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Old August 4th, 2005, 12:17 AM   #16
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Check out the picture samples at

http://www.enormousapparatus.com/35adapter.htm

Although the thumbnails look OK, once you enlarge them to full size you can easily see this "haze" and grain in the out-of-focus areas. There's also a bit of vignetting. I guess this is what they are referring to.
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Old August 4th, 2005, 12:23 AM   #17
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But James Webb didn't use Optosigma GG. He ground his own.
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Old August 4th, 2005, 04:51 AM   #18
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OK, I need to explain myself I little more.

What i mean by 'kills the depth of field' is, because the optosigma ground glass is not diffusing the light enough, you can see far too much ariel image.

So, in 'out of focus' area's of the frame, you can see the 'ariel image' mixing back into the image, making that area seem more 'in focus' when it should be completly blurred.

For example, filming a window from inside, adjust the focus so that the window is completely out of focus. You will still see sharp focused lines of the window because of ariel image.

Now, I have been testing microwax screens the last few days, and when the layer of wax is too thin, I get the same effect. With a slightly thicker layer of wax, the light is diffused properly. So this proves that the light on the optosigma ground glass is not diffusing the light as much as it should. Because of the mix of sharp ariel image, I beleive it is killing the depth of field effect, which goes against the whole point of this adapter.

The 'haze' effect looks more like if you were to give an image a glow eefect in photoshop. Not to that degree, but thats how i feel it looks.

I beleive there to be a trade off between diffused light and light loss, a sweet spot. More diffused means less of the above problem but also means more light loss. less diffused and the problem comes back (also hotspotting becomes more of a problem) but you do get a brighter image.

I hope this clears things up,

Regards,
Wayne.
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Old August 4th, 2005, 08:06 AM   #19
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I guess I just dont get what you mean by "ariel" image, and I understand what you mean by the glow effect but I dont see it in the in-focus areas.

Do you see the effect you are describing in these shots?
http://ase.tufts.edu/turbo/noah/still1.jpg
http://ase.tufts.edu/turbo/noah/still3.jpg

I see haziness in the background but I dont think I see what you are describing. Perhaps I cannot see it because I do not understand what to look for.
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Old August 4th, 2005, 08:21 AM   #20
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Quote:
I understand what you mean by the glow effect but I dont see it in the in-focus areas
No, you only see it in the out of focus area's. Here is a test. Take out your glass from the adapter, hold it close to your eye and look out a bright window. You can see the window and all its details in focus. That is the 'ariel' image, light passing through the glass that is not diffused. its this what is happening inside the adapter, so you see a mix of out of focus and in focus image. now do the same to some lights. same thing. Basically, with a good ground glass, you should not be able to see details of objects when looking through the glass like this. I can see the letter's 'JVC' on my VCR about 2 foot away from me.

Here is an mock up example of what i mean:
http://homepage.ntlworld.com/wayne.k...us_example.jpg

You can see in the bottom image, the hard focused lines mixing into the image.

as i have said, its mostly apparent on bright area's with high contrast and especially on bright highlights, where the highlights remain sharp with a glow, instead of being out of focus. I do not get this effect with my microwax glass.

I beleive i see the effect on the + cross of the windows of the doors in the background in still3. its not so bad in that example though.

Its not too bad, but i feel it it is a property of the glass that goes against the purpose of the adapter.

Wayne.

Last edited by Wayne Kinney; August 4th, 2005 at 08:54 AM.
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Old August 4th, 2005, 09:40 AM   #21
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Interesting...I always thought that might be a problem but never thought to look for it.

Wayne, sorry I haven't posted directions regarding capillary action, by the way--these past few days have been busy (as are my next two weeks.) It sounds like you've got some method working well, though, but if you want I'll still post pictures when I get the chance. How have your results been? I'm thinking of moving on to thicker spacers since my thinnest wax coating (twice the thickness of scotch tape) has considerable grain.
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Old August 4th, 2005, 09:47 AM   #22
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Matthew,
i have capilary action working well, but i cant get consistant results. I have 1 glass of perfect thickness, but grain is there. Would work well on a vibrating setup. If you could still post directions that would be great. I have ordered some 1000 grit aluminium oxide to see how that compares with wax. Either way, it needs to diffuse the light just enough as not to get the effects as described on my post above.

Cheers,
Wayne
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Old August 4th, 2005, 10:13 AM   #23
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Pictures of what I'm doing probably wouldn't help then. I have the same problem: perfect thickness, but visible grain. Would vibrating while cooling really reduce the grain? It's worth trying, I suppose.
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Old August 4th, 2005, 10:18 AM   #24
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Mathew,
I mean a vibrating setup as in Quyen Le's design. But who knows, has anyone actually tried vibrating while cooling? Probably end up in a big mess:D

Wayne.
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Old August 4th, 2005, 09:02 PM   #25
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Nobody has answered Jeff's latest question, so I will.

Quote:
Originally Posted by Jeff Tyler
Ok Now im confused. What am I supposed to do if the cd thing sucks and the ground glass makes it not even work properly? Is this a massive conspiracy or something?
Yes. It is a massive conspiracy.
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