December 11th, 2004, 07:15 PM | #1156 |
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one more thing, i'm using a uv filter for the ground glass as many people have. so which direction should the frosted side be facing, towards the 35mm lens or the camera?
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December 17th, 2004, 03:57 PM | #1157 |
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An idea occured to me recently:
Would it be possible to use some form of semi-rigid polyurethane as a GG? What sort of grain structure does this stuff have? As far as I am aware it's grainless. |
December 17th, 2004, 11:13 PM | #1158 |
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Location: Poplarville, MS
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CONDENSERS
Hey guys!
Ok, I've been working on my microcrystalline wax adapter and, although the hotspot isn't as bad as with a glass adapter, I still have vignetting so I want to get some condensers. I've seen references to this before: http://www.surplusshed.com/pages/item/l2119.html Anyone using these? Can I get some user feedback? Also, what about this one here: http://www.surplusshed.com/pages/item/l3136.html They're not expensive, so it's not like I'm taking a risk here, but I would still like to know what sort of quality they are. Thanks! |
December 17th, 2004, 11:49 PM | #1159 |
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Frank I think you would want the aspheric condenser rather than the rectangle. It may end up having some strange anamorphic type squeeze effects otherwise. I could be wrong though - someone please correct me if I am!
On an entirely separate note: Since I seem to be great at coming up with bad ideas for diffuse surfaces to use in place of a ground glass I thought I may as well suggest one more option: Polyethylene film. This stuff is plastic so it's in all practicality grainless, it lets in approx 84% of colored light while blocking out UV! That could provide for an amazing alternative. I'm going to go buy some tomarrow and see if I can't throw something together. Will post results! |
December 18th, 2004, 12:00 AM | #1160 |
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Aaron: Thanks for the quick reply! The plano convex lens looked to be curved on all sides, as opposed to just a cylindrical curve, but I may be wrong.
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December 18th, 2004, 12:15 AM | #1161 |
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Mmm good point. If the lens is square you should be fine. I can't quite tell from the photo. That said I have this unexplicable feeling that a fully round lens would provide less distortion. Don't take that too seriously though. Just a feeling.
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December 18th, 2004, 12:21 AM | #1162 |
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Hrm...you guys are probably right.
Well at those prices I can maybe get two of each type and experiment. :-) Thanks for the feedback! |
December 18th, 2004, 12:24 AM | #1163 |
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If you do let us know which works best.
You might also want to wait and hear others opinions. It might save you some money and frustration. |
December 18th, 2004, 05:25 AM | #1164 |
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Location: cambridge ma
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parts list
http://www.thorlabs.com/ProductDetai...roduct_ID=1481
two of thesehttp://www.thorlabs.com/ProductDetai...roduct_ID=1483 http://www.optosigma.com/miva/mercha...+%26+Apertures you want the 50mm with 70 fl and the 50mm groundglass with 1500 grit http://www.optosigma.com/miva/mercha...herical+Lenses you will be able to mount the plcx directly on the ground glass the threaded retaining rings will allow perfect focal length from the slr lens to the groundglass. |
December 18th, 2004, 09:58 AM | #1165 |
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Rich you rock!! What type of camera do you have, and how do you end up mounting it?
Thanks p.s. Maybe we could start a thread with just parts listed and where to get them? And focus discussion in this thread? It's so hard to wade through all these posts looking for something, and it keeps growing.
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December 18th, 2004, 10:39 AM | #1166 |
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Good info, thanks. But how does the lens mount fix to the Thorlabs tube? Does a C mount screw directly on?
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December 18th, 2004, 11:29 AM | #1167 |
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parts list
I was happy to find when the thorlabs tube came in .that it
is the same as a 52mm camera filter thread so common step up and step down rings will work. the key is the tube. the first one I made was with 52mm filter rings I never was able to get the focal distance from the slr lens to the ground glass perfect or place the plcx directly on the ground glass.I did try the thorlabs groundglass the opto sigma is better. and when you build this dust is your enemy start with the 35mm lens then c mount then tube insert ring at about focal length the ground glass comes dust free adjust threaded ring untill sharp focus don't let your fingers touch the ground glass. gently place plcx on top and thread the ring down with your finger nail if you didn't trap any dust the glass surface will stay clean. one trick I used is to use a poor ground glass attempt to set the focus . then took the pristine ground glass and set it in. |
December 19th, 2004, 02:58 PM | #1168 |
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Thanks again Richard, that's exactly what I'm going to try.
But just to clarify if I may - does the C mount adapter fit directly to the 2" thorlabs tube? Sorry if this is obvious. I'm using Nikon lenses so I want to attach this: http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=77558&is=REG Best |
December 19th, 2004, 10:40 PM | #1169 |
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parts list
this is a link to some pictures of step up rings. http://www.cs.mtu.edu/~shene/DigiCam...ead-rings.html the tube is 52mm you would need a ring 52mm to whatever the thread size is in the adapter . and a second one 52mm to whatever your camera thread is
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December 20th, 2004, 09:08 AM | #1170 |
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Do you have any footage with this setup rich?
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