In-built ND-filters: tech. details about their mechanism?

I think the greatest benefit of plastics is that you can mold any shape imaginable. Creating aspheric glass elements is a really complex grinding process. With plastics, it's no harder to accomplish than any other lens shape. I really think most people underestimate plastics. There's absolutely no reason it can't compete with glass, and even out perform it in some cases.

The only real downside to plastics are there susceptibility to temperature changes. Like anything it's a trade off.
 
Shaw said:
I think the greatest benefit of plastics is that you can mold any shape imaginable. (....)
The only real downside to plastics are there susceptibility to temperature changes.
Click to expand...

Shaw, I agree with you in the first point and disagree in the second point:

"The only real downside..." it's not the "only": I'm not sure how HARD a real hard-plastic's grade can be, but doubt that it would get scratched easier than a good glass. For a built-in ND-filter that would not be important, but for a filter or the last lens in an objective - in other words: for unprotected parts the grade might be a problem.

Or does anybody know a polymer that has a higher grade than glass?

We clean our objectives with (e.g.) microfibre as carefully as we can to avoid scratches from dust/sand/towel, but what material would we need to clean a smooth hard-plastic lens? What would we take for cleaning a fat-spot on the objective? Anything that solves fat could attack the surface of the plastic-lens/filter.

On the other side: many (cheap) cameras use plastic lenses, so perhaps it's not that easy to scratch them as I think..... I just want it to be at least as hard as glass...

Any material-specialist around here? :huh:
 
Great point. I guess I should have been more careful with my wording. :)

Honestly, I'm not entirely certain. I just haven't had enough experience with plastic to know if it's hard or soft (at least the commonly used materials). I don't *think* it would be any more difficult to clean than glass, though. Both are coated (or should be!) so unless you break down the optical coating I imagine it would be relatively similar (maybe?).
 
To all:

Just a short post. I cannot imagine where this rumor of a plastic lens got started, except for the fact that the lens housing is plastic. Plastic is an interesting material but is available in a very limited number of types for optical applications. Lens designs rely on mixing a wide variety of glass types of varying indexes of refraction and dispersion to achieve the desired image quality.

The cost savings of using plastic is primarily in the ability to mold the finished lens, as opposed to grinding and polishing. It is not possible to achieve the high levels of surface accuracy required to produce a high performance zoom lens.

Plastic also tends to lack the homogenity and clarity of optical glass, using even a single element in the lens could result in lowered (and unacceptable) contrast. The fact that it has been used successfully in low cost still cameras and other applications does not mean it is usable in high performance lenses at this time.

Bill Turner
Century Division
Schneider Optics
 
I'm not getting my pictures to work so I will try to explain the workings of the lens the best I can.

There are a total of four lens elements, the two ND-filters, and IR filter, and the CCD block in the lens assembly.

This is the order they go in starting at the main lens element:

Main Lens element,
ZOOM Lens element,
ND-Filters,
OIS Lens element,
Focus Lens element,
IR-Filter,
CCD Block.

All of my tests show that all lens elements are GLASS.
Scratch test passed. Tapping test passed. Even checked to feel the material with a dental pick to see if it felt gritty and it did.


cici said:
Can anybody explain me about the ND-filters inside DVX100:

- how tall are they?

- where are they positioned exaclty? (Position ON and positon OFF)

- how do they technically get pivot into the incoming light?


Thanks for explanations and for PICTURES OF ND-on / ND-off MECHANISM!
Click to expand...

The ND-Filters are simply gels. They are on a wheel that when turned; by the ND switch, spins the wheel causing the desired ND-Filter to be placed in the light path. It's a well built mechanism. Each gel is approximately 2/3"H X 1/3"W.

I hope that this answers everybody's questions. If you would like the pictures sooner, I may be able to e-mail them to you. Please post any questions that you might have.

My e-mail address is andrewh@spec-comm.com.

I will try to get those pictures up tommarrow. :thumbsup:

Best regards,

Andrew Hoffman
Senior Operations Manager
Specialized Communications Corp.
20940 Twin Springs Dr.
Smithsburg, MD 21783-1510 USA
800-359-1858
Fax: 301-790-0173
andrewh@spec-comm.com
www.spec-comm.com

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Is is theoretically possible to swap one of the ND's for another type of filter as on the SDX900? In other words, do they look like the same kind of filters used in the filter wheels on 2/3" cameras?

I would never, ever, ever want to remove the ND's; I'm just curious, that's all.
 
No. They are a proprietary size and are clamped in with molded tabs on the wheel. If you wanted to get risky and don't mind playing with the insides of you DVX, you may be able to buy standard gel filters and cut them and bend the tabs so that they are held there but I wouldn't recommend it!

Andrew Hoffman
Senior Operations Manager
Specialized Communications Corp.
20940 Twin Springs Dr.
Smithsburg, MD 21783-1510 USA
800-359-1858
Fax: 301-790-0173
andrewh@spec-comm.com
www.spec-comm.com

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Pro cameras usually just have daylight and star filters preloaded, in addition to the ND. You can buy those for the front of the lens.
 
Thanks a lot, Andrew for your effort! - I'm still very curious for the pictures, because I still can't imagine where the ND filters are "hidden" in the off position. As they are 2/3" x 1/3" tall, the light ray that hits the filter in the ON position can't be much smaller, so there's really not a lot of space left for a whole 2-position-mechanism.

So the mechanism is working with 1 single axis: like a single rotorblade. If the axis (wheel) is very small, it could be a turn of 180 degrees from OFF to ON. Perhaps you could please either clarify this or perhaps the pictures will show the angle from OFF to ON.

Thanks again! - In my opinion a cameraman should know the inside of his cam at least a little...
 
WOW! - I guess I just found a picture from Panasonic where you can see the place of the ND filter in ON position at least on a simple profile-picture and I guess the measurements could be to scale too!

The picture is on page 3 of Panasonic's DVX100A brochure (page 4 on PDF see link below). It shows actually where the sapherical lenses are (red) and where the OIS is (aspherical lens in the middle).

The groups that Andrew mentioned are CLEARLY identifiable and the ND filter must be the thin line in front of the two-parts-OIS -is this correct, Andrew?. Now that I know the position from Andrew's explanations, it's logic that the thin vertical line can not have any other optical function that beeing the ND filter I was looking for. If the scale on the picture is correct, then the ND-filter(s) is as tall as the OIS. -is the scale/ratio on that picture correct for DVX100, Andrew?

Andrew, of course I'm still looking forward to seeing the photographs because the picture from the brochure is a) very abstract b) without details c) not showing anything about the ND-filters' mechanism or yet parts of it...

The DVX100A brochure can be found here:
http://catalog2.panasonic.com/webap...14571&modelNo=AG-DVX100A&surfModel=AG-DVX100A

and the picture is on page 4 of the PDF, downloadable from that page.
 
cici said:
WOW! - I guess I just found a picture from Panasonic where you can see the place of the ND filter in ON position at least on a simple profile-picture and I guess the measurements could be to scale too!

The picture is on page 3 of Panasonic's DVX100A brochure (page 4 on PDF see link below). It shows actually where the sapherical lenses are (red) and where the OIS is (aspherical lens in the middle).

The groups that Andrew mentioned are CLEARLY identifiable and the ND filter must be the thin line in front of the two-parts-OIS -is this correct, Andrew?. Now that I know the position from Andrew's explanations, it's logic that the thin vertical line can not have any other optical function that beeing the ND filter I was looking for. If the scale on the picture is correct, then the ND-filter(s) is as tall as the OIS. -is the scale/ratio on that picture correct for DVX100, Andrew?

Andrew, of course I'm still looking forward to seeing the photographs because the picture from the brochure is a) very abstract b) without details c) not showing anything about the ND-filters' mechanism or yet parts of it...

The DVX100A brochure can be found here:
http://catalog2.panasonic.com/webap...14571&modelNo=AG-DVX100A&surfModel=AG-DVX100A

and the picture is on page 4 of the PDF, downloadable from that page.
Click to expand...

You're correct. That is the ND-Filter placement.

Andrew Hoffman
Senior Operations Manager
Specialized Communications Corp.
20940 Twin Springs Dr.
Smithsburg, MD 21783-1510 USA
800-359-1858
Fax: 301-790-0173
andrewh@spec-comm.com
www.spec-comm.com

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and is the ratio of the parts more or less correct, Andrew? (e.g. Are the ND-filters as tall as OIS? And size of parts etc.)
 
Below is a picture of the entire lens assembly:

AGF00114e.jpg


The next one is of the Main Lens Element. It comes first as we all know.

AGF00115e.jpg


It is interesting (and completely understandable) that the Main Lens Element is the only Lens Element that has thin-film.

I thought that you would be interested in the CCD block. The blue tint is actually the IR-Filter that is mounted in-front of the prism.

AGF00118e.jpg


Next is the ND-Filter assembly on the left and the OIS Lens Element on the right.
The OIS system is interesting to look at. You can probably make out the electro-magnets. The OIS Lens Element is mounted on two tracks; one vertical and one horizontal. Hidden away in the lens; somewhere that I couldn't get to; is a GYRO scope that feeds reference to a Servo Circuit. The Servo Circuit sends a voltage to the Electro-Magnets surrounding the two tracks; thereby floating the lens. Whenever there is jitter, it moves the OIS Lens Element which feeds a voltage back through the Electro-Magnets to the Servo Circuit. This sends an inverted voltage back to the coils to correct the jitter.

The ND-Filters are in the off position in this picture. The Iris closes whenever the camera is off so that's why you won't see an opening.

AGF00121e.jpg


Next, the ND-Filter is in the 1/8 position...

AGF00124e.jpg


Then the 1/64 position.

AGF00125e.jpg


This is just a closer view of the ND-Filter in the OFF position.

AGF00126e.jpg


Here is the ZOOM Lens Element. There are small shafts that act as a cam mechanism that move the Element back and forth. The lens is part of a gear that has teeth. The Servo ZOOM motor is what drives that gear and moves the lens. I've been replying to some posts on dirt and sand causing rough zoom-ins and zoom-outs. The cause for that is dirt and sand particles get into the cam-shafts and teeth.

AGF00127e.jpg


Last but not least; is an exploded view of the entire Lens Assembly. All the way to the right is the Focus Element Assembly. It works (and looks) exactly like the OIS Lens Element with the exception of two differences; 1. The shafts that the lens element travels on goes back-and-forth, not up-and-down; 2. The housing is deeper to facilitate that back-and-forth motion.

AGF00128e.jpg



I would like to thank cici and thisiswells for egging on this project. :thumbsup:

Best regards,

Andrew Hoffman
Senior Operations Manager
Specialized Communications Corp.
20940 Twin Springs Dr.
Smithsburg, MD 21783-1510 USA
800-359-1858
Fax: 301-790-0173
andrewh@spec-comm.com
www.spec-comm.com

************************************************************************
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Reserve today, and receive FREE Shipping and a FREE cleaning for your new camera.
Visit http://www.spec-comm.com/hvx200.php for details!
 
cici said:
and is the ratio of the parts more or less correct, Andrew? (e.g. Are the ND-filters as tall as OIS? And size of parts etc.)
Click to expand...

Yes. The ND Filters overlap just little for the OIS Lens Element.

Andrew Hoffman
Senior Operations Manager
Specialized Communications Corp.
20940 Twin Springs Dr.
Smithsburg, MD 21783-1510 USA
800-359-1858
Fax: 301-790-0173
andrewh@spec-comm.com
www.spec-comm.com

************************************************************************
Now taking Pre-Orders on the Panasonic AG-HVX200 HD Camcorder.
Reserve today, and receive FREE Shipping and a FREE cleaning for your new camera.
Visit http://www.spec-comm.com/hvx200.php for details!
 
Andrew, thanks so much for giving the best possible answer to my question!

How lucky we are to have got you just in the right (rare) moment and how lucky we are that you are a man who knows using this chance of having an open camera for taking these absolutely precious pictures and making all the surgery it takes to understand how the parts work!
 
But the real question is why are they using physical filters at all? Will the CCD be damaged by too much light? If not, why not do it electronically?
 
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