Homemade 35mm Adapter

Chris Hurd · December 19th, 2003, 06:51 PM

Wow, 450 posts! This is the longest thread we've ever had. I've got an idea -- I was thinking about making a copy of this thread and boiling the copy down to the technical essentials, which would make it a little easier to read that way. You'd still have this one to reply to. I can update the copy with important info as it comes up. Let me know what you think,

Agus Casse · December 19th, 2003, 06:51 PM

I have been working in trying to flip up the image, but i still dont have any good results.. btw Paul, your designs wont work, i tried them and they are no good.

Joe Ryan · December 19th, 2003, 07:13 PM

chris, great idea, i've been an interested observer of this thread since day one, and there sure are a lot of the same questions getting asked over and over again.

jim, about 25mm/inch.

agus, i don't think paul was trying to pull a fast one, besides, copywrites (which only cost about $50, btw) aren't given to works in progress, and a patent would cost you about USD 15 000 (at least) if any of us had that laying around, we could just buy a p&s mini35. anyways, looking forward to your commercial version. way to go man.

happy holidays

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

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

Charles King · December 20th, 2003, 03:11 AM

Hey Agus, great shots. Love the look. Can't wait for the commercial one. I'll be your first customer.

BTW, what is the humming sound in the background? Is it coming from the spinning of the CD?

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?

Stewart McDonald · December 20th, 2003, 06:32 AM

Agus, that new footage looks superb. What lenses are you using to get rid of the vignetting?

Helen Bach · December 20th, 2003, 08:53 AM

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.

December 19th, 2003, 06:51 PM	#451
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	Wow, 450 posts! This is the longest thread we've ever had. I've got an idea -- I was thinking about making a copy of this thread and boiling the copy down to the technical essentials, which would make it a little easier to read that way. You'd still have this one to reply to. I can update the copy with important info as it comes up. Let me know what you think, __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

December 19th, 2003, 10:26 PM	#458
Devin Doyle Regular Crew Join Date: Jun 2003 Location: Los Angeles, CA Posts: 188	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! __________________ http://devin.par-t-com.net

December 19th, 2003, 11:00 PM	#459
Fenn Jacob New Boot Join Date: Dec 2003 Location: Thatcher UT Posts: 14	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...

December 19th, 2003, 11:07 PM	#460
J. Clayton Stansberry Major Player Join Date: Sep 2003 Location: Colorado Posts: 316	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 __________________ I understand everything about nothing.

December 20th, 2003, 03:11 AM	#461
Charles King Major Player Join Date: Mar 2003 Location: sweden Posts: 795	Hey Agus, great shots. Love the look. Can't wait for the commercial one. I'll be your first customer. BTW, what is the humming sound in the background? Is it coming from the spinning of the CD? __________________ Charles 'What we perceive to be may not be what we believe to be.'

December 19th, 2003, 06:51 PM	#452
Agus Casse Major Player Join Date: Jul 2003 Location: Guatemala Posts: 322	I have been working in trying to flip up the image, but i still dont have any good results.. btw Paul, your designs wont work, i tried them and they are no good.

December 19th, 2003, 07:13 PM	#453
Joe Ryan Regular Crew Join Date: Oct 2003 Location: Calgary, AB, CANADA Posts: 36	chris, great idea, i've been an interested observer of this thread since day one, and there sure are a lot of the same questions getting asked over and over again. jim, about 25mm/inch. agus, i don't think paul was trying to pull a fast one, besides, copywrites (which only cost about $50, btw) aren't given to works in progress, and a patent would cost you about USD 15 000 (at least) if any of us had that laying around, we could just buy a p&s mini35. anyways, looking forward to your commercial version. way to go man. happy holidays

December 19th, 2003, 10:03 PM	#456
Agus Casse Major Player Join Date: Jul 2003 Location: Guatemala Posts: 322	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.

December 20th, 2003, 03:30 AM	#462
Nathanael Jackson New Boot Join Date: Dec 2003 Location: Wheaton, IL Posts: 7	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?

December 20th, 2003, 06:32 AM	#463
Stewart McDonald Regular Crew Join Date: Feb 2003 Location: UK Posts: 130	Agus, that new footage looks superb. What lenses are you using to get rid of the vignetting?

December 20th, 2003, 08:53 AM	#464
Helen Bach Regular Crew Join Date: Nov 2003 Location: New York, NY Posts: 120	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

December 20th, 2003, 09:47 AM	#465
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,476	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.