Brett,

How sure are you about the holographic diffusers? I see no reason that they should exhibit the characteristics you have given them.

You can define how spread out the light becomes from several degrees into much larger numbers. These are used in TVs and monitors all the time precisely for their ability to show a great image. Who tested the holographic diffuser in the past?

somewhere in times past someone tested the holographic diffusers. I just can not find it

Neither can I. I know these things are used in projection displays as well so they _can_ work... somehow.

I suspect the person tested the material using a LSD that had a high angular divergence (60+ degrees).

Just a guess though. I may be entirely wrong!

Just sent off an email to POC detailing our specific needs and asking for guidance. I'll let you guys know if/when I hear back from them and whether they think their materials can be benefitial to us.

Once again I wasnt the one who tested the holographic diffusers so I cant tell you first hand. I only recal what others have said about them. I wish I could point you to all the post when it was a hot topic but I dont know where they are. You'll notice though that they didnt say it wouldnt work. In fact they did but it would be much too dark. I know it has a cool name ("holographic") but they arent doing anything magical. Just think about what light is doing when it hits a diffused surface and how much it would have to be diffused in order for it to appear equally bright from different angles. Very diffused. Its a physical impossibilty for a diffuser to be viewable from multiple angles AND be bright. This is why they are using less diffused GG and field lenses and/or fresnel lenses in cameras to focus the light where it needs to go.

>>>>>>Hi Dan,

Thank you for your interest in POC. Depending on your source divergence, it is possible that a diffuser will work without the Fresnel lens. If you have a large source divergence, you can laminate a POC diffuser to a Fresnel lens. The Fresnel lens reduces reflection and scattering losses.

Best regards and happy new year,
Jeff Laine
POC>>>>>>>>>>

Brett,

I see what you mean. However, how diffuse you get can be precisely specified in the manufacturing process. Anywhere from percents of a degree to full blown 180.

What effect this would have upon the ability to remove hotspots I don't know. In any case I think the real benefit that these *may* provide is a very high transmission efficiency - especially with the ability to precisely control where that light is going (even if you end up with a hotspot).

Aaron-
You just answered your own question. The angle rating of the diffuser IS how you can tell how effective the diffuser will be at removing the hot spot.

As far as their transmission efficency I would recomend going by what others that have tested them for this project had to say. They said they were too dark.

Yeah I seem to be good at doing that sort of thing :D. Ah well...

I'm still going to find one to play around with though. Just in case I can get decent results. It's too bad that there have been negative comments about them. They could have been a very good solution!

On a side note: does anyone know where to find lenses large enough to work with MF? I'm having trouble finding this sort of thing for my project.

EDIT: Lenses as in condensers, cylindricals etc not actual MF lenses.

Edmunds Scientific, Surplus Shed or Anchor Optics. Google it for the web sites.

Thanks Brett. I have looked at Edmund Optics, the Surplus Shed, and Opto Sigma but the largest I can usually find is 50mm in diameter. I would like to get 60mm at least. For instance, Opto-Sigma only makes a 50mm GG. :(

Hi Dan,

Are you progressing on the adapter? When do you expect to have a testable prototype? Also do you have in the meantime some high(er) quality footage??

Keep the good work up!

Steven

Thanks Steven,

I have to wear a few hats (at the same time) in this process, which made me bang the walls, but it's refreshing.........whoa!

I allready have tested the prototypes I made, but I have improved the design. I can drop it on concrete now, pick it up and shoot (if the lens is still there....lol)
Not that I recomend it!!!!

I have seen too many times what an "early release" can do to a lot of work. I can not AFFORD THAT.

I will keep my promise to deliver what I promised.

Anyone ever used a BosScreen? I hear it's a completely grain-free ground glass with excellent picture contrast. If this is so, it may be an excellent choice for a non-oscilating ground glass unit.

I'm thinking about ordering a sheet just for test-purposes unless someone on here has used it before.

Here's the link:

http://www.stabitech.nl/Bosscreen.htm#top

G'day, I do know that link and the only con ---it melts if it is hot
and or direct sunlight --after the sreen is gone to be useless.

Yea, I saw that - kinda sucks ... but if it's really as good as I've read, it'd be totally worth it to me to treat it with 'special' care.

I've sent them an email to get pricing on a smaller sheet without grid lines. We'll see.

I've been experimenting with microcrystalline wax and it is definately better (in terms of grain (( none visible )) and sharpness) than any ground glass I've tested. I think it is the best static solution. I've yet to have any wax melt, but I have taken a hairdryer and intentionally melted the wax that was sealed between glass (couldn't escape) to see the effects. After it cooled it was right back to normal. I'm not sure if there would be any discoloration due to reheating over the long term, but I don't think it would be a big problem.

Given the quality of Microcrystalline wax (if you get the right thickness w/o bubbles), I think it would be easier to go through the trouble of building some kind of small cooling system than to build rotating / oscillating glass solutions. (Taking into consideration the precision required with the non-static adapters.)

There's no reason to expect a Boss Screen or any other microwax screen to "melt" provided you keep your camera away from blisteringly hot circumstances -- which you do normally, right? An example of how you could melt such a screen would be to leave your camera and adapter in the trunk of your car on an exceptionally hot day for hours at a time.

Frank,
Would it possible for us to see a 4 sec clip showing something sharp ECU (about 1/3 of the frame) while barely panning? It would be nice to see how clean the BG looks like when soft. Or even easier: 1.4 (or otherwise wide open ) 50-85-135mm lens, night shot, city lights, focus at the closest setting of the lens. Sloooow pan. It should look nice.

Dan: I will definately try and capture some closeup, barely-panning footage. I won't be able to do the "city lights" thing for ya, though as I live out in the woods. LOL!

Here's some of the footage / framegrabs I have available now, in case you haven't seen them:
http://209.214.235.122/mwtest/

Frank,

I saw the pics and first clip (slooow download to go for the other two but I will watch them) so will only comment on what I have seen so far:

The "look" is definitely there. You've got it and is BEAUTIFULL. Bravo!!!

Sharpness? Is subject to precise focusing (on the SLR lens AND the camcorder lens on the screen)
That is why I suggested a sloooow pan with a CU (precise focused) but since there is too much about focus (and focusing techniques while in motion) a static still is best to demonstrate the apparatus.

So far, the pics seems a touch soft (overall) It may be that the lens was not focused on the GG at best, or.... the thickness of the wax was too big. I have not experimented the wax technic but I can only imagine that if it is too thick, focus will not happen on a plane, but in the thickness of the wax layer (hence soft) you know better what can be done.
However it is amazing (to me) how well and even you managed to spread it.
One "sin" is still there though.
Vigneting. Not your fault (of course).
Here is a thought to overcome it:
Take a "normal focusing screen" from your SLR and wax the matte side. You will get rid of any AF marks or anything may be there and get the best of a static GG that can be made. The Fresnel (from the other side) will help you with vigneting while having the mattest matte surface to focus on, on the opposite side, and you are in business.
I will not try it since I have experienced a great loss of screens trying to "matte" the matte side with acetone, milling them, clear nail lacquer, etc while keeping CLEAN the Fresnel side!!!!. Did not get them to a satisfactory surface. Maybe wax is the solution. I'll be curious if you can get acceptable results. I will define what I see as acceptable: If you can take a still (high rez) and footage (nothing fancy, nothing moving too much, a slow pan at most or just a slow focus roll between MARKED distances!)and display it on a 50" plasma (in a local electronics retailer) and you like the image, than is not acceptable, is very good. You may be your best critic.
I hope this helps.

PS1
Try a 4, 5.6, 8 as well to find out limitations (if any...)
PS2 Saw the second clip. All of the above still valid.

Dan,

Thanks for checking out some of the footage! Thank you for the compliment!

You are absolutely right about the wax layer. If it is too thick, the image/light gets distributed throughout and becomes too soft. I am not working with the most precise measurements. - I would have to express the distance in terms of how many times the aluminum strips are folded. :-)

As far as the vignetting - I recently got some condensers in and have yet to shoot some new footage with them. They clearly make a difference when I look at the projected image, holding the pieces together by hand, but how the camera will see it is yet to be determined.

I have wondered if waxing a ground glass would work. I know it would help lessen the grain, but I dismissed the idea thinking that I might as well just go for all-wax to get the best possible image. HOWEVER, given the fact that the ground side of the glass is diffuse the wax should distribute more evenly, catching the wax in the 'pits' where the glass has been ground. I think gravity would do the work here. As long as you have an even grind, you should get an even layer of wax.

Once it cools, you would still need a glass covering for the wax layer.

Hrm...sounds like something worth a try.

Thank you for all the feedback and advice!

Frank great job on he wex technique. I did notice something else that hasnt been mentioned though. It appears that the image becomes increasingly more out of focus near the edges of the screen. I've seen this happen in some of my tests as well. The problem and solution is this:

The problems is your video camera's lens is too close to the wax screen. When ever a video camera films something flat thats extremely close the video camera lens it can not keep the entire object in focus at one time. The reason being is that the distance between the center of the wax screen (or object) and the cameras CCD vs. the distance between the outter edges of the screen (object) and the CCD is slightly different. Its extremely minor but at these very short distances every mm counts when it comes to DOF.

The solution is simple. Simply increase the distance between the wax screen and the camera's CCDs. A few inches should do. This also fixes another problem that you may or may not have noticed - barrel distortion. At these extremely close distances on wider lenses your going to get some. Moving the screen away a few inches and zooming in a tad to reframe will fix this.

To test both of these problems simply shoot a piece of graph paper and make sure the lines stay in focus and perfectly square.

You are right about the edges being out of focus. I just assumed a condenser could fix it, but what you are saying makes perfect sense. I will mount the glass further away from the camera and zoom in a bit more. This, combined with condensers, should give a pretty nice image.

Thanks for the info, Brett!

wax diffuser
 

Frank- Can you tell us how you made your wax diffuser? Sounds like a good alternative to gg.

Hi Kyle!

Check out this thread:
http://www.dvinfo.net/conf/showthrea...threadid=33489

I have completed a few test (clips and pics) and I need some feedback. More to come.
Since web clips are limited, I took HIREZ pics (under the same conditions aside from video) to show the real resolution of the images.

1.4 to 16 is done.
uncontrolled and less than ideal light, done.
A few different lens (50, 135, 200mm) done.

Here is the link; (CHECK ALL 5 PAGES, please)

http://dandiaconu.com/gallery/ALL-CLIP-TESTS?page=1

They all have explicit information and examples about the shooting conditions.

What other tests would you like to see?

(I do want to hear crane and/or steadicam unless you are willing to play "producer" :-))

Dan,

Thanks for putting up some framegrabs and video clips! Looks like you've gotten around the hotspot and vignetting problems. Excellent quality!

What about some underwater footage? ;-)

Thanks Frank.
Just in case there are others like me;
if you click again on the same pic, you will see the hirez pic (down to the CCD pixels)
You can open two windows for same pic ; STATIC and MOTION to compare the dif. made.
As for the underwater footage, I might post it today.

<<<--
What other tests would you like to see?
-->>>


Looks promising so far Dan. I'd like to see some daytime shots panning with people moving at different f-stops and focal lengths. I'd also like to see a closeup of a face with and without camera pan.

A swedish bikini team test shoot would probably the be best.

Thanks Joel,
Bring the bikini team, I'll take care of the rest.
Here is your test Frank (as requested)

http://dandiaconu.com/gallery/albums/ALL-CLIP-TESTS/underwater.wmv

WHAT?!?! Nice job! Thank you!

LOL! My masking-tape-sealed adapter wouldn't have passed that test. ;-)

If I give you my address, will you send me one of your adapters? I could be a beta-tester or something.

Dan excellent job. I have to admit that I held my breath when you submerged the adapter into the bowl. I own a DVX100, will your adapter work and are there any problems shooting 24P? Once again great work.

Thank you Ernest,

>>>>>I have to admit that I held my breath when you submerged the adapter into the bowl<<<<<<<<<<

Me toooooooooo!!!!!!!!!!!!

Naaaaah. I would have not risk it!

I kinda know what I am doing here (or at least I am very good at pretending, aint I? ....lol)

I did not test it yet on any camcorders (other than Panasonic)
When I finish MY image tests, I will look into mating it with other cameras.

Awesome. I'm looking forward to the day this thing is available. Great work Dan. You da man.

Dan, what is your DOF device made out of?

Tough ABS plastic. I stood on it today but I did not record the video. Tomorrow will be posted on my site as one of the "must have" tests. How did you like the "underwater footage"?

I didn't really understand it. You took the device and put it underwater, right? I didn't know if that was to show that it was water-proof or you wanted to actually shoot footage underwater?!

I think it was intended to display the waterproof characteristics :)

To actually shoot underwater you need lenses (and a housing for them and the camera) That "underwater footage" was a joke: HA, HA, HA and you were supposed to laugh.
But accidents happen. There was an ARRI dropped from a small boat (some 10 years ago) How long it took to have it back, I do not know. The insurance covered the incident.
But it could happen.