Bob Hart-
Great frame grabs. Your really making the effort to make a pro adapter. I like the shots of the chart. BTW I noticed your just a hair soft near the edge of frame. This could be cause by a few things but the most common is either the quality limitations of some optics along their outer edge or your GG may be mounted too close to the video camera. Yes there is such a thing as too close. Its only half of the solution to have a camera that has a short minimum focus. Something unique happens when you focus on a flat object and your too close - the whole frame isnt in sharp focus. You can set focus for the center of the frame and it will be in focus but if you look closely the out side of the frame will be alittle bit soft. Changing your focus to bring the outside of the frame in focus will only make the center of the frame soft. Technically speaking this is happening because the distance between the center of the GG and the camera's CCD is slightly shorter than the distance between the outer edge of the GG and the camera's CCD. A mm at these extreme short distances and wide aperatures makes a difference.

The solution:
Increase the gap between the GG and the video camera just a bit (ie: a inch or two) until you can keep everything in focus.

Hope that solved something for you - and for everyone else thats making a adapter.

Also, if its not too much trouble could you sketch the design you described above. Im changing my design to allow for both 35mm and medium format lens and going with a micro oscillating GG. Im coming to realise that grain is only one of the problems. The highlights glow too much because of how light diffuses when it hits GG. The smaller the GG the larger the highlights bloom and the less detail you can see over all. I've seen some crystal clear results from larger, more professionally made GG. Not to mention its alot brighter. There are other reasons too. I made a great little 35mm adapter with static GG. Its small as hell and has no grain except in the highlights of the image but its time to make one with no compromises.

-Brett Erskine
www.CinematographerReels.com

P.S. Thanks for the credit

Brett.

The test pattern was shot with the SW5042 lens set which is a bit small at 50mm for the PD150. It was wide enough for the TV safe area but on the full scan frame grab I caught the corners.

A little more zoom through and it tidies up but remains a bit soft on the left corners in part due to the offset 3xCCD array in the camcorder which puts the optical centre to right of the chip centres as viewed.

With the SW5042, pincushion or barrel distortion occurs within a millimetre or 1/16" either side of the ideal position which resolves best at just under the 4:3 academy frame size, which verifies what you mention above.

Once I get the definition and prism erector sorted I'll probably go for the Century Optics 4x achromatic lens for PD150. 4x or 5x is all that is needed due to the longer path through the prisms.

Brett.

Furthur to above, I have sent you an .pdf email attachment of the "plumbers version" in its current evolution as a side view. I have not published it here as I have to dimension it.

You will notice the image tube I refer to goes right through the appliance. The lens mount of choice is a PVC pipe cap which has been machined and filed to replicate the lens mount, in my case the Nikon lenses for FM2. For the Nikons and most others, about 8mm has to be taken off the open end of the cap to get close enough to the GG.

This detachable adaptor arrangement should suit your mixed use of 35mm SLR and medium format lenses as inexpensive joiners can be bought to extend the tube if extra distance from the focal plane is needed. I have marks filed on the tube to maintain backfocus for different lens types and their adaptors.

The material is quite adequate as to wear if lenses are not changed too often. The tube has to be dressed slightly to make it a slightly looser fit in the cap. The normal fit is a slight taper which is glued in its normal plumbing use. If I was making in metal, I would thread the tube and adaptor for attachment and fine backfocus adjustment.

Look at our (internal) details (it´s 99,5% like the original).

http://de.geocities.com/raiorz/vibro_old/vibro1.jpg

Next days you will found more details and also a different and more simply way to vibrate the GG...

Furthur to above, I have decided to ask Chris Hurd to post two separate .pdf files of the side-view which have been page setup for A4 and US letter pages. This hopefully should preserve 1:1 scale on the printout which should be adequate for getting the general idea. Also sent were three jpg images ohara010.jpg to ohara012.jpg which in conjunction with ohara001.jpg demonstrates what a little bit of filmlook in post can do for an AGUS35 origination

Oscillating Design
 

Rai-
Buddy you are DEAD on! Thats a perfect example of how to make a smooth, professional oscillator. Our designs are so similar its scary right down the where and how its counter weighted. I looked everywhere for off set shafts that are ready made but couldnt find them (at least not that small). You have to make me some of those. If anyone else has a idea of where you can get some let me know. I may have to have them computer lathed. My set up makes it oscillate alittle too wide.

Im on the hunt for a ultra quiet motor. What do you plan on using? Im hoping to find a tiny 7.2v DC motor so that I can just use another camera battery to run it. It would be nice to know what the RPMs of the P+S Technik motor but my guess is at around 1000rpm we shouldnt have any problem. Early on in this project people were using motors out of CD players but reported that they didnt spin quite as fast as they needed to. Then again back then people werent using quality GG or focusing screens so maybe it will be fast enough now. A CD player motor runs at 500rpm. Going alot faster will insure that you wont see the grain but you have to remember the faster the motor the noiser it generally is and you dont want to pic up the sound of the motor in your on camera mics. 1000rpms sounds like a good ball park because we are oscillating the GG instead of spining it. But the best solution would be to have a variable speed controler on a motor that can go alot faster than that. Why? Sometimes we shoot at 1/500sec shutter speeds instead of 1/48th. This quick shutter speed is sure to catch the imperfections on the glass if it isnt oscillating fast enough.

I wouldnt change anything on your design ;-) Everything looks good. I could only recomend that you add a few things that you havent shown yet. Make the mount the motor and the oscillating mechanism on the same plate and when it comes time to house everything in a project box have the everything inside attach to the project box by mounts that have rubber bushings. This is the best place for them. I noticed that you are using rubber bushings where the bearings sit. This is a good idea because you made your own off set shafts but if you switch to some that are precision made (all exactly the same) I would loose the rubber bushings because they cause a little slack in a system that doesnt need it at that point. It some speeds it might actually create strange vibrations if you have the bushings there. You want thoughs three points to be solid.

Lastly if you havent already made it you might find it alittle easier to build if you have 4 off set shafts instead of three. Its easier to find something ready made with 4 holes pre drilled equally apart than 3 holes in a triangle. But more importantly you can make your over all design smaller then. The reason is the off set shafts dont have to be set so far out from the ground glass in order for the O ring to clear it. This is even more aparent if you plan on using a rectangle shaped focusing screen instead of round GG. Personally Im going to go with a Beattie Intenscreen or a Minolta Acute Matte focusing screen. These screens are anywhere from 1 to 4 stops brighter than anything else out there and our adapters need all the light they can get. They do however use fresnels to focus the light instead of a optical lens but Im starting to get real tired of buying a bunch of different plano convex lenses trying to do the same job. As many of us know the optical quality of fresnels arent as good as a plain lens BUT these Minolta and Beattie screens use a much finer etched fresnel lens then others out there. You cant see it. They are perfectly calibrated to give you a even field without any hot spots as well. They are extremely light weight which is a must if you plan on oscillating it. Lastly the microscopic fresnel rings act to contain light that would otherwise diffuse alot more with traditional GG. The result is a sharper image with more contrast. On top of that you can increase most of these advantages if you use a medium format focusing screen instead of a 35mm screen. Grain gets smaller and image gets sharper and has more contrast by at least a factor of 4X. Now this is all true if you plan on using medium format lenses but you can also use 35mm lenses with at least some of the benifits mentioned. You cant use a 35mm sized focusing screen anyways on a oscillating style adapter because the focusing screen needs to be a bit larger than the target area of the lens because its oscillating. You can also get alot of them pre mounted in a frame. Perfect for attaching to your off set shaft.

Alright I better stop there and save the rest for later otherwise people wont want to read all of this info because the post is too long. Anyways Rai since we are working in the exact same direction we really have to work together on this. Email me and/or post info on parts and I'll do the same.

Brett Erskine
BErskine@mail.com

P.S. What camera are you using? I've got a source for cheap DVX100 battery docking mounts to power the motor.

Brett.

Have you examined making your eccentric shafts in the manner small-scale aero engine cranks are made.

They make the shaft and crank wheel as one piece but press a hardened pin into an offset hole.

The optical application would not impose anywhere near the loadings that an internal combustion engine does so it would be feasable to press a simple plain shaft into a crank wheel as well.

I imagine your machinery could stack drill three crank wheels to sufficient accuracy. It is a whole lot easier than setting up a fourjaw chuck to these accuracies.

You could then use needle rollers as used in automotive universal joints for the crank pins. These have a fine hardened finish to a standard none of us could hope to match. You might even find larger rollers for the crank shafts themselves.

Getting the holes to size and finding a strong enough press in a home workshop environment would be an issue but this is the way I would go about it.

It might be worth a search on the Sarich Orbital engine. It was an innovative design but was a commercial dead-end because automotive piston engine production lines would have had to have been heavily redesigned. Instead, Sarich moved to licence the supporting techologies such as fuel injection.

One of their early difficulties was with the idler cranks. These were not driven but were free locators for the orbital piston which ran on a centre crank. The problem was to be resolved with "diaphragm bearings". I don't know how far they took this but I think it was an innovation to permit larger tolerances in mass production machining and misalignment in fit-up.

I think these operated in a similar manner to self-aligning roller bearings.

Since last test on the 5 micron oharadisk I have tried two clear disks with a layer of 90%/10% paraffin wax and beeswax blend. The two disks were separated by pieces of alfoil arranged around the outer edge and are permanently embedded in the composite disk.

I found difficulty in getting a consistent grading of crystallisation across the entire disk. The grading appears to be no smaller than 5 micron aluminium oxide which has been allowed to wear to exhaustion and backpolish has commenced.

Early tests indicate the resolution does not appear to have improved.

Variable density flicker is apparent in high contrast lighting conditions.

Subjectively the colours seem to be richer.

The glass disks used were rejects due to cracks. These were not in the image area but I was not keen to use them and risk scratching up my lenses if they flew apart. With two disks bonded together with a wax layer that is no longer an issue.

The glass-wax composite disk is much heavier - (2 x 0.9mm plus thin wax layer). I expected severe run-out and vibration across the focal plane however the wax disk runs perfectly true. Run-up and run-down of the motor takes much longer.

It is also much quieter as the wax dampens the ringing of the glass disk. The single glass disk was transmitting more motor bearing noise than the plastic CD-Rs.

When I capture some frames I'll ask Chris Hurd to post them. So far the rotating "boss screen" looks promising and capable of furthur improvement.

ADDENDUM: The images from the composite disk are named "waxds002.jpg" or similar.

Furthur to above, Chris Hurd has kindly posted the .pdf files, the filmlooked Agus35 frame and the wax composite disk tests as www.dvinfo.net/media/hart.

The wax disk seems to require more diligence on white balance than the other versions or direct into camcorder. There is a 1.5 f-stop density variation around the disk which is where the flicker is coming from, so more work to do yet.

The matching faces of the two glass disks may have to be finished to plano specs which is beyond the capability of my home made finisher.

Due to the low melting point of the wax blend, it should be feasable to make composite disks out of dressed CD-R disks or CD-R spacer blanks. They may have to be temporarily stabilised by glueing to a firm face. - So maybe the wheel travels full circle, back to plastic.

Furthur to above, I have requeseted Chris to post another .jpg of a wax composite disk image which was shot in overcast conditions against the light also a proposed layout for an erecting version of the plumber's AGUS35 as a .pdf file. This file should not be used as a builder's diagram as it is yet incomplete. It looks bulky but is so due to need to use available low cost components. It should not be overly heavy.

Those have been uploaded... see http://www.dvinfo.net/media/hart.

SOME NOTES ON THE AGUS35 ERECTOR PD150P VERSION.

If anyone is developing along the lines of the erecting Australian plumber's version using PVC sewer pipe, some issues have emerged.

The use of pipe caps for the lens and camera mounts. - There are a few suppliers of plastic end caps. Whilst they all comply with the dimensions of the pipe they are meant to cap, some are thicker and more robust than others. I suggest staying with the Iplex cap which is thicker, provides material to machine down and seems to have a slightly higher melting point.

The vertical position of the image tube may have to be amended in the side view published in www.dvinfo.net/media/hart. To provide clearance for the camcorder mount, the tube centreline has to be offset to the right relative to the SLR lens centreline which introduces a close fit to the left lower diameter of the front cap for the lens mount. If machining it directly into the cap as I do, this may not matter but if metal mounts are used, there may not be sufficient material for them to be screwed onto unless the image tube centreline is lowered about 12mm (1/2").

If the appliance is to be entirely supported by baseplate and rods and the end cap needs only to block light and carry a hole to pass the image to the camcorder, this offset may not be required.

Due to the wider diameter there is now a greater span between the upper edge of the lens mount and upper edge of the front SLR lens mount cap. Use of heavy or long SLR lenses may require a metal plate to be added inside the cap for support or for a metal mount to span the full internal diameter of the cap to prevent trembling of the image. The use of a baseplate and rod mounting system is recommended for the appliance in this circumstance as the camcorder itself will likely fall apart.

The original idea of using ply or craftwood caps to hold the prisms down onto the prism parterplate will not work for two reasons :-

The timber will bend because large holes have to be made to pass the image.

To be strong enough, they have to be too thick. This adds too much distance to the optical path for a 4+ dioptre to frame the 4:3 academy frame without zooming in all the way which then introduces too much light loss.

The traditional method of retaining the prisms with small bars is recommended. Do not use rubber as an anti-chip cushion. It will comply or cut through and the prism may drop out. (Did in my case onto cement = lamentations.) Hard woollen felt has been a good substitute so far.

For the parterplate, craftwood has turned out to be a scizoid beast. It is fine grained, routs and carves nicely but has poor strength in the horizontal direction. It delaminates randomly with drilling and fitting of screws. Compession between two pieces of hardwood is recommended for this task.

Pattern Question
 

Does anyone know a way of getting rid of the *pattern* created by the spinning CD grain? I've got some 1000 AO arriving monday. Has anyone used this on a plastic cd?

Here are a couple of pics of my rig so far. I'll be working on the rods in the morning. The video is of my wifey. She was on a computer so don't let the blue glow fool you. (The matte blox was just for fun...)

http://www.sunrushmusic.com/agus35/1.jpg
http://www.sunrushmusic.com/agus35/2.jpg
http://www.sunrushmusic.com/agus35/Test1.wmv


Thanks for any comments!

I am unsure of the "pattern" you describe. I am assuming that it is a scintillation or moving film grain style effect.

If this is what you are getting, it is I think caused by pinpoint highlights occurring in the disk image sharply and intensively enough to register is a motionless object in a single frame even though the disk is spinning fast enough past the camera view to eliminate texture from the image.

It should by and large go away when you achieve a finer groundglass texture on your disk.

When you dress your next disk, get hold of a sharp scalpel or fine trimmmer blade and remove the raised ring in centre of the data area of the disk and the raised rim. You can dress these off with a coarser grade of abrasive but at the inconvenience of having to dress out larger scratches in the image area.

These larger scratches are a real pest with plastic. The only solution is absolute cleanliness and very little pressure.

I achieved a good finish by rolling one in a tumbler I made for dressing glass disks, in about 15 minutes. You need to mount the disk to an accurately flat circular object slightly larger and firm, not flexible. Keeping the dressed surface of your disk flat is essential otherwise you are going to make yourself a lens or two or three or more around the disk and you will get movement of the image however slight which will degrade it.

Beeswax, candlewax or paraffin wax is good for mounting for our purposes. It melts below boiling point of water and seems not to injure the disks so far. I do it by placing the disk (in my case glass oharadisks on my flat pieces of metal), putting this on top of a ceramic topped electric cooker then turning on the element below to a slow setting, waiting for the wax to melt and spread beneath the disk, then sliding the whole thing off the hotspot to a cool place on the stovetop for the wax to set. With a flastic disk you may need to keep it pressed flat with another perfectly flat object on top of it through the whole mounting process of melt to cool down.

Dont dismount it on the stovetop but cook it off in a pot of water. You don't need to boil it. When the wax floats off pick up as much as you can off the water surface with tissues befroe hauling the disk out.

If it is a glass disk you have to let it cool down in the water after it has been separated from the baseplate. A plastic disk can probably survive the sudden cooling in air without warping.

Cleaning off the wax is hard. With glass you can peel it off with a fine razor blade. With plastic that is not an option as you will scratch it. A trigger spray laundry stain remover (Preen) seems to do it followed up with a water and detergent wash, then metholated spirit or blue window cleaner.

If you dress a CD-R, then use this method to polish off the metallic layer.

If the finish is a little too opaque, you can back-polish with a soft dry flannel cloth or felt to restore a little transparency. This is best done by putting the disk back onto the waxed baseplate and dressing lightly against a flannel stretched over a flat surface. A table or benchtop corner would be adequate. If you polish by handholding the disk, there is too much chance of variable density around the disk and undesirable flicker in the image. With 1000 grade AO, I don't think you will need to back-polish.

No guarantees.

Initial tests with the erecting path through 40mm right-angle prisms are encouraging. These have been done with the prism assembly unenclosed so there is some whiteout. There is light loss via the prism path and this seems to aggravate any tendency towards hot-spotting.

Provision for fine parallel adjustment and right angle adjustment of the prisms relative to each other appears to be essential as the image skews noticeably even with only a minute defect in cutting the mount channels in the parterplate. A metal plate may be the only realistic option as the timber is too compliant when the mount screws are tightened up.

*Pattern*
 

Thanks for the response Bob. The pattern that I'm seeing is the grain of the CD spinning. I'll try a couple of your ideas and see what happens!

Thanks again!

*pattern*

I forgot to ask if you are keeping the camcorder shutter speed at 1/100th of a second or slower. 1/50th is better but not always an option. A fast shutter speed is going to cause the motion of the disk to be frozen in each frame which will cause a random grain pattern.

If your camera is auto and won't allow you to control the shutter speed, then you may find you have to reduce the amount of light into the camcorder with neutral density filters to force the camcorder into longer periods of exposure per frame. Unfortunately, having learned on film cameras, I don't know the equivalent electronic terms for shutter speed or exposure time.

*Pattern*
 

Thanks Bob!
I remember reading that from one of your posts. I'll try it (my camera supports many shutter speeds)! I played around with some wax last night. It looked pretty good at first, but when comparing it to the frosted CD, it looked like I was going to be losing quite a bit of light.

Did you say using 1000 AO would work on a plastic CD?

Thanks!

Wax.

It needs to be a thin layer. Thats when the variable density problems occur. I tried a thicker layer but found the severe light loss you described.

From my informal tests so far, it seems the losses through a thicker wax layer plus an erecting prism array may bring the "film speed" of a PD150 camcorder from around ASA320 down to about ASA50 or slower which for my purposes will defeat any creative advantages the system provides..

So I am staying with the glass disk for the time being as the resolution on the spinning disk does not seem different, only the grain in still frames is less evident on the wax image.

The AO should work. If you hand dress your disk on a piece of glass, make sure everything is absolutely obsessively clean. A scritch on glass becomes a great gouge on plastic. Also don't use too much pressure but let the slurry do its work unhurried.

If you use a razor to trim the raised areas on you plastic disks, wear gloves and bend the blade into a slight curve and use a slicing action. With practice this works fine. A Stanley knife blade or snap-off blade is better. Use a lateral rocking motion to ease the blade along at about 25 degrees inclination if you have not enough fine control over it. It is less likely to skid off across the disk into the image area.

No more grinding?
 

At least for moving glass.

I have a vinal plotter/cutter machine to make stickers, signs, etc. Well several years ago I made a sign out of a thin vinal material to was supposed to mimic etched glass. So today, I took a clear cd, stuck the vinal on the cd and trimmed the excess sticker off. It's amazing. Absolutely no grain or spinning pattern like I got with the pre-frosted cd from maxell. I also compared it to the cd I used AO100 on and it's clearly a better picture with no hotspot. To be honest, I think I'm through looking for ground glass! And, I've got a 100' X 1' of this stuff!

Now for the erecting! (and maybe oscillation...)

James. Could you post a very short but full res./full screen video of you doing a pan shot of a high contrast scene? Also please share the make and part number of the material that your talking about.

Whats your stop loss?

I havent mentioned this before but at least with GG if its extremely bright it sometimes lets too much light thru and not enough is used to create the image on the GG. The result is a lessing of the shallow DOF look.

-Brett Erskine

Stuff to Stick to CDs
 

I gave up on real ground glass when I found single-ply architectural mylar film. It does have grain - at roughly 9 micron GG size, but when spinning it's reasonable. And at $2/11x17 sheet, its much more cost-effective than glass and powder and hours and hours... For me it offers the perfect amount of diffusion, though - my condensor removes all hotspot (very noticeable without the condensor) but my light loss seems reasonable. You can also buy double-matte which is more diffused, less light, etc.

I'd love to find a grainless, yet diffused material to attach to the CD. So far, the mylar film is the best I've found.

What kind of adhesive does your stuff have, James? Does it cause visual problems? (can you see globs of glue?) I'd also love to see some video...

Erecting Agus35 - first image - very furry as some optical components were hand-held. May soon be found here at www.dvinfo.net/media/hart. Filenames are aguserct.jpg and aguserc2.jpg.

*Vinyl* Material
 

Jonathon, the material comes with the adhesive. It's made to mount directly to glass outdoors or indoors. We've had this vinyl on the front door of our office for 4 years facing the west and there's been no UV discoloration.

I'll post some pics and video tonight. I've been testing with a high resolution monitor (SMTPE). The monitor picked up the spinning grain on the pre-frosted cd from Maxell. The AO1000 cd had a hot spot (probably needed more grinding). But the vinyl etch was perfect. (and I mean perfect).

Brett, the stop loss is no worse than the frosted cd or AO1000 cd.

I've got the mylar film as well but the grain is too big.

The vinyl material seems perfect so far. Just peel and stick. You can probably find similar materials at sign stores on the web. Just be careful because I've seen some etch look vynl with more grain and 'sparkel'. My vynl grain is very fine. And seems to be scratch free (so far).

If anyone if doing the prism erector and basing anything on my side-view layout - stop. Go no furthur for the time being as the drawing is WWWWRRRRRONNNGGGGG.

The prism hypotenuse faces are 56mm not 52mm as drawn and this messes up a few assumptions in terms of where they go in the image tube. They still work however. I have also misread the vernier on the disk diameter by 10mm whilst back engineering my clamps-and -gaffertape prototype onto the diagram.

Onto a 4:3 academy frame onto a fixed groundglass the image is as sharp as the non-inverter but there is a slightly more noticeable hotspot. This is best alleviated by positioning the prism block as close to the groundglass as it can be placed without the window frames in the block themselves drawing in upon the image as you zoom in.

I am using 7+ which is not an achomatic diopter. I shall get one as soon as I can. A 52mm diameter may fit by one of the prism retainer bars which will enable a closer couple than the 55mm from camcorder to image plane current available. This will confer the benefit of less zoom therefore slightly less light loss.

James can you post some pictures and how much do you want for a small piece (enough for 4 CDs) of the material?

Post Vinyl Shots
 

I'll try to get to that tonight. Now that I've got the GG solution resolved, I'm finishing up the rails and packaging.

Ernest, I can hook you up with a peice.

James-
Did you get that make and part number for your vinyl material yet?

Vinyl
 

Brett,
To be honest, the vinyl is on a perfrated roll that's used for my cutter/plotter. There is no part number nor name. I'm going to go to the sign shop where I bought it (~$40/100ft) and try to find the same stuff. I should have a part number after that.

On another note, after a few days of finalizing my rod system, I got everything put back together so I could do some more testing with the vinyl. It appears it wasn't just a dream, the stuff really works well. To be honest, I couldn't ask for anything better. I can't even tell the difference when the adapter is on compared to when it's off other than the ~1 stop loss. I'd like to get the size down by going to an oscillator and would like to get the image errected, but hey, other than those issues that only affect me as the photographer, the image couldn't be better.

I'll get some stuff posted this weekend.

J

Incredible! Only one stop loss? Are you sure? Check it with auto exposure and a full framed shot of a gray card for both with and without adapter to find out for sure.

- BOB:

http://pub.alxnet.com/guestbook?id=2559599



Wich side of the disk should point to the camcorder? The blank or frosty?

Why do flicker occur? It goes away with 3V-power.. but why is it really there at 1.5V?

My experience has been that flicker occurs due to subtle differences in the texture of the groundglass finish around the disk which causes local areas of varying density. This affects the amount of light passing through.

I think the camcorder automatic exposure might also try to chase the light level and maybe aggravates it because under certain lighting/contrast conditions it becomes more apparent-(Last two words are later amendment to message).

At faster disk speeds the camcorder may be just going with the flow.

The disk defect is nearly impossible to see by eye and harder to control when making a plastic disk. An oily fingerprint on the groundglass surface is enough to make it happen.

3 volts seems to make it go away with the plastic disks. I couldn't control it at all with the wax composite disk and I gave up on that although it gave the sharpest images.

My personal preference is to have the groundglass surface closest to the camcorder so the camcorder sees the projected image without going through a layer of glass or plastic. It may not be the correct method.

definitely interested in the vinyl, good work James!

I'm also really interested in the no-name vinyl. Do you think the grain structure would work if it was laminated to an oscillating piece of glass?

James, what type of CD are you currently using to be a backer to the vinyl? If you're unable to find a part number, I'd also be interested in buying a couple sheets from you. I'm currently working on a spinning CD version, but am REALLY interested in getting an oscillating version up and running.

Brett, have you made any further progress with your oscillating design? I haven't kept up with the forums lately, and reading yours and Rais posts from the beginning of July has gotten me motivated to see what I can piece together.

(Found the post dealing with the oscillating design, sorry for the question before I searched the forums :P)

I am not sure if this would help anybody or not. I just started reading about the 35mm adapters and have been very interested in this topic.

Anyways I had a thought the other day about solving the inverted image problem. Since we are sort of using the lens from our old 35mm cameras how about somebody rip their camera apart and steal the mirrors, and prisms. Clearly everything is right there in the camera that we need. If nobody wants to rip apart their camera then maybe somebody can find a broke camera and try it. If we use the same system that is in our current 35mm cameras then the image will be corrected when captured by the video camera. This may also solve our ground glass problem since we wouldn't need it. Instead of projecting the image on a ground glass the image would be reflected by smooth mirrors. It would be like having your video camera shoot the viewfinder of your 35mm camera. No distortion, light problems, inverted images, or grain. I don't know if any of this would work but I never heard anybody really talk about this.

That line of investigation has pretty much proven a dead-end although I think someone with a very small camcorder has claimed to have succeeded with it. You may find by searching this site for "roof prism", discussions where this option is mentioned.

Yeah - I thought about that as I took my Canon AE-1 apart when I was first starting. The problem is the viewfinder is tiny.... the prism ends up with an exit aperture which is down in the 10mm across range and it's very hard to get the camcorder focused on it.

I mount my camera upside down and use a $20 external b/w CRT monitor, mounted on the left side, like a viewfinder. It's a 5" diagonal and the CRT is much better for focusing than LCD. It works great. Should have pics and things in a couple days.

how do cameras work to go onto the 35 mm film then? I thought the viewfinder method might be just a little to small. Does the image go through another prism to output to film? I would take apart my camera to take a look at it but my wife would kill me. Also I thought maybe of not using the actual parts inside a camera but creating a larger version based on using the design as a reference. If you flip the camera upside down isn't the image still horizontally flipped? Maybe if we forget the prisim the mirrors could at least fix this problem. Then if we flip the camera or external monitor upside down then everything will be correct.

Film cameras record their images onto film upside down. Then when you get the pictures back, you turn 'em right side up :)

The viewfinder (at least in a 'reflex' viewfinder) is an 'alternate' path that the light takes whenever the shutter button is not depressed.

In my AE-1, the light comes in through the lens - inverted at this point and hits a mirror that can flip up out of the way. It bounces from the mirror up into a roof prism and its exit aperture is right next to a powerful mangifying lens that you look into to see the image.

Once you press the shutter down, the mirror flips up out of the way and the (inverted) light goes straight back to the film, without anything else in the way, recording inverted.

So - the viewfinder is not actually the same path of light as that which goes to the film. In the Canon AE-1, for example, there is a fresnel in there to help reduce hotspot - but that also means the visible rings of the fresnel in the viewfinder image -- at least when you magnify it enough. Recording the viewfinder image directly is not a good solution primarily for this reason.... yucky fresnel rings in most.

Here's a good picture of the inside of a camera like mine -

http://entertainment.howstuffworks.com/camera7.htm