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Old October 17th, 2004, 10:39 AM   #1186
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Ok, so basically the only feesible option to getting rid of grain and unwanted optical effects is to have the gg moving? If so, is the 1500 a good option for a moving gg?

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Old October 17th, 2004, 09:11 PM   #1187
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A glass disk dressed with 5 micron aluminium oxire works fine for me.

When the image is output to DVD-Video, there appears to be some fine scintillation which looks like film grain on moderately bright areas. This may be momentary higlights of reflection which endure for only one frame.

It goes away when output to standard definition TV. I don't really know if it is electronic noise or actually there in the raw image but I suspect it is in the image.

There have been some more interesting discoveries here for alternative groundglass surfaces. One is a type of plastic archectural film which the user reported as very promising, finer than AO5 dressed surfaces but still opaque enough to provide a true non-coherent image transfer. I think reference to this material is on the ALDU thread.

Don't take my word for it on this subject. There are others here with better knowledge and qualification to offer advice.
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Old October 17th, 2004, 09:44 PM   #1188
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Yeah I have been experimenting with a similar material called Mylar. It is used when putting land maps on public record in town halls ( my dad is a land surveyor). You can get it at any blue print shop, though I feel like it hotspots a bit.

*edit for Rich! YES! Also ocean, tree, and mountain withdrawal... Sooo bad.....
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Old October 18th, 2004, 07:38 PM   #1189
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way off topic

fred have you gone into seafood withdrawal yet?
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Old October 19th, 2004, 07:53 AM   #1190
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RE: PRISM VERSION.

I have emailed 4 .jpg images to Chris Hurd in the hope he still has some server space left to post them on www.dvinfo.net/media/hart. The filenames are agusprz1.jpg to agusprz4.jpg.

It's early days yet. There's a tendency for a hot spot which was not present in the non-inverting version. The alignment is still off with the projected image center on the grounglass being to left and low as viewed in the camcorder.

The close-up lens is a Century Optics +7 achomatic diopter. The rainbows have gone away.
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Old October 22nd, 2004, 01:15 AM   #1191
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Thanks to Chris Hurd. The prism images mentioned above are now up on www.dvinfo.net/media/hart .

They are about midway down the file list.
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Old October 29th, 2004, 08:58 AM   #1192
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ONE THING TO ADD HERE:


" the AGUS35......................................
one step for the 'wanna be speilberg-man' at home, one giant improvement for mankind '


_____

AGus 35 made me wonder why I should buy expensive cameras. You can do it all with a cheap camcorder and a homemade 35 mm effect.
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Old November 5th, 2004, 09:59 AM   #1193
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For interest of anyone building prism erecting versions, I have sent an email attachment to Chris Hurd to place on www.dvinfo.net/media/hart. The filename is agusert1.jpg

It is a 1956 EIA test chart shot through the AGUS35 prism erecting version under poor lighting conditions to bring out the worst. As you will observe, compared to non-erecting versions, there is a resolution loss and a hotspot problem. The disk in this test was not rotating. In improvement in resolution and a lessening of the hotspot problem is expected in better lighting conditions.
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Old November 9th, 2004, 04:28 AM   #1194
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Okay. The prism erecting version of the Agus35 for PD150 constructed with the following components works to non-recting resolutions subject to some caveats.

Optical path.

SLR lens > gg > 2 x 40mm x 40mm x 56mm prisms > Century Optics 58mm 7+ Achromatic Diopter > camcorder.

Caveats.

Good lighting > Manual white-balance > 1/50 Shutter > Frame on smaller than 4:3 academy movie frame > Meticulous care when focussing relay path and SLR lens backfocus > Meticulous care when focussing.

This limits the depth of field effects to somewhere between 2/3" video and 4:3 motion picture frame. If you shoot electronic 16:9 you can allow the groundglass frame to be a little wider before the corners darken.

This limitation may be solvable with use of plano-convex condenser lenses already extensively discussed but would require a lower power Achromatic diopter to permit the condenser to occupy space between the rear (forward facing) prism and the groundglass, or with the 7+, a custom plano-convex condenser with square or rectangular side faces or at least one flat face no more than 10mm outboard of center to allow fit on the optical path center axis and clearance of the lower side face of the front (rearward-facing) prism.

With an upright image in the viewfinder, life is so much easier, especially when handholding.

I'll get some pics up soon.
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Old November 9th, 2004, 10:29 AM   #1195
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Hey Bob,

You got a source for the prisms?

Thanks!
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Old November 10th, 2004, 03:21 AM   #1196
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James.

I only have an Australian source. Francis Lord Optics. I think they are sales@flo.com.au

I think they buy in from outside Australia.

If you search under right-angled prism or right angle prism or permutations of those keywords you should be able to trace a local supplier.

Anders Floe may be going another route, that of a single prism and two surface coated mirrors which may replace one prism. He is using the same relay lens P+S Technik use and has discovered a similar coverage-of-groundglass limitation as my setup only with the size of his relay lens as the limit, not the hot spot as is the case with mine.

I've sent two .jpgs to Chris Hurd. One is an untitled image with AF Nikkor zoom SLR lens at 80mm at approx 7ft distance from subject which would approximate the over the shoulder one-shot in drama production. The other is a focus pull through a rainy window. The frame on the gg was a bit wide into the dark edges.

The .jpg filenames are "agusdbt5.jpg" and "agusdbtm.jpg" and are intended for www.dvinfo.net/media/hart
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Old November 18th, 2004, 03:59 AM   #1197
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Furthur news on the prism version.

Rubbish in = rubbish out. All of my posted pics so far have been with f3.5 or slower lenses. If f2.2 or faster lenses are used, the hot-spot problem pretty much goes away without need for condenser or you can widen the image area on the groundglass to movieframe or near it.

With f1.8 you can pick up the edges of the prism path without getting the hotspot.
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Old November 18th, 2004, 09:16 PM   #1198
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Im making a quick version with a cdr,

Ive looked thru some posts but cant find the exact answer.

My questions are
Which sandpaper do i use, and which way do i rub it circular or straight across, also do i add water etc.

Also if this vinyl stuff is better where can i get some from, and can i apply it to the cd GG.

Thanks
Ben
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Old November 19th, 2004, 01:41 AM   #1199
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Ben.

Don't use sandpaper, you'll only get furry scratches. Use a 5 micron grit with water and be extremely careful about getting contamination from sand and dust. Also with the CD-R try not to get fingerprints on the gg side as they will not come off without polishing the gg texture.

Send me your snail-mail address by email and I'll post you one of my old CD-Rs as I have gone to glass now. It is abused and scratched after much testing but it will give you a guideline at least.
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Old November 19th, 2004, 06:29 AM   #1200
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thanks for the support Bob,
will do.

Cheers,
Ben

What is 5 micron grit, can i get it from the hardware store?
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