Homemade 35mm Adapter

Bob Hart · April 2nd, 2006, 08:54 AM

There is another clip up at savefle.com

The list of all files is at :-

http://savefile.com/projects/338360

The direct web address of the new file is at :-

http://www.savefile.com/files/6290311

The new file hopefully won't have the interlace defects the earlier clips have.

The conditions were - under canvas awning, intermittent overcast, time about 3-30pm. There is no soundtrack for two reasons, to reduce the data load and to avoid any copyright issues relating to the original musical composition.

Bob Hart · April 6th, 2006, 02:17 AM

If anyone has time to waste, I have put another two short H264 clips up at the following address :-

http://www.savefile.com/projects/338360

The names on the project file list are :-

AGUS35 TO HDRFX1 NO ENHANCEMENT 01

AGUS35 TO HRDFX1 NO ENHANCEMENT 02

"No enhancement is probably a little bit untrue. There's been an effort at de-interlacing them and they have been letterboxed but otherwise are not sweetened."

From a practical standpoint, I still think using the camera's own lens direct for wides and lots of movement and using the adaptor for the mid to close-ups may be a best approach.

The wides seem to lose a little sharpness at max aperture. They confer a interesting perspective effect in motion of objects moving directly towards and away from the camera.

Jamie Roberts · April 6th, 2006, 03:41 AM

Hi Bob,

checked out 02

footage looks great

no flicker there!!

Jamie

Roberto Lanczos · April 8th, 2006, 02:08 AM

I've spent like a week reading all of the posts. And when i started reading, i don't even knew what "GG" means.

Now, i don't have words for this. Is just great. Amazing.

But it's time to help a newbie. :D yes.

I've collected everything i need, and i've done some rough tests with all the parts on the fly, and it seems that i'm going to need a good macro lens, cause i'm still suffering from the vignetting.

So... Like i don't have a super cam, like the GL, XL, DVX, PD150, etc, i couldn't get the right information for the macro lens.

If anyone could guide me on this, that would be great.

Thanks in advance.

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

Here's what i have:

Camcorder ----- Sony DCR-TRV110 ( f=3.6 - 72mm, 1:1.4 @37 )

Lens ----------- Minolta SR-7 "50mm" ( Auto Rokkor-PF, 1:1.8, f=55mm )

GG ------------ Frosted CD from Maxell (25-pack)

If this macro lens can do the job for my cam, let me know to start building my adapter right now.

http://articulo.mercadolibre.com.ve/MLV-4973856-_JM

Wayne Kinney · April 8th, 2006, 02:21 AM

Quote:

Originally Posted by Roberto Lanczos

it seems that i'm going to need a good macro lens, cause i'm still suffering from the vignetting.

A macro lens, inside a 35mm adapter, is not intended to help with vignetting, although it does very slightly depending on its strength. The Macro lens is placed as close to the camcorder and possible and it's purpose is to help the camcorder focus on the GG while zoomed in. If your camcorder can zoom in and focus on the GG as it is, you dont need a macro lens.

What you do need is a condenser lens. Most commen type of lens to use is a PCX lens (plano convex) which is flat on 1 side and curved on the other. The flat side faces the GG and sits as close to the GG as possible. This is a good PCX lens to start with, and was used in the original letus and SG35:

http://www.surplusshed.com/pages/item/l3385.html

Good luck

Roberto Lanczos · April 8th, 2006, 02:34 AM

Quote:

Originally Posted by Wayne Kinney

Good luck

Good Luck? :(

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

I can't get close enough to the GG to avoid vignetting.

According to the info i've readed so far, i need a macro lens to get closer to the GG.

So... my question is: wich one will do the job for my cam?. Do i need 10x, 5x, 7x ?
Will this macro work ?
http://articulo.mercadolibre.com.ve/MLV-4973856-_JM

I wish i could buy any of the products you use, but i don't live in the US.

I will really appreciate any help. The only place where i can buy stuff, is Amazon.

Thanks

Wayne Kinney · April 8th, 2006, 02:46 AM

Hi,

No, the macro is indended to aid in the camcorders focusing. However, I think some have used the macro lens as a condenser lens (replacing the PCX lens) simply because this is what they have laying around already, and this is what you have read. But if your looking to buy a lens, I would recommend getting a PCX lens.

Please read this article:

http://en.wikipedia.org/wiki/Depth_of_field_adapter

There is a helpful diagram showing the most commen way of putting together a 35mm adapter, and illustrates what i meant with the plano convex lens against the GG.

Roberto Lanczos · April 8th, 2006, 02:56 AM

Quote:

Originally Posted by Wayne Kinney

No, the macro is indended to aid in the camcorders focusing.

You're totally right, sorry.

In fact, that's my problem. I get out of focus if i try to get closer to the GG. I tried everything, but it's imposible to get rid of the black corners.

I'll take a look to the article, thanks.

Wayne Kinney · April 8th, 2006, 03:13 AM

OK, i understand now.

Do you have a 35mm frame inside your adapter? Its a good idea to have a 36x24mm frame/window close to your GG, and this will be a reference for how far you need to zoom into your GG.

If you can zoom in enough to fill your LCD with this small 36x24mm frame, and focus, then you do not need a macro. If you still get vignetting while zoomed in to this point, you will need the PCX lens to avoid vignetting.

If you cant zoom in and focus on this 36x24mm frame, then yes you will need a macro of some sort. This macro will go as close to the camcorders lens as possible (probably a screw in macro). After this is installed, and you can now zoom in enough to fill the LCD with the 36x24mm frame, you will still propably find that you get vignetting and a PCX will be needed as well.

You can see in this diagram that both a macro and a PCX are used:

http://upload.wikimedia.org/wikipedi...nstruction.png

General rule is for the macro to go as close to the camcorder as possible, and the PCX as close to the GG as possible, with the flat side of the PCX facing the GG.

I hope this helps...

Roberto Lanczos · April 8th, 2006, 03:27 AM

I've tried every position, zooming, etc, etc, and no matter how hard i try, i always get the same portion of the screen on black.

something like this:
http://www.fdivisions.com/circle.jpg

I'll try to get the PCX. I just tought, i was close to build my adapter.

Wayne Kinney · April 8th, 2006, 03:39 AM

Roberto,

It looks like you dont have a 36x24mm frame inside your adapter. I think this should be your next step, as it will serve as a reference point to determine what lenses you need, a macro, a PCX or both. Without it, you are trying to setup the unit blindfolded, not knowing if you are zoomed in enough or not. Dont use the vignetting as a reference for zooming, use the 36x 24mm frame/window. Vignetting should be eliminated via a PCX lens, not by zooming in more.

So, first thing i think you should do, is forget about the vignetting for a second, and concentrate on getting your camcorder to zoom in and focus on a 36x24mm area of the GG. Best way to do this is as i've said to put in a 36x24mm frame/window in front of your GG. If you can't zoom in and focus on this area, then you will need a macro as you say. Once you can get focus on this frame area, the next step is to avoid vignetting, if any. And this is where the PCX comes in.

Either way, the aim is to zoom in only enough to fill the LCD with this 36x24mm frame, and not to zoom in more to avoid vignetting, as this will loose your FOV and it will no longer be a true 35mm image.

Roberto Lanczos · April 8th, 2006, 04:08 AM

Quote:

Originally Posted by Wayne Kinney

...concentrate on getting your camcorder to zoom in and focus on a 36x24mm area of the GG.

Sorry for asking so much, but what you mean, is that i have to have an image of 36x24mm projected in the GG ( in my case, the frosted CD )

something like this ?
http://www.fdivisions.com/portion.jpg

...and then i have to try to focus on that portion, right ?

Wayne Kinney · April 8th, 2006, 05:34 AM

Yes that is exactly it. Reason i asked this, is i was not sure if you were zooming in blindly, and simply trying to zoom in until the vignetting has gone. If you were, you would probably zoom past this 36x24mm image, which is not good.

So yes, first step is to get the cam zoomed into the frame area and focused regardless of vignetting. As you have said you probably need a macro close to your camcorders lens to do this, depending on what camcorder you have and its distance from tthe GG. After you have got this far, it is then that you start to tackle vignetting, if any. Ofcourse this is just my system of doing things.

Bob Hart · April 8th, 2006, 10:33 AM

Roberto.

Your cam seems to have a similar zoom range to the PD150. If it has a 1/3" CCD then it should behave in a similar manner.

Before you go to the trouble of putting a frame inside your adaptor, try a little experiment first. Draw a 36mm x 24mm frame on a card. Inside that frame, draw a grid of crossing lines.

Put this in front of your camera and try to focus on it and frame inside it. If you can't get inside the frame without losing focus, you will need a close-up lens or adaptor. The camera on a tripod and the card sitting upright on a table may be the best simple way of doing this experiment.

The 36mm x 24mm frame is the 35mm still-camera image size. For best sharpness off a groundglass, especially a fixed groundglass, then this is a better size image.

This image size is fine for still-camera film, but in a rear projection process which is what these adaptors use, there is a problem. The outer corners of the image are darker, the centre brighter. f1.8 aperture lenses help solve this problem but it does not go away entirely. Many builders use condenser lenses or PCX lenses to solve this problem.

I have taken a different course for my adaptor. I have chosen to use the smaller 35mm motion picture film image size, which is 24mm x 18mm. This image is more faithful to the theatre motion film image an audience views but has problems of its own as well as advantages. Chief is a reduced potential sharpness of image.

It requires a groundglass to be of as fine a texture which can be had and still relay an image without the hotspot problem becoming worse. The best texture seems to be the finish created by dressing with 5 micron aluminium oxide. This material is used for dressing glass.

I have experimented with CD-R plastic spacer disks, DVD+R clear spacer disks and split DVD+R disks and some special CD sized glass disks I imported from Ohara in Japan. I have settled on the glass disks as they are the only ones I have been able to achieve a consistently predictable finish on.

They require some machinery not available to the average home-builder, so for practical reasons, the plastic CD-Rs or similar will be your most likely option.

The smaller image frame fits inside the hotspot of f1.8 aperture lenses so the condenser element can be deleted.

The smaller image size will almost inevitably require a close-up lens or macro to enable the camera to frame inside of it.

As far as I am aware and I could be wrong, the P+S Technik uses an even smaller image size of 21mm corner to corner. This would eliminate entirely any hotspot problem but require a very good groundglass indeed.

My setup flips the image.

The path is :-

SLR still-camera lens >> Groundglass >> 2 right-angle prisms >> Century Optics 7+ Achromatic dioptre for PD150 ( a very good quality close-up lens or macro ) >> camcorder.

If you don't use prisms, with the 7+ dioptre, the groundglass will have to be about 5" or 125mm from front of the close-up lens. A stronger close-up lens will enable the camcorder to be closer to the groundglass and make a non-flip adaptor shorter.

To experiment to find the best power of close-up or macro lens, you could buy cheap close-up lenses made from a single piece of glass but for good images you need an achromatic dioptre which is made of two pieces of glass.

The motion images at www.savefile.com were created using this setup. At www.dvinfo.net/media/hart, there are a lot of still-image .jpg frame grabs which were made on successive improvements from the very first adaptor I made.

My personal preference would not be to position the frame along the disk radius as your diagram illustrates but across the radius line.

This reduces the possibilty of part of the image showing the groundglass texture as there is less of the inner portion of the disk area used.

The linear speed of the disk surface is slower the furthur towards the disk centre you go.

Roberto Lanczos · April 8th, 2006, 02:45 PM

Ok, everything is more clear to me now. Thanks a lot guys.

I did some experiments, and i've just realize that i can get pretty close to the GG. So close to the glass, that i can touch the lens and i'm still in focus.

It seems that my problem is between the photo lens and the GG:

Quote:

Originally Posted by Bob Hart

...The outer corners of the image are darker, the centre brighter.

That's exactly what's going on.

I drawed a 36x24mm square in the glass, and I can't fill the complete square. It gets darker in the corners.

So, in this case, the PCX is the way to go ?

I'm using an (Auto Rokkor-PF, 1:1.8, f=55mm) from a Minolta SR-7.
http://www.fdivisions.com/front.jpg
http://www.fdivisions.com/back.jpg

April 8th, 2006, 02:46 AM	#1357
Wayne Kinney Major Player Join Date: Jun 2005 Location: Brighton, East Sussex, UK Posts: 938	Hi, No, the macro is indended to aid in the camcorders focusing. However, I think some have used the macro lens as a condenser lens (replacing the PCX lens) simply because this is what they have laying around already, and this is what you have read. But if your looking to buy a lens, I would recommend getting a PCX lens. Please read this article: http://en.wikipedia.org/wiki/Depth_of_field_adapter There is a helpful diagram showing the most commen way of putting together a 35mm adapter, and illustrates what i meant with the plano convex lens against the GG. __________________ Thanks, Wayne.

April 8th, 2006, 03:13 AM	#1359
Wayne Kinney Major Player Join Date: Jun 2005 Location: Brighton, East Sussex, UK Posts: 938	OK, i understand now. Do you have a 35mm frame inside your adapter? Its a good idea to have a 36x24mm frame/window close to your GG, and this will be a reference for how far you need to zoom into your GG. If you can zoom in enough to fill your LCD with this small 36x24mm frame, and focus, then you do not need a macro. If you still get vignetting while zoomed in to this point, you will need the PCX lens to avoid vignetting. If you cant zoom in and focus on this 36x24mm frame, then yes you will need a macro of some sort. This macro will go as close to the camcorders lens as possible (probably a screw in macro). After this is installed, and you can now zoom in enough to fill the LCD with the 36x24mm frame, you will still propably find that you get vignetting and a PCX will be needed as well. You can see in this diagram that both a macro and a PCX are used: http://upload.wikimedia.org/wikipedi...nstruction.png General rule is for the macro to go as close to the camcorder as possible, and the PCX as close to the GG as possible, with the flat side of the PCX facing the GG. I hope this helps... __________________ Thanks, Wayne.

April 8th, 2006, 03:39 AM	#1361
Wayne Kinney Major Player Join Date: Jun 2005 Location: Brighton, East Sussex, UK Posts: 938	Roberto, It looks like you dont have a 36x24mm frame inside your adapter. I think this should be your next step, as it will serve as a reference point to determine what lenses you need, a macro, a PCX or both. Without it, you are trying to setup the unit blindfolded, not knowing if you are zoomed in enough or not. Dont use the vignetting as a reference for zooming, use the 36x 24mm frame/window. Vignetting should be eliminated via a PCX lens, not by zooming in more. So, first thing i think you should do, is forget about the vignetting for a second, and concentrate on getting your camcorder to zoom in and focus on a 36x24mm area of the GG. Best way to do this is as i've said to put in a 36x24mm frame/window in front of your GG. If you can't zoom in and focus on this area, then you will need a macro as you say. Once you can get focus on this frame area, the next step is to avoid vignetting, if any. And this is where the PCX comes in. Either way, the aim is to zoom in only enough to fill the LCD with this 36x24mm frame, and not to zoom in more to avoid vignetting, as this will loose your FOV and it will no longer be a true 35mm image. __________________ Thanks, Wayne.

April 8th, 2006, 05:34 AM	#1363
Wayne Kinney Major Player Join Date: Jun 2005 Location: Brighton, East Sussex, UK Posts: 938	Yes that is exactly it. Reason i asked this, is i was not sure if you were zooming in blindly, and simply trying to zoom in until the vignetting has gone. If you were, you would probably zoom past this 36x24mm image, which is not good. So yes, first step is to get the cam zoomed into the frame area and focused regardless of vignetting. As you have said you probably need a macro close to your camcorders lens to do this, depending on what camcorder you have and its distance from tthe GG. After you have got this far, it is then that you start to tackle vignetting, if any. Ofcourse this is just my system of doing things. __________________ Thanks, Wayne.

April 2nd, 2006, 08:54 AM	#1351
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	There is another clip up at savefle.com The list of all files is at :- http://savefile.com/projects/338360 The direct web address of the new file is at :- http://www.savefile.com/files/6290311 The new file hopefully won't have the interlace defects the earlier clips have. The conditions were - under canvas awning, intermittent overcast, time about 3-30pm. There is no soundtrack for two reasons, to reduce the data load and to avoid any copyright issues relating to the original musical composition.

April 6th, 2006, 02:17 AM	#1352
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	If anyone has time to waste, I have put another two short H264 clips up at the following address :- http://www.savefile.com/projects/338360 The names on the project file list are :- AGUS35 TO HDRFX1 NO ENHANCEMENT 01 AGUS35 TO HRDFX1 NO ENHANCEMENT 02 "No enhancement is probably a little bit untrue. There's been an effort at de-interlacing them and they have been letterboxed but otherwise are not sweetened." From a practical standpoint, I still think using the camera's own lens direct for wides and lots of movement and using the adaptor for the mid to close-ups may be a best approach. The wides seem to lose a little sharpness at max aperture. They confer a interesting perspective effect in motion of objects moving directly towards and away from the camera.

April 6th, 2006, 03:41 AM	#1353
Jamie Roberts Major Player Join Date: Feb 2006 Location: bendigo, australia Posts: 204	Hi Bob, checked out 02 footage looks great no flicker there!! Jamie

April 8th, 2006, 02:08 AM	#1354
Roberto Lanczos Regular Crew Join Date: Mar 2005 Posts: 113	I've spent like a week reading all of the posts. And when i started reading, i don't even knew what "GG" means. Now, i don't have words for this. Is just great. Amazing. But it's time to help a newbie. :D yes. I've collected everything i need, and i've done some rough tests with all the parts on the fly, and it seems that i'm going to need a good macro lens, cause i'm still suffering from the vignetting. So... Like i don't have a super cam, like the GL, XL, DVX, PD150, etc, i couldn't get the right information for the macro lens. If anyone could guide me on this, that would be great. Thanks in advance. ------------------ Here's what i have: Camcorder ----- Sony DCR-TRV110 ( f=3.6 - 72mm, 1:1.4 @37 ) Lens ----------- Minolta SR-7 "50mm" ( Auto Rokkor-PF, 1:1.8, f=55mm ) GG ------------ Frosted CD from Maxell (25-pack) If this macro lens can do the job for my cam, let me know to start building my adapter right now. http://articulo.mercadolibre.com.ve/MLV-4973856-_JM

April 8th, 2006, 03:27 AM	#1360
Roberto Lanczos Regular Crew Join Date: Mar 2005 Posts: 113	I've tried every position, zooming, etc, etc, and no matter how hard i try, i always get the same portion of the screen on black. something like this: http://www.fdivisions.com/circle.jpg I'll try to get the PCX. I just tought, i was close to build my adapter.

April 8th, 2006, 10:33 AM	#1364
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	Roberto. Your cam seems to have a similar zoom range to the PD150. If it has a 1/3" CCD then it should behave in a similar manner. Before you go to the trouble of putting a frame inside your adaptor, try a little experiment first. Draw a 36mm x 24mm frame on a card. Inside that frame, draw a grid of crossing lines. Put this in front of your camera and try to focus on it and frame inside it. If you can't get inside the frame without losing focus, you will need a close-up lens or adaptor. The camera on a tripod and the card sitting upright on a table may be the best simple way of doing this experiment. The 36mm x 24mm frame is the 35mm still-camera image size. For best sharpness off a groundglass, especially a fixed groundglass, then this is a better size image. This image size is fine for still-camera film, but in a rear projection process which is what these adaptors use, there is a problem. The outer corners of the image are darker, the centre brighter. f1.8 aperture lenses help solve this problem but it does not go away entirely. Many builders use condenser lenses or PCX lenses to solve this problem. I have taken a different course for my adaptor. I have chosen to use the smaller 35mm motion picture film image size, which is 24mm x 18mm. This image is more faithful to the theatre motion film image an audience views but has problems of its own as well as advantages. Chief is a reduced potential sharpness of image. It requires a groundglass to be of as fine a texture which can be had and still relay an image without the hotspot problem becoming worse. The best texture seems to be the finish created by dressing with 5 micron aluminium oxide. This material is used for dressing glass. I have experimented with CD-R plastic spacer disks, DVD+R clear spacer disks and split DVD+R disks and some special CD sized glass disks I imported from Ohara in Japan. I have settled on the glass disks as they are the only ones I have been able to achieve a consistently predictable finish on. They require some machinery not available to the average home-builder, so for practical reasons, the plastic CD-Rs or similar will be your most likely option. The smaller image frame fits inside the hotspot of f1.8 aperture lenses so the condenser element can be deleted. The smaller image size will almost inevitably require a close-up lens or macro to enable the camera to frame inside of it. As far as I am aware and I could be wrong, the P+S Technik uses an even smaller image size of 21mm corner to corner. This would eliminate entirely any hotspot problem but require a very good groundglass indeed. My setup flips the image. The path is :- SLR still-camera lens >> Groundglass >> 2 right-angle prisms >> Century Optics 7+ Achromatic dioptre for PD150 ( a very good quality close-up lens or macro ) >> camcorder. If you don't use prisms, with the 7+ dioptre, the groundglass will have to be about 5" or 125mm from front of the close-up lens. A stronger close-up lens will enable the camcorder to be closer to the groundglass and make a non-flip adaptor shorter. To experiment to find the best power of close-up or macro lens, you could buy cheap close-up lenses made from a single piece of glass but for good images you need an achromatic dioptre which is made of two pieces of glass. The motion images at www.savefile.com were created using this setup. At www.dvinfo.net/media/hart, there are a lot of still-image .jpg frame grabs which were made on successive improvements from the very first adaptor I made. My personal preference would not be to position the frame along the disk radius as your diagram illustrates but across the radius line. This reduces the possibilty of part of the image showing the groundglass texture as there is less of the inner portion of the disk area used. The linear speed of the disk surface is slower the furthur towards the disk centre you go.