<<<-- Originally posted by Richard Mellor : I think the holo35 is going to work. I will join in on a power buy
when we have a parts list . -->>>

Great, when people want to buy these diffuser together, please post the number of diffuser you like. I'll add them up and post the current number somewhere.

One thing about the diffusers, is they need to be taken care of very carefully, even more careful than you would with your Nikkor lens. Emund's web page has instruction on how to clean it. basically, you would only use water and air to wash and dry it. After a few scratchs on mine, I think it's best to keep them in the plastic bag it came in and only take it out when you are ready to put it in your adapter housing, and never touch the surface (hold with the edges).

Because they are very thin, you can cut the 2x2in (51x51mm) piece into two 25.5x51 pieces, since you only need one with 24x35mm. With the extras on the left/right, you can use paper(or something else) to sandwich the diffuser in between, and then you can stick it on to your housing.

The prisms I got are from the links Nicholi posted earlier in the thread. The cost me about $55 in total. Not perfect quality but certainly useable and worth the price. If you can find a roof-pentaprism, then you only need another front side mirror, basically the same setup as the 35mm SLR camera (see the photo I have in my photo gallery).

I'm getting a 10 and 30 degree HD to see if they will improve the image brightness.

Thanks Louis.....
 

I'm in for two. The basic element is to determine which would be better. You mentioned that a 10 to 40 degree element might be better suited to concentrate the light more directly into the lense of the cam. I await you experiments.

As I mentioned before, I'm in for one diffuser too.

As for flipping the image, I think there is a way to rotate the image 180 degrees with a series of 4 mirrors. If anyone knows where to get cheap 45 degree mirrors (90 degree image deflection)...
I think finding the right size mirrors to get the entire 35x24mm frame would be a lot easier than prisms... and there aren't big pieces of glass the light goes through either, as we do need to conserve as much light as we possibly can.

Anyway, I would assume that optical mirrors would be loads cheaper than these prisms.

Current group buy list

http://wwwcsif.cs.ucdavis.edu/~fengl/diffuserbuy.txt

louis (vendible)
 

i suggest to keep updated list on the very same site as you mentioned

http://wwwcsif.cs.ucdavis.edu/~fengl/diffuserbuy.txt

but to contact you via your e-mail. it will be easier (i think), then to use this thread just to say : i'm also in, need ... pieces etc.
after, say, 20 people replies like "me too, me too" nobody will find the real thread here.

let's discuss the proper things on this thread and contact you directly when hologlass is needed?

is this ok with you?

(by the way, i'm also in - for two pieces.)

filip

Filip, that sounds good.

So anyone interested just email me with number of pieces. I'll add it to the list. I can be reached at coppercapt (at) yahoo.com.

Am I correct in assuming that this order won't be purchased until after you've figured out the most usable angle of diffusion? I don't mean to sound like a jerk, but I tend to be a bit skeptical about everything. I am waiting until you finish your experiments, but I do plan to be in on this group buy as long as I'm getting the right stuff. Just making sure before I send the official email :).

<<<-- Originally posted by Nicholi Brossia : Am I correct in assuming that this order won't be purchased until after you've figured out the most usable angle of diffusion? I don't mean to sound like a jerk, but I tend to be a bit skeptical about everything. I am waiting until you finish your experiments, but I do plan to be in on this group buy as long as I'm getting the right stuff. Just making sure before I send the official email :). -->>>

Certainly, if it doesn't work, I won't buy any myself either although I did get them for testing. This is not a promise or any kind of contract. It only tells how many people want to get it IF it works and gives hope to get them at OEM price. I plan to post videos without any modification and full resolution snapshots before we decide whether it's good enough. I know many have posted their videos with color corrections but I don't think it shows exactly how good/bad it looks. In fact I'm going to video the same thing with and without the adapter to compare the quality and light loss.

If it doesn't work, then we'll look for something else. I have nothing to complain about the holo diffuser I have at 80 degree other than it is not bright enough. It solves all other problems (image quality, hot spot etc.). As I posted earlier, a 10 degree and a 30 degree diffusers are on their way to me. I suspect they will improve the lighting dramatically but I'm uncertain about the grain. If the 10 degree version doesn't make any visible grain, then I think that's the way to go, since it will be the brightest of all holographic diffusers.

I also notice and Helen has also mentioned, those light stops on the lens are quite important. I have a Nikkor 35-70 with f3.5, that's a lot less light compare to my Fuji 35 with F1.9. Get lens with smaller f number if you can.

I'm having my fingers crossed.

russian monster lens
 

louis,

i bought on sunday on the second hand photo market rare piece of russian lens, as i was told it was used on russian cosmic program (spy?) it's a huge ang weights "a ton" - and has f1,5. which makes picture VEry bright in my adapter. i agree that "f" is very important. keep this as low as possible! (which also helps in shallow DOF).
just a thought.

filip


p.s.

(O.T.) if someone is curious how it looks - i can send the picture to louis.

Here is the link to Filips frosted CD 2 for 1.

http://www.moorefilms.com/frosted.htm

Late to the game here.
 

sampling frequency (Niquist) theory says you have to sample at 2X the frequency to capture all the detail. However you may still capture multiples that coincide with pixel frequency.

So the comment about DV not having enough resolution to capture the full details of the diffuser is correct. Also because the width of each line is so much less than the width of a pixel, I think it's unlikely that artifacting of coincident multiples (like a morray effect) would happen.

I've lately built and automated film recorder and have been working out my video production chain.

My camera is a DVCPRO25 which has a removable lens and I'm already doing a lot in post to get things right for xfer to film so all the optics besides the diffuser are out of the question for me.

Having just found this thread and Agus' thread. I think static is the way to go for a production environment friendly piece of equipment. Not to mention I don't want to have an injunction slapped on me for shooting a movie with someone elses intellectual property.

I definately plan to build one of these babies.

Thanks to everyone who got in early.

Can someone explain to me what the degrees mean in reference to this holographic glass? Does it mean the glass has to be slanted at that angle when put in your design? Or does it just mean that something in the glass itself (the granule's?) is slanded at that angle?

thanks

I've been trying for a while now to find information clarifying exactly what Mike just asked. All I can find is information on "scattering angle." Diffusion and scattering basically mean the same thing, so what I think is that the angle of diffusion represents the amount (specifically angle) that the visible area of image is projected onto the diffuser. Basically, when you look at the back of a lens, you will see only a small circle of the image coming through the lens. This is because you can only see what is directly in your line of sight, directly in front of your eye. As you move your eye in a linear motion side to side, still remaining the same distance from the lens, you will see different areas of the image coming through the lens. The diffuser takes the infinitely different "angles of sight" and concentrates them on one area - the ground glass/diffusion surface. The angle of diffusion causes a variation in how much is being diffused.
Okay, now that I've confused everyone, including myself, here's a link... http://topcontechnotes.home.att.net/...tem/page4.html.
Hopefully, someone has found some other information regarding this question that either proves or disproves my theory.

My understanding of this term (and most likely to be correct) is it's the angle of the viewable area. This measurement is also used for LCD screens and projector screens. When you are within the specified angle in front of the screen, you will see an acceptable image, if you are outside of the area defined by the angle, you will not see the image correctly (too dark etc.), and the reason for that is light are not scattered (enough) to the areas outside the specified angle.

For some applications, you want to have a wider view angle for the screen, for LCD and projector screen etc. so that more people can see the image.

So the holographic diffusers can control where to diffuse the light and control the area where it targets to.

That makes sense. Which would indicate, like you plan to experiment, that a smaller angle of view would provide better results due to the camcorder lens always remaining at the same "straight shot" angle. Am I understanding correctly?

That's exactly what I think.

If I have understood the formula for the angle of diffusion given on the POC website correctly, the amazing thing about the holographic diffusers is that they diffuse off-axis rays less than on-axis rays. For example, with a 10 degree diffuser, a ray hitting the diffuser at 40 deg to the normal will only be diffused to a 2 deg cone. This appears to explain the lack of hot-spots and it also suggests that a small-angle diffuser will work if the rest of the system is correct.

I'm attempting to have a discussion on this with the folks at POC (they make the diffusers sold by Edmunds et al) but haven't had much luck so far. I think that I'll end up getting the 10 degree sheet and testing it myself. As I've already mentioned, my current setup works without a diffuser as far as even illumination and full frame viewing goes, but it needs a diffuser to form a single image plane instead of a 3-D aerial image.

Best,
Helen

Thank you for answering that question. Makes sense now. Sounds like it should work out great. I'm excited to see the results.

I have a couple other question though:

http://f2.pg.photos.yahoo.com/ph/lou...m=DSC00142.jpg

The prism at the top of the image. What kind is that and what will it do? Is it the same type speculated to be used in the movietube design where it will flip the image but the camera needs to be mounted at a 45 degree angle to it? If so that doesn't sound that bad. Might even be kind of nice ergonomically to have the camera slanted. At least for my camera which is a vertical design and could use some extra space at the bottom.

The prism at the top of the page with a smokey black surface is called a pentaprism. Basically it reflects the image 90 degrees but doesn't invert or revert the image (utilizing two reflective surfaces to accomplish the 90 degree angle). That's what we're using to make the camcorder located at a horizontal angle.
Not much is known about the MOVIEtube yet, not even the price or availability. My theory, however, is that they use a Schmidt prism (http://www.edmundoptics.com/IOD/Disp...Productid=2430) which inverts and reverts the image (which is what we need), yet deviates it 45 degrees. That means the camcorder would have to be located at a 45 degree angle in order to properly capture the image. The prism might even provide the required distance from the 35mm lens to the diffuser surface which would make the adaptor much shorter. The camcorder lens could be right up to the diffuser, almost as close as a filter? At least that's my theory.

Here's a neat link that has drawings, characteristics, and names of many different types and variations of prisms.
http://www.tecplusplus.de/ManualLu/prisms.htm

Ultimately, the mirror/roof pentaprism would be a great solution. Right now, I'm using the prism I pulled out of an old SLR camera. Unfortunately, probably to save space, the "roof" is right on top of the "floor" surface. Many of the drawings on the internet show a distance between the two surfaces (like a house with walls), however mine only has a small distance (like a roof on the ground). This will still work fine, but I have to place the prism further away from the diffuser in order for the camcorder to zoom in far enough to capture the entire frame but not be cut off by the roof. That makes my adapter really tall, which I'd hoped to avoid. Maybe SurplusShed will get in a shipment of roof pentaprisms exactly like we need. Here's hopin' :).

great link
 

nicholi,

just great link!
i was surfing on the net just to find single place with everythig about prisms explained and showed. i already have tons of different jpgs. from many places, but this one RULES! thank you for that.

filip

p.s.
did you tryed to "construct" something with sowtware mentioned there? how it looks?

free software for prism "construction" ?
 

does anyone knows about free software for prism "construction" and virtual testing?
i mean - i'm not expert on optics, but if that kind of software exist - then (i suppose) is much, much more simpler to make your own construction of static adapter. i'm confused when i'm checking different prism - how and why certain picture will look. will it be reversal, left-to right or what...

any links are helpful.

filip

p.s.
i checked the link mentioned by nicholi and there is demo etc. but with some options disabled... :(

Anamorphic prism
 

How about working this in...

http://www.optima-prec.com/prism.htm


Great work guys! I think what you're doing is awesome. I come from a still photography background and also thought Boss Screen might work, but the temperature would be an issue. I have a DVX100 and I intend on using stacked achromatic diopters. Any word on exact prism sizes and sizes of the hologram material? What should I get for a 72mm lense? All the best in your endeavors. I'm eager to try this myself.

Best regards,Mike

Frank....
 

I'm a bit of a neophyte when it comes to prisms. How does an anamorphic prism constructed to regulate laser beams correlate to prisms that reflect pictures? Is there a difference? Does it control the light better than say a holo-difuser with a 10 degree light scatter? It's anamorphic, so, does that mean it captures or transfers a larger picture? I'm using the DVX100 as well.

Just throwing fat on the fire...
 

You know what Dean, I'm not well-versed in this either. Maybe it doesn't need to invert, just project an anamorphic image.( if that's what this prism even does.) I'll try and contact the company today and find out. Best- Frank/ Mike, actually my middle name is Mike and that's what everyone calls me and for some reason, I put Frank as my user name. But I answer to either and I've certainly answered to worse. :)

Great Work
 

Great work folks! Vendible I've been following your idea from the Agus35 posts. I also own a DVX100 and pending your experiment on the 10 degrees Holo diffuser, I will place an order for two.

To Lewis...
 

Lewis, in regards to your holographic material, and forgive me if this had been covered in another post, is there any way to introduce illumination to it? I.E. It is isolated somewhat from the prisms, correct? Is there anyway to expose only the holographic material to illumination of some sort. Just curious. Best- Mike

to daniel moloko
 

hey, daniel!

did you finally find that guy who has a shop with full of old zenits?

did you find the exact model where from yo tooked your GG with no grain?

filip

p.s.

need this info desperatelly!!!

What about this?
 

Beattie bright screen.

http://www.tallyns.com/Beattie.htm

Frank....
 

the beattie screen looks interesting. I've asked them about the size and micron thickness.

<the beattie screen looks interesting. I've asked them about the size and micron thickness.>

I just pulled the focusing screen out of our Hassalblaad, and it's 2 1/4 x 2 1/4". I'm not sure about the thickness, but it's about like an acrylic lens filter. The Beattie screan should be about the same.

Mark....
 

That's about the same size as the holo. if it's about the same thickness as an acrylic lense - I'm going to guess about 3 microns? Mark - does that sound right?

louis,

did you finished your holo35?
any news, any photos?

just curious

filip

Apochomatic Lens for homemade Mini35
 

Hello everyone. Until not too long ago I thought I was the only one that had tried to build my own Mini35. When I found this thread I was inspired to get working on the project again. Its nice to see there are more people putting their heads together on this problem. Because I wasnt bouncing my ideas off of anyone my design has evolved totally seperate from you guys and while we have gone down similar designs paths I thought I would bring up some things that have been totally over looked and sooner or later we are all going to have to deal with if we are striving for perfect looking footage:

1) Apochomatic Lens - for just about anyone planing to use a 3CCD video camera other than a XL1 your most likely going to need some form of a diopter/closeup filter lens in order to both keep in focus and fill the frame of our target object size: a 35mm film gate (same size as the inside of a individual film slide mount).

But two problems arise when focusing on something so close to the cameras lens.

Spherical and chromatic aberration.

Spherical aberration is the barrel effect you see exagerated on extremely wide angle lenses where straight vertical and horizontal lines of a given subject are bent outward as they approach the outside edges of the frame (fisheye effect). Your going to see the same unwanted effect (although to a lesser degree) when you try to capture that image projected on the ground glass. Try shooting a grid with your current homemade mini35 setup and you'll see what Im talking about.

And if you look real closely you will also notice the effect of something called chromatic aberration at the outer edges of the frame as well. Its characterized by the bleeded and blending of colors along with a over all ever so slight out of focus appearence. Technically speaking this is due to how different wavelengths (colors) of light react and bend at slightly different degrees as they go thru glass (ie a prism's rainbow)

But dont worry. Im not only the bringer of bad news but good as well because both can be corrected for with prefection with what is known as a APOSPHERICAL compound lens.

Which brings me to one of the reason why I temporarily dropped the idea of making my own a long time ago. I can't seem to find someone that manufactures exact what we need:

-----------a APOSPHERCIAL Macro Lens------------

In my case one with a +10 to +12 power because I have the DVX100.

So I hoped we could put our heads and resources together to find one. I tried Edmunds Scientific. Nothing. Anyone have any other links?

Brett Erskine
Director of Photography
Premiere Visions

Hi Brett,
I have started a post over at

http://www.dvxuser.com/cgi-bin/DVX/YaBB.cgi?board=news;action=display;num=1070228577

there is a fellow from Century optics who has put up some specific information relating to the dvx and correct lens.

Hope this helps.

APOCHROMATIC Macro Lens for homemade Mini35
 

ha ha I ment to say we needed a:

APOCHROMATIC Macro Lens

not a apospherical.

-Brett Erskine

Some folks were using, or planning on using, Century Optics' achromatic diopters. The apochromatic are basically a step above achromatic. Just so everyone can understand exactly what these lenses accomplish, here's a link: http://hyperphysics.phy-astr.gsu.edu...opt/aber2.html.

"When we speak of
 

"When we speak of correcting chromatic aberration, the term should not be taken literally, as meaning "eliminate," but should be understood more in the sense of "suppress." from the link below:

http://www.astronomysite.com/mapug/13/msg13371.htm

This guy tells the differences between apochromatic and achromatic with a discussion of is it "worth" the extra$. It's for telescopes but is salient.

He also discusses 3 element acromats (l think Edmund has these)

apromatic lense....
 

Since it seems that the blue spectrum aberrance effects the image would an 85B filter in front of a acromatic lense work to correct the light?

GG
 

I looked at the movietube construction and saw that it uses a special developed microcrystalline grain glass as ground glass. Couldn't we use a normal piece of glass and wax it with microcrystalline wax to get almost the same effect? Just an idea.