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-   -   Homemade 35mm -- Edited Copy for Reading (https://www.dvinfo.net/forum/alternative-imaging-methods/18950-homemade-35mm-edited-copy-reading.html)

Peter Sciretta December 18th, 2003 11:24 AM

both of the items have the standard tripod screw... so the shoulder mount is screwed into the telephoto lens mount which is screwed into the video camera.

Peter Sciretta December 18th, 2003 11:29 AM

unfourtunately I do not know the brand for the shoulder mount, but I'm sure someone in another area of this forum could point you to a good cheap one like it... i know varizoom makes some stuff like it...

http://www.varizoom.com/pages/supportindex.php

EDIT: I think I found a model that looks to be the newest model of what I have at:

http://www.studio1productions.com/dvbrace.htm

its 149.99

you may be able to find something cheaper....

Jim Lafferty December 18th, 2003 12:36 PM

Alright...questions for those of you in the know about optics and/or those of you with a GL1 or similar cam that has an Agus35 working:

1) I cannot pull focus with my 35mm lens. I'm talking both alone and with the adapter attached.

Upon investigating -- and here my ignorance of optics will show -- I found that I need to place the lens about 6 inches from the surface of the projection (in this case, my eye) in order for anything to come into focus. Which begs the questions: 1a) how do you shrink the distance between the 35mm lens and the GG, or 1b) am I stuck keeping the lens to a distance of 6in. or greater from the GG? (i.e. making my adapter larger?)

2) Anyone having success with a CD motor/clasp setup at a proper speed? By proper, I mean that I assume these motors have a max speed they're rated for -- with the typical portable CD player runningg off of 2 "AA" batteries (3 volts), I assume hooking one up to a 9 volt battery to be a mistake.

However, running through tests today, I noticed a palpable shimmer in my (as yet focused) imagery that was directly related to the slow RPM of the motor. Hooking it up to a 9v battery cured the problem, but I have doubts as to how long the motor will run in this mode.

- jim

J. Clayton Stansberry December 18th, 2003 02:52 PM

Agus,

I think if you are going to make a commercial product and sell it that way, you need to flip the image. I personally would not want to spend around $1000 for an Agus35 and not have my image correct. Maybe you can offer a cheaper version that doens't flip the image? Give the people a choice!

Clay

P.S. I don't know any good way to do this, but I think it needs to be done. You might just study exactly how SLR cameras flip the image and then find some way to use that???

Bob Hart December 18th, 2003 07:42 PM

To Jim Lafferty:

Could you tell us what 35mm camera lens you're using. If you have to place it so far from the groundglass there's something not right there - unless you are using a projector lens. Some sit off about 6 inches from the film plane.

Just for curiosity sake, take the groundglass out and see if you are getting the same result direct into the camcorder. I have observed in my tests, the camera aquires the aerial image.

To All:

I dismantled the VCR16B lens set and tried that last night. It underscans the 35mm image frame into the VX2000/PD150, by about 15% so it's not a viable option. It is about 7x power, 3x was too small so 5x may be about right.

Paul Doss December 18th, 2003 07:49 PM

Webpage on the subject.
 
Here's a page I put together rather quickly about these adapters and the principals involved. Let me know what you think.

Paul

www.thecountrybulletin.com/dv_dof.htm

Danny Tan December 18th, 2003 08:01 PM

nice page. but i think if you have fresnel lense, then you don't need the magnifier cause they just do the same thing. correct me if im wrong

Paul Doss December 18th, 2003 08:38 PM

Danny <if you have fresnel lense, then you don't need the magnifier cause they just do the same thing. correct me if im wrong>

Things are just getting started on all of this. So I guess you could say that the jury is still out. See the links to the graphics showing the effect on the ground glass by the fresnel. It brightens the edges. The magnification is to allow your camcorder's screen to be filled with the image (24 x 36mm). I'm not trying to build that kind of adapter so I'm not sure. That's just my take on it.

Paul

Jim Lafferty December 18th, 2003 10:47 PM

"To Jim Lafferty:

Could you tell us what 35mm camera lens you're using. If you have to place it so far from the groundglass there's something not right there - unless you are using a projector lens. Some sit off about 6 inches from the film plane."

This is a standard Nikon Nikkor 50mm lens with an aperture of f/1.4. The same effect can be seen from my Pentax 50mm lens with f/1.7. They're both standard lenses fitted for 35mm cameras. Neither of them can get a focused image on my GG which sits about a 1/2 inch from the rear of the lens, and three inches or so from my GL1's macro (which, incidently, can pick up the grain on the GG fine).

- jim

J. Clayton Stansberry December 18th, 2003 10:59 PM

Jim,

I could be wrong, if so forgive me! But, I thought the GG must be closest to the video camera lens, and further from the Camera lens. It may be a whole different can of worms with the GL series. But from what I have seen, the GG needs to be really close (1/4"?) to the video camera. You might try reversing what you have already tried, or have you? Just a thought...

Clay

Dino Reyes December 18th, 2003 11:21 PM

XL1 image flip solution
 
Working towards a solution at reversing the image the Agus35, I had already picked up one of these great gadgets http://www.zgc.com/zgc.nsf/active/6FA3DA5F0C16A24985256B82007B576D a little shock absorber/mic/eye-piece extender. So to right side the image all you have to do is flip the mic/eyepiece arm to the other side of the support T and turn off the evf display. I'm still awaiting a few key pieces to build out my Agus35, I will be on vacation for the next few weeks but I hope to show pics and tests of my mod the early week of january.

D

Robert Knecht Schmidt December 19th, 2003 02:36 AM

I have no plans of my own for building an Agus35 yet and I'm not an expert in optics, but here are my thoughts on the subject just from having read through the thread--

- The name of the game in building one of these should be preservation of light. Additional generations of reflectance/transmittance are going to substantially reduce the amount of light that gets to your CCD.
- To that end, why fool with mirrors to invert the image. This is something best done in post. If you're having a hard time visualizing on the set, put the inversion apparatus outside the camera after the viewscreen/viewfinder.
- Similarly, it's hard to imagine the amount of light reflected from a built-in white screen (as in Paul's diagram on his web site) would be as good as what's being transmitted through a ground glass.
- Someone mentioned using something other than a frosted CD as a ground glass. The nice thing about the CD is that it's already very round. Use anything with a center of mass in a different spot than the center of rotation and your implementation is going to vibrate like the dickens.
- When's the XL2 coming out again?

John Gaspain December 19th, 2003 03:35 AM

<<<-- Originally posted by Danny Tan : nice page. but i think if you have fresnel lense, then you don't need the magnifier cause they just do the same thing. correct me if im wrong -->>>

yea thats wrong.

The Fresnel lens is to even out the light recieved from the 50mm lens, so you dont get a really bright spot in the middle of the GG.

The Magnifier (macro lens) is so you can get your DV camera really close to the GG and be able to focus a clear image on the GG.

------------------------------------------------------------------------------

Please people- read the previous posts, I know 28 pages is daunting but its really not that hard.

Emmanuel Decarpentrie December 19th, 2003 03:46 AM

"- Similarly, it's hard to imagine the amount of light reflected from a built-in white screen (as in Paul's diagram on his web site) would be as good as what's being transmitted through a ground glass."

Indeed: at best, Paul could get a regular 1.0 reflection rate for his screen. Spinning disk implies he can't get any sort of gain for his screen, because gain would make the screen highly directional. "No gain screen" means the light is gonna end up being scattered everywhere, in every direction. So lots of photons are gonna be lost in the process of reflecting the picture.

Furthermore, I just can't see how he could possibly get a correct picture geometry with this setup... The adjusting process must be daunting. Paul must be ending with a very dim and somewhat distorded picture IMHO.

Paul, why don't you take the "KISS" approach (Keep It Simple, Stupid)?

Bob Hart December 19th, 2003 05:52 AM

To: Jim Lafferty.

Jim.

Perhaps we should talk about two distinct functions which happen and call them stage one and stage two.

Stage one is in effect a camera and setup (= AGUS35 system). -- Object>>>lens>>>focal plane |, in this case it's the groundglass.

Stage two is another camera and setup. -- Object, in this case the image on the groundglass>>>relay lens or close-up lens if needed>>> camcorder lens>>>focal plane |, in this case, it's your camcorder's CCD chip.

It sounds to me like your problem is in stage one. You have your 35mm objective lenses too close to your groundglass. The rears of those lenses must be the same distance forward from your groundglass as they would be from the film plane (focal plane) if still installed to the cameras they came off.

This distance will be in the ballpark of about 1 and a half inches or so, not the half-inch of so you are using. To get the exact measurement, grab the camera bodyn dismount any lens you have on it and look for a mark on the top to left of the viewfinder prism enclosure for the Nikon (FM2).

The mark will be an "O" with a line drawn through it. This line corresponds to the focal plane (film plane) of your 35mm camera.

Put a straight-edge (a ruler is fine) across the lens-mount face of the camera so that you can then measure the shortest direct distance from the focal plane to the edge of the straight-edge. That distance is the space which needs to be between the mount face of your objective lens and the groundglass. Once you get that right things should start to look a lot better with a sharp image projecting on the groundglass you can see with your eyeball.

The issue from that point will be stage two, being able to frame and focus sharply upon the image projected onto your groundglass.

Between your camcorder and the rear of the groundglass is where any of the close-up lenses, macros etc talked about here will have to be placed if your camera cannot frame close enough and hold sharp focus on that projected image on the groundglass.

To initially set this part up, forget about trying to project an image onto the groundglass and use a barcode panel off a food packet to see if you can get your camcorder close enough. The barcode will show any distortion of focus defects.

Once you've got that sorted, then you can mate up stages one and two with a lot less grief, knowing each of the stages in themselves are working properly.

This leaves you with the task of rotating your groundglass and putting the whole thing inside a nice looking enclosure. Don't forget to paint the inside with blackboard paint to eliminate internal reflection which may cause a fogging effect.

If your groundglass is not opaque enough, the image into your camcorder will have a hotspot in the centre, most evident when your objective lens on stage one is stopped down.

To all:

Best frosted effect with the plastic CD disk is achieved by finding a flat surface, (sheet of glass on a benchtop) laying on it a piece of dense soft cloth which is not going to scratch the smooth side of your disk, placing face-down on your disk, a sheet of 500 grit silicon carbide (wet and dry) paper, using a short screwdriver handle or similar blunt object with both round and straight edges, then scrubbing away to press the grit against the disk. Do not let the paper scrub across the disk as you want pits, not scratches in your disk. For the broad surface of the disk you can scrub the ridged grips of the handle across the paper. Towards the edge of the disk you will need to use the rounded end of the handle to scrub with as the disk rim is slightly raised and the frosting effect will not reach the edge.

It will take you about 80 minutes of patient work. The job will be done when you cannot see through the disk but a lens will project an image on it.

Cleanliness is next to godliness and most importantly, do not touch the ground surface as finger grease will spoil it and no amount of furthur work will remove that smooth mark. Efforts to clean it will polish the groundglass pattern because the plastic is soft.

Thomas Bruegger December 19th, 2003 07:15 AM

cosmin rotaru says in a early post to agus that he should use a fresnel lens in order to get rid of the hot spot on the GG. Another user posted a link to an american store who sells fresnells, i live in europe and i have not been able to get a fresnel to eliminate the hot spot on my agus35. does anyone know where they're sold in europe? or perhaps another device where they can be taken out?

thanks

Thomas

Daniel Thornton December 19th, 2003 08:09 AM

Use a dove prism to flip the image.

http://www.doveprism.com/

Jim Lafferty December 19th, 2003 01:43 PM

Quote:

I've used a 25 cd spindle box, and a 50mm lens. But when I have the lens focus all the way in, I need the ground glass to be as far from the lens inside the spindle box as it can to focus on anything thats about 2-3 metres away. Anything closer than that and I can't focus.

Any ideas?

Thanks
I experienced something similar, and it's one of the trials of experimentaion. If you look at Agus's design, you'll note that there's an extender between the front of the adapter and the back of his 50mm lens -- bringing the rear of his 50mm lens about a half to three-quarters-inch away from the adapter's surface.

Likewise, his motor is mounted at the front of the adapter, with the spindle facing back toward the DV camera -- with the CD mounted at the tip of the motor's spindle, placed very close to his macro lens.

I did a quick-n-dirty mockup last night with a 9v battery hooked up to an on/off button and my motor and ran tests with the GG within a half-inch of my 50mm lens, and then as far away as I could get it inside of the CD case -- in order to get focus on the GG, your film lens must be placed 3-4 inches away. Maybe slightly more. Experimentation will find your answer.

- jim

Tom Jensen December 19th, 2003 03:31 PM

Jim, about the distance from the lens to the GG
 
I measured my SLR camera from the front of the body where the lens mounts to the film plane, the distance came out 46mm, I adjusted my box so the distance matched to the GG. I still haven't tried any video yet, I haven't made mine light tight yet, too much to do and never enough time!

Tom

Jim Lafferty December 19th, 2003 09:00 PM

Quote:

Has anyone made one of these sucessfully for the gl1? If so which macro filter are you using and what are the distances between the macro filter and the gg and the fresenel lense and the 35mm lense?
I can answer your questions with partial confidence, as I'm about 85% done my GL1 adapter.

The macro power should be +7 or greater -- this allows you to move your camera in close enough to the surface of the GG and still zoom in to avoid vignetting.

I've got probably a half inch between the surface of my Century Optics +7 macro ("achromatic diopter") and the GG. I'm working on having about two inches between the GG and the rear of my 50mm lens.

If you've got a macro, you'll likely not need a fresnel.

However, and this goes back to my comment about partial confidence:

I put together a mock-up of my final adapter design last night and I couldn't pull focus accurately. I'm making an educated guess that this is because of the distance between the 50mm lens and the GG, which I figure was too short. I'm now extending the distance with a rubber ring between the F-mount and the front of the adapter.

Also -- I haven't actually shot anything yet, only looked through the viewfinder while holding my adapter up to the camera. No telling if my guesses, educated or ingorant, will prove to make for a functional adapter.

I will be done tomorrow, and plan to have footage up by Sunday. Check for it at http://ideaspora.net then...

- jim

Robert Knecht Schmidt December 19th, 2003 09:08 PM

I don't know whether anyone has already posted this link to a diagram and explanation of the Agus35 CD + spindle concept.

Quote:

And after we have all this crap put into a box strapped to the camera, we finally have a picture that's more blurry, darker, and harder to focus and zoom. But that's what we want, because it will fool people into thinking you're filming on film instead of video. Isn't photography wonderful?
Not exactly a rave endorsement; nice schematic though. And check out the Fresnel link while you're there.

Agus Casse December 19th, 2003 10:03 PM

here is a new video made with a beta version of the adapter
like you can see.. there is no vigneting.

http://altoque.tv/35mmAdapter/35mmtestBETA.wmv

Now we are working on fliping the image for perfect control and making all the pieces to look pretty and profesional, as well as making a pro rod system and baseplate. as well as a matte box.

Jon Yurek December 19th, 2003 10:11 PM

Quote:

Not exactly a rave endorsement; nice schematic though. And check out the Fresnel link while you're there.
Of course it's not a rave endorsement. The footage still isn't perfect because the device is still in development. But even if it were done like the Mini35, it's still harder to focus, blurry (because the background is in focus), darker (this adapter doesn't create light, you know), and we're doing it to try to make it look more like film.

Of course, I meant that ending line rather tongue-in-cheek anyway (yes, you linked to my website. Thanks. :) ). When I have the time, I want to make one of these adapters myself. And thanks about the schematic. I haven't put the macro lens nor any flipping scheme into it yet. Actually. I'll do that now.

Edit: Wow. Agus, that footage looks amazing. I had some doubts after some of your earlier footage, but that last clip really does look wonderful.

Edit 2: Near the 3:30 mark on that footage and onward, I could start to make out the edge of the hotspot on the edges of the frame. I assume this was because the sun was setting so you didn't have the same light, but how bright was it at the time, and how much light should we expect to have to work with as you have your adapter right now?

Devin Doyle December 19th, 2003 10:26 PM

I promised I wouldn't contribute anymore to this already gigantor thread, but after reading about someone else (Jim Lafferty) building their own mini-50mm for a GL1, I had to post a question!

Ever since the beginning of this thread several weeks ago I was under the impression that the fresnel between the SLR lens and the GG was solely there to focus the image onto the GG - even in my own "beta" version of the mini-50mm the fresnel performed this action. Jim , I noticed you said "If you've got a macro, you'll likely not need a fresnel." I must be missing something here, or maybe your adapter is built a little differently than mine - but I can't see why you wouldn't benefit from having both a fresnel lens to focus your image onto the GG and having a macro to allow you film something up close. Can you shed some light on this? Also...

You said you use a century optics +7 achromatic diopter. If I had the cash to squander, you'd be certain that'd be my "macro" lens of choice. However, I'm a cheap college student on a tight budget. I remember reading that the century achromatic diopters allow for zoom thru to a certain extent. Regular macros don't pull that off as well, correct? So in essence if you fail to get a powerful enough macro lens to get you close enough to the GG to fill the frame and avoid "vignetting," you wouldn't be able to zoom in and pull sharp focus would you? I guess in this case it's better to overkill and get a +10 macro lens - better to be closer than further?

Anyways, Jim I'm very interested in seeing how your set up looks/works as a fellow GL1 owner. Unfortunately my cam is in the shop for a faulty LCD and so I haven't gotten a chance to test things out, so I'm living vicariously through this thread!

Fenn Jacob December 19th, 2003 11:00 PM

Lovely pre-sanded GG (from CD spindle)
 
I have followed this thread from the beginning, and was thrilled to rush into buliding mine. I collected all the materials, except lens, and was worried to find that I could not locate a clear CD. All of the ones I had were already frosted. I went through about 5 or 6 of them until I finally found a clear one, I was quite relieved. I should have just tried the frosted to see if it would work, now I'm glad to see that they are preferred. (I hope I didn't throw those frosted ones away...) As far as where to get them from I'm not sure. I know that most of them came from 100 pack spindles, gotten for free after rebate (boy was that a hassle) on the day after Thanksgiving. I don't know if its a feature of the higher count spindles or what. The Discs are old ones, so I'm not certain, but I think there is a decent chance they came from KHypermedia or Memorex. I'm not sure on this, but if your desperately against grinding the CD yourself, it could give you a start.

I am loving this thread! This is the funnest little project to work on, and impress your friends with. My following of this post here has been kind of sparratic, I just got to previewing Aguss's newest beta posting. BEAUTIFUL! I'm about 90% done on mine, 90% as far as consturuction goes. I think I'll have a lot of tweaking to do, so maybe only 30% as far as complete finalization. I've got to run to the local pawn shop and see if I can't find me a 35 mm now...

J. Clayton Stansberry December 19th, 2003 11:07 PM

Chris,

Please, please, please extract pertinent information and post to an Agus35 information thread. I think that would help us all! It would definite help me, because I can't find anything when I need it...

...on that note...I have completed stage one and wanted to offer what I have done and ask a question.

For connecting the box to the camera, I bought a UV filter, drilled a hole that size and super-glued it in. That way, you just screw the box onto the camera (just make sure you have it so when screwed all the way on it is straight! I didn't...learn from my mistake!) Also, you can then screw the macro right into the front of the filter due to their similar thread size! I have been using super-glue with good results...I got hot glue and super glue and decided to use super glue. It has worked great so far. The lens cap that goes on the back was used for the front to connect the lens. Thank you to whomever posted about that idea!

I have recorded footage without the fresnel lens (by the way, thanks Ryan for confirming that the fresnel lens is the same as a reading magnifier...I bought one in hopes that it was) or the spinning glass and it just seems to be darker. I haven't tried it in the day yet or on close ups. I also didn't notice a huge difference in the DOF as compared to footage without the Agus35 on. I hope (and know someone has stated it before, am too busy to read through 450 posts - another reason Chris!) that someone can tell me that the GG and fresnel will give me the DOF Agus is getting??? Please tell me this is what is missing for the DOF! If so, that's what tomorrow will be...a quest for DOF. Sorry for the long post. Thanks in advance from my fellow Agus35er's.

Clay

Nathanael Jackson December 20th, 2003 03:30 AM

Hey, I've been following this thread and im scheming out my own little project...

We're mostly all using 35mm SLR lenses right? There should then be no need to put a fresnel in between that lens and the GG, as long as the GG is the same distance away as the film plane for that lens (there was a post on this maybe two or three pages back). If anything, I would think the fresnel would be just like the macro lens (but cheaper)...

Im not sure if I missed something, but what is the order of elements in your device, Agus? Seems like you've got the vignetting problem mostly solved. Does any vingetting become visible when the 35mm lens is stopped down, or filming in low light?

Another thing... Im worried that the box and the relatively heavy lens will pull down slightly, warping the image. Or the whole thing move as I'm filming...
Is there any place I can go to find out how to make a rail mount system, or where I can find specs/dementions of the real ones?

Helen Bach December 20th, 2003 08:53 AM

Flange Focal Distance / Depth / Length; Support Rods
 
Here is a link that gives FFDs for various lens mounts.
http://www.gregssandbox.com/gtech/filmfacts/flange.htm
There are also tables in the likes of the American Cinematographer's Manual and David Samuelson's Hands On manual - but these are biased towards movie camera mounts.

The FFD is the distance between the mating surface of the body/lens (not the bayonet lugs, screw thread or whatever) and the image plane.

One inch is 25.40 mm.

If your lens isn't there do a search: just use 'flange focal minolta' or whatever because of the various names used for this.

If you want an upscale alternative to using a rear lens cap as your mount, look around for second-hand bellows adaptors. These are the mounts made for using lenses on bellows for close-up work. Try http://www.srbfilm.co.uk/ They also make custom parts very cheaply compared to movie industry places. They export.

Standard 'lightweight' Arri support rods (also used by everyone else for DV cameras) are 15 mm diameter, 60 mm centre to centre. These dimensions have to be very accurate for some standard equipment to fit. The rod axis is 85 mm vertically below the lens axis and the rods are equidistant from the lens axis (at least they are on my Petroff matte box). Some adjustment is usually possible for the exact lens axis / rod axis alignment. Plenty of people offer rod adapters as standard items. They aren't terribly expensive even when custom made.

Best,
Helen

Bob Hart December 20th, 2003 09:47 AM

To Chris: The condensing of the thread. Good idea. Soon enough we will be beginning to see thread deja-vu otherwise.

To All: A useless and unproductive curiosity question?

Has anyone added controlled lighting onto the groundglass to achieve an effect similar to that of pre-fogging motion film. It might be interesting in situations where the contrast exceeds the workable range of the DV camera. It might be interesting creatively if different colours were used, even more so if a known colour temperature offset was used and the lighting then adjusted back in post., ie., an effect perhaps similar to using an 81EF filter at sundown with tungsten balanced film.

Jim Lafferty December 20th, 2003 10:19 AM

Quote:

I must be missing something here, or maybe your adapter is built a little differently than mine - but I can't see why you wouldn't benefit from having both a fresnel lens to focus your image onto the GG and having a macro to allow you film something up close. Can you shed some light on this?
Devin,

Well, maybe you're right -- I thought I'd read something in one of the earlier posts where Agus discarded his fresnel after installing the macro. Now I see, going over the old threads that this wasn't necessarily the case. My mistake, sorry. And so I have to ask -- is everyone using a fresnel and are they helpful?

Agus -- is the fresnel in your latest version of the adapter?

Quote:

So in essence if you fail to get a powerful enough macro lens to get you close enough to the GG to fill the frame and avoid "vignetting," you wouldn't be able to zoom in and pull sharp focus would you? I guess in this case it's better to overkill and get a +10 macro lens - better to be closer than further?
I think this is all correct. I'd go with a more powerful macro either way you slice it.

I'll definitely keep you posted,

- jim

Filip Kovcin December 20th, 2003 11:40 AM

frosted cd - chemical method?
 
hello there,

as far as i can see - there is no info about manufacturer of frosted fake cds.
i have suggestion that anyone who knows the manufacturer who is definitelly NOT producing frosted/sanded CDs - to put it on the list, so we will be closer to that real one.

second thougt - does anyone knows how to make CD frosted with some chemicals? maybe this is much simpler than making it "mechanically"

filip

Jim Lafferty December 20th, 2003 12:00 PM

Just picked up a cheap fresnel and it doesn't help me -- at least, not yet.

I'm convinced my focusing problems are a flange focal length issue, but I've yet to find the proper distance between my lens and the focal plane (the GG). It's better, but still not acceptable.

When/if all else fails -- is a longer distance between the lens and the focal plane the best solution?

Incidently, I've got a Nikon Nikkor 50mm f/1.4 lens, part # 3958069. If anyone has the info that Google doesn't seem to turn up for me, I'd love to know...


edit: Helen -- the link you posted was down when I first clicked on it -- the link now works and I see that the distance for a Nikon SLR lens is 1.83 inches. Thank you for the info!!

- jim

Louis Feng December 20th, 2003 12:31 PM

The focal plane for the 50mm lens are 50mm away from the lens. That's the distance from the middle of the mirror to the focal point. On the lens it usually says something like f=50mm. If it doesn't say that, I would assume that because it's very common. If you measure the thickness of the camera, it gives a good approximation of where your GG should be.

J. Clayton Stansberry December 20th, 2003 05:18 PM

Anyone find out where the pre-frosted CD's come from? So far from the thread this is what I have:

CD Packs that do not offer Frosted CD's:
Imitation
Fugifilm
Philips
100 pack $20 at Best Buy

Possibly have it:
Khypermedia
Memorex

Please let us know and add to the list so we can find out which pack it is...and then run out and buy their stock because you know they will be selling a hell of a lot of them!

Agus,
That beta footage is awesome! Do you have any recent pics of your new design so we can start drooling for the commercial version? Thanks.

Bob Hart December 20th, 2003 09:45 PM

Chemical means of achieving frosted surface on disk!!

Those chemicals might be a little dangerous.
There may be some solutions but it would be irresponsible to post them here.

It could render me and the host of this service possibly liable for suit should tiny vexations like chronic dermatitis, blindness, chronic obstructive airway disorder and death emerge as collatoral consequences.

This is one area I would commend anyone not qualified to avoid like the plague. If you don't know it or can't do it, don't try. Chemicals are very socially enlightened. They don't discriminate. They just drop everybody. Seek help from somebody who has accreditation in this very specialised industry.

So you are going to go for it anyway. Whatever chemical you choose to experiment with, be extremely careful, avoid the vapors and don't leave the stuff lying around for little bro or sis to encounter. And for heaven's sake read the Hazmat notes, know what to do beforehand if it all goes wrong. Devise your personal or household counter-disaster plan if you have not already.

I don't think you will achieve by chemical means, anything you can't do with a lot less risk or hassle with graded silicon carbide grit or wet and dry silicon carbide grit papers or jobbing the task out to somebody who can gritblast with graded grits. That final 5% to perfection everybody looks for might only be achieved by experienced practitioners of specialised crafts.

The frosted CD disks people have been mentioning here?? Are they "frosted" right through the thickness of the disk or only on one surface??

If the "frosted" feature goes right through the full thickness of the disk, you will likely get inferior resolution, a halation effect into neighbouring image from pinpoint highlights and lower light transmission.

If the disk is only lightly translucent, your camcorder is going to also see through it into the front lens and you will get a hotspot in the centre of your recovered image.

There were two versions of the small "Pringles Chips" container press-on caps. One cap which originated from Belgium was a clear plastic with a frosted finish applied to one surface. These containers made excellent pinhole cameras for kids. The US cap was made of a translucent plastic which did not work as an image plane.

J. Clayton Stansberry December 20th, 2003 10:02 PM

Another solution might be to do what they do to make ground glass. It may also work on the clear CD's...just another thought...

Check out this website:
http://www.phototechmag.com/previous...kas/dokas.html

I am sure there are others, but may be another option.

Bob,

Agus has stated, after using the frosted CDs, that his resolution increased and there weren't any problems. In fact, by his latest footage, I would say he pretty much got it right! Don't know about where it is frosted as I can't seem to find one of these bloody things:( Will let you know if I can ever find one.

Paul Doss December 20th, 2003 10:59 PM

Agus Casse <btw Paul, your designs wont work, i tried them and they are no good.>

You are absolutely right! The one or two mirror versions do flip the image vertically but not horizontally. Back to the drawing board. Looks like the only way is to copy the SLR in as far as the light path through the viewfinder.

Paul

Don Berube December 20th, 2003 11:06 PM

For what it is worth - In the past, I have had clear pieces of glass turned into frosted pieces very nicely via sandblasting. I didn't do the sandblasting though, it was done by an ordinary local glass & window service company. The pieces were very consistent with each other and it only took the shop an hour to perform the job.

- don

Randy Reyes December 21st, 2003 03:33 AM

I have one frosted CD that came in a spindle but I forgot which brand it came i in. It could be Maxell or Primaris. They are definitely not from Fujifilm... :]

http://www.imagestation.com/picture/...e/fa3e9a51.jpg

http://www.imagestation.com/picture/...b/fa3e9a4e.jpg

http://www.imagestation.com/picture/...0/fa3e9a54.jpg

Jim Lafferty December 21st, 2003 12:10 PM

Well, I got 'er functional today -- she's not pretty yet, and without a rail system in place the image shakes a bit much (going in and out of focus with it.) But, what can I say, I'm proud:

http://ideaspora.net/agus35/agustest.mov

(12.8mb Quicktime 6)

- jim


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