Yes, we know at least the diffusion angle Dan used for his test. He said it was 50 degrees. I guess that is what he meant by 50%.

http://www.dvinfo.net/conf/showthrea...poc#post306340

It is quite possible POC offered this angle at that time.

Could be 50°, but we are still in the dark with respect to material and thickness, which seem to me very important. I am thinking that the screen Dan tested was not thin-film and possibly the angle is not optimal.

I just think that if I am getting much better light results from the materials I am testing, the POC guys must certainly have even better stuff. They show a graph where light transmission for a regular diffuser and a ground glass diffuser is at around 60%, and their materials are at 90% transmission. So it must be good.

Here is a DV AVI with two short segments:

http://www.filefactory.com/get/f.php...01e6c226bc1bbe

and a larger version:

http://www.filefactory.com/get/f.php...9476e79626f645

File was rotated 180 deg and recompressed as DV.

I got one of those secondhand for $5 or $15.

Perfect diffusion and perfect light transmissivity are mutually exclusive concepts. You can't have both. After reading a lot here, and doing a lot of experimenting, I'm pretty convinced there's no free lunch to be had in this department. From looking at intenscreen's tech docs, it would appear that intensescreen does a good job of diffusion, then immediatly redirects light back to the viewer using a fresnel...either as a condenser or a magnifier. I'm thinking that a fresnel mounted very close (like .1mm or so) to a spinning GG would offer similar? performance (about 1/2 to 1 stop gain)

Logically, to provide enough diffusion you need to scatter light to form an image. To much scattering = f/stop losses. Too little and you get my pro-mist low diffusion GG look. The only way IMO to get that stop of light loss back is to eliminate the GG altogether...but this would take a much larger CCD to duplicate the DOF properties of 35mm.

I think a fresnel lens will loose you res, and there is the possability of the camcorder pcking up the fresnel's 'rings'. The be honest, the frensel lens is doing the same job as a PCX lens, only slightly differently. But give it a go and see what you get.

Wayne, I think the advantage in integrated diffusion/fresnel solutions is that the fresnel is in direct contact with the GG surface, therefore max light redirection. I guess the question is, could you get a DCX that close without distortion?

Dennis, you are right. There is always a tradeoff. But I have found in my testing with these film materials, that I can get the same light transmission for different diffusion levels. So they may not be as mutually exclusive as we think. Of course you cannot have all light transmitted (not even a lens can do that), but we can try to get the best possible scenario. The advantage of the polymer materials is that we can get lots of diffusion for very little light cost, something that doesn't seem very easy to achieve with glass.

BTW,

http://www.poc.com/images/lsd/overvi...ms_graph_b.jpg

That's the graph I was referring to from POC.

Wayne, I agree with your assesement of the fresnel. It is only acting as a condenser, just like a PCX would. The only difference is that a fresnel is very thin and therefore has less light loss, which is why I think they are using it on the Beattie.

Yes you can (well a DCX would touch just at 1 point, a PCX would touch on the flat side). Many SLR camera screens do it that way (Nikon for example). Just a PCX touching the screen. I don't think the "touching" is the critical aspect. BTW, the Beattie seems to use a fresnel that acts as a PCX with a focal length of about 150mm.

Besides, there are setups to reduce distortion, like using lens pairs.

I want to try a aspherical lens as a condenser. Anyone with experience with asphericals?

Alain, I've seen that graph...which makes the POC light loss a bit of a mystery. I would assume that no one has actually tried a 10 degree POC in an adapter yet. I believe Dan's test was at 50.

I sent a message to POC, and they have not responded, I guess they may have just received quite a few emails from people from the forum :)

If we can figure out if one of their films at some diffusion angle works for us, then we may just buy a roll for all of us ;)

Ha, I requested samples today. I was looking at some a few weeks ago, but the POC news in the forum was not postive so I didn't bother. It's worth a shot. Now my guess is that a few of commercial guys are sitting back right now and saying "Tried that, waste of time....."

Hehe, they will wonder if we are serious with all those requests.

I wouldn't be too certain with regard to the commercial guys, many of them are just like us trying out stuff. And I think there is ample opportunity to miss on details like thickness, material (polycarbonate vs. polyester) and diffusion angles. Get one wrong and you may think they all suck. :)

From my own tests, adapter aside, I believe that the screen material I am using at the moment surpasses everything I have seen (except for the Beattie) in terms of light loss. And my previous material was even up there as the smallest grain (but I got a rotational variance in the diffusion that gives bad bokeh). There is a material that already gives both great qualities but its not wide enough. (check out the Alternative screens thread)

Hey, I am an optimist! :)

Alain, are you still testing the Office Depot tape?

Latest shot at night out my window, porch light. I changed my condenser and got rid of the barreling I was experiencing with my rig. The light loss is about 1 stop maybe? Hard to tell, but definitely better than anything I have used before - home depot bags or anything like that is a great way to go.

http://dvstuff.250free.com/bag.htm

leo mandy can u tell me how u apply the bag...do u glue it or something?

also, we don't have home depot here, but would these bags u refer to be the variety that come on a roll where you 'rip' them off for veges?

BTW how do u gauge light loss?

I've found a few bags. One is a trash bag. Not the kind you buy from a grocery store, but the ones a grocery store uses. It's very large and clear. Also, a doughnut shop has these types of bags. They use them to pick up the doughnuts most of the time. The veggie bags are about the same I think but I thought they seemed different to me for some reason. I'm trying this adapter as well and would like to know something. Do you apply these "bags" to a uv filter and make that a "gg" or just use the "bag" alone and add some condesors/macros? This would be helpful.

Rh

Yes, I just glued it to the surface of the CD.

In my initial experiments, I tried these shop bags as I had actually used one in a Muray 8/16mm home editor whose stick-on rear projection material had begun to peel off. Mine seemed to add a slight cyan hue but it might have been my imagination. Between two clear CD-R disks I found a flciker similar to the wax so I did not go furthur with them. If there is a better consistency of opqueness and thickness, one should perhaps give them another look.

So, would you guys consider this concept better for spinning/vibrating or for static?

Rh

A bit off-topic...

Where have you been hiding, Alain? You wrote some of the best trueSpace plugins around. Didn't know for sure if this was the real Alain Bellon or not until I saw that you had some images linked to your old site.

How's tungsten|SOLID coming along?

To get it back on-topic, nice images!

Frank

Thank you for your comments. :)

tungsten|SOLID became a suite of 10 stand alone applications. The first one of them is about to be released.

I have been having good success in a vibrating setup. Leo has used it in a spinning setup. Some bag materials have really small grain so it could be used for static under certain conditions.

Additional advantages of vibrating light materials
 

I've just written some lines on the propagation of vibrations in 35mm adapters. Alain's low weight bag-approach might have additional advantages allowing lower propagation of vibration in the camera+adapter setup.
see:
http://www.dvinfo.net/conf/showpost....9&postcount=11

Some questions
 

Also, are there plans for this puppy to be found? The plans for a straight vibrating adaptor no longer exists at the links I found either. Gak!
Finally, the vegetable bag plastic, is it the real clear stuff or the frosted type?

I found the Quyen Le plan that Craig Bellaire did for him.
It had moved to:
http://bellaire.homestead.com/files/..._Adaptor_2.pdf

And the question about the plastic bags was admittedly a brain fart from going from one thread to another on these adaptors. Doh!

http://www.dvxuser.com/V6/showthread...=45972&page=65

Here's something, nothing indepth but pretty good.