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Old March 7th, 2004, 08:15 PM   #496
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Jonathon Wilson-
While you wait to get better GG you can fake a lightless situation and swap out the different condensers but simply shuting off all the lights in the room your in at night and point the 35mm lens thru the crack of a door to another room that has all of its lights on. If its day time try cuting a small hole in a thick black plastic trash bag(s) and put your 35mm lens through it - making sure to use tape to seal any possible light leaks around the outside of the lens. Get your head inside the bad (both like a large format photographer and...a idiot) and test your GG/Condensers.

As far as the Canon laser etched GG the other problem is that I believe they decided to have the GG and the fresnel on opposite sides of the same piece of glass so - no good.

-Brett Erskine
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Old March 7th, 2004, 08:20 PM   #497
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Good idea Brett, sounds fun climbing into a hefty bag.

I'll try that and report back... Probably not until at least tomorrow night - looks like I'm pulling yet another all-nighter at work.
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Old March 7th, 2004, 09:09 PM   #498
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Joe Holt: Thanks for that advice! Yep, I played around with it some more and it seems to be working better now. When it's just a thin layer of primarily water with an even, thin spread of aluminum oxide, that seems to work best.

I took it out for a test yesterday (we're having some beautiful weather down here) and was impressed with the results - especially since I don't have an achromatic diopter or a condenser.

Basically, I have the ground glass, 35mm lens, and a regular curved lens, in this arrangement:


35mm Lens -----> Ground Glass -----> Lens ------> Canon GL2

The regular lens is right against the back side of the ground glass, with the outwardly-curved side facing the camera. This cuts down on the hot spot I was getting with just a 35mm lens and ground glass.

I will try to get some images up in the next couple of days.

,Frank
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Old March 7th, 2004, 09:21 PM   #499
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Aldu35 for Xl1/XL1s

I have successfully made an XL1/XL1s version! I haven't even begun to perfect the design or address other simple issues-but still, lacking these improvements-my images are, easily, as good as, or superior to what I have seen so far.

All I can say is wow!!!
D
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Old March 7th, 2004, 09:27 PM   #500
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Sounds exciting, Dino! Congratulations! It'd be nice to see some of your footage if you can find a place to put it.
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Old March 8th, 2004, 04:49 PM   #501
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thanks jonathan, i'll start posting up some samples as soon as i get a second of breathing space from work-jeez, these 70 hour work weeks are starting to get to me...
-d
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Old March 8th, 2004, 09:13 PM   #502
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good news in deed for the xl1/xl1s people

geaux Dino, good news for you is also good news for the rest of us. keep up the good work.
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Old March 8th, 2004, 09:46 PM   #503
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My framegrabs

I have uploaded 9 test frames. They can be found here:

http://www.frankladner.com/testpics.htm

Thanks!
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Old March 8th, 2004, 10:39 PM   #504
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Frank, I bet if you got a Condensor AND Macro it would help out the vignette and how close you can get to the gg with your camera.
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Old March 9th, 2004, 05:39 AM   #505
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for a bit of theory see

http://www.cartage.org.lb/en/themes/Sciences/Physics/Optics/Optical/Lens/Lens.htm

and

http://homepage2.nifty.com/optas/lore-e.htm

look like we can have the condenser lens act as the gg because the way you mount the flat side has no effect on the picture.
a positive meniscus would be even better according the text, as projection of the picture on a curved plan would increase quality versus flat plane. problem is then to gg a concave surface :-)
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Old March 9th, 2004, 07:45 AM   #506
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Thanks for the links Giroud! Very informative.

Another problem I see with using a concave surface would be getting a clear focus from your camcorder. At the close distances we are dealing with, I believe you couldn't get an exact focus on the entire concave surface. (different focus planes) If I'm wrong and focusing isn't an issue, then the ground glass could be made comercially using the laser etching Canon is using for their GG mentioned earlier in this thread. I know most of us don't do laser etching in our basements but if we are all still talking about putting together a standard/manufactured version, then it might be feasible to contract a company to do it for a limited run. What would be ideal at this moment would be to have a supply of laser etched GG/condenser elements (50MM dia.) That sure beats grinding our own. Does anyone know who is doing Canon's laser etching?

Frank,
Nice images but I did notice a good bit of grain, dust and the scratch in the top right corner(or was it a hair?) Did you shoot that in the evening, in low light? I think you've proven that we need to do some finer grinding to reduce the grain. I believe a brighter image would help too. What was your video camera's iris setting? Did you try slightly over exposing the GG image to "burn out" a little of the grain. I'd be interested in your results with a bright scene. I also noticed during my own tests that opening my camera's (PD100A) iris really made the hotspot stand out but the image overall was more acceptable (sharper focus, less grain). I too am waiting for a set of condenser lenses to begin experimenting. I look forward to seeing your next set of images. Joe
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Old March 9th, 2004, 08:51 AM   #507
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Joe: That was shot in the evening. I turned my shutter speed up to around 100 and had the iris about half open. You're right about the hotspot. I tried to keep the center from being blown out, so that way, I'd have some detail throughout the frame. One trick I have done (not with these images) was to create a 720x480 black and white radial gradient in photoshop, which I would import over the footage in After Effects, setting the mode to Overlay. This would balance out the image some. I do believe, though, that if the hotspot problem gets fixed with the condenser (or some other solution), then recording a brighter image would help the grain situation.

Yeah, there are a few nice little scratches I managed to put on the ground glass. I had absolutely no problems with the 600 grit, but the 1000 seems to clump together, requiring lots of water, as you mentioned before.

Joe, where did you order your condensers from? I have not been able to find an old SLR body to get one from.

Thanks!
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Old March 9th, 2004, 10:32 AM   #508
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Condenser source

Frank,
I ordered the below products from Surplus Shed. Here is the link.
http://www.surplusshed.com/pages/category/educationaloptics_1.html

They have a large selection of optics at greatly reduced prices. I called on the status of my order today and the guy said that my stuff shipped on Friday (1 week after I placed my order online GRRRRRR!) I should get my lenses today or tomorrow. I'll let you know how they are as soon as I can get my eager paws on them. I ordered these initially to have a broad range of types for testing.
SKU: L1875D
EDUCATIONAL SET OF 50MM LENSES 1 12.00 12.00
SKU: L1961D
EDUCATIONAL DCV 50MM X -50MM 1 2.00 2.00
SKU: L1951D
EDUCATIONAL DCV 38MM X -50MM 1 1.50 1.50
SKU: L1574
RECTANGULAR PLANO CONVEX LENS 1 0.50 0.50

These are educational quality lenses. That means they are not of consistant enough quality for manufacturing purposes. (focal lengths vary slightly from lens to lens) But for our single unit applications, I believe they'll be perfect for testing.

Great Idea about the overlay in AE. I'm going to give it a try.

BTW, Has anyone made any progress on correcting the image orientation? I shoot a lot of sports footage and following action and focus with an inverted image would be impossible. How about a rectifying lens like in a spotting scope? I was considering a large pentaprism and mirror set up(like SLR system for a medium format camera) I personally would be willing to loose an F stop or two to gain a correctly oriented image. Anyone know where I can find an old medium format pentaprism viewfinder? (35mm is too small) Edmond Optic sells large enough pentaprisms but they're outrageously expensive. I'm willing to spend $20-$50 to experiment but not $500.
Joe
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Old March 9th, 2004, 10:54 AM   #509
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moinitor

Forget prism and mirror
i did whit upside down 5"6 monitor
(119 $ )
is working perfect even on a steady-cam
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Old March 9th, 2004, 11:24 AM   #510
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Joe: Thanks a lot! I'm headed over to their website to look around.

I was just thinking, and - don't scream at me if this sounds ignorant :-) - can't you rig up a system that basically projects an image onto a solid surface, enclosed in a light-tight box, for the camera to pick up? (You know how you can hold the 35mm lens over a piece of paper and see the image projected?)

Basically, the whole idea is to pick up an intermediate image - thus the Ground Glass. But......if you can use a system of mirrors or a prism and project the image on a plain, solid surface (not sure what'd be the best surface, but the grain wouldn't be a problem any more.)directly in front of the DV camera...wouldn't that be the same principle?

Also, in the manner that the image is relayed, would it eliminate the inverted image problem?

Again, forgive me if this sounds crazy, but I was just thinking about it as I was typing this post and thought I'd throw it out there.

Thanks!

,Frank
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