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Old December 12th, 2003, 12:11 AM   #301
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John what's the size of the fresnel lens 2x3?
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Old December 12th, 2003, 12:16 AM   #302
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<<<-- Originally posted by Peter A. Smith : John what's the size of the fresnel lens 2x3? -->>>

it was 2x3 :) then I cut it up into 2x2
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Old December 12th, 2003, 02:59 AM   #303
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Is the Fresnel lens a subsitiute for a macro lens?
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Old December 12th, 2003, 07:20 AM   #304
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http://scientificsonline.com/search.asp?t=ss&ss=fresnel+lens

Here's are several decent Fresnel lenses you can get and then cut down to what size you need.

Here's another place as well:

http://www.3dlens.com/fresnellens.htm

Do you see the lines from the fresnel lens on your recorded image?
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Old December 12th, 2003, 07:44 AM   #305
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would it be possible to rip a fresnel out of a 35mm slr camera?

Zac
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Old December 12th, 2003, 08:32 AM   #306
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To invert the image you could also inster a dove prism in between the GG and the camcorder lens or fresnel:

http://www.optosigma.com/miva/merchant.mv?Screen=PROD&Store_Code=OS&Product_Code=pg137&Category_Code=Dove+Prisms
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Old December 12th, 2003, 09:07 AM   #307
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John,

Thanks for the answers. I am going to try to get started this weekend. Is the fresnel lens used so that you don't have to zoom in so far? And, how much does it help the problem of not having enough light? Thanks again...

Clay
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Old December 12th, 2003, 09:52 AM   #308
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Quote:
Originally posted by John Gaspain : HELL YEA! thats what i needed! its adjusted out a little over 1/4". This fixed any vignetting.
Let's see some footage!

If you don't have hosting for your footage, drop me a line at info@ideaspora.net and I'll park a 15mb file on my server for you.

- jim
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Old December 12th, 2003, 10:30 AM   #309
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So is the fresnel a good replacement for a macro adapter? Which would be better?

Thanks
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Old December 12th, 2003, 01:28 PM   #310
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Fresnel and Macro

The way I see it, the fresnel is placed between the SLR lens and the GG to focus the light more directly onto the GG.

1..2.3....4..5.6.7.........
[| < |==== | [|[|CCD

1.SLR lens
2.Unfocused light rays from SLR lens
3.Fresnel Lens (about 1/4 inch from the GG)
4.Redirected Light Rays (reduced vigneting)
5.GG
6.Macro Lens attatched to Video Camera's lens to allow it to focus on the 35 mm negative sized image on the GG while zoomed in.
7.Video Camera

Hope this helps some ppl out...excuse my terrible ascii art skills,
Spencer
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Old December 12th, 2003, 01:43 PM   #311
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Re: Fresnel and Macro

<<<-- Originally posted by Spencer Houck : The way I see it, the fresnel is placed between the SLR lens and the GG to focus the light more directly onto the GG.

1..2.3....4..5.6.7.........
[| < |==== | [|[|CCD

1.SLR lens
2.Unfocused light rays from SLR lens
3.Fresnel Lens (about 1/4 inch from the GG)
4.Redirected Light Rays (reduced vigneting)
5.GG
6.Macro Lens attatched to Video Camera's lens to allow it to focus on the 35 mm negative sized image on the GG while zoomed in.
7.Video Camera

Hope this helps some ppl out...excuse my terrible ascii art skills,
Spencer -->>>



Have you even tried that ? cause i believe it wont work, the fresnel have to be after the GG and before the Camera.
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Old December 12th, 2003, 01:49 PM   #312
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So does it help light and focus then?
Thanks for the diagram Spencer.

John,
can't wait to see the footage.

Clay
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Old December 12th, 2003, 02:36 PM   #313
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Re: Re: Fresnel and Macro

<<<-- Originally posted by Agus Casse :

Have you even tried that ? cause i believe it wont work, the fresnel have to be after the GG and before the Camera. -->>>

I've tried it and its the only way i belive it will work. Also take a look at John Gaspain's design:

http://www.imagestation.com/picture/...c/fa531009.jpg

I don't think the fresnel is accomplishing anything optically if you place it after the GG. By then all is done in terms of vignetting on the GG, nothing you can do to change it from the Camera side besides zooming past it.

Anyone else try out a fresnel?

Spencer
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Old December 12th, 2003, 02:39 PM   #314
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Post some footage i am actually curious cause i didnt use a fresnel, i use a magnifying glass in the Dv lens.

Nice evolved model dude :) how much are you spending so far ?
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Old December 12th, 2003, 04:02 PM   #315
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I am experiencing a high flicker... anyone have any idea why?

here are two pics (after film look post) from video i did today

http://www.orfilms.com/luke1.jpg

http://www.orfilms.com/luke2.jpg
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