Mini35 Oscillating Ground Glass Idea

Giroud Francois · August 2nd, 2004, 05:53 AM

0.001... laser...
you start to understand now why these gadget cost the hell to build. I think we reach the point were the usual workbench in the garage is not more of any use.
try some small springs to keep all the stuff in place.

Valeriu Campan · August 2nd, 2004, 06:22 AM

<<<-- Originally posted by Giroud Francois : 0.001... laser...
you start to understand now why these gadget cost the hell to build. -->>>

Giroud,
A laser pointer can be purchased from gift shops or night market stalls for ~3-5 dollars or for less euros. They come in various flavors, even as keyrings.

Giroud Francois · August 2nd, 2004, 10:37 AM

... and i already got so many of them.
They are fine to kick the cat, but i doubt they can be of any use
for chasing the .0001 inch.
When you start to deal with real fine mechanics (i used to deal with micron when i was in tool machining), you need some serious tools.

Les Dit · August 2nd, 2004, 11:10 AM

The laser idea is good. Just looking at a distant object using the GG shiny side does the same thing, really, but the laser would make it easy to actually measure the thing.
Springs: I am already taking the bearing lash out by using a pair of magnets and steel disks.
I don't think I need 0.0001 tolerance. Just a bit better than what I have now.

-Les

Richard Mellor · August 4th, 2004, 08:28 AM

hi everyone I just recived a piece of 5x9 ground glass from ebay seller .It looks real good. he has quite a few pieces. my winning bid was about ten dollars. I tried to have a circle cut once ,it has to be perfect. but maybe this could be of use. please let's share this.

http://cgi.ebay.com/ws/eBayISAPI.dll...830724092&rd=1

Les Dit · August 7th, 2004, 03:57 AM

I now have my GG orbiter working. I redid the shafts and made them longer. There is no noticeable image vibration or shift, and it looks like it holds HD focus now. My GG has some rather gross pits in it when viewed static, but those look like they are gone when it's moving. I have no corrective optics to minimize the center hot spot, and I flip the image in the computer.

This weekend I will post a link to some video which I'll shoot on Sat.

-Les

Brett Erskine · August 7th, 2004, 06:38 PM

Les-
Whats the target size your actually focusing on?
It should be 36mm X 24mm but without corrective optics you might have to zoom in farther than that.

Les Dit · August 8th, 2004, 12:27 AM

OK, my first test footage is up. Media9 and Mpeg2, both the same test. See the new thread:
http://www.dvinfo.net/conf/showthrea...863#post209863

-Les

Martin Lindstedt · August 26th, 2004, 03:48 PM

Heey!!

I'm preparing to give this oscillating adapter a try, but I'm unsure if it's possible to oscillate my GG condenser, since it might be too heavy..

.. but let's say I get around this somehow ( a more powerful motor ? ), do you think I would see some wierd optical distortion because I'm oscillating my last condenser? .. I'm thinking it will scatter the incoming light all over the place .. resulting in a hotspot .. but I'm just guessing! .. anyone know for sure?

Brett Erskine · August 26th, 2004, 04:34 PM

Martin-
Yes it will. Dont do it.

Martin Lindstedt · August 26th, 2004, 04:50 PM

alright, brett, thanks for clearing that up!

by the way, do you have any footage with your orbiter in action ? I'm very curious!

Brett Erskine · August 26th, 2004, 05:19 PM

I've been too busy to work on it lately. Trust me as soon as its done I'll post it for you guys.

About vibrating the condenser dont do it for all the reasons you mentioned. The way to do it is make the GG and the Condenser two seperate pieces and rotate the GG only. This will solve all of your problems. This is also how the Mini35 works.

Brandt Wilson · August 30th, 2004, 01:49 PM

How have you guys been working out how much mass to be offset for the counterbalances? What are you basing these calculations on? As small as they seem to be, it seems too easy to over compensate and cause instability and vibration.

Les Dit · August 31st, 2004, 11:27 AM

I just guessed on my first pass. I could see calculating the correct amount, but there are other things I would redesign before I make a new version.
The vibration I had on my first test, which I posted a while ago, is reduced when it is mounted in a more secure manner.
-Les

<<<-- Originally posted by Brandt Wilson : How have you guys been working out how much mass to be offset for the counterbalances? What are you basing these calculations on? As small as they seem to be, it seems too easy to over compensate and cause instability and vibration. -->>>

Ray Zschau · August 31st, 2004, 05:20 PM

Is it possible to mount the motor on the same stationary plate as the three other bearing/shaft/counterweight assemblies? Sort of taking the place of one of the corners in the 4 shaft design. One possible problem is that the motor may get in the way of some of the optical components. You could always make the spacing between shafts a bit larger, but because of the larger overall design, that may defeat the purpose of having all of the stationary components on a single plate. I'm also assuming that the motor would have to have an offset shaft, or be fit into some sort of pin which would offset things appropriately so that the motor wouldn't get beat up. P+S probably went through all of the variations that have been talked about in this thread, and ended up with the one they're using because it seems to be the most efficient and stable design.

Les, your footage looks really nice. Especially under the conditions which the assembly was mounted. Are you using a condenser in that shot, or are you just shooting through your GG and primary lens?

August 4th, 2004, 08:28 AM	#140
Richard Mellor Major Player Join Date: Nov 2003 Location: cambridge ma Posts: 247	ground glass hi everyone I just recived a piece of 5x9 ground glass from ebay seller .It looks real good. he has quite a few pieces. my winning bid was about ten dollars. I tried to have a circle cut once ,it has to be perfect. but maybe this could be of use. please let's share this. http://cgi.ebay.com/ws/eBayISAPI.dll...830724092&rd=1

August 8th, 2004, 12:27 AM	#143
Les Dit Major Player Join Date: Oct 2003 Location: Southern Cal-ee-for-Ni-ya Posts: 608	here is my first test. OK, my first test footage is up. Media9 and Mpeg2, both the same test. See the new thread: http://www.dvinfo.net/conf/showthrea...863#post209863 -Les

August 30th, 2004, 01:49 PM	#148
Brandt Wilson Major Player Join Date: Jan 2003 Location: Portland, OR Posts: 220	Counterbalances How have you guys been working out how much mass to be offset for the counterbalances? What are you basing these calculations on? As small as they seem to be, it seems too easy to over compensate and cause instability and vibration.

August 31st, 2004, 11:27 AM	#149
Les Dit Major Player Join Date: Oct 2003 Location: Southern Cal-ee-for-Ni-ya Posts: 608	Re: Counterbalances I just guessed on my first pass. I could see calculating the correct amount, but there are other things I would redesign before I make a new version. The vibration I had on my first test, which I posted a while ago, is reduced when it is mounted in a more secure manner. -Les <<<-- Originally posted by Brandt Wilson : How have you guys been working out how much mass to be offset for the counterbalances? What are you basing these calculations on? As small as they seem to be, it seems too easy to over compensate and cause instability and vibration. -->>>

August 2nd, 2004, 05:53 AM	#136
Giroud Francois Inner Circle Join Date: Feb 2004 Location: switzerland Posts: 2,133	0.001... laser... you start to understand now why these gadget cost the hell to build. I think we reach the point were the usual workbench in the garage is not more of any use. try some small springs to keep all the stuff in place.

August 2nd, 2004, 06:22 AM	#137
Valeriu Campan Major Player Join Date: Mar 2004 Location: Melbourne, Australia Posts: 223	<<<-- Originally posted by Giroud Francois : 0.001... laser... you start to understand now why these gadget cost the hell to build. -->>> Giroud, A laser pointer can be purchased from gift shops or night market stalls for ~3-5 dollars or for less euros. They come in various flavors, even as keyrings.

August 2nd, 2004, 10:37 AM	#138
Giroud Francois Inner Circle Join Date: Feb 2004 Location: switzerland Posts: 2,133	... and i already got so many of them. They are fine to kick the cat, but i doubt they can be of any use for chasing the .0001 inch. When you start to deal with real fine mechanics (i used to deal with micron when i was in tool machining), you need some serious tools.

August 2nd, 2004, 11:10 AM	#139
Les Dit Major Player Join Date: Oct 2003 Location: Southern Cal-ee-for-Ni-ya Posts: 608	The laser idea is good. Just looking at a distant object using the GG shiny side does the same thing, really, but the laser would make it easy to actually measure the thing. Springs: I am already taking the bearing lash out by using a pair of magnets and steel disks. I don't think I need 0.0001 tolerance. Just a bit better than what I have now. -Les

August 7th, 2004, 03:57 AM	#141
Les Dit Major Player Join Date: Oct 2003 Location: Southern Cal-ee-for-Ni-ya Posts: 608	I now have my GG orbiter working. I redid the shafts and made them longer. There is no noticeable image vibration or shift, and it looks like it holds HD focus now. My GG has some rather gross pits in it when viewed static, but those look like they are gone when it's moving. I have no corrective optics to minimize the center hot spot, and I flip the image in the computer. This weekend I will post a link to some video which I'll shoot on Sat. -Les

August 7th, 2004, 06:38 PM	#142
Brett Erskine Major Player Join Date: Dec 2003 Location: Anaheim, CA Posts: 445	Les- Whats the target size your actually focusing on? It should be 36mm X 24mm but without corrective optics you might have to zoom in farther than that.

August 26th, 2004, 03:48 PM	#144
Martin Lindstedt Regular Crew Join Date: Jul 2004 Location: Malmö, Sweden Posts: 25	Heey!! I'm preparing to give this oscillating adapter a try, but I'm unsure if it's possible to oscillate my GG condenser, since it might be too heavy.. .. but let's say I get around this somehow ( a more powerful motor ? ), do you think I would see some wierd optical distortion because I'm oscillating my last condenser? .. I'm thinking it will scatter the incoming light all over the place .. resulting in a hotspot .. but I'm just guessing! .. anyone know for sure?

August 26th, 2004, 04:34 PM	#145
Brett Erskine Major Player Join Date: Dec 2003 Location: Anaheim, CA Posts: 445	Martin- Yes it will. Dont do it.

August 26th, 2004, 04:50 PM	#146
Martin Lindstedt Regular Crew Join Date: Jul 2004 Location: Malmö, Sweden Posts: 25	alright, brett, thanks for clearing that up! by the way, do you have any footage with your orbiter in action ? I'm very curious!

August 26th, 2004, 05:19 PM	#147
Brett Erskine Major Player Join Date: Dec 2003 Location: Anaheim, CA Posts: 445	I've been too busy to work on it lately. Trust me as soon as its done I'll post it for you guys. About vibrating the condenser dont do it for all the reasons you mentioned. The way to do it is make the GG and the Condenser two seperate pieces and rotate the GG only. This will solve all of your problems. This is also how the Mini35 works.

August 31st, 2004, 05:20 PM	#150
Ray Zschau New Boot Join Date: Apr 2004 Posts: 6	Is it possible to mount the motor on the same stationary plate as the three other bearing/shaft/counterweight assemblies? Sort of taking the place of one of the corners in the 4 shaft design. One possible problem is that the motor may get in the way of some of the optical components. You could always make the spacing between shafts a bit larger, but because of the larger overall design, that may defeat the purpose of having all of the stationary components on a single plate. I'm also assuming that the motor would have to have an offset shaft, or be fit into some sort of pin which would offset things appropriately so that the motor wouldn't get beat up. P+S probably went through all of the variations that have been talked about in this thread, and ended up with the one they're using because it seems to be the most efficient and stable design. Les, your footage looks really nice. Especially under the conditions which the assembly was mounted. Are you using a condenser in that shot, or are you just shooting through your GG and primary lens?