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Old January 1st, 2005, 07:46 PM   #1
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Frosted CD - which way does it go?

I have found a toy with a motor in it and the top of it fits the inside of the CD exactly! This is going to be my protype until I can find a used CD player for cheap (right now, I only find new at about $20.00 each). So I want to glue the frosted CD (I have two frosted and two clear, but I don't think I need the clear, right?) to the little motor, but I noticed that
1) the frosted CD has a smooth side and a rough side
2) so which side faces the 35mm lens and which side faces the camera lens?

Thanks in advance!
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Old January 2nd, 2005, 01:36 AM   #2
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The choice is not set in stone but my personal preference is for the frosted side to be closest the camcorder.

Often-times handily, the camcorder's autofocus will lock onto the groundglass image plane even if the SLR lens is off-focus and the image soft.

Once the camcorder finds focus, switch to manual so it doesn't get tempted to take off and chase the aerial image. This makes for quick setups in real-world locations.

If the frosted side is closest to the SLR lens, the camcorder sometimes chases focus upon defects or dust on the clear side and then keeps going on after the aerial image then hunts back and forth to the dust then after the aerial image again.

This forces you to go the slower route of manual focus which is difficult unless you have a large CRT monitor.

Use bathroom water-cleanup silicone sealer to glue your disk on. It is strong enough but will peel off non-destructively if you need to reset the disk or change it.

Does your motor have a hub consisting of a shoulder and spindle center which pops snugly into the disk center?

If it does not, you are on a hiding to nowhere because the disk must run true not only centered which you seem to have covered, but also precisely on the image plane.

Any flutter of the groundglass surface back and forth across the image plane will make it impossible to get sharp focus. To have any control of this condition, there needs to be a shoulder for the inner face of the disk to rest on.

Best practice in assembling the disk to spindle with glue seems to be to have the motor ready to go, put on the glue, position the motor so the disk will be oriented horizontally, place the disk, then spin the motor for a few minutes until the glue firms.

After the glue sets, add spots later in front of the inner rim to stop the disk from popping off when panning or tilting energetically.

Be prepared for momentary shifts off-focus. Most CD players were never intended to be agile-portable devices.

The motors have end float which in the player is normally controlled by the pressure hub which keeps the CD disk in place.

Many AGUS builders do not re-use the pressure plate. The magnetic field of the motor keeps the disk in place most of the time but when tilted, the shaft will sometimes chatter in end-float when weight of the disk and armature of the motor overcomes the stabilising effect of the magnetic field.

This end-float can be enough to throw the focus off or create interlace artifacts in the camcorder image.
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Old January 2nd, 2005, 09:41 AM   #3
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The toy that came with the motor has a 4 point compass-like object on top with a circular gem in the middle in which a CD can sit perfectly (after the glue). I will upload a picture soon.

>>Use bathroom water-cleanup silicone sealer to glue your disk on. It is strong enough but will peel off non-destructively if you need to reset the disk or change it.

That sounds like a good idea.

>Does your motor have a hub consisting of a shoulder and >spindle center which pops snugly into the disk center?
>If it does not, you are on a hiding to nowhere because the >disk must run true not only centered which you seem to >have covered, but also precisely on the image plane.

As I said it has a circule protrusion that fits the center of the CD perfectly, and a four point support system on the outside which the CD can rest on. Now, I haven't tested it with glue yet to see how it spins, but this is my test before I go and spend $15-20+ on a CD player only to break it open for the motor.

Now, I don't have a 35mm lens yet - but what exactly should I be looking for? I am scouring the flea markets today and hitting the charity shops this week - but I am still unclear exactly what I want from a 35mm lens? Do I want a full pro camera and steal the lens from it?

BYW, Thanks for the info Bob!

I will upload the picture of the device in the next couple of hours which might give you a better idea what I am talking about.
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Old January 2nd, 2005, 04:59 PM   #4
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Ok, here is what the little toy/motor with controller and frosted CD looks like.


http://cameratest.250free.com/
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Old January 2nd, 2005, 05:10 PM   #5
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when i checked this link:

http://cameratest.250free.com/

i cannot see anything - just site info and no pictures, just small icons in all pictures. what's wrong? is it my browser or your host?


filip
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Old January 2nd, 2005, 05:33 PM   #6
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It should work now. I uploaded it again, not sure what happened.
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Old January 2nd, 2005, 05:35 PM   #7
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yes, now is ok. i can see it. thanks


filip
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Old January 2nd, 2005, 05:48 PM   #8
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Thanks for pointing it out for me. What do you think of the motor/CD ? The only thing wrong for me is that it does not have a casing and will need some work to get it to sit in the shell properly. The CD player motor will work better when I get one, but for now, it was a cheap alternative.
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Old January 2nd, 2005, 05:55 PM   #9
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hm,

what can i say - if you ask me...

try to play with it and find best solution you can. expecially try with your toy-unit in proper (vertical) position of CD. this is in my opinion crucial - check the stability and noise level... and read as much as you can in agus35 thread. nothing more :)

filip
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Old January 2nd, 2005, 06:27 PM   #10
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Looks like you've got a good starting prototype! One thing you'll notice is the noise, with that type of motor.

The good thing about a portable CD player motor is you can use replaceable frosted CDs, in the event that one breaks. I was fortunate enough to get a 50 cent one at a thrift store.
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Old January 2nd, 2005, 06:27 PM   #11
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Yes I have read the entire thread - twice! It was alot of reading as well, but I understood it a little better. I am not sure whether I am going with the Agus or the Aldus or the Mini35 design. Just trying to make prototypes to minimize cost right now and see what works best. Most of all - I need to find a cheap 35mm camera!!!
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Old January 2nd, 2005, 10:41 PM   #12
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That's a recent build of an earlier Mabuchi style electric motor, usually in the ballpark of 1.5 to 6 volts and should be more than adequate for an entry level appliance.

The really early motors of 30 years ago sold as hobby motors did not use carbon brushes, but thin brass strips which used to wear through quite rapidly.

The bearings appeared then to consist of plain brass but may now be self-lubing sintered bronze. What the current generation of these motors uses I don't know.

For continuous duty I would suggest staying with 1.5 to 3v no more.

I did not see from the pics the mounting system for the motor. The later Mabuchi style motors used very small screws through the appliance into the front bearing carrier.

To mount yours, if those screwholes are not there, you may need to make a rubber glove out of black foam rubber hotwater pipe insulation, itself rammed into a piece of PVC pipe which can be split to make a clamping piece and glued to a plastic panel or inside of a plastic case.

If the screwholes are there and you use a thin piece of plastic or timber to mount onto, take care not to let the ends of the screws go in too far and touch the armature of the motor inside.

Test by pulling to the front and turning the motor shaft as you screw them in very slowly and gently. If there is any binding at all, add some washers or shorten the screws as the motor will ruin very quickly otherwise.

Your frosted disk should yield adequate light performance but will not be as sharp as an A05 dressed disk.
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