I was taking a look at the images from that site and may have thought of a way for it to work without a prism. Instead I can use mirrors in the place of the prism. If they are at the correct angle they should bounce properly. The design would almost be the same as how the viewfinder works on a camera. Instead however large mirrors would be used to keep the image the same size as it would be with the ground glass method. We may still need the rotating ground glass however. Instead it would rotate on its side to take the place of the translucent layer of glass in a film camera that the light hits before the prism. The mirrors however should at least fix the upside down image. I'm not sure about the backwards image however. Basically we would just be making a slightly larger version of what is in a viewfinder for a photo camera. It isn't actually all that complicated to use mirros to filp images. It is basic high school geometry. I use to do lab experiments in school like this. We once took everybody in the class and gave them all mirros and placed them at different points and angles in the room. We then bounced an image between 30 people and projected it onto the wall. I do realize however it is much harder to get this stuff working inside something the size of a lens then it is to do it in something the size of a classroom. I might be able to come up with a diagram of the design if somebody else wants to build it.

Another thought I had was to take a second 35mm lens and rip it apart to take one of the convex/concave lens out and use that before the image hits the ground glass. So basically if a camera lens usually has 3 lens inside of it we would create a lens with four lens instead which might flip the image back to normal. I am not sure at this point if this would introduce any more distortion to the image because the lens would have been optimized for the way it was designed. The reason I thought this may work is because when light passes through the first lens it is flipped. Then it goes throught a second convex/concave lens and flipped back to normal. Finally the light hits a third lens and once again gets flipped. The forth lens should hopefully flip it back again. Note I don't know the exact number of convex/concave lens inside right now. I just threw three out there to test the theory.

I had a go at replicating the porroprism (90degree) prism and roof prism arrangements with simple mirrors between the taking lens and the subject.

Mirrors are viable but in that position the assemblies, (especially the roof prism arrangment) have to be too large to be useful in a practical sense.

The mirrors also must be surface coated otherwise you end up with all these beautifully creative but otherwise useless parallel lines writ all over your image.

Between the taking lens and the GG is not an option for either due to the field of view/focal length combination we are dealing with.

Between the GG and the camcorder is an option with 90 degree prisms. Surface coated mirrors should also work. Any roof prism or replicating mirror path which would yield sufficient field of view for the prosumer camcorders many people are using would have to be be too large to be a practical proposition.

This is not to say it is impossible. It is simply my opinion relatively unqualified on the topic. I did not do any more than superficially examine the possibilities with mirrors and decided not to go any furthur.

I found a right angle prism that is 50mm x 35mm x 25mm. That should be big enough to give us a larger image for the video camera. I also found some nice 50mm x 50mm optics mirrors that could be used. These objects are a little large right now but they could be cut down if needed. I figured size was going to be a restriction. I am almost positive this can be done will simple math and science. Yes the adapter might be pretty large but it would work. It would at least be smaller than a rig to flip the camera upside down. If I can make it to not have to use the rotating ground glass then it would be smaller than the current boxes people are making. I think I might still need the gg though to enlarge the image. I thought of getting a magnify mirror to enlarge but it might add to much distortion. I haven't done anything like this before but it should work "if" I can make everything small enough with the needed precision. Good thing my dad owns his own machine shop where he has tools to cut things down to the micrometer. The problem right now is that I understand the math and science of the optics but not the rest of it.

Thomas.

You might have a look at www.dvinfo.net/media/hart and anything in the files there which refers to "erector" or "prism erector" which illustrates where I have been heading in the matter. None of these diagrams should be built to as they are wrong. The hypotenuse face of 52mm referred to is incorrect. It should have been 56mm.

I have a working erector version of the Agus35 using prisms but am waiting for a 7+ achromatic dioptre. Currently there is far too much chromatic smear and muddyness in the colours for it to be of any use.

In my tests to work up this version, I found that the right-angle mirror arrays in ninety degree opposition, needed to be as if they were 40mm x 40mm x 56mm prisms to permit sufficient coverage of the 24mm x 18mm 4:3 academy motion picture frame. This arrangement would just fit within the focal length permitted by a 7+ stack of Hoya close up lenses.

The 56mm hypotenuse face gives you two half faces of 28mm which is just enough to provide 24mm less 2mm to allow for disk circumference and safe clearance of the front prism/mirror edge.

Allowance also has to be made for a face contact for mounting which takes the form of a plane face with a hole in it for the image area. Anything approaching correct alignment is otherwise impossible.

My prisms were 40mm wide across all faces as this was the version economically available to me. You might get away with 30mm wide across all faces but this would require a custom build thus more expense.

25mm wide across all faces might be a bit tight. You will be left no headroom for poor build quality of the adaptor and this would put it out of reach of many kitchen-table home builders which is one objective of this exercise.

I am not an optical engineer or any sort of engineer for that matter. Hopefully these comments may be of some help in your researches. Please keep us posted on your progress.

lilliput 5" lcd
 

Hi all,

Does anyone know if and where you can buy this: http://www.lilliput.cn/207.htm
seperately? I've seen tons of the 7" versions around on ebay and other retailers but i can't find the 5" versions... They are X/Y flipable so great for an agus35.
Also, the resolution of these screens is 960 x 234 = 224,640 pixels so comparable with the viewfinder of for example a vx2100 (211k pixels), this could be enough for focusing (imho it's possible to focus on a vx2100-lcd at normal conditions). Or am i wrong?

Thanks a lot.

The good news is that an erecting Agus35 is achieveable. There seems to be no rainbows when the +7 achromatic diopter is used. So far the rough tests have been in low light and there is much work to be done yet.

The bad news is that it is a much trickier precision build than the more or less 5mm (1/4") build error tolerance of the non-erecting Agus35.

The prism path will not tolerate bad alignment and some form of precision adjustment is mandatory.

The timber (craftwood) mounting method is pretty much of a dead-end for long term stability.

Cold-casting nolathane in a precision mold may be an alternative. The other alternative is having a precision prism mount machined = expense.

The SLR lens mount, camcorder mount, prism path and disk, must be maintained in a closer alignment along three centerlines, all of which have to be maintained in close alignment with each other.

Provided the home-handyperson can work to the skill level required, the erecting version can still be an economic alternative but if it is to be entirely shopped out, then for cost-effectiveness, the professional products either as a purchase or rental investment are probably a better option

Chromatic abr.
 

Does anyone have a good idea of what kind of DCX/PCX I should use to kill the blue high-lights around the edges of the glass? I'm using the spinner. Everything seems to be working great except for the high-lights around the edges... Will post some pics soon!

Thanks for any help!!

James.

Brett Erskine seems to have the most clues on this subject.

Here's a list of questions which may help pin it down a little which hopefully some others with the knowledge will respond to.

What sort of close-up lens are you using between the disk and the camcorder? (Simple singe-piece close-up or macro add-on lens) or more complex achromatic diopter ( an add-on lens made of two or more pieces of glass ).

What camcorder are you using?

What size image are you framing with your video camcorder on the projected disk image? (24mm x 18mm academy motion picture 35mm film frame or the almost 2x larger still-camera 35mm film frame.

What aperture (f stop or t setting) are you using on your lens on front of the Agus?

The achromatic diopter matched to the camcorder or the 2" (50mm) telescope eyepiece -(unfortunately only 44mm effective diameter) seem to take care of the rainbows.

From my understanding of posts which refer to a PCX, this may be a separate condenser lens intended to minimise or eliminate the center hotspot problem (the dark corners). My understanding is that a PCX will not eliminate chromatic errors already existing at a previous stage in the image path.

Thanks for the response Bob,

1. The macro is a Hoya +15 diopter I believe. (Could be a 10+. It's the largest they make for a 72mm thread).
2. DVX100A
3. Haven't measured that yet. (Interesting... 24x18)
4. It's a canon EOS. Focus and Zoom.

I'm using a DCX 50mm Diameter with a Focal Length of 250mm.

DVX-DIOPTER-DCX-GG-Lens


Interesting point on the frame size. Maybe I'm not in far enough..

Some Pics:
http://www.sunrushmusic.com/1.jpg
http://www.sunrushmusic.com/2.jpg
http://www.sunrushmusic.com/mini35_cap1.jpg
http://www.sunrushmusic.com/mini35_rack2.wmv (Shaky video. Using a different lens and hadn't got everything fastened down yet...Encoding maybe wrong too.)

James.

That's a serious looking piece of hardware there. did you machine it up yourself or buy it in?

From looking at the pics, the cam to groundglass distance seems about right for 10+. I can't say for sure but your close-up lens seems to be a single element, not an achromatic. If it is no thicker front to back than about 1/4 to 3/8 of an inch, it is likely to be only a single element.
You can expect to get rainbows on the outside and some softness in the corners depending upon how much area of the groundglass image you are taking in.

There seems to be softness in the lower left corner which corresponds to the right upper corner of your cam's CCD array. I can't tell whether it is your Canon EOS lens center axis being parallel with but not being centered upon the center axis of your camcorder's optical path, or a slightly skewed groundglass throwing the SLR or the camcorder focus off in the left of imager.

It seems to me that the camcorder is framing the projected image about 2mm (1/10th of an inch approx) to right and slightly higher than center but the subject could also be soft in that area which would be correct. If your cam and Canon EOS lens center axes are correctly centered, you may have a very slight bend in the optical path to the right and downwards.

There is another factor which may be in play. The subject may be moving from left to right, which would soften the closer objects in the image more. Due to the superior image of the progressive scan, interlace artifacts are not there to tell me if this is the case.

There is another factor which occurs in the Sony DSR PD150/VX2000 and DSR PD170/VX2100 camcorder families. I understand the GL1 may have a similar issue but I don't know for sure.

Whilst it does not degrade the camcorder image in normal operation, the center axis of the optical path of the camcorders does not co-incide with the image center of the 3 x CCD array but is offset to the right which sets the image frame off to the left as viewed.

You will see this offset in some night-vision news-footage where in difficult lighting circumstances, the intensifier display has been deliberately vignetted by zooming back to enhance apparent resolution.

Because of this effect with the PD150, I found that setting up the centers by viewing through the cam itself did not yield as clear an image as setting up the centers and alignment by mechanical methods and measurement. This is not to say the Panasonic optical path is not centered to its 3 x CCD array, but it would be worth testing for if you want to get into that last 15% of sharpness, before you start trying other remedies.

That area of softness to the left in your .jpg image is consistent with the softness I get with the PD150 on the left margin if I am not zoomed in quite right enough to the groundglass in the AGUS35 or the intensifier display in the NV.

It would be interesting to set up a test with a center mark aligned mechanically with the center axis of the optical path and then shoot a test to see where the center point falls in the aquired image. For this test, you would only use the cam and the close-up lens to film the test card, not the rest of the Agus appliance.

Don't take all this too seriously as it is almost all speculation and theory. I am also neither engineer nor industry professional.

Due to my woeful landline speed I did not attempt to download the .wmv file.

Bob,
Very possible that I don't have the SLR mount exactly aligned with the dv lens. I'll get that right on my new housing.

I'm trying to talk Les out of one of his oscillators. I'm putting together a low-cost micro35 kit for those guys who don't want to build them for themselves.

I did all the machining my self. The diopter is a dual element. Half of the coupler around the dvx lens is filled by diopter. It's a Hoya. I've got a call into century optics about getting one or two of theirs. My feeling is that's what's causing the halos.

I'll have some new footage and caps this weekend using the setup above.

Thanks for the input Bob!

James.

If the Hoya is dual element then there probably should be no rainbows or edge softness.

I would be inclined to give it another chance.

When I set up the telescope eyepiece adaptor I found that the exact positioning of it relative to the groundglass was quite critical even though I could get sharp focus with the camcorder focus adjustments over a range of distances.

Because I machined up the new enclosure for the lens set I was able to play around with the distance between the camcorder lens front element and the diopter rear element. I found close was better for the vignetting problem I had with the internal 44mm diameter I was stuck with on the lens set. You don't have the same options with a factory diopter but you also don't need it as you don't seem to have a vignetting problem.

The telescope eyepiece front element sits only 12mm to 18mm off the groundglass so the magnification is a bit savage. A lower power magnification such as yours will have a wider permissable depth of focus but the ideal camcorder to groundglass distance may be just as critical, though probably less difficult to set up. With your rod mounting arrangement finding that best distance will be a lot easier than messing around with toilet roll centers and gaffer tape as I did.

Brett Erskine created a 4:3 24mm x 18mm image target for printing on inkjet color however I ended up using a standard barcode which gave me more contrast and used Brett's for the finer adjustments. Brett's target has a grid pattern of squares at millimetre intervals

I found furthur away than ideal or closer than ideal caused either a barrel distortion (( II )) or a pincushion distortion )) II ((. Both gave me color errors at the edges.

The final arrangement for my setup was a bit of a compromise in that I had to settle for losing about a millimetre off the 4:3 frame edge in order to get a true image. I went this course because on the PD150 it gave me a very close couple to the camcorder body which facilitated unsupported handholding with lightweight SLR lenses.

7+ gives me a nicer image but the adaptor has to sit off furthur outboard which pretty much negates handheld shots.

For the prism erector version I ordered a Century Optics 7+ achromatic diopter and first rough tests conferred a rainbow free image. The earlier proving images through a stack of three Hoyas to get 7+ was muddy and rainbowed at the corners.

7+ is about as powerful as you need to be for an erecting version through prisms as they shorten the distance from camcorder front to grounglass plane. If you are eventually going for an erecting version, you won't want more than 7+ as the prism path won't fit inside that distance.

The prisms are next. Any recommedations?

I remember seeing Brett's directions on setting up the frame. I need to dig through the posts to find that link

Thanks again for the input Bob. I'm not going to stop this time until the adapter is finished! Look out PS!

James.

Re: Prisms. I'm using two 40mm x 40mm x 56mm prisms which are also 40mm thick across all faces. These are a sort of standard commonly stocked size. Anything else is going to be expensive if it has to be custom made. There is wasted area of about 8mm on each down one edge but this also allows for some misalignment.

In matching up the prisms themselves, I found it impossible to design a simple method of mounting and alignment which was in the league of 5mm construction error the non-erecting Agus35 layout will tolerate and still work.

So far I am examining fusing two prisms together at the hypotenuse faces to take care of the most difficult alignment errors, that of parallel axes and exact 90 degree opposition and to eliminate one generation of internal reflection.

There is a Loctite product No 358 which is a clear bond which is set off by ultraviolet light. You don't have a problem of glue setting until you are ready for it to set.

With the prisms unitised, the mounting whilst a little more awkward initially because of the odd combined shape, will lend itself to more unskilled construction providing adjustment can be built in and the prisms can be protected from mechanical damage.

For initial mounting I am examining using several blunt-ended brass screws to hold the arrangement in place and adjust alignment of the composite prism array in the plastic tube.

Once that is set correctly, the idea then is to coat all nonreflecting surfaces with optical black, then mask off the reflecting faces and in/out faces and inject yellow foam into the enclosure to permanently immobilise the prisms, then remove the adjusting screws. That should be pretty bullet-proof for impact damage from being dropped.

The external Agus35 version I built around my original prism path will not have to be altered. It is still made from plumbers parts, a bit bulky but light enough, about the weight of a SLR camera.

Sounds interesting Bob. Do you have any pics? Where did you pick up the prisms?

James.

As I am in Australia, the source may not be a lot of use for you except they may know who supplies into your neighbourhood.

The supplier was Francis Lord Optics. Their email is sales@flo.com.au. the contact person who arranged my order was John Schmid. The 40mm x 40mm x 56mm x 40mm thickness on all faces was something they had to order in so it may be available readily in the US.

The designs Chris Hurd posted for me at www.dvinfo.net/media/hart were posted as conceptual information only and attempts to directly build to them should not be made. It's been a while since I made this warning and its probably buried a bit deep on this discussion by now.

I have some other committments right now so have not advanced the drawn designs any furthur to the point of reliability.

Ok this may be dumb but...

Why is it that people use GG adapters instead of an purely glass system?

It wouldn't be that hard to design a relay type lens which would compress the 35mm frame size down to that of a 1/3" CCD.... In fact I have been thinking about designing such an adapter.

My only question though: would this retain the 35mm depth of field? I can see good arguements both for and against the idea...

It would not retain the DOF.

Can you explain why that would be?

Brett Erskine:

I gathered from some posts that you are the resident expert on condensor lenses.

I am trying to narrow down what to purchase from opto sigma, as I don't want to buy 5 or so lenses. What is your advice on focal lengths for pcx condensor lenses, as well as any general advice on condensors.

this is the link i plan to chose from:
http://www.optosigma.com/miva/mercha...herical+Lenses

If anyone else can field this question, have at it. I am starting the arduous process of trying to build an adapter for an xl1s, as it seems that no one but Dino Reyes, who seems to have disappeared, has been at all successful in building an adapter for this camera. Now that the xl2 is out, it seems like this adapter would be in high demand. But alas, the groundbreaking is yet to be done.

If anyone is curious on the progress, or wants to lend their knowledge, I, and everyone else involved would much appreciate it. Both threads:
http://dvinfo.net/conf/showthread.ph...5&pagenumber=1
http://dvinfo.net/conf/showthread.php?threadid=23451
are being posted in.

we have decided to try to build from scratch, using an achromatic doublet as our relay lens (20-25mm), a pcx as condensor, and gg from optosigma (1500 grade).

stephen birdsong

Stephen.

Awhile back, I did some rough and ready tests with "C mount lenses into a 1/3" Kampro single chip security camera. The results I posted on one of the XL1 discussions.

Do C-mount to Canon XLI/2-mount adaptors exist or is the back of the C-Mount lens too close to the filter face in the XL1/2 optical path? As a macro lens, the C-mount lens I tested with had to be mounted about 3mm furthur away from the camera focal plane.

With a bit of luck, this extra distance forward just might allow enough clearance to fit up to the XL1/2s and not touch the camcorder's internal bits. A small C-Mount lens body may fit back inside the XL1/2 mount if it has to be brought closer to the image plane than a 35mm still-camera lens might be able to be positioned.

The task I guess is to find out from someone who pulls the cams apart for a living :-

If there are any extra internal lenses in the optical between the mount face and the CCDs. I have seen reference to "on-chip" lenses in Sony and JVC 3xCCD products.

What is the flange to focal plane distance? Given that dimension, it should then be possible to test with a single chip security camera to find the right lens focal length.

Don't take too much notice of my comments. I'm full of theory and not much proven fact on this subject.

Let us know how this works -- my bet is that 1500 grade GG will show noticable grain, especially with the higher-res sensors of the XL-1/XL-2.

- jim

Jim,

If 1500 grade is not fine enough, what alternative to I have?

Bob,
I *think* c mount to xl adapters do exist. The fortunate thing about c-mount lenses (perhaps all lenses), if you increase the flange depth, you decrease your min focal distance. Thats a bit of information I got from a schneider optical engineer. Schnieder makes the lens used in the mini35 xl relay lens.
From what I understand, a c-mount lens would not need to be behind the cameras flange, or in other words, in the recess of the camera body, it would be able to mount similar to the stock lens. I vaguely remember seeing an adapter for c-mount, but it was pretty pricey.

stephen

1) Accept the look of the grain.
2) Rotate or move the glass somehow.
3) Perfect a micro-crystalline wax screen.
4) Pioneer a new focal plane material :D

- jim

Stephen.

1500 seems to be about the practical limit. You can force the grade in the slurry to become a little finer by working the grit to exhaustion but that will require a machine as you will become exhausted before all the particles of the grit do so, ie., there will remain one or two larger particles which will get back into the mix when you get almost to the end if you do it by hand and you will have to start over. (Do the words RSI mean anything.)

I found that forcing the slurry yields a finer groundglass texture but this then results in a partially transparent groundglass. I understand 3 micron does the same thing. The partial transparency improves light transmission and apparent sharpness but causes a sort of halo or ghosting effect when highlights in a softfocussed background are overlit. Normal lighting and compositional practices can resolve this but the image does have a slightly surreal and un-natural look. It would work great with a human face in a dark environment overlit by only a key light as an effect.

I am also using a spinner and cannot vouch for how uniform the texture from a forced slurry will be across the grounglass.

Ok, so basically the only feesible option to getting rid of grain and unwanted optical effects is to have the gg moving? If so, is the 1500 a good option for a moving gg?

stephen

A glass disk dressed with 5 micron aluminium oxire works fine for me.

When the image is output to DVD-Video, there appears to be some fine scintillation which looks like film grain on moderately bright areas. This may be momentary higlights of reflection which endure for only one frame.

It goes away when output to standard definition TV. I don't really know if it is electronic noise or actually there in the raw image but I suspect it is in the image.

There have been some more interesting discoveries here for alternative groundglass surfaces. One is a type of plastic archectural film which the user reported as very promising, finer than AO5 dressed surfaces but still opaque enough to provide a true non-coherent image transfer. I think reference to this material is on the ALDU thread.

Don't take my word for it on this subject. There are others here with better knowledge and qualification to offer advice.

Yeah I have been experimenting with a similar material called Mylar. It is used when putting land maps on public record in town halls ( my dad is a land surveyor). You can get it at any blue print shop, though I feel like it hotspots a bit.

*edit for Rich! YES! Also ocean, tree, and mountain withdrawal... Sooo bad.....

way off topic
 

fred have you gone into seafood withdrawal yet?

RE: PRISM VERSION.

I have emailed 4 .jpg images to Chris Hurd in the hope he still has some server space left to post them on www.dvinfo.net/media/hart. The filenames are agusprz1.jpg to agusprz4.jpg.

It's early days yet. There's a tendency for a hot spot which was not present in the non-inverting version. The alignment is still off with the projected image center on the grounglass being to left and low as viewed in the camcorder.

The close-up lens is a Century Optics +7 achomatic diopter. The rainbows have gone away.

Thanks to Chris Hurd. The prism images mentioned above are now up on www.dvinfo.net/media/hart .

They are about midway down the file list.

ONE THING TO ADD HERE:


" the AGUS35......................................
one step for the 'wanna be speilberg-man' at home, one giant improvement for mankind '


_____

AGus 35 made me wonder why I should buy expensive cameras. You can do it all with a cheap camcorder and a homemade 35 mm effect.

For interest of anyone building prism erecting versions, I have sent an email attachment to Chris Hurd to place on www.dvinfo.net/media/hart. The filename is agusert1.jpg

It is a 1956 EIA test chart shot through the AGUS35 prism erecting version under poor lighting conditions to bring out the worst. As you will observe, compared to non-erecting versions, there is a resolution loss and a hotspot problem. The disk in this test was not rotating. In improvement in resolution and a lessening of the hotspot problem is expected in better lighting conditions.

Okay. The prism erecting version of the Agus35 for PD150 constructed with the following components works to non-recting resolutions subject to some caveats.

Optical path.

SLR lens > gg > 2 x 40mm x 40mm x 56mm prisms > Century Optics 58mm 7+ Achromatic Diopter > camcorder.

Caveats.

Good lighting > Manual white-balance > 1/50 Shutter > Frame on smaller than 4:3 academy movie frame > Meticulous care when focussing relay path and SLR lens backfocus > Meticulous care when focussing.

This limits the depth of field effects to somewhere between 2/3" video and 4:3 motion picture frame. If you shoot electronic 16:9 you can allow the groundglass frame to be a little wider before the corners darken.

This limitation may be solvable with use of plano-convex condenser lenses already extensively discussed but would require a lower power Achromatic diopter to permit the condenser to occupy space between the rear (forward facing) prism and the groundglass, or with the 7+, a custom plano-convex condenser with square or rectangular side faces or at least one flat face no more than 10mm outboard of center to allow fit on the optical path center axis and clearance of the lower side face of the front (rearward-facing) prism.

With an upright image in the viewfinder, life is so much easier, especially when handholding.

I'll get some pics up soon.

Hey Bob,

You got a source for the prisms?

Thanks!

James.

I only have an Australian source. Francis Lord Optics. I think they are sales@flo.com.au

I think they buy in from outside Australia.

If you search under right-angled prism or right angle prism or permutations of those keywords you should be able to trace a local supplier.

Anders Floe may be going another route, that of a single prism and two surface coated mirrors which may replace one prism. He is using the same relay lens P+S Technik use and has discovered a similar coverage-of-groundglass limitation as my setup only with the size of his relay lens as the limit, not the hot spot as is the case with mine.

I've sent two .jpgs to Chris Hurd. One is an untitled image with AF Nikkor zoom SLR lens at 80mm at approx 7ft distance from subject which would approximate the over the shoulder one-shot in drama production. The other is a focus pull through a rainy window. The frame on the gg was a bit wide into the dark edges.

The .jpg filenames are "agusdbt5.jpg" and "agusdbtm.jpg" and are intended for www.dvinfo.net/media/hart

Furthur news on the prism version.

Rubbish in = rubbish out. All of my posted pics so far have been with f3.5 or slower lenses. If f2.2 or faster lenses are used, the hot-spot problem pretty much goes away without need for condenser or you can widen the image area on the groundglass to movieframe or near it.

With f1.8 you can pick up the edges of the prism path without getting the hotspot.

Im making a quick version with a cdr,

Ive looked thru some posts but cant find the exact answer.

My questions are
Which sandpaper do i use, and which way do i rub it circular or straight across, also do i add water etc.

Also if this vinyl stuff is better where can i get some from, and can i apply it to the cd GG.

Thanks
Ben

Ben.

Don't use sandpaper, you'll only get furry scratches. Use a 5 micron grit with water and be extremely careful about getting contamination from sand and dust. Also with the CD-R try not to get fingerprints on the gg side as they will not come off without polishing the gg texture.

Send me your snail-mail address by email and I'll post you one of my old CD-Rs as I have gone to glass now. It is abused and scratched after much testing but it will give you a guideline at least.

thanks for the support Bob,
will do.

Cheers,
Ben

What is 5 micron grit, can i get it from the hardware store?