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Old March 29th, 2004, 11:19 AM   #616
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Alain, do you have any footage, taken with the cylinder lens that we could see?

Also, what are the specs of your cylinder lens and what would the specs of a cylinder lens that has the horizontal power of 1.33x be?

Basically, what effects the horizontal power, of a cylinder lens?

thanks
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Old March 29th, 2004, 12:32 PM   #617
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Louis Demontez

Actually I have use a Bar Magnifier to make the test. I cut it ,grind it and I have remove the GG and the condenser to put this instead .

Bar Magnifier Model # if F.
http://www.ultraoptix.com/Pages/suprvision.html

Now I have to find the good lens.
For the exact spec I don't know yet.

http://www.oriel.com/netcat/VolumeII...ge/v3t1cyl.htm

http://www.oriel.com/netcat/VolumeIII/pdfs/v31cyl.pdf

Before I put footage I will try to have better result.

Alain
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Old March 29th, 2004, 06:52 PM   #618
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anamophic

alain this looks great . I have been working with a anamorphic lens on my aldu35 it is a kowa 16-h 2x lens it has a adjusment from
5 feet to infinity I guess the image created is a2.66 I have to put it in power dvd ,and stretch it out .I emailed chris some stills of the setup ... I need a rail system..... some of the clips look realy cool .I plan on building a 2.66 screen to play this on with a dlp.
this adapter could also be used to turn a4:3 projector into a 16:9
panamorph makes a lens for projectors that does just that it,s around $700
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Old March 29th, 2004, 07:12 PM   #619
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Lapping Film for GG

Has anyone tried this instead of Grit for ground glass grinding? I was doing a search recently for 3 micron grit, and came across these 'Lapping Films' for polishing fiber optics. Apparently an even coat of 3-micron Aluminum Oxide 'fastened' to a piece of film. You would use it like sandpaper... supposedly used for hand-polishing. I was thinking about giving it a try... In general you can get around 100 sheets (3" x 6") for approx $25 USD... Just wondering if anyone else has tried this approach? Btw - they make lots of 'grits' of this stuff - 1 micron, 0.5 micron - 9 micron, etc...

I have a heck of a time getting a good grind at even 1000 grit (9 micron) without causing scratches. I have tons and tons of water, but it just never seems to work out - and I end up scratching. How 'hard' to people press down when grinding? (Doesn't seem to matter - I scratch no matter what I do).

Any advice?
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Old March 29th, 2004, 08:05 PM   #620
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Scratches are a real burden. For what its worth, here's my suggestions. I'm not a glass worker so this may be all wrong.

Chamfer or rub back the corners and edges so that chips don't spall off sharp corners and get into your mix. I find one of the new diamond had laps for sharpening kitchen knves handy for this. Clean up scrupulously afterward.

Don't wear out your grinding mix before renewal to the stage where the glass "sticks". That's where your scratches may happen when the surface pressure goes way up.

Using separate glass sheets for dressing your groundglass on for each grade of powder. With each dressing, clean off the sheet entirely between adding each renewal of powder. Don't use too much at a time.

Be absolutely careful not to allow the powders to become cross-contaminated. Only one grain and it's all over for that particular level of fine finish.

Patience. Lot's of rubbing in small circles and not too much pressure.

The work area must be absolutely clean.
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Old March 30th, 2004, 01:55 AM   #621
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Interesting Find

I found this while doing some research:

http://www.arri.com/infodown/cam/broch/viewfind.pdf
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Old March 30th, 2004, 02:55 AM   #622
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Wow! I didnt think my idea to use cylinder lenses would be so popular. Great! Thanks Alain for the credit. He's right about the mag. number btw. A cylinder lens with a 1.33X mag. will give you 16X9 if your dealing with a DV format frame ratio. Now if you want perfect cinescope (around 2.35. Not 2.66) you'll be hunting down a cylinder lens with a X1.78 mag. Since your unlikely to find a "X1.78" lens exactly just go with a X1.75. You wont be able to tell the difference. Hey Alain did I tell you it was going to work or what? Hows the hot spot correction working out for you with that 2X? Its a cleaner looking picture with the GG and cylinder lens combined. Thats because you wouldnt ever be able to get a seperate GG that close to the cylinder lens. I wonder though about your chroma abberations. After all the cylinder lenses used in the Panasonic 16X9 attachments are two element achromat cylinder lenses. Check your edges and post some high res pictures.

Im cooking up another idea now too that will add another dimension to the adapters but its pretty out there so let me screw around with it first before I post it and get people going in the wrong direction. Thanks Alain and everyone for all the great links posted recently. I didnt know about the Arri directors viewfinder. Should look into that.

Brett Erskine
Cine/Videographer
www.CinematographerReels.com
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Old March 30th, 2004, 08:33 AM   #623
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possible image inversion solution

I don't know if this has come up already. What if:

1. the roof pentaprism was placed directly behind the lens, re-orienting the image and projecting it 90 degrees upward

2. a 45 degree mirror is placed directly above the pentaprism, turning the light path horizontal

3. the groundglass was placed immediately after the mirror.

lens > prism > mirror > gg

two potential problems come to mind:

a. would the prism behave properly with the light beam coming out of the back of the lens, which is different from a focused image on a ground glass.

b. could the light path be short enough (e.g. about 45mm from rear of lens through all elements to the gg?

I don't have the parts to try, maybe someone else in the forum can give it shot.

2 cents worth, josh
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Old March 30th, 2004, 08:45 AM   #624
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Brett Erskine wrote:
<< you'll be hunting down a cylinder lens with a X1.78 mag. Since your unlikely to find a "X1.78" lens exactly just go with a X1.75.>>

Brett,
Thanks for the tip. How do I get a X1.78 mag. or X1.78 mag. cylinder lens? all of the suppliers I've been searching through only offer dimensions and Focal Length. Is there a supplier that describes their cylinder lenses in magnification power? I've checked with Thor, Edmonds and others that have been posted here. They all use dimension and focal length.



Thanks Richard Mellor for the link to the Arri Viewfinder. It goes to prove that a correctly oriented version is very obtainable. The roadblock I've run into is finding a roof pentaprism with a large enough clear aperature to accomodate the video camera's lens. 35mm SLR pentaprism is too small. Does anyone know of a source for a large roof pentaprism? I thought about using a roof pentaprism from a medium format camera but I don't have one laying around and they're quite expensive for a test. If anyone out there has one, could you test to see if the viewfinder is large enough to zoom your video lens to get a clear picture through the camera without seeing the edges of the viewfinder? Thanks! Joe
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Old March 30th, 2004, 01:47 PM   #625
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Michael, that Arri adapter looks interesting. With the little handle there, it resembles an old 8mm camera. I've been searching on the net and can't seem to find any information other than the brochure you posted. It looks a lot like the mini35 with handle. Either way, its certainly interesting.
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Old March 30th, 2004, 03:57 PM   #626
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Hi,

Is there any other caracteristics whe should hunt (a part for the 1.33 / 1.78 magnification power) for the cylinder lenses ?

And what about the condenser lens what are the "best caracteristics imaginable" we want ?

I ask so because we (french guys from Kandinsky's "Mini35 Faq" forum) may have the opportunity to have thoses type of lenses especially made for a very reasonnable price.

We may also have them precisely grinded by an optic company, but what should we ask for ? a 3 microns grinding ? less than 3 microns ?


Besides all that, i'm a DVX100 user, should i look for specific Cylinder / Condenser lens (72mm diameter for example) or not ?

Thank you optic pros for answers !

Nico
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Old March 30th, 2004, 05:19 PM   #627
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Oops

Michael,
I mistakingly thanked Richard Mellor for the Arri link. Sorry. Joe
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Old March 30th, 2004, 08:01 PM   #628
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Nico whos the manufacturer? I can give them specs. Send me a link/contact info. Thanks
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Old March 31st, 2004, 02:32 AM   #629
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We have two possibilities for now

http://www.legrand-optique.com/

http://www.optique-commerciale.com/presentation.htm


Both are small french manufactures and usally only deal with other companies / stores. we contacted them and they have accepted to have a look at the "problem".

I don't know if they speak english and / or deal worlwide for now.

Their contacts are on their websites, but i think it would be better if their contact was a french speaking and french based person (don't you think ?)

you can post all specs here or on our french forum

http://forum.aceboard.net/?login=36808

or e-mail them to me

Thanks Brett

Nico
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Old March 31st, 2004, 01:46 PM   #630
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hi, my result with my panasonic nvgs70 and mini35 kit.

a camcorder with a mini35 kit :)
http://www.ifrance.com/mini35/Image%20002.JPG
http://www.ifrance.com/mini35/Image%20004.JPG

a picture of my test.

http://www.ifrance.com/mini35/Comp%201%20(0-00-29-14).jpg
http://www.ifrance.com/mini35/Comp%201%20(0-00-52-00).jpg
http://www.ifrance.com/mini35/Comp%201%20(0-00-15-15).jpg

are you a sugestion ?
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french touch :)
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