he, he, i already tested it some time ago, and it works.
(shame on me, that i didn't tell you...)

if you are looking for it - just find the cheapest binocular but not with porro prism. the other one - straight one, with that schmidt roof prism. i found one here in poland for 4$ - used one, and bit out of order, but that prism part was not infected, and this works for me. to be honest the picture inside that prism is little bit too small, but it definitelly works. and by conisidence fits perfectly without any glue to rubber eyepiece of my pd100.

filip

Yes! Shame on you for not sharing! ha ha.

I too have ordered the close-out mounted roof prism. I also ordered two other mounted errecting prisms from that site. They should arrive by week's end. I WILL share which of the three work the best.

Is there anyone else holding out on us???? Now's the time to come clean and spill the beans. They say confession is good for the soul. It can't hurt our adapters.

Joe

Her is a link to making your own HD camera, it includes a reference to:

Minolta manufacturers some high
tech GG called lentilinear???, or
something that consists of many
micro sized lenses that make the GG
brighter. They may sell us the
material.

In it's homemade idea.

http://www.cinematography.com/forum2004/index.php?showtopic=434

I have to say, that it should be perfectly possible to make a projection plane that takes the projected image, and projects it directly forward like a laser, or on low angle, or even straight towards the image plane (progressively narrowing the angle as it reaches the centre of the image). Result would be near 100% light. If you asked the optical manufacturers some of their staff should know something, if you searched through the US and EU online patent databses you should be able o find references to all the designs under the relavent section. A image plane of the first sort would just consist of a surface array of microscopic condenser lenses.

CD sized optial glass disks have arrived - nearly. They're in customs.

Preliminary methods for mounting these thin disks for hand dressing/polishing are likely to be to use doublesided adhesive tape cut into small 10mm or 3/8"squares to stick glass to a plane metal surface.

Spacing between adhesive squares to be about 1mm or 1/16" to enable entry of solvent to dissolve adhesive. Whole disk to be dipped and left to enable removal from metal surface without mechanically stressing the disk.

The optiCal people I have been observing have not been polishing glass on glass but using a steel surface to polish the glass against, so I shall try doing the same. this may reduce the scratch problem.

Furthur to above, I got the Ohara disks out of customs hock.

They are light enough that the CD motor won't have any trouble spinning them and they are concentrically true.

The downside is that because they are raw cut disks, I now have to polish the front side to clear transparency. the machine at the optical shop takes about an hour to polish a glass lens.

Unfortunately my disks won't fit within the workspace of that wonderful machine

Based on the number of orbits per second I've got four hours of rubbing ahead of me by the armstrong method.

Impatience has prevailed and I have shot some footage through an optical-grade glass Oharadisk which is as yet hastily and incompletely finished.

I have asked Chris to post some images. These are named "agusgla1.jpg" through to "agusgla7.jpg" with number 5 missing. If they are posted they will be found at www.dvinfo.net/media/hart

The disks come in raw unfinished form and are described as cut disks.

The first one spins up on the CD spindle just fine and runs truer than the plastic spacer CD I have been using.

The front surface of the glass disk which should be shiny I have only yet dressed to what might be best described as a satin finish. The rear groundglass face is still the raw form as received.

I was curious to see whether the unfinished front surface, which is a shiny plane surface with pits in it, whilst partially transparent, might also perform much like an anti-reflective coating to reduce flare from internal reflection within the disk.

The results are of course soft and I did not take meticulous care in setting up the backfocus and focus of the lens itself with the tests which were with the camcorder handheld. I wanted to see how it performed for contrast.

The SLR lens was the CIMKO zoom I used on the music video. For comparison through the unfinished glass disk and a finished plastic CD-R disk, the files "mtatk2f1.jpg", "mtatk2f2.jpg" and mtatk2f4.jpg" can serve as references as these were shot through the same lens.

Update on the glass disk.

So far, contrast and colour is good with nice whites. Resolution comes up in moderately dull lighting conditions - just, to the pressed groundglass/backpolished plastic disk but texture or "grain" is more obtrusive.

In bright light or strong highlights, sharpness falls over and the image bright spots bleed more into surrounding image.

So far I have polished the front face clear and the rear face to 300 grade aluminium oxide opacity. I have to try for a finer finish on the groundglass face, or give the boss-screen method a try with two clear disks.

Grainless GG by Minolta??
 

Anyone knows part number/how to order the Minolta's clear focus screen that supposedly has no grain and no markings?

Strange how people don't seem to want to talk about that in this forum, do you have a link? I asked about something like this recently, as well. What ever the case is, the wavelength of light, should enable a screen to be made with a grain far beyond HD.

I have a number of links to technology they use to control and diffuse light in LCD pannels (3M is a good source). They tightly controll light, and it's direction. What ever we get we want the lght rays from the projection to go straight down to CCD size (like a laser, so no 35mm DOF loss), how to do this is another thing, but most attempts so far try to do this. Maybe a projection screen that shoots straight and then a lense to downsize the straight rays, for 3-10% light loose through the projection system. I haven't got time to sort out the refs on this yet, but it is there for anybody to look at. 3M optical products (I think they are the leaders), the Society of Information Displays (SID) has a list of Manufacturers and products, and I have seen about three new style high gain screens (no they don't produce light, they shine it over a more limited angle), one that can be stuck on plain glass, floating around here.

Thanks

Wayne.

Wayne.

I guess in my case it is what I don't know about I haven't talked about. I did enquire about fibre-optics and there are products which can invert and others which can reduce image size in the sense that I understand you suggest. The advice given me was that the resolution would not come up to our requirements.

My modification of a night vision unit to a PD150 would seem to bear this out. There seems to be a 500 TV line limitation though a new product offers sharper resolution which suggests fibre-optics are getting better.

The 3M material seems like it has to have already an existing planar image immediately against it. Of itself it may not be able to behave like a groundglass screen. One would have to have a piece of it to find out.

The material may confer benefits such as less bleeding of highlights into surrounding image which might be aggravated by the relay lens into the camcorder.

For myself, I have too many committments for me to go down another research path at present before I find this one to be a dead-end if it turns out to be.

Understood, it is only a suggestion for research, as there is still some optical issues with the present scheems. I too have about 8-10K of printed research pages left around here (most not read), and have spent 100's of hours in relation to some specific display/projection subjects (with an earnest desire not to do so again). While one manufacturer might not have the right product, that doesn't mean that another doesn't have a much better version of it. Maybe if I spent another 100 hours I may well find a extremely good projection material, but maybe this Minolta has something real to offer us (have to look it up).

I think there are some optical effects filter products which perform similarly.

The purpose is apparently to confer a soft image with sharp highlights and microlenses is the way it is achieved.

RE: Prism image erector for Agus35.

I have sent an updated conceptual diagram and support note to Chris Hurd in hope he can post it with the others on

www.dvinfo.net/media/hart

There is much more to be done on it and hopefully, someone with superior electronic drafting skills to my own (nearly none) might be able to translate original 2D plans to 3D model. I have tried and failed. The drawings can be provided in .tcw and .dxf formats

So far it seems the most practicable method will be to make the prism array in craftwood. This material has very small particles and remains reasonably stable if not dampened.

The disk motor drive plate will have to be fastened to it or kept in accurate alignment. The whole assembly will have to be movable for either backfocus and final axial alignment purposes.

This could be achieved by having the motor mount plate adjustable with three spring loaded screws or pillar bolts/nuts which would give two directions of angle and one of adjustment parallel to the lens axes.

Separate fixings would have to be used to provide parallel adjustment across the lens axes.

This might be as simple as three spring loaded set screws tapped into the outer case and oversized holes in the mount plate and oversized washers for the mount plate screws to permit a lateral sliding movement.

Provided the initial build accuracy is accurate, this second adjustment method should not be needed but might be sought by builders concerned with precision.

The precision issue is not with the image from the 35mm camera lens onto the groundglass as the 35mm motion picture frame is smaller that the frame the lens was designed to project.

Critical positioning of the disk outer edge and prism edges will already be fixed in the prism mount/disk motor assembly.

This method however is a very significant departure from the original simplicity of the Agus35.

Desirably, the prism/disk motor assembly would be a separate assembly from the rear camcorder lens mount to reduce noise. The CD-R case would cease to be a structural element and become a simple cover for the groundglass disk.

They're posted now, Bob -- thanks,

Thanks Chris.

To all.

RE: DRESSING AND GRINDING DISKS.

I have been scheming and planning for means of
cheaply automating the process. The machine is yet to be completed and the following is all unproven theory.

So far it looks like being a gemstone tumbler style thing :-

1 x washing machine AC pump motor.

1 x automotive engine water pump. - or -
1 x automotive power steer pump.

1 x oversize elastic band or flat drive belt.

1 x 50 disk CD-R case outer cover.

1 x 25 disk CD-R case outer cover.

1 x 25 disk CD-R case inner spindle. (Pillar cut off).

Several scrapped CD-R disks for spacers.

One custom brass donut shaped roller, with deep
concentric grooves cut in it about 2mm (1/16") apart.

1 x door hinge.

3 x pieces of chipboard or scrap ply panel.

Assortment of screws gutter bolts etc..

METHOD:

Water pump or power steer pump is mounted by its
bolt-holes to a wooden panel. A clearance hole may
have to be cut out for the impeller.

The 50 disk CD-R outer is mounted to the pulley with bolts or screws. Use sealer or contact adhesive on the heads to lock them.

The washing machine pump motor is mounted to drive
the water pump or power steer pump with a flat belt straight off the motor shaft like a flat belt turntable. (The plastic pump housing, seal and impeller will have to be removed. The plastic seal retainer may be an integral part of the motor and have to be retained for mounting purposes.)

The timber panel is mounted to a base plate with the door hinge. The third piece of timber is a prop. Another door hinge could be used and nails or screws used to make a ledge for the edge of this to hold the main panel at the correct angle.

The whole thing will look like a small cement mixer.

The CD-R 25 disk outer case will slip inside the 50 disk outer case. They are handily tapered. It needs to be removable as it will wear out. The spindle with its pillar cut off is now a lid.

The spacer disks may have to have the centres cut out and stacked until the centre hub of the CD-R case no longer touches an entire disk and the disk will sit flat and steady. These might best be glued in place. The glass disk sits on top of them.

The brass donut rolls along the face of the glass disk in a polish slurry. The tilt angle has to be adjustable for best pressure versus the disk continuing to roll smoothly. The tilt must also be there to keep the slurry pool inside not on the floor.

My version uses a Ford 6 cylinder automotive water
pump. This yields about 70 rpm with an AC 50hz electric washing machine pump motor driving off a 4mm approx shaft. For 60 Hz motors, the larger power steer pump pulley may be needed to keep the drum speed down. Buick V6 water pumps have a larger pulley but may be more awkward to mount.

All the automotive water pumps are doing is providing a bearing, a pulley and something with bolt holes in it to mount it with.

For the Aldu disks, a much smaller drum, maybe a small plastic food jar with a pressed lid and a smaller donut would be needed. For contact pressure the donut might have to be thicker for weight. In both examples the donut should not cover more than about 5/8th of the disk diameter otherwise the rolling action will become erratic.

The motor and pumps should be found in waste bins at repair shops. Whilst components essential to their function as pumps may have become completely ruined, often the bearings and the electric motor in the case of the washing machine pump remains serviceable. Do not wire the motor up yourself but have a qualified electrician do it for you.

No warranty of satifactory performance is made either express or implied.

Image inverting solution
 

Hi All,

Alex here. I have been going tru this site for the past couple of months and with all the info i learnt alot and got down to buidling my very own Agus mini35. I finally sorted out the image inverting problem. I am using the pentaprism from an SLR camera and its 45 degree reflecting mirror. The whole set up is installed close to the ground CD and I just zoom in on the image reflected tru the pentaprism using my MX500 (PV953) DV camera. it worked well when i just place the individual items together by hand. So I have no doubt it works when I fit them all together. Its down to getting the alignment right for the whole set up. Will definitely show you guys the pictures of the set up.

I am actually using 2 nos. of 4 inch white UPVC end caps, four 25mm/6mm dia. nuts and bolt (Stainless Steel preferred), 3mm thick perspex glass cut to shape to hold a small size motor and a 90mm dia. cut CD grounded with a 1000 carbon carbide paper. I am using a 50mm f1.8 lens (Very fast) and a 80-210 f3.8 zoom lens for the canon FD mount. great stuff. everything fitfed properly.

I am having problem with the placement of the pentaprism as its offset alot from my agus 35 setup and it kinda look funny sticking out higher than the agus 35. (I know its hard to understand with words but once I send the pics, you will know what I mean) I am trying to send an autocad file or a jpeg file into this forum. How do I do that?

Anyway, thats all for now. will email some more once I got my pictures safed into the computer. I lost my digital camera cable. So can't download any pic.

Sounds great. Look forward to seeing it. Sounds like you have one of the few compact video cameras that has a lens that can focus and zoom in close enough to see thru the opening of a 35mm pentaprism. Unfortunately this area is too small for most pro-sumer/pro cameras. You lucky bastard ;-) Alright we'll send off thoughs drawings. If you cant seem to be able to post them email them to me at BErskine@mail.com

Good luck with the rest of your design
-Brett

Hi Brett,

Actually, the pentaprism and reflector mirror create a distance between the camera lens and the image on the ground cd. I think the distance is equivalent to roughly 50 to 60mm. I have to infact zoom in 5-6X in order to get a good view. That roughly means placing my camera lens 50-60mm in front of the image. I hope that makes sense. Of course I am not entirely sure but i guess most cameras can focus on something at that distance, if not 2mm distance.

Sure, I am about to finish off the drawing on the proposal and I can send to you.

Alex

Hello!

I just read through the entire thread and is feeling a bit dizzy. Ah well, time to start on the Aldu35 thread then.

But! Why is my first post ever in this thread?
Well, I e-mailed the MOVIEtube people, asking for an approximate price.

Here is the answer:

That is about 18,000$ for a Movietube, and 8,000$ for a Movietube Lite.
Wow! That's a lot of money! Especially if you check out the lite version on their page, it seems pretty simple...

I guess that won't be an alternative. Back to the old plans of making and Agus or Aldu then.

Mini 35 adaptor with inverted image
 

Hi guys,

Finally completed my mini35 adaptor with inverted image. The setup is good but the lighting sucks. Mostly because my MX500 (PV-DV953) sucks in low light. But very good in daylight. Anyway, I can send the images for everyone to see but can someone tell me how to post the image on line. I made the Agus35 version as well. But I am using a small monitor turned upside down to view the inverted video. This version is much better as it allows more light in.

Hi Brett, I can send it to you. I will do that tomorrow as I still have the images in my camera.

By the way, this web page is interesting as it describe how to install and use of the P+S Pro35 adaptor. It even has close up photos of the parts. http://www.dvxuser.com/articles/mini35/

Alex

An update on the raw Oharadisks and the tumbler method of finishing them and dressing out the scratches from failed attempts at a groundglass finish.

The disks are supplied in raw cut form and have to be dressed and polished before a groundglass surface can be created on one face.

So far, the tumbler method seems to work but the conundrum is finding out the right diameter for the polishing disk (donut, roller or whatever it should be called,) It also needs to be much, much heavier than the one I used to polish the glass by hand.

When using the initial coarse grit for dressing out the cutting marks in the glass, the tendency is for the disk to have concentric circles of varying abrasion. Because the donut rolls across the face of the disk as itself is rolling in the tumbler, there are infinitely varying surface speeds between the two faces across the radius of the disk. I would have thought that as high spots occurred, localised pressures would remove the high spots but such is not the case. It may be that the initial coarse cut and intermediate grades of abrasive will have to be done by hand.

As for polishing, a ten minute run with polish shows immediate beginnings of a polished finish, so restoration of disks which have been damaged looks to be an option.

As I mentioned previously, I intend to try dressing the intended groundglass face of the polished disk with 3 or 5 micron AO abrasive by rolling small loose bicycle ball bearings over dry grit on the glass in the tumbler. By this method I hope to create pits, not scratches. I hope it will be also easier to control the amount of frosting effect so that the surface is not too opaque.

The 70 rpm drum speed seems to be okay.

Wow,

I am sorry that i couldnt made a new version of the adapter, the work is killing me. But i really have some good ideas to start making a new version of it. This time i want to really beat the mini35, i think the first shoot was a good start, and seeing how many people got interested got me thinking that i should use again my imagination to come back to this project and make a new and improved version.

So, i will start posting back soon... with a new design of the Agus35 ...

:)

Greetings, and keep the project alive.

Agus Casse

Mini35
 

Hi all,

My inverted mini35 was ok but not satisfactory. I have seen better results with static version. The image coming out was abit washed out and I attribute it to the ground CD. It is so difficult to get a properly ground CD. So I scrap the Idea completely and now working on something new.

I got this solution which i think its really good. I was using the focusing screen from my minolta camera (faulty ones) and found that the light dispersion and image formed on the screen is really good. Even my PV-DV953 (which is bad in low light) performed well with it. Then I thought, why not vibrate this screen in a vertical axis using the cam shaft mechanism similar to the car engine. I did a prototype and it worked very well. Except for the vibrations and sound. Its just too much. I am just wondering how the P+S manage to vibrate their GG without creating noise and vibration. I know this method works and the focusing screen really give a good image when put to the tests.

Is there any mechanism out there for models that has this sort of oscillating motion? The distance travelled by the up and down motion need only be 5mm or so to create the effect of a rotated ground CD. And because the Focusing screen is finely made (i.e. no scratches) its perfect. You can use the all matte Type D Nikon screen or the Canon PH screen. (p.s. got the idea from the guys who did the marla video. Thanks)

Agus,

Any idea how to vibrate the screen without so much noise and vibration from the motor. Can you pass me your email. I can send you a schematic of the design so we can all think about how to make it. If this work and I know it will with the proper parts, you can get really close to the P+S equipment at the fraction of the cost.

Alex

UPDATE ON THE ROLLING DONUT IN TUMBLER :-

There needs to be a machined baseplate in the bottom of the CD-R case. Two or three stacked CD-R disks are still too flexible, the glass disk bends and then the donut wears concentric grooves in it.

The donut also has a tendency to hook up then drop across the glass which causes a ripple effect. The face of the donut should have concentric grooves in it at about 2mm spacing. There also needs to be at least eight radial grooves in the donut wearing face and also the baseplate otherwise it is too hard to get the disk off. Even then, the donut has to be carefully slid sideways off the glass disk, then the glass disk off the CD-R or the baseplate whichever releases first.

The outer rim of the donut also needs to be tapered so that the rim closest to the wearing face is the widest part. A tyre (rolling contact) area of about 2mm or 1/10" seems to work okay. This makes the wear pressure adjustable across the glass. More tilt of the drum increases pressure to the centre of the disk, less tilt brings pressure to the outer edge of the disk.

Due to the hollow centre of the donut, a hub builds up in the centre of the glass disk. This is a good indicator of how much wear has occurred. It may not hurt to have the thicker centre. It is not in the projected image area. But it may cause other difficulties in the polishing.

Times for the grits appear to be :-

600 silicone carbide or emery. - 1 hr per face.

300 aluminium oxide. - 1/2 hr per face or until larger pits can no longer be seen.

Polish powder. - unpredictable.

Polish seems to occur within 1/2hr to 3 hrs.

Another stage of 5 micron or even another of 3 micron before polish could be desirable.

Once two faces are polished, the chosen face for the groundglass can be roughened. The best method is yet to be discovered.

Re: Mini35
 

<<<-- Originally posted by Alex Chong : Any idea how to vibrate the screen without so much noise and vibration from the motor. Can you pass me your email. I can send you a schematic of the design so we can all think about how to make it. If this work and I know it will with the proper parts, you can get really close to the P+S equipment at the fraction of the cost.

Alex -->>>

There is a suggestion of using piezo vibrators. See this post:
http://www.dvinfo.net/conf/showthrea...threadid=27509
I have a GG from a Canon F1 cameras. It has a convex shape top (almost like a fresnel lens). I don't know what will happen with a vibrating optical axis.

Valeriu, nothing will happen to the axis. Mike

FURTHUR INFO ON THE ROLLING DONUT/TUMBLER FOR DRESSING AND POLISHING GLASS DISKS.

I managed to get hold of a piece of soft grey cast iron and turned a metal donut up from that. I did not put the hole in as the bronze version with the hole had caused a hub to build up in the centre of the glass disk. This did cause some problems with the polishing as I suspected might occur.

Otherwise, the iron version is identical to the bronze one with concentric grooves at 2mm spacing and eight radial grooves. The iron roller is not quite as heavy as the bronze. Early indications are it polishes okay but I have not yet gone to clear finish with it.

The hole will remain in the small bronze version for the hand polishing as this did immediately release the disk from sticking and binding.

Piezo Actuator
 

Hi Valeriu,

Thanks for the link. Unfortunately its difficult for me to get somehthing like this where I live. Is this what P+S are using to vibrate their GG. It will be interesting to know. I am getting alot of vibration from my vibrating GG setup (although the setup is crude) I hope a finer setup will create less vibration. Will still work on it.

Alex

Vibration can be elimated if you design it to be counter balanced. This will be the big issue for most people if they are designing one from scratch. If its counter balanced right the only purpose for having rubber bushings is to reduce noise. You should also keep in mind that you'll want to make a noise proof housing. Save yourself alot of headaches and keep your eyes open for something ready made that can be adapter for this purpose. Much better than making from scratch.

-Brett Erskine
www.CinematographerReels.com

FURTHUR INFO ON THE ROLLING DONUT/TUMBLER FOR DRESSING AND POLISHING GLASS DISKS.

The hole in the centre of the bronze polishing roller (20mm) turns out not to be the cause of the raised hub area on the glass disk so much as a construction error when machining the grooves. I had in effect skimmed a wider centre hole only .5mm deep of 55mm diameter which was not apparent to me at the time. (More haste = less speed).

The circular grooves probably need to be off-centred relative to each other in pairs as concentric grooves seem to reproduce themselves in negative on the glass disk during the initial surfacing of the disk, how?? I do not know as the centre of the disk is in no way related to the centre of the roller which is smaller. Having fewer, more widely spaced, off-centred circular grooves and more radial grooves in the metal polishing disk may be the answer.

Piezo actuator
 

The piezo actuator method to vibrate the screen as suggested by someone in this thread is good but unfortunately not possible as you need an amplifier to drive the actuator. This amplifier thing is too big to fit into the mini35. I think the best solution as rightly suggested by Brett is to absorb any vibrations by mounting the screen on a rubber mount. Well! back to the drawing board. Does anyone on this thread know how P+S vibrates their GG? Somebody must know or is it suppose to be a company secret?

I am checking out a solenoid instead. I hope there is one that vibrates rather than just pushes buttons.

FURTHUR INFO ON THE ROLLING DONUT/TUMBLER FOR
DRESSING AND POLISHING GLASS DISKS.

Since last post, I have removed the concentric grooves from the face of the rollers (donuts) and kept only the radial grooves. This has fixed the rings on the groundglass problem. The donuts tend to hang up on the glass more and have to be taken off and cleaned more often, not a big chore.

The performance between the full roller and donut version seems identical but the full version wears way at the edges leaving a very slight dome shape whereas the hollow version seems to self-correct.

I also found that the drum (cement mixer barrel) made from a 100 x CD-R cover needs to be fastened centrally on the hub of the water pump or whatever might be used as a bearing and axle. At the 70 rpm I am using, if the drum runs out, there is enough loft to the roller with each turn to cause an uneven cut on the glass disk.

The fine AO powder is also fatal to oilite type electric motor bearings. The bearing is fine but the shaft is gone in 10 minutes, so care is needed when adding more powder to a used mix.

An alternative source for small induction electric motors is older overhead ceiling exractor fans as used in kitchens of bathrooms. The open style motors have a smaller diameter drive shaft. The newer enclosed motors have larger drive shafts and generally these motors have been removed due to failure whereas the older motors have been removed purely because of noise from worn bearings and are still perfectly usable.

FURTHUR INFO ON THE ROLLING DONUT/TUMBLER FOR DRESSING AND POLISHING GLASS DISKS.

Am now getting good results for frosted finish on gg side of disks using 300 grade AO using the tumbler machine. I allow the grit to literally wear itself out which seems to bring it down to a finer grade. A better result may come from the 5 micron which is on its way from t'otherside of the country with the prisms for the image erector. The texture of the frosted finish is probably still not down to the fineness needed for the Aldu35 developments but is finer than by the hand dressed method. The finish is fine enough that a dome lamp can be just barely seen through it. any finer and it may be too transparent with the hot spot problem occurring.

Polishing the frontside is another matter. The tumbler barrel is too small and the amount of movement (friction) across the outer half-inch of the disk is insufficient to get a polish. The tumbler barrel will need to be wider so that there is a good wipe of the polishing roller face across the entire disk. I will also experiment with floating the disk in a holder across a fixed polishing surface on the bottom of the tumbler barrel.

I have tried using felt-like materials and these when glued to the roller faces with contact adhesive ( "sniffing glue" for the youthful among you ) give a good result. The felt has to be a hard grade and thin. Its hard to find and I discovered that a local Oates brand felt-like cleaning/polishing cloth works well. It is about 1mm thick.

FIRST TEST WITH OHARADISK WITH 5 MICRON GRIT.

Looks good so far in night time low light conditions. The 5 micron seems a little fine on the machine and I could see through the glass so had to hand dress it to make it more opaque. No hot spot in low light. How it fares in daylight is yet to be seen. My version of the AGUS35 with CD-R disk was not good in bright light.

The image through the glass disk subjectively seems a little sharper but the grain when the disk is stationary is more evident.

The prisms look good on initial handholding tests but the 4:3 academy frame is going to be very tight. Have yet to design the mounts.

SECOND TEST WITH OHARADISK WITH 5 MICRON GRIT.

The 5 micron groundglass disk was tested in late afternoon conditions against the sun and with sun behind and later against the sun at sunset.

The results seem superior to the CD-R disk. There seems to be better contrast.

The light loss seems to be about two and a half f-stops.

In grinding and dressing the disk I used a holder which included a stub engaged in the centre hole. This caused the centre hole to become larger and loose on the spindle centre. The disk runs out enough to cause a periodic tremor in the image when a 130mm Nikon lens is on the front of the plastic case.

With the Nikon 55mm lens stopped down to f8, a tendency to a hot spot develops.

The glass disk and CD-R disk appear to confer more tolerance in the camcorder for pinpoint highlights. The glass disk seems to hang onto contrast better. With both there is less tendency for vertical bars. I expect the fixed groundglass would confer a similar benefit.

The glass disk was worth the effort and can be furthur improved.

Furthur to above, I have sent some images to Chris Hurd with a request for favour of them being posted at www.dvinfo.net/media/hart

The images can be identified by the filename "ohara001.jpg" or similar.

The optical path was as follows :-

Micro-Nikkor 55mm SLR lens for Nikon > Groundglass disk Ohara optical glass - 5 micron groundglass finish > 2 element SW5042 50mm telescope eyepiece lens set (similar apparently to an achromatic diopter) (for Tasco) > Sony DSR PD 150P.

There are no improvements such as condenser lenses or fresnels so the defecits from not having these are evident in the images. Until I can improve the groundglass image itself, I won't be sending good money toward a result that may not be satisfactory to me.

Furthur to above, I have emailed some furthur .jpg images to Chris with request they be posted at www.dvinfo.net/media/hart.

These are of a test pattern via the 5 micron AO finished oharadisk whilst stationary and a split image of test pattern via spinning disk and direct to the camcorder. These are named oharatp1.jpg and oharacomp.jpg

There are also three images of the disk tumbler with captions. These are named tumbler1.jpg to tumbler3.jpg and illustrate the basic principle.

All of Bob's most recent images are now online: see http://www.dvinfo.net/media/hart.

Sorry for the delay there, Bob...

The Flamer
 

My 35mm experiment

I started it about two months ago when I saw the Marla rig the first time.>>>http://img20.photobucket.com/albums/...ma/35mmCam.jpg

The bottom image:
This is what I currently have built. Its just My GL1 fliped upside down and shooting the film gate where I have my static ground glass. The whole platform can be mounted on a tripod, and is made of thick plastic and aluminum.
Having the camera upside down fixed the whole "flip it in post" situation but its a bit tricky to shoot on location... nothing a little LCD couldn't fix though.

The top image:
The top image is a 3D model of what I'de like to end up with. The lens would be mountable directly onto the camera and then the camera put upside down on an all aluminum rig. The ground glass would spin like a record to maximize the film grain look.

And here are some test pictures. This is my friend's car>>>
http://img20.photobucket.com/albums/...FlamerPics.jpg
By reading this thread I've come to realize that I need a condencer lens BADLY, and would like to know the best place to get one.
also, has anyone tryed getting a 55mm condencer lens and grinding the flat side to project the image on?

Alex

Chris.

No worries or grief felt. It's one of the issues of today's I-want-it-all-now consumer world that many people have lost their ability to let things just flow as they will and focus on the important matters.

Alex.

You've probably already read through it. There is another thread on the Aldu35 which deals comprehensively with the fixed groundglass option you employ including condenser lenses. The Brett Erskine posts discuss the condenser optics extensively.

Upside-down with a separate small monitor works up to a point. You nearly always have to use some sort of shield so that you can see the LCD screen in bright daylight. You however need to pay strict attention to camera hygeine as turning it over will liberate any loose bits of dust back into your tape cassette.