Homemade 35mm Adapter

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

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

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

Agus Casse · December 19th, 2003, 12:56 AM

Hey there, i just read the webpage from Paul, and let me tell you that i was really disapointed when i saw the diagram of the design and below it says "copywrite paul E. Doss, JR"... dont get me wrong, but it is too sad that all the work to make this adapter for free now seens to be created by some one else with no credit at all in the webpage.

the basic design was really hard to adchieve... or if you dont believe me read the from the begining of this thread... well, maybe now its not my design anymore cause i let it go for everybody, but for that reason, if it is not mine, it cant be from anyone... but for all...

Aykut Ozen · December 19th, 2003, 01:38 AM

i think you should credit/mentioned agus casse's name there dude...he sparkled this idea and he helped people to build this thing...

Agus you should better go get the Real copyrights of that thing soon man!

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)?

Robert Knecht Schmidt · December 19th, 2003, 04:42 AM

I always thought it was, "Keep It Simple, Stupid!"

Emmanuel Decarpentrie · December 19th, 2003, 05:01 AM

"I always thought it was, "Keep It Simple, Stupid!"

Ooops! Thanks for pointing that out Robert! : )

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.

December 18th, 2003, 07:49 PM	#422
Paul Doss Regular Crew Join Date: Feb 2002 Location: Gulf Shores, Alabama Posts: 57	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

December 18th, 2003, 10:47 PM	#425
Jim Lafferty Major Player Join Date: Dec 2003 Location: Brooklyn, NY Posts: 636	"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 __________________ Realism, anyway, is never exactly the same as reality, and in the cinema it is of necessity faked. -- J-L G

December 18th, 2003, 10:59 PM	#426
J. Clayton Stansberry Major Player Join Date: Sep 2003 Location: Colorado Posts: 316	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 __________________ I understand everything about nothing.

December 18th, 2003, 11:21 PM	#427
Dino Reyes Regular Crew Join Date: Dec 2003 Location: brooklyn Posts: 66	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

December 19th, 2003, 01:38 AM	#429
Aykut Ozen Regular Crew Join Date: Dec 2003 Location: Seattle,wa Posts: 39	hmm i think you should credit/mentioned agus casse's name there dude...he sparkled this idea and he helped people to build this thing... Agus you should better go get the Real copyrights of that thing soon man!

December 18th, 2003, 07:42 PM	#421
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	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.

December 18th, 2003, 08:01 PM	#423
Danny Tan Regular Crew Join Date: Dec 2003 Location: Rowland Heights, CA Posts: 62	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

December 18th, 2003, 08:38 PM	#424
Paul Doss Regular Crew Join Date: Feb 2002 Location: Gulf Shores, Alabama Posts: 57	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

December 19th, 2003, 12:56 AM	#428
Agus Casse Major Player Join Date: Jul 2003 Location: Guatemala Posts: 322	Hey there, i just read the webpage from Paul, and let me tell you that i was really disapointed when i saw the diagram of the design and below it says "copywrite paul E. Doss, JR"... dont get me wrong, but it is too sad that all the work to make this adapter for free now seens to be created by some one else with no credit at all in the webpage. the basic design was really hard to adchieve... or if you dont believe me read the from the begining of this thread... well, maybe now its not my design anymore cause i let it go for everybody, but for that reason, if it is not mine, it cant be from anyone... but for all...

December 19th, 2003, 02:36 AM	#430
Robert Knecht Schmidt Wrangler Join Date: Feb 2002 Location: Cleveland, Ohio Posts: 1,933	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? __________________ All the best, Robert K S Search DVinfo.net for quick answers \| The best in the business: DVinfo.net sponsors

December 19th, 2003, 03:35 AM	#431
John Gaspain Major Player Join Date: Oct 2003 Location: WA-USA Posts: 371	<<<-- 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. __________________ The glory of the World passes by.

December 19th, 2003, 03:46 AM	#432
Emmanuel Decarpentrie New Boot Join Date: Dec 2003 Location: Belgium Posts: 9	"- 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)?

December 19th, 2003, 04:42 AM	#433
Robert Knecht Schmidt Wrangler Join Date: Feb 2002 Location: Cleveland, Ohio Posts: 1,933	I always thought it was, "Keep It Simple, Stupid!" __________________ All the best, Robert K S Search DVinfo.net for quick answers \| The best in the business: DVinfo.net sponsors

December 19th, 2003, 05:01 AM	#434
Emmanuel Decarpentrie New Boot Join Date: Dec 2003 Location: Belgium Posts: 9	"I always thought it was, "Keep It Simple, Stupid!" Ooops! Thanks for pointing that out Robert! : )

December 19th, 2003, 05:52 AM	#435
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	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.