Has anybody tried to incorporate an oscillating motor into their homemade mini35's to move the ground glass? I was at an arcade the other day and saw a ticket game called Big Haul that gave me this idea.

Here is a crude depiction (500 Kb animated gif) that demonstrates what I saw... the arm connected to the ground glass and the arm connected to the motor would have to be shorter in length in order to restrict the ground glass from moving so far to each side.

http://www.geocities.com/millertiller12/GG.gif

I have no idea if the 400 series mini35 oscillates the ground glass in this fashion or if this will even work.

Dan: Server not found at: http://us.f2.yahoofs.com/bc/40c66bf9_40cb/bc/My+Documents/GG.gif?bfz8oxABWpLLNYwF

But:
I build a working oscillating 35mm adapter. It will works also with a HDTV Cam because you can´t see any grid. (Excuse my bad English) After very long time, test different construction units and constant new calculation, now it works:
First i used the finest GG i found (with no motion the grid must very, very fine!!! See with HDTV but only a little see with a standard cam). Then the GG is mounted on a plate. This plate is fastened at 3 points with spezial rubber bolts, that allowed mouvement only left and right, NOT!! up and down. On this plate is a motor, like a CD-ROM Motor, with a very low imbalance. With power on, the motor, the plate and the GG is oscillating 3 to 5 times more that the very fine grid. (This oscillating makes an very little circle). You can´t see with your eyes that oscillating, but the gid is never see with the camara. The vibration is very small and kill together with any sounds by using another 3point rubber bolts. This last one is also used to adjust the GG distance to the lens. The whole thing is small and very insensitive in relation to outside vibrations or movements.
Possibly I will arrange a self made kit or will sell the complete equipment. See times

Sorry, try this link:

http://www.geocities.com/millertiller12/GG.gif

Rai, I have a HDTV camera I am building can you send me info for the GG you made right away? I want to try it with HDTV

Find something no more than a 1/2 inch long that can hold two mini bearings side by side and I'll post a picture of a design that works just like the Mini35 400 series. Its the only thing I havent been able to find.

-Brett Erskine

Brett,

When you say find something no more than a 1/2 inch long... I assume you mean an arm or an extension right?

Obin: Next week i have some web space and i will upload more information about my adapter.

Brett: Do you know in details like the original adapter works? how large is the oscillation (in mm)? Which frequency? Can you post the picture, becouse I have my own finemechanical and electronic workshop, so everything is possible...

Dan,

You need to make the travel as short as possible and the oscialtions or vibrations as quick as possible. The short travel is necessary becuse it is easier to keep the distance from the lens constant. The quick movement change is needed because you don't want this thing to be staionary at the end positions too long.

I suggest that you attach the motor at the top of the ground glass, not in the middle of the arm. It would also help in keeping the distance to the lens constant. If you need some help with the design, you can email me directly.

Mike

Mike,

It did occur to me to connect the oscillating arm from the spinning motor directly to the ground glass as you mentioned. As in this example:
http://www.geocities.com/millertiller12/OscGG2.gif

Yes. The Mini35 series 400 oscillates a round piece of ground glass in a very tight circular motion. To clarify this is a oscillating motion which is different then spining or rotating the GG. I've seen the system first hand but I dont have exact specs when it comes to measurements but if asked to give a estimate I would say the GG was about 55mm in diameter and the oscillations moved the glass in a circular path no larger than 5mm in diameter. The speed, by eye, wasn't too fast as to create a blur but near to it. For example you wouldnt be able to count the rotations by eye. Of coarse that is at the highest speed setting. The Mini35 is adjustable in speed (more or less apparent grain).

As far as the part I was referring to in a previous post- Yes a arm with one bearing on both sides will work. You will need at least three of these arms all together in order to make a perfect oscillating movement. When I get a chance I'll draw up my design and post it. The design is basic in concept but will need to be made with precision and its important that it finely tuned to be counterweighted as to not add any subtle shake to the footage - let alone noise. Many people may end up making oscillating designs not only for their adapters to be grainless but also because builders of the static version are finding it impractical to keep the GG surface PERFECTLY clean. Because if you dont anything and everything - no matter how small - shows up in your footage.

-Brett Erskine

Hey guys,

Circular motion is the best. I heard that Pro 35 claims to have an elipsoid movement. They have some patent on that unit. The Mini 35 has no patents as far as I know.

A circular motion would mean that there would not be any time when the adapter is stationary. Problem are vibrations and Pro 35 has variable speed mainly to prevent vibrations / oscialtions of the lens.

You could have another identical drive on the top. The two drives would work in mechanical or elecronic sync.

There woiuld be no pivot, just sime kind of sliding mechanism to hold the GG from moving back and forth.

You could also have one drive only, connected to the GG at one end with an arm and you would fix the middle of the arm with a pin and the arm would have a slot about a fraction of an inch long with the pin inside. Then the glass would then make the same circular motion as the pin on the drive.

Mike

thank you Rai

Not the PRO35 or the mini35 are patented, it is the principle which is patented, so every design with a moving groundglass is covered by this patent.

For the german speaking guys between the community I found the patent (you have to search for the patent):
http://de.espacenet.com/
Beschreibung: Videokamera-Einheit
Veröffentlichungsnumme r : DE10164138 A
Veröffentlichungsdatum : 2002-10-24
Erfinder : WEIGEL WOLFGANG (DE)
Anmelder : P & S TECHNIK GMBH (DE)
Aktenzeichen:
(EPIDOS-INPADOC-normiert) DE20011064138 20011230

I also found a description how the PRO35 works, including a very informative graphic, but I actually don't know where I have it, at home or at work.

The oscillating is very minimal, I barely could't see the movement of the groundglass at the Pro35, so I guess it is less than 0,1mm that the groundglass moves.

dietmar

The patent is from 2002. It only covers the Pro 35. There are no patents on the Mini 35. That overall principle is not covered. Because the overall principle is not covered, you have many ways to go without infringing on the Pro 35 patent. P+S cannot patent the overall principle because a product was already introduced that is using this overall principle and is not patented.

Why was not the Mini 35 principle patented? Because it was not patentable; the principle existed in other products already and was not originally patented or the original patent expired.

I wander what does that 2002 patent cover, and if it is even enforcable.

Mike

Don't forget that both Mini35 an Pro35 use a smaller GG that covers the area of 35mm motion picture film, about half of the stills camera. Diffferent issues regarding vibration and DOF and FOV also.

Mike you're absolutely wrong, the patent covers all kind of moving groundglass systems including the mini35, the PRO35 an the Video Director's Finder "VDF-35 / 16", too.

You're telling things you cannot proof, because I think you don't understand German. The Patent is written in german, so I believe you got no Idea what is covered by the patent.

There is something you might not know, when you apply for a patent it is usual that you have to wait about 2 to 4 years until it is published or refused.

dietmar

Dietmar,

Thanks for letting me know. I just noticed that the Mini 35 unit had nowhere any Patent Pend., or Pat. labels, the Pro 35 had them. I wonder what is really patented? Could you be more specific?

Mike

It is correct, i read the patent yet. The patent covers the Idee of all kind of moving groundglass systems (in a adapter for video cameras). Each kind of movement. Rotating, vibration, etc... the Idee of Movement ist the Point, not the way to do that!!!
But:
1.) Many people converted the same idea years before. I enclosed.

2.) For homemade, you can cover everything. You can sell or buy Parts of them. Parts without patents and then you can put it together and you have an fine working adapter.

That changes things. So everyone should be careful and don't offer to make these for someone else. If you refer to these adapters, refer to them as projects for another purpose. When someone starts making parts for these and what eceryone will be doing with these parts is nobody's business. The patent is from the year 2002. It will be good for a long time. I have no clue for how many years a patent is valid. Seven? Fourteen? It should be however noted that there are many patents that are worthless and will not stand in a courtroom. Also I believe that the company needs to apply for patent registration within a year in other countries. So if the patent is registered in Germany and USA, and not in Mexico, someone can make a million dollar business in Mexico making these. If you drive there from L.A. and buy one, it is a different situation tan trying to make them yourself. Another point is that they may not have US registration. I did patent search here and there was no P+S registration, but I may not have been too thorough. Someone should attempt to do that and maybe some patent attorney can advise in case they are registered. Can someone describe details of that patent? No patents are foolproof and you can always get around them. This is 100% legal.

Mike

Guys,

This amy be a sneaky way of putting us on a notice that the principle is patented. But it does not talk about US patents. Any attorneys on this board? If you start answering in this thread you may legally admit that you are aware of a potential patent infringement. So those who make their own adapters should not read this thread and if someone asks, you should not know anything.

Mike

<<<-- Originally posted by Dietmar Zonewicz : Not the PRO35 or the mini35 are patented, it is the principle which is patented, so every design with a moving groundglass is covered by this patent.

-->>>

I was intrigued by this having read the patent. The patent is very specific about the type of motion covering

a) axis of rotation perpendicular to the center of the image plane

b) axis of rotation perpendicular to an offest outside the image plane (bad news for rotating CD afficionado's)

c) axis of rotation perpendicular to an eccentricly moving point in the image plane - type a) motion with a vibrating axis

d) linear motion in the image plane


Most surprising of all is that pendulum movement is not covered - tick tock motion - just like my German Grandmother clock

PS - frequency must be 100Hz or greater to avoid a stationary GG frame

Well, it would be nice to find out if they have US patent. You can't do pendlum at 100 Hz. How about patents in Asia?

John,
I come from Germany and i read this german patent exactly. The motion you indicated are called in the patent as possible examples (to show witch directions, only side by side). In the paragraph of "patent claims" they call it only motion, without specification. I think this means: all kind of movement.

A pendulum movement has a disadvantage: There are 2 points of no motion, that means the grid is at this points visible.

Hi Rai

The fact that 4 specific motions are referred to without the caveat 'such as but not restricted to' is a weakness in the drafting of the patent and would not necessarily be deemed to cover all motion

An unequivacable way of expressing all motion would have been a single diagram showing rotation and linear motion arrows in all directions - a 'catch all' for the general case

Mike - oops my bad (half period should equal shutter speed) thus should be 25Hz

the 25 hz frequency was based on the Pal frame rate at 50i - in other words - although it is static at 2 points - it is still on average in motion over the 1/50 th of a second timeslice, so the GG would still be blurred.

well I for one only want this piece of vibrating ground glass .
to hold in my hand to look up at the sun . If someone later decides to attach it to a camera thats there business . lets keep working on " hand held vibrating groundglass" thank you rai
and hope when I look at your design for "handheld vibrating groundglass" that It will suit my needs for looking at the sun.
and in no way used as a camera attachment to attach at "the focal plane" reebok has a patent on a air pump in a sneaker not on an air pump.


rotating axis ground glass circa 1955


http://www.oldchristmaslights.com/color_wheels.htm

Hi everyone
I found this site which may be of help with parts.
If anyone knows a site that sells parts could you give us a link. ---- thanks

http://www.budgetrobotics.com/shop/index.php?shop=1&cart=96359&cat=111&

Richard, thats right. I have made a web side with exact details and pictures. And i can help with working parts, but i will change the web side, so it is for a vibration proportioning filter or something similar, but not for a camcorder attachment (because: see your posting from 16th). The exact formulation (what can i say, what not) will this time examine a attorney. Therefore, please still wait a little time.

Another question: I looking for a reseller so that our parts can be dispatched from the USA

I'm thinking of providing a parts kit for the micro circular movement system also. I have a good source for the mini ball bearings and motors here in Los Angeles. I have the usual machine shop equipment to make the offset eccentric drive for the motion.
I'm going to sell it as a 'mini paint shaker' or something. ;) You provide the substrate in the middle, whatever it may be.
-Les

they both sound like great names .
looking forward to this project.
-thanks guys

I saw this device in an electronics shop: It has a high frequency oscillating mechanism based on some solenoids?! It was very quiet:
http://www1.jaycar.com.au/productView.asp?ID=XC0198&CATID=&keywords=oscillating&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

They don't seem to have a fluid optical filter covered. (Some text here was deleted by myself until some tech patent details are checked.)

Just wondering why you guys aren't figuring out exactly how P+S Technik moves their ground glass...The design plans have already been posted you know. No tape, no glue, no wood and they dont even use bubble gum to put their together. There is a difference between cheap and inexpensive.

There is a post on how p+S puts it together.
The reason most people are not going that route is that they don't have the machine tools to do so.
I do.
This weekend, I will be assembling something to wiggle a small substrate myself. It will use 9 ball bearings in it's construction, and be made of AL.
I may make a kit of this available to others to experiment with.
-Les




<<<-- Originally posted by Brett Erskine : Just wondering why you guys aren't figuring out exactly how P+S Technik moves their ground glass...The design plans have already been posted you know. No tape, no glue, no wood and they dont even use bubble gum to put their together. There is a difference between cheap and inexpensive. -->>>

Les, you know how the original adapter work. I also know it. We build those one, and some different models. One is more quietly than the original, but with the same optical features, and we have the better GG. Also, i found ways to go around the patent and will have own patents. I think we should talk together, and maybe... we can work together? Let´s email

Hey guys I am working on an idea as well but all this patent stuff is freaking me out. I would like to build a rig that I could sell but I would also like the idea to be free to everyone. I have a way to work around the PS patent as well but I am not sure Rai and I have the same thought. Either way if my idea is different I would like a way to make sure it never gets patented and anyone can use it if they want. I am also a little wary about just announcing it for fear some one else tries to patent it. Does anyone no how these patent laws work, is there a way to give an original idea free license?

Make sure your movement is extrememly small to avoid excessive vibration of the camera itself. You only want to make the GG move. Anything more and your might have vibrations show up in your footage because you camera itself is shaking. This will also help in reducing sound problems.

Here are some other things that will help produce a oscillating mechanism thats not only quiet but only vibrates the GG and not the camera.

1)Make whatever is oscillating (the GG and mechanism) balanced as perfectly as possible and as LIGHT WEIGHT as possible.

2)To make it alot quieter use large rubber O-rings instead of gears to move your mechanism.

3)Mount anything that moves or makes noise on rubber mounts to contain not only sound but vibration

4)Use a housing that is completely enclosed and perhaps even insulated.

5)Always use tiny bearings on moving parts v.s. bushings

6)Find a small electric motor thats runs quiet and smoothly at a speed thats works for the gg, noise, and vibration problems.

Good luck guys.
-Brett Erskine
www.CinematographerReels.com

One possible source for small bearings, motors, etc, would be a hobby store (r/c car parts)

I worked on the prototype of my 'mini-shaker' and it is about 80% complete. It moves a substrate in about a 1 mm radius. The alignment of the bearings is pretty critical, and I will have to remake one of the parts to get it moving a bit smoother. It's constructed mostly of Aluminum,stainless steel, Nylon , Lexan and 9 micro ball bearings. No office or kitchen supplies used ;)
I'll post pics of the core tomorrow.

Les.

Are you rotating a hollow eccentric around a fixed center carrying the GG? This is the most compact way to go but would need to have more than five mini-ballbearings, more like about fifty. Method for this would be two snug fitting races the outer eccentric ring driven by a belt, the inner ring + gg retained from spinning by another fixed belt = less noisy and wear-prone than a linkrod or sliding keyway and pin. The broader crescent portion of the eccentric ring might have to be drilled to bring the balance back to the mass of the GG and its own ring, or maybe some lead mass added into drillholes if you use hard aluminium alloy.

To centre the loading on a single row bearing there would have to be two drive belts, one each side of the bearing row and the third fixed belt might have to be doubled for loading balance too. Skewing the two fixed belts equally would assist to stabilise the gg assembly.

It would be simpler to home-build on a hobby lathe and superior to P+S Teckniks' published mechanism but more prone to wear and contamination from belt particles which is probably why they didn't go there.

Roller wheel drives are fine but are a mongrel to keep correctly set up and compensate for wear without introducing too much friction unless you use a third relay roller like an older style turntable which regulates its own pressure with a spring arm.

I did the three offset shaft type. I don't think the belt will shed too much, I am looking for a nice silicon belt, they last a long time and are sticky as well.
-Les

Les-
Looks like we are both working in the exact same direction. I'm going with a belt and off set shaft system as well. I found a single pulley wheel that houses everything for one shaft. Im using two micro bearings (each just a few mm in size) and a wheel that has pre drilled holes for the two bearings to drop into. The wheel also has a notch along the outer edge for a pulley to set into. I was looking for something ready made because at such a small scale all of the parts that are duplicates have to be EXACTLY the same. If you drill or make your own ...they better be carbon copies otherwise your going to have a loud or rough running mechanism. For thoughs interested I found the micro sized bearings and the pulley wheel at a hobby store. Sounds like you are using a shaft instead that is off set and then you've attached bearings to it. That should work well. In fact your design opens yourself up to having a tighter oscillation radius. Mine is a bit larger - about the sized of a dime. Where did you find thoughs shafts?

-Brett Erskine
www.CinematographerReels.com

Brett,
I made the eccentric shafts on my lathe. I'm guessing on the radius, I think the diameter of the motion is about 3mm now that I look at it in motion. I'm still only turning it by hand, I'm wondering if I will have to do any special vibration isolation. I made the part that moves from lexan to keep it light.
You are right about the precision needed to make this work, I did the drilling of both support plates at the same time to keep good alignment. I'm going to work on it a bit more tonight, to tune it up a bit. I'll try it with my HDV camera in a few days.
-Les

Les and Brett,
tighter oszillation produce also small (outside) vibration. A good GG need only small oszillation. It looks you working in the same direction like P+S (The original is also not 100% loudless. If you hold it in your hands, without lenses, you feel the vibration. It need the mass of lenses+camera to reduce the vibration!).

We had also tray this way. Here our 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 Rai

rai, exellent drawings. this is something i missed when i recently looked at p+s shematics. now i understand how it works.

exellent job.

can you just explain me how the platform with GG is mounted not to move in anoter directions (closer/further) but just to turn in excentric circles.

thank you

filip

Filip,
our ball bearings are all firmly pressed in (But also you can hold it with springs, clasp or simply bonded), so the GG platform can not move clother or further. The only play is in the bearings. It is far under 1/100mm. But (if you want, and we found there is no need) you can place little magnets on the still platform and on the GG platform, so the magnetic power pulls the platform always to itself.

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 $10 DVX100 battery docking mounts to power the motor.

Funny, the drawing looks like what I built!
Form follows function!

I just got some GG, so I can finish it all this weekend.
I may use 4 shafts next time, because it's hard to get the GG size
to fit with the 3 shaft setup.

I'll post a pic of what I have tonight. It's all shiny still, but I'll matte black it as I finalize the machine work.

You can test the Z axis motion by looking at a reflection of the GG plane. It should be without warpage or image shift if it's perfect. Look at it at a 45 degree reflection. It's an easy way to test it out. The spinning CD people had a problem with the Z axis going in and out ruining the focus.
-Les

Here is where I am at with my 'substrate shaker' .
http://home.earthlink.net/~lesd/hd/

Still needs a bit more work, like mounting the motor, preloading the bearings with springs or magnets, and milling out a hole in the lexan. I'm still thinking of where I want to put the counter weights, maybe in the pulleys. I hand held the motor and it drives it nicely. The whole thing fits in a PVC pipe coupling with the motor outside.
-Les

Les-
You werent kidding. Join the club. Very nice work btw. Could you post a picture of your off set arm and tell us where you found it or how you made it. Also hows that motor working out for you? Is it quiet enough? Whats it's RPM's? Voltage?

I was thinking about the counter weight issue some more and you could also put it on the far side of the shaft. The opposite side than where Rai put his. That way when you add more or less weight its not only easiler but you arent changing the position of the GG. Either way will work though.

I remember someone mentioning the magnet idea before (maybe it was you). You may not need that if you switch to a micro sized bearing because the slack in those things are a fraction of 1 mm. Hobby store. 5 bucks a pop though. Let keep working and sharing ideas. Thanks.

-Brett Erskine

Brett.

Deceased video-cassette players might warrant investigation as a possible quiet longlife motor source. My understanding is that the drum motors are designed to slave to 60hz for US or 50hz PAL country. This may mean 1800rpm or 1500rpm if slaved to their reference.

They have to be powerful enough to drag a half drum past half-inch tape and for accelleration and retardation sharp enough to match the sync signal off the tape against a reference. Best of all, they have a miniature ball-bearing set, an inbuilt balanced flywheel and a nice thick robust precise shaft. They are a bit big and heavy however.

Earlier specimens used a separate high speed DC motor capable of more modest acceration and retardation which was made responsive and powerful enough by a high reduction ratio belt drive to the drum which was effectively an idler or contained a less powerful motor which contributed the final more precise accelleration and retardation needed. These drive motors may not be robust enough and more likely to have been the cause of the appliance failing.

Another source might be the mirror motors from fixed window - bench type supermarket checkout scanners.