35mm Adapter Static Aldu35 - Page 22 at DVinfo.net

Go Back   DV Info Net > Special Interest Areas > Alternative Imaging Methods

Alternative Imaging Methods
DV Info Net is the birthplace of all 35mm adapters.


Reply
 
Thread Tools Search this Thread
Old February 24th, 2004, 03:46 AM   #316
Major Player
 
Join Date: Dec 2003
Location: Anaheim, CA
Posts: 445
See now we are back to what I was talking about before - the apparent fact that SLR's use BOTH a condenser AND a fresnel. We need to confirm the proper order of them including the GG. Once we have that its a matter of replacing the fresnel with the same power condenser. From what I've seen SLR viewfinders have a single piece of plastic (or glass) that has a very fine fresnel pattern pointing towards the 35mm lens and the ground glass texture on the otherside. Following that is a condenser lens.
Brett Erskine is offline   Reply With Quote
Old February 24th, 2004, 04:14 AM   #317
New Boot
 
Join Date: Feb 2004
Location: Cannes, France
Posts: 6
A field lens with sufficient power to bend the edge rays into the DV cam lens results in a lens with great curvature.

Not only will a lens with such a short radius of curvature produce:
- a viewed image with unacceptable pincushion distortion
- a large amount of chromic aberrations.

Two thin lenses in series will give the same power as the thick lens with great curvature.
But each of the two lenses have less curvature, thereby greatly reducing the pincushion distortion and chromic aberrations.
But for a camera it has the disadvantage of taking up space, making the camera larger.
Camera designers realized that what they needed was a very thin lens with reasonable power.
Fortunately, such a device was available: The Fresnel Lens.


But are we really concerned by space problems here with this adapor...i don't think so...



http://topcontechnotes.home.att.net/viewingsystem/page5.html

http://www-optics.unine.ch/education/optics_tutorials/field_lens.html
Olivier Hericord is offline   Reply With Quote
Old February 24th, 2004, 04:52 AM   #318
Contributor
 
Join Date: Dec 2001
Location: Frankfurt, Germany
Posts: 571
What about using white frost lamp effect filter material. The stuff they hang in front of film lights to defuse it? This material is cheap in small amounts, durable and grainless.

Just an idea.

Great ideas here.

DK
__________________
Daniel Kohl

Frankenstein meets XL1
Daniel Kohl is offline   Reply With Quote
Old February 24th, 2004, 09:44 AM   #319
Major Player
 
Join Date: Oct 2003
Location: Vancouver, BC. Canada
Posts: 209
a freasnel would be fine to use in the adapter, there are fresnels available that have rings fine enough that there's no way the dv's ccd would pick them up, but you need to combine a condenser WITH a fresnel, like this http://topcontechnotes.home.att.net/...tem/page6.html
Tavis Shaver is offline   Reply With Quote
Old February 24th, 2004, 09:51 AM   #320
Major Player
 
Join Date: Dec 2003
Location: warsaw, poland
Posts: 440
<<<-- Originally posted by Daniel Kohl : What about using white frost lamp effect filter material. -->>>

I tryed with that. when you zoom in to find appropriate picture - the grain is visible. i checked different types, but the grain is always visible. the good side is that is very equally placed. so, maybe someone will like it.

filip
Filip Kovcin is offline   Reply With Quote
Old February 24th, 2004, 11:32 AM   #321
Regular Crew
 
Join Date: Feb 2002
Location: Gulf Shores, Alabama
Posts: 57
Tavis Shaver,

What a great link. For anyone interested in this subject the whole site should be required reading.

Starting at: http://topcontechnotes.home.att.net/viewingsystem/page3.html

all the way to page 16.

Paul
dvdof.com
Paul Doss is offline   Reply With Quote
Old February 24th, 2004, 12:48 PM   #322
New Boot
 
Join Date: Feb 2004
Location: Cannes, France
Posts: 6
<<<-- A fresnel would be fine to use in the adapter, there are fresnels available that have rings fine enough that there's no way the dv's ccd would pick them up, but you need to combine a condenser WITH a fresnel, ... -->>>

This solution was chosen only for a matter of size...
2 low power condensers are better then one of high power to avoid spherical distortion.
And when u REALLY need space u can replace one condenser by a fresnel...but optically the fresnel MUST not be used in a system dedicated to record a sharp image...

is space really a limiting parameter in our equation?
Olivier Hericord is offline   Reply With Quote
Old February 24th, 2004, 01:54 PM   #323
Inner Circle
 
Join Date: Feb 2004
Location: switzerland
Posts: 2,131
what about coating some stuf on a regular glass.
For example if you already have used cyanoacrylate (instant glue) on glass, there is always a white haze around the glued parts.
You can try to heat some of this glue under a glass.
They do this for looking at fingerprint on glass.
<b>Caution: cyanoacrylate contains cyanure (lethal gaz), so it is good to take care of doing this outside and not let the gaz reach your skin, eyes or lungs.</b>
Giroud Francois is offline   Reply With Quote
Old February 24th, 2004, 02:18 PM   #324
Major Player
 
Join Date: Dec 2003
Location: Anaheim, CA
Posts: 445
Alternatives to GG

Giroud-
Your talking about a similar technique as a product called a "Bosscreen". They are 4X5 and 8X10 focusing screens that are grainless. They achieve this buy melting and then hardening a very thin layer of wax sandwiched between to flat clear pieces of glass. The results are amazing!

Heres the bad news. Its going to be nearly impossible to not only find the ideal thickness of the layer of wax to use but having it lay down completely flat and even is a real feat that may only be possible by a commercially machined process. The other thing that there is a chance that Bosscreens will melt and be destroyed on a hot day. And dont even think about cutting down a commercially made one to size for the same reason. They are expensive too.

One interesting note though. Bosscreens advertise their product as having a microcrystaline layer (the wax). I know another company that says the same about their product...Movietube.

Good luck.
Brett Erskine is offline   Reply With Quote
Old February 24th, 2004, 03:13 PM   #325
Major Player
 
Join Date: Dec 2003
Location: Anaheim, CA
Posts: 445
Just got off the phone with a highly recomended camera repair man. He confirmed that there is both a fresnel AND a condenser lens in a SLR as shown before here:

http://topcontechnotes.home.att.net/viewingsystem/page6.html

He also confirmed that without one of the two you will have chromatic abberation problems.

Bottom line is we are back to my idea of finding a replacement condenser lens for the fresnel and having two condensers working together to make a achromat field lens. This way we wont have any "pincushion" (barrel) distortion or chromatic abberation. Damn I wish we could of K.I.S.S. but that would be S.

-B
Brett Erskine is offline   Reply With Quote
Old February 24th, 2004, 03:24 PM   #326
Regular Crew
 
Join Date: Feb 2004
Location: Austin, TX
Posts: 182
Thoughts on 'correct' grit size

Hey you glass grinders!

Those of you that chose to go with the 1000 grit - did you like the results? I've heard of people using 320, 600 and 1000. There was some speculation at some point that there was a point where you've gone 'too' fine and would start to lose the diffusive properties... You can go finer that 1000 grit Aluminum Oxide as well, wondering what the pros and cons of finer and finer grit are...

Any comments from the polishing among you?
__________________
http://www.aqua-web.com
Jonathon Wilson is offline   Reply With Quote
Old February 24th, 2004, 03:48 PM   #327
Regular Crew
 
Join Date: Jan 2004
Location: Montreal Canada
Posts: 86
Jonathon

I have mine done whit 9Y (9 micro bryte capsule) that is a bit smaller than 1000 and it's ok ,but after that ,there is something call Red pollishing that I have try ,but then I start losing the diffuse properties and I start to see thrue it , so ,no good.In fact it can reduce the grain more but I was not able to control the grinding enought so I start having some tranparent spot and this apend just in couple of second.

Alain
__________________
http://www.kheops-tech.com/~ad3d/
Alain Dumais is offline   Reply With Quote
Old February 24th, 2004, 05:14 PM   #328
Major Player
 
Join Date: Oct 2003
Location: WA-USA
Posts: 371
I did mine w/ 1000 alum ox, I just did a quick 1hr grind which I should do another 1hr final grind.

here is a pic, look at the top pic- notice a very small amount of grain in the edges where the light is less strong. I will do a final grind shortly to clean it up but overall I am pleased with the results of 1000.

http://aequantum.com/fresnel.jpg
__________________
The glory of the World passes by.
John Gaspain is offline   Reply With Quote
Old February 24th, 2004, 05:15 PM   #329
Major Player
 
Join Date: Dec 2003
Location: Brooklyn, NY
Posts: 636
Alright, here's a dumb question for Alain (or anyone with the answer):

I've got a Tiffen UV filter here and it has on both sides a raised ridge at the edge. How, if I'm supposed to have a piece of glass as my grinding implement, do I make contact with the UV filter's surface with the grit and the grinding tool?

My piece of grinding glass exceeds the diameter of the filter, and so the ridge prevents the two pieces of glass from touching. Did you use a smaller piece of glass to do your grinding? Or, did you remove the filter from its mounting ring? (and if so, how?)

Thanks...

- jim
__________________
Realism, anyway, is never exactly the same as reality, and in the cinema it is of necessity faked. -- J-L G
Jim Lafferty is offline   Reply With Quote
Old February 24th, 2004, 05:18 PM   #330
New Boot
 
Join Date: Feb 2004
Location: Cannes, France
Posts: 6
yet another question about ground glass...

Is there anybody who really tried an holographic diffuser....
Theoretically they make the post condenser useless...

anybody with real tests?

thanks
Olivier Hericord is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Special Interest Areas > Alternative Imaging Methods

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 12:16 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network