Mini35 Oscillating Ground Glass Idea

[Les Dit]

The hardest, most critical part, is the part that generates the motion, and how that interfaces with the GG mounting platform.
That's where the focal plane stability is determined.
Thor labs does not have those elements, unfortunately.

The GG used is not very critical. The voodoo recipes for making your own GG aren't needed, because the motion removes the grain even if the GG has minor defects.

I am preparing a simple web page for those interested in my assembly, it will include more info and a picture of my first 3 shaft prototype that I used for the high def video I posted a while ago.
I'm going to ask for a small deposit of Paypal $30/person to go ahead with the project, I don't want to invest a lot of time and parts on this and get burned with no real buyers. Before full payment, I will post a video shot with the mechanism to make sure it's good enough for the people interested. Stay tuned!

-Les

[Dogus Aslan]

hi les i am also interested in ur mini35... i would be happy if you sent me info to dosealas at tumgorsel.com...

[Richard Mellor]

the last part of the cage system will be the addition of right angle lenses. to solve the upside down image problem . this is the system used to flip the image in the $10,000 mini 35 .
http://www.thorlabs.com/NewGroupPage...ctGroup_ID=142

[Joel Aaron]

<<<-- Originally posted by Richard Mellor : the basic design is around this system . I have not recived all the parts yet. -->>>

Thanks. Looks like you're onto a good set of parts there. My rails were too wimpy. Hopefully those will keep everything rock steady.

Keep us posted! It's encouraging to see the good progress.

[Jonny Dee]

Does anyone know where to find a cheap spanner wrench? Or know a good alternative? Looks like we'll be needing one.
www.thorlabs.com/ProductDetail.cfm?&DID=6&ObjectGroup_ID=58&Product_ID=15637

Jon

[Richard Mellor]

hi jonny this is not a spanner wrench but it has worked for me putting in filter rings. it opens and the blades fit the filter rings .
will only work only about 3/4 inch deep . but great to have anyway.

http://www.surplusshed.com/pages/item/m1612d.html

[Jim Lafferty]

Did a little research and for those of you building this adapter for your GL1/GL2 you may find this info helpful:

Interior diameter of the 2" lens tubing from Thorlabs is 50.08mm, so 50mm UV filters (whether ground or with microwax) should be ideal.

I'm unsure but proceeding in ordering and testing the theory that I can run a 58mm to 49mm step-down ring from the front of my Century Optics achromatic diopter at the front of the GL1. My hope is that, given that 49mm is the closest standard diameter to the 2" tubing, my adapter will flow like this:

1) +7 CE Achromat
2) 58mm to 49mm step-down ring
3) 2" external thread coupler joining the step-down ring to the 2" dia. tubing
4) 3" deep, 2" diameter tubing, with an extra retainer ring and two 49mm UV filters with microwax sandwiched between them inside
5) Adjustable focusing element (to set proper FFL)
6) F-to-C mount adapter (B&H is currently out of stock)
7) Nikon F-series lens (f/1.4 or faster, used)

The entire rig will be held in place with this device which I've purchased and am very pleased with.

For those of you going the Thorlabs way, how do you intend to keep the focusing element in place once proper FFL is set? What's your rigging secret for that? :D

Thanks to everyone for the Thorlabs info, BTW -- the end product will be greatly enhanced by their stuff.

- jim

[Richard Mellor]

Hi jim this is a picture of a static adapter I made with lens tubes. the plcx will be replaced with a circular plcx.I think all that would be needed is camera lens to c-mount to tube then insert retaing ring ground glass next adjust retaing ring untill correct focal length then plcx and then
retaing ring the problem with the filter tube version was I could not get the focal length perfect . not enough adjustment in retaing ring, and the plcx would not fit directly on the ground glass .


http://www.dvinfo.net/media/mellor/aldu-test-44.jpg

[Jim Lafferty]

the problem with the filter tube version was I could not get the focal length perfect . not enough adjustment in retaing ring, and the plcx would not fit directly on the ground glass .

Richard,

I can't get your link to show an image, unfortunately.

WRT to the focal length problem, my thoughts are that I will use the retainer rings to place the GG inside the tube at an appropriate distance from the achromat at the front of my camera, and also from the rear of my 35mm lens. Then, using the adjustable focus element from Thor, adjust flange focal length.

For the moment, I've got my GG sitting inside PVC coupling measuring about 3" deep, with the GG about 1 inch from the front (where the 35mm lens goes), 2" from the back (where the achromat is inserted.) I've manually adjusted ffl simply by moving my 35mm lens element forward or back, eyeballing for the sweet spot. I bet the adjustable focal element will make this task that much more precise, but the problem then becomes -- how do I keep it from moving once it's in the right place? Attaching a slip ring to the adjustable segment isn't the answer -- it will always be able to move in one direction. I guess I've got to build something special...

- jim

[Brett Erskine]

"For those of you going the Thorlabs way, how do you intend to keep the focusing element in place once proper FFL is set? What's your rigging secret for that?"

I checked out the lens support you want to use...If you decide to switch to traditional rail system instead you could solve the above problem the same way they support long telephotos in film. Simply tighting down on the hardware that goes between the rails and the lens itself. Heres a picture of one system: http://www.members.optusnet.com.au/mike.k/jpg/lens_2.jpg

[Richard Mellor]

hi everyone I just fixed the link. as you can see in the picture just thread retainer ring and ground glass untill you get sharp focus, then plcx on top and retaining ring.

I am going to try and build a rail system from these parts too this is what 1 of the parts might look like.

http://www.thorlabs.com/ProductDetai...oduct_ID=26353


this is a still from the static adapter made with filter tube . can,t get sharp focus.

http://www.dvinfo.net/media/mellor/PDVD_540.BMP

[Jonny Dee]

Jim,
I looks to me like the outside of the SM2V10 is threaded, so that when you tighten the included locknut down against the static part it will secure itself. Maybe I'm seeing the tech drawings wrong. I do think the combination of those two parts will be a great setup.

On another note: I own a DVX100A and am wondering whether a 72-49mm stepdown setup would be unheard of. My concern is that it will it cause vignetting? Looking at James Webb's set up below, he goes from 72-55 with little or no vignetting, but is 49 pushing it?

www.enormousapparatus.com/images/StaticAdapter_JWebb_03.jpg

Thanks everyone for your help
Jon

[Richard Mellor]

funny if you look real close at the overpriced arri system in bretts photo . you will see this part in the sale dept at thorlabs.

http://www.thorlabs.com/ProductDetai...oduct_ID=27061


I guess this and a few other parts and you have a rail system.

http://www.thorlabs.com/ProductDetai...oduct_ID=26756


I found this one it's more money but it is as long as a key board.

http://www.thorlabs.com/ProductDetai...oduct_ID=31705

[Jim Lafferty]

On another note: I own a DVX100A and am wondering whether a 72-49mm stepdown setup would be unheard of.

You'd have to step down in two stages. 62mm to 49mm is the biggest leap, I believe, so find yourself a 72 to 62 and you're set.

I looks to me like the outside of the SM2V10 is threaded, so that when you tighten the included locknut down against the static part it will secure itself.

Indeed it does -- thanks for the eye-opener!

- jim

[Richard Mellor]

I think the distance from the c-mount to ground glass is just around 1 1/2 inches to focal point . it may be just right to fit between c-mount and ground glass. this would be a dream to get super sharp focus on the ground glass. this may be all that's needed to make a static adapter . I am not going to buy it because it won't work in my ocillating adapter.I think the front will be 1 inch tube. in side cage plate. and make the focal adjustment from there.

http://www.thorlabs.com/ProductDetai...roduct_ID=1486