube. This now filters air born partials. They can't enter from the front because of the air flow. I ended up using the fan's stand for the stand of this rig. It fits in a small sports bag and I was even able to take it to Melbourne as carry on to service an MK4 lens last year.

All up, it cost me about $40.00 to make and seems to work very well.

Quote:


Now that's a lens with great transparency!

It really is about technique and one I am still learning. Getting rid of the dust is the easy part. Getting rid of oil from finger prints is not so easy and using cloths and fluids to remove these can often leave further smudges or residue.

I use a bright LED light behind the optics when cleaning so I can see if I am actually removing or adding more. I have not mounted the light yet, and am not sure I want to because you do need different angles at times.

Mark Techer

I love my Constant Image Height system!
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post #37 of 37 Old 04-09-2012, 04:05 AM
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Quote:
Originally Posted by Gary Lightfoot View Post

Have you done much (any?) measuring of your own? It's around 1%.

That would depend on the thickness of dust and the type

Quote:
Originally Posted by Gary Lightfoot View Post

Lol. You're showing your ignorance - you don't need 'SOTA' equipment to take basic contrast measurements.

Are you saying SOTA gear is a waste of time.....accurate measurement requires good equipment.

Quote:
Originally Posted by Gary Lightfoot View Post

And if you continue to read further down you will see he has this to say in reply to someone who is questioning his methods:



Seems you want to use one unusual result as a metric to which all others should be judged by.

I believe I did leave in the make of lens

Quote:
Originally Posted by Gary Lightfoot View Post

Like I said, the effects (measured or otherwise), are inconsequential in real terms.

Gary

In your opinion, not only the additional glass but the dust too will act as a filter.

Would you take a photograph with a dusty lens?

May the success of a Nation be judged not by its collective wealth nor by its power, but by the contentment of its people.
Hiran J Wijeyesekera - 1985.
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