Homemade 35mm Adapter

AJ Briones · November 30th, 2003, 01:14 PM

I'm one of the Canon XL1 users who are waiting with bated breath to see if one of you can come up with a solution for our beloved camera. I have money in hand for the first one of y'all who comes up with a commercial, professionally useable solution, as I'm way too busy and clumsy to build one for myself.

Rock on!

Jon Yurek · November 30th, 2003, 01:48 PM

Not to put a damper on the whole commercialism of this awesome idea, but I would imagine that P+S has some sort of protection (patent or otherwise) on the ideas that are being used here, seeing as how Agus said he read the Mini35 manual and just replicated that using common household items (how mad scientist-sounding).

While I agree this could easily drive their prices down (that is... if the footage is good enough and the information is spread wide enough, of course. If no one knows, P+S won't care), I don't think the "homemade" version could be sold commercially.

That said, I've been trying to get my roommate to lend me his 80mm-200mm lens so I can try some of this stuff out. <g> Keep up the good work.

Agus Casse · November 30th, 2003, 03:07 PM

I just shoot a Go karts racing event, the footage is really awesome, i will make a video, showing a demo footage.

about the comercial stuff, well, actually, i dont really think that P+S have invented something new... the tech is the same from SLR cameras, they only make the ground glass to spin, which is not a big discovering. WHat i have to admit is that their product is top noch, it is really pro, you can adapt all kind of lens, they have adjustable GG (ground glass) speed, and you can use the camera batery power to operate it.

They will never loose their clients because of this homemade device, i think it is all the way around... this device will show everybody why they should use it !!! because it is a homemade version, you will never the the perfect picture as the mini35, but you will get the same DOF.

As for a comercial Adapter, yes, i am currently working on building one, what i am pretending to sell, but keep in mind, that this is for poor people, (like me, who make it from the first thing i saw), and it will never be as good as the P+S mini35... i really doubt it... still... For all we indie filmaker, that we only own a miniDV camera, now we can have awesome shoots, for really no money, and in a way train ourself to handle profesional DOF, so if the oportunity comes, we will be able to handle a 35mm camera with no trouble.

Have fun, and the plans will be ready for next week, until then... i will be editing this footage and upload it as soon as i get it.

Thanks everybody for their support, also i want to thank to all the ones that were before me, explaining the theory of the adapter. and how it should be built.

Dillon Thomas · November 30th, 2003, 04:35 PM

Hello Agus,

I'm blown away by what you've done. Kudos and bravo to you! I'm really looking forward to seeing the tutorial you post online, so I can replicate one of these things for myself!

I'm still stuck on the "lowly" Sony Vx1000. I've been dying to get shallow depth of field, without breaking an arm to get it. It looks like youv'e done it.

Thank you, and good luck!!!

Regards,

Dillon Thomas

AJ Briones · November 30th, 2003, 05:12 PM

re: commercialization of this product

I don't think this product will cannibalize sales of the real mini35. For those production companies and filmmakers that can afford it, they will get the real mini35 setup because it is better. Just like cheaper prosumer stabilizers, cranes and steadicams do not cannibalize sales of their professional counterparts.

The difference is, there has never been a prosumer alternative to mini35... until now?? (please Agus, make this so!)

I'm hoping this becomes a real product that I can purchase and use on my XL1 for music videos, short films, documentaries and wedding videography (yes, imagine a prosumer mini35 setup used in a wedding!).

I will pay good money for this product, because I simply cannot even fathom spending $8k on a real mini35 setup. There needs to be a prosumer alternative to the mini35.

Paul Doss · November 30th, 2003, 06:08 PM

I am still not sure why you need the frosted glass if you are going from the 35mm lens straight to the DV Camera. I understand why it is necessary if you are going through the veiw finder, bouncing off of mirrors etc. It is further from the first mirror to your eye than it would be from the point of the first mirror to the film. So the frosted glass is there the same distance as the film and you are looking at it when you look through the veiw finder. Here is a diagram: http://entertainment.howstuffworks.com/camera7.htm

It seems like the light or image will be at the film plane with or without the frosted glass. It seems like the trick is to get the DV camera focused on that plane. Would it be possible to say insert a slide with a focusing pattern and a grid showing the area that should be covered, focus and then remove the slide and block off all light. If this worked it would cut down on the loss of light because of the frosted glass.

Agus, can you focus on the frosted glass and then remove it? If so, what do you get?

The image will still be upside down. Also remember focusing on the move or follow focus will still be a problem with still camera lens because of breathing. See Charles Papert's explanation here: http://www.dvinfo.net/conf/showthread.php?s=&threadid=7713&perpage=15&pagenumber=3

Still I'm sure we can all live with these problems for this kind of DOF. Add some color correction and 24p or 30p good enough for many projects.

Paul

Agus Casse · November 30th, 2003, 07:32 PM

Once you understand why the Ground Glass work, you will know how the adapter works.

The image from the lens, create a projection in the ground glass, there is where the image with DOF is made

http://entertainment.howstuffworks.com/camera2.htm

then you shoot that image with your DV camera, pick a SLR lens and try it without the ground glass, and you wont get nothing, just an image upside down.

Stewart McDonald · December 1st, 2003, 04:25 AM

Wouldn't frosted glass compared to clean glass affect the image quality?

Jean-Philippe Archibald · December 1st, 2003, 08:03 AM

IMO:

The frosted glass is used like a projection screen, and the camcorder "film" the image produced by the 35 mm lens on this "screen". A clean glass would not preserve the focal lenght of the 35 mm lens.

Brandt Wilson · December 1st, 2003, 11:06 AM

I'm not sure of the proper optical terms here, so I hope I amd able to convey this idea...

The ground glass essentially is acting as a rear-projection element and is re-establishing your depth of focus by reimaging what you are seeing through the 35mm lens.

If you used a condenser lens, you would simply be adding the 35mm lens to your DV lens and would not be gaining the same effect. Again, I don't know the specifics, but you wouldn't be seeing the 35mm image. By recapturing the depth of focus onto a flat screen, you are able to take advantage of the optical properties of that 35mm lens.

Also, the grainier the ground glass, the more contrast you will see. As you remove the grain, the contrast is reduced. Hence the spinning ground glass.

Dino Reyes · December 1st, 2003, 12:29 PM

Agus35 vs Mini35

Unbelievable Agus, i'm very impressed, currently i've done some preliminary testing of your prototype which i hope to flesh out over the next many weeks. True the Mini35 is nothing new, just a different take on the "Camera Obscura" (http://brightbytes.com/cosite/what.html). But you are ingenious, daring and ABOVE all inspiring...! That's why I want to dub your creation the Agus35.

Some quick questions... Your using the clear CD from the 25-CD pack, correct? (or is there another component I'm missing which you refer to as the "ground glass"?)or did you aquire an actual circular cut glass which you have "sanded" on one side? Else, I'm also thinking of trying to aquire an actual circular glass and using some etching acid from an arts store to frost one side for a finer "sanded" finish. Would you think that makes a difference in quality? Technically it seems it might. Also have you found an ideal place to put the rotating motor? And another, once you have adjusted the image to appear in the ground glass, the sweet spot, have you tried other lenses to check on their results? Like a zoom???

Agus Casse · December 1st, 2003, 12:40 PM

Well, yeah, if you use a cutted groud glass, made of glass and not plastic, you will have more quality, and you will loose less light steps.

Also, the ideal place for me for the motor is in the center of the spindle, it even have te same diameter to fit those very popular chinese motor toys.

I love all that about calling this adaptor the Agus35 ... heheheh

Paul Doss · December 1st, 2003, 03:01 PM

Posted by Brandt<<The ground glass essentially is acting as a rear-projection element and is re-establishing your depth of focus by reimaging what you are seeing through the 35mm lens.>>

I understand all that. I just can't picture why the light isn't at that same place, plane or distance if you focus on it. I guess the light must actually strike something to be seen.

I see how there are advantages to using mirrors, prism, etc. so as to be looking at the other side of the frosted glass and not having to look through it. That has to really cut down the light as has been discussed. Plus looking at other side it's possible to flip the image. Good bit more involved to make though.

Agus Casse · December 1st, 2003, 03:20 PM

Ok, this is quite simple, it seens that you havent even tried up the adapter, and also you seen not to understand how it works.

The adapter is way to simple to use, to build and the picture quality is amazing clear and pefect DOF... now, if you want to build another adapter using no ground glass and mirros... well... i think that is another topic.

The challenge was to build an adapter which would cost less than 10 dollars, and you could get equal image to the mini 35... i have succeded, the image is clear, i have DOF control, no vigneting... no noise...

the mini35 offers many more really advanced features, but i have adchieved the simpliest ones and the most important.

You need the ground glass.. i dont know why you are putting that you can do it, when you havent even tried. When i look at the mini 35, ithought it was just as simple to put the SLR lens in front of the DV camera, NO... it doest work that way...

So, pick up an SLR camera lens, your dv camera, and tried like you said, to use mirros, and no ground glass, the point is that this topic is about this adapter, which was built only using a 25 cd spindle, and cheap toy with an electric engine...

no means to offend, just to continue moving forward with this project.

Matt Gottshalk · December 1st, 2003, 03:24 PM

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2968796829&category=29981&rd=1

I think this may be a way to get better ground glass. It's a 8x10 ground glass used for large format still cameras.

All you have to do is have it cut so it is round, and drill the hole in the center.

Great thread we have here.....

November 30th, 2003, 01:14 PM	#76
AJ Briones Posting disabled - Contact Admin. Join Date: Nov 2003 Location: San Diego, CA Posts: 8	amazing! I'm one of the Canon XL1 users who are waiting with bated breath to see if one of you can come up with a solution for our beloved camera. I have money in hand for the first one of y'all who comes up with a commercial, professionally useable solution, as I'm way too busy and clumsy to build one for myself. Rock on!

November 30th, 2003, 04:35 PM	#79
Dillon Thomas Tourist Join Date: Nov 2003 Location: San Francisco, CA Posts: 3	I joined just to reply to this Hello Agus, I'm blown away by what you've done. Kudos and bravo to you! I'm really looking forward to seeing the tutorial you post online, so I can replicate one of these things for myself! I'm still stuck on the "lowly" Sony Vx1000. I've been dying to get shallow depth of field, without breaking an arm to get it. It looks like youv'e done it. Thank you, and good luck!!! Regards, Dillon Thomas __________________ How sweet it is!

December 1st, 2003, 08:03 AM	#84
Jean-Philippe Archibald Trustee Join Date: Sep 2003 Location: Saguenay, Québec, Canada Posts: 1,051	IMO: The frosted glass is used like a projection screen, and the camcorder "film" the image produced by the 35 mm lens on this "screen". A clean glass would not preserve the focal lenght of the 35 mm lens. __________________ Jean-Philippe Archibald http://www.jparchibald.com - http://www.vimeo.com/jparchib

December 1st, 2003, 11:06 AM	#85
Brandt Wilson Major Player Join Date: Jan 2003 Location: Portland, OR Posts: 220	Ground glass v. aerial image I'm not sure of the proper optical terms here, so I hope I amd able to convey this idea... The ground glass essentially is acting as a rear-projection element and is re-establishing your depth of focus by reimaging what you are seeing through the 35mm lens. If you used a condenser lens, you would simply be adding the 35mm lens to your DV lens and would not be gaining the same effect. Again, I don't know the specifics, but you wouldn't be seeing the 35mm image. By recapturing the depth of focus onto a flat screen, you are able to take advantage of the optical properties of that 35mm lens. Also, the grainier the ground glass, the more contrast you will see. As you remove the grain, the contrast is reduced. Hence the spinning ground glass.

December 1st, 2003, 03:24 PM	#90
Matt Gottshalk Major Player Join Date: Dec 2003 Location: Potomac Falls, VA Posts: 215	Ground glass http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2968796829&category=29981&rd=1 I think this may be a way to get better ground glass. It's a 8x10 ground glass used for large format still cameras. All you have to do is have it cut so it is round, and drill the hole in the center. Great thread we have here.....

November 30th, 2003, 01:48 PM	#77
Jon Yurek Regular Crew Join Date: Sep 2003 Location: Worcester, MA Posts: 64	Not to put a damper on the whole commercialism of this awesome idea, but I would imagine that P+S has some sort of protection (patent or otherwise) on the ideas that are being used here, seeing as how Agus said he read the Mini35 manual and just replicated that using common household items (how mad scientist-sounding). While I agree this could easily drive their prices down (that is... if the footage is good enough and the information is spread wide enough, of course. If no one knows, P+S won't care), I don't think the "homemade" version could be sold commercially. That said, I've been trying to get my roommate to lend me his 80mm-200mm lens so I can try some of this stuff out. <g> Keep up the good work.

November 30th, 2003, 03:07 PM	#78
Agus Casse Major Player Join Date: Jul 2003 Location: Guatemala Posts: 322	I just shoot a Go karts racing event, the footage is really awesome, i will make a video, showing a demo footage. about the comercial stuff, well, actually, i dont really think that P+S have invented something new... the tech is the same from SLR cameras, they only make the ground glass to spin, which is not a big discovering. WHat i have to admit is that their product is top noch, it is really pro, you can adapt all kind of lens, they have adjustable GG (ground glass) speed, and you can use the camera batery power to operate it. They will never loose their clients because of this homemade device, i think it is all the way around... this device will show everybody why they should use it !!! because it is a homemade version, you will never the the perfect picture as the mini35, but you will get the same DOF. As for a comercial Adapter, yes, i am currently working on building one, what i am pretending to sell, but keep in mind, that this is for poor people, (like me, who make it from the first thing i saw), and it will never be as good as the P+S mini35... i really doubt it... still... For all we indie filmaker, that we only own a miniDV camera, now we can have awesome shoots, for really no money, and in a way train ourself to handle profesional DOF, so if the oportunity comes, we will be able to handle a 35mm camera with no trouble. Have fun, and the plans will be ready for next week, until then... i will be editing this footage and upload it as soon as i get it. Thanks everybody for their support, also i want to thank to all the ones that were before me, explaining the theory of the adapter. and how it should be built.

November 30th, 2003, 05:12 PM	#80
AJ Briones Posting disabled - Contact Admin. Join Date: Nov 2003 Location: San Diego, CA Posts: 8	re: commercialization of this product I don't think this product will cannibalize sales of the real mini35. For those production companies and filmmakers that can afford it, they will get the real mini35 setup because it is better. Just like cheaper prosumer stabilizers, cranes and steadicams do not cannibalize sales of their professional counterparts. The difference is, there has never been a prosumer alternative to mini35... until now?? (please Agus, make this so!) I'm hoping this becomes a real product that I can purchase and use on my XL1 for music videos, short films, documentaries and wedding videography (yes, imagine a prosumer mini35 setup used in a wedding!). I will pay good money for this product, because I simply cannot even fathom spending $8k on a real mini35 setup. There needs to be a prosumer alternative to the mini35.

November 30th, 2003, 06:08 PM	#81
Paul Doss Regular Crew Join Date: Feb 2002 Location: Gulf Shores, Alabama Posts: 57	I am still not sure why you need the frosted glass if you are going from the 35mm lens straight to the DV Camera. I understand why it is necessary if you are going through the veiw finder, bouncing off of mirrors etc. It is further from the first mirror to your eye than it would be from the point of the first mirror to the film. So the frosted glass is there the same distance as the film and you are looking at it when you look through the veiw finder. Here is a diagram: http://entertainment.howstuffworks.com/camera7.htm It seems like the light or image will be at the film plane with or without the frosted glass. It seems like the trick is to get the DV camera focused on that plane. Would it be possible to say insert a slide with a focusing pattern and a grid showing the area that should be covered, focus and then remove the slide and block off all light. If this worked it would cut down on the loss of light because of the frosted glass. Agus, can you focus on the frosted glass and then remove it? If so, what do you get? The image will still be upside down. Also remember focusing on the move or follow focus will still be a problem with still camera lens because of breathing. See Charles Papert's explanation here: http://www.dvinfo.net/conf/showthread.php?s=&threadid=7713&perpage=15&pagenumber=3 Still I'm sure we can all live with these problems for this kind of DOF. Add some color correction and 24p or 30p good enough for many projects. Paul

November 30th, 2003, 07:32 PM	#82
Agus Casse Major Player Join Date: Jul 2003 Location: Guatemala Posts: 322	Once you understand why the Ground Glass work, you will know how the adapter works. The image from the lens, create a projection in the ground glass, there is where the image with DOF is made http://entertainment.howstuffworks.com/camera2.htm then you shoot that image with your DV camera, pick a SLR lens and try it without the ground glass, and you wont get nothing, just an image upside down.

December 1st, 2003, 04:25 AM	#83
Stewart McDonald Regular Crew Join Date: Feb 2003 Location: UK Posts: 130	Wouldn't frosted glass compared to clean glass affect the image quality?

December 1st, 2003, 12:29 PM	#86
Dino Reyes Regular Crew Join Date: Dec 2003 Location: brooklyn Posts: 66	Agus35 vs Mini35 Unbelievable Agus, i'm very impressed, currently i've done some preliminary testing of your prototype which i hope to flesh out over the next many weeks. True the Mini35 is nothing new, just a different take on the "Camera Obscura" (http://brightbytes.com/cosite/what.html). But you are ingenious, daring and ABOVE all inspiring...! That's why I want to dub your creation the Agus35. Some quick questions... Your using the clear CD from the 25-CD pack, correct? (or is there another component I'm missing which you refer to as the "ground glass"?)or did you aquire an actual circular cut glass which you have "sanded" on one side? Else, I'm also thinking of trying to aquire an actual circular glass and using some etching acid from an arts store to frost one side for a finer "sanded" finish. Would you think that makes a difference in quality? Technically it seems it might. Also have you found an ideal place to put the rotating motor? And another, once you have adjusted the image to appear in the ground glass, the sweet spot, have you tried other lenses to check on their results? Like a zoom???

December 1st, 2003, 12:40 PM	#87
Agus Casse Major Player Join Date: Jul 2003 Location: Guatemala Posts: 322	Well, yeah, if you use a cutted groud glass, made of glass and not plastic, you will have more quality, and you will loose less light steps. Also, the ideal place for me for the motor is in the center of the spindle, it even have te same diameter to fit those very popular chinese motor toys. I love all that about calling this adaptor the Agus35 ... heheheh

December 1st, 2003, 03:01 PM	#88
Paul Doss Regular Crew Join Date: Feb 2002 Location: Gulf Shores, Alabama Posts: 57	Posted by Brandt<<The ground glass essentially is acting as a rear-projection element and is re-establishing your depth of focus by reimaging what you are seeing through the 35mm lens.>> I understand all that. I just can't picture why the light isn't at that same place, plane or distance if you focus on it. I guess the light must actually strike something to be seen. I see how there are advantages to using mirrors, prism, etc. so as to be looking at the other side of the frosted glass and not having to look through it. That has to really cut down the light as has been discussed. Plus looking at other side it's possible to flip the image. Good bit more involved to make though.

December 1st, 2003, 03:20 PM	#89
Agus Casse Major Player Join Date: Jul 2003 Location: Guatemala Posts: 322	Ok, this is quite simple, it seens that you havent even tried up the adapter, and also you seen not to understand how it works. The adapter is way to simple to use, to build and the picture quality is amazing clear and pefect DOF... now, if you want to build another adapter using no ground glass and mirros... well... i think that is another topic. The challenge was to build an adapter which would cost less than 10 dollars, and you could get equal image to the mini 35... i have succeded, the image is clear, i have DOF control, no vigneting... no noise... the mini35 offers many more really advanced features, but i have adchieved the simpliest ones and the most important. You need the ground glass.. i dont know why you are putting that you can do it, when you havent even tried. When i look at the mini 35, ithought it was just as simple to put the SLR lens in front of the DV camera, NO... it doest work that way... So, pick up an SLR camera lens, your dv camera, and tried like you said, to use mirros, and no ground glass, the point is that this topic is about this adapter, which was built only using a 25 cd spindle, and cheap toy with an electric engine... no means to offend, just to continue moving forward with this project.