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Old January 2nd, 2004, 01:47 AM   #661
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A little help

Taylor, I'll be glad to help out as much as I can. Here are some more photos of our mini-50 adapter:


As far as construction goes - we just went with what worked. Both Spencer and I have made simpler versions via trial and error - that and frequenting this thread. We decided to go with the project box for the sheer fact that it had space to work, could easily house the spinning cd, and was light tight. That idea can be chalked up to Jim Lafferty, I believe. I'd say that finding a nice sturdy enclosure is half the battle here. My first version was a 30 pack like Agus used, but I found it to be too flimsy - that and there wasn't an easy way to install an adjustable cd motor. For those of us using larger cameras (esp. with your DVX's 72mm threads) the place to mount the motor on the center of the cd spindle is taken up by the lens. At least that's the way it was on my 58mm GL1. Anyways, the dimensions on the project box are 8"x6"x3", it can be had for $7 at radio shack. While you’re there be sure to pick up a AAA battery enclosure and a toggle switch. The 3 volts provided by the batt. pack is perfect for running the cd. The switch is a nice touch too.

The particle board with the opening for light to pass through helps a ton. Because it rides on those 4 bolts you're able to easily adjust it to the focal point of your lens - this is done by simply adjusting the nuts that hold it in place on either side. The fresnel resides right below the spinning cd and helps punch up the light level. I had a tough time finding a "fresnel" at office max, but all it really is is a pocket magnifier. It shouldn't cost anymore than $2 and is usually located around the magnifying glasses and books at Office Max or any of those office type stores. I believe others have found them at Walgreens.

Our +10 macro is a bit much and introduces some distortion at the edges, so we're going to take it down a notch to a +7. The distortion could also be attributed to the fact that our macro's glass doesn't take up the whole of the ring diameter, the glass is really only about 45mm of the 58mm lens, you can see that in the pic above. You can stack multiple macros to achieve more magnification, IE stack a +1, +2, and +4 to get +7 - but then you've got some vignetting from the stacked glass. I also tend to want to keep the glass in front of my lens to a minimum (except for a UV), so a single glass element is always my first choice.

We used a pre frosted cd....not much else to say about it. Spence just found it in a stack of old cds. We tried using fine sandpaper, but it was too grainy. We also tried a form of sandblasting with fine glass grain at Spencer's dad's machine shop - but that yielded the same, grainy results. The pre-frosted cds work best in my opinion. Jim Lafferty found that Maxell's 48x/700mb 50 spindle contains pre-frosted cds. http://ideaspora.net/agus35/frosted.jpg.

For the portion where the camera actually attaches to the box we used a flanged piece of PVC from lowes, it's actually called a "2" fitting cleanout body". We then used the clamping end of a "flexible drain + trap connector" to actually seal the macro lens light tight. Once again, Jim used the same material. As far as connecting the 50mm lens - I was lucky enough to find parts for the Olympus OM-10 camera on ebay, specifically the ring where the lens snaps into place. What stinks is that this ring isn't universal for all makes of lenses, each company creates their own adapter rings that only work with their lenses, thus forcing you to buy glass from them. If you want you can use a back lens cap for whatever lens you're using and cut off the back. The lens will easily lock into it, but it won't be a tight fit, and the lens will easily fall out. Regardless, it can be had for $5 at your local camera store.

The support - we designed it so that the camera would film the bottom of the spinning cd and would allow us to use a straight piece of aluminum to support the box. This bar provides all the support for the rig, the portion where the DV cam's lens and the adapter meet only acts as a light-tight coupling.

Precision played a large role in this, and many parts of our adapter. Luckily Spencer's father is an engineer-type and left no stone unturned when it came down to brass tacks. We also had Spencer's dad's machine shop at our disposal. This allowed us to perform some precision tasks such as cutting holes in the project box to exact dimensions. This is a distinct advantage that many don't have. BTW - We used expoxy to glue everything together, it should be at your local hardware store.

Anyways, I would have to suppose that the reason exacting details/schematics for this thing don't exist is due to the fact that there are too many variables. My Olympus OM-10 50mm SLR lens would yield a diff. focal point than your Canon 35mm (for example), and each of our DV cams have various differences: focal abilities, lens sizes, macro abilities. I hope this post has helped you on your way to contructing your own adapter. If you decide to create that website and want to use any of my post, feel free. Our adapter is a "melting pot" of everyone's ideas and experiences around here, and it comes together to yield quite a neat little tool to have in the kit. This is a community, and we can all benefit from each other's experiences, I hope ours will help. Thanks, and good shooting in the new year!
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Old January 2nd, 2004, 05:25 AM   #662
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I was under the impression that a fresnal lens was not needed? can someone please explain?
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Old January 2nd, 2004, 05:28 AM   #663
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For those who might be thinking of ornamentation there is a quick and dirty "Agus 35--" logo at ---- www.dvinfo.net/media/hart/ --- as a .pdf file. The web address is here at this site.

There's also a few .jpg images captured as the local flavour of the Agus 35-- has improved and evolved and a few which demonstrate the raw relationship between the front lens and the disk.

The most recent are the "agusroto" series of images which were captured via the path :-


The chain from Adobe Premiere introduces about a 2 stop darkening of the image.

On some of the still images you will observe some interlace artifacts. There was a fair bit of wind blowing and leaves were moving. - but, there is also artifact on some shots where there was no movement which leads me to think there is still some shimmer caused by the rotating groundglass.

There is some apparent "grain" on brighter images with the spinning groundglass which cannot be blamed on low-light noise. I have upped the disk speed to about 3200RPM. This hopefully will deal with the disk motion being "frozen" by the camcorder but introduces another problem if a compliant motor mount or disk-to-spindle mount has been used to try to keep the disk image from shivering. Quick pans or tilts are not good. The disk moves off the focal plane momentarily due to gyro effect, with softening mostly on the outer (lower) edge of the recovered image. - In my specimen, the disk centre axis is directly below the lens centre axis.

Of the clear CDs which might be used to make a groundglass, there are some from Sony which appear to be incomplete CD-Rs. They have guide tracks on them but no silver or top layer. These may have been diverted from production, a sensible alternative to molding disks just for packaging purposes. As genuine CD material they should be optically superior and should run true. Some of the clear CDs used for packaging are not optically true and some have obvious casting marks on them. If you use these for a home-made groundglass you will never get them to run true and stay on the focal plane and you may also get a shivery image when the molding marks pass by.
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Old January 2nd, 2004, 05:46 AM   #664
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How can Premiere introduce a 2 stop darkening of the image?

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Old January 2nd, 2004, 05:58 AM   #665
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2-stop darkening of image? I wish I knew why and that it would go away for purposes of authentically representing test results. There may be settings which do this but I haven't found them yet.

As stills the pictures actually look the better for it. I'm using de-interlace when saving frames to .bmp files which might have something to do with it.

I've chosen not to re-adjust the images for brightness so that they stay closer to genuine.
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Old January 2nd, 2004, 09:49 AM   #666
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I just returned from Home Depot to pick up parts for a rod system, and came across a steel 2.5" conduit hub -- it fits perfectly over the Century Optics achromatic diopter and, in fact, "clips" onto the bayonet tabs on the front of my GL1. The diopter then fits very snugly inside the ring at the other end of the hub. I will be using this as a replacement for the rubber ring I'd fashioned to fit over the diopter originally, which allowed too much movement. It will be potentially useful for those of you with a GL1 with or without the diopter. The trouble now will be milling out a notch for my CD motor at the back of the adapter...

Here are pics:


- jim
Realism, anyway, is never exactly the same as reality, and in the cinema it is of necessity faked. -- J-L G
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Old January 2nd, 2004, 10:39 AM   #667
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In earlier post I referred to putting a fullstop after the web address for the .jpg files Chris posted. I was confused. The address as quoted should be used without the full stop.

Out of curiosity, I cut out a 35mm 1.85:1 gate from a piece of paper and framed my camcorder on that. Compared to the image I have been framing in the Agus35 it is a lot smaller.

Given this smaller target size, I tried the modified telescope eyepiece again and found it will frame the 35mm widescreen gate with the PD150 in 16:9 setting. This adaptor screws straight in to the PD150 filter thread.

For those who are into roll-your-own optics and machining, the lens set comes from a no-name 42mm eyepiece for Tasco 2" scopes and has a handwritten part number "SW5042". I believe it is sourced from China.

An equivalent "Maxview" eyepiece has a 58mm thread already built on but how it performs in this application I do not know.

(For those who cannot get their hands on a widescreen gate, the open end of a Ventolin puffer cap is close enough in size on the side of larger, for a rough assessment target.)

A bit is cropped off top and bottom of the image in standard 4:3 frame and there is vignetting and too much of the widescreen gate area is lost zooming in to get rid of it.

If there is any advantage to using eyepiece optics it might be in closer coupling to the camcorder with the gg 52mm from the front of the camcorder. The lens set might couple even closer however my adaptor has metal on the front which prevents this.

The stack of Hoya 58mm close-up lenses (1x +2x +4x) will also frame the 35mm widescreen gate with the gg 127mm from the front of the camcorder.
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Old January 2nd, 2004, 10:57 AM   #668
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See all of Bob's images from the list at www.dvinfo.net/media/hart -- hope this helps!

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Old January 2nd, 2004, 11:09 AM   #669
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Hey guys.. the original logo to put it anywhere that you want is here....


in IE will look bad... try opening in photoshop or after
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Old January 2nd, 2004, 11:55 AM   #670
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Spencer Houck & Devin Doyle,

I would be honored to put your info and photos on my page:
www.thecountrybulletin.com/dv_dof.htm soon to be under the domain name: www.dvdof.com

Really like the simple but effective answer to a mounting bracket. Please let me know.

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Old January 2nd, 2004, 12:44 PM   #671
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colonia35 zenit

my footage from january 01.



to me it looked GREAT.

the best i can get from a trv18 with the 35mm adaptor.

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Old January 2nd, 2004, 01:12 PM   #672
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Paul, i just saw your last design and it is so very similar to ours, only that we are using a smaller GG now smalller....

The macro lens wont be necesary now using that design. as the image now comes up corrected and bigger from the source thanks to the fresnel lens.
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Old January 2nd, 2004, 01:41 PM   #673
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Agus:"i just saw your last design and it is so very similar to ours"

Really it is just a copy of the light path to the viewfinder in an SLR. Will work as shown or inverted depending on how it is to be mounted. Hard part is finding a prism large enough that wouldn't cost $1000. Have you had any luck? I have duplicated the prism with mirrors and it can be done, but it's not easy.


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Old January 2nd, 2004, 03:25 PM   #674
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Yeah, i think the same, copying the same way a SLR camera will do trick. I think you will have some problems when making the adapter, because of its size and teh camera... i am making all the model in 3dsmax to test in a 3d world.
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Old January 2nd, 2004, 03:43 PM   #675
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"new" sort of GG

i just bougth the proper self adhesive frosted foil for home use (for windows, screens, panels etc.), and it looks almost the same as Frosted MAxell CD.

just sent my pictures to TAYLOR (thanks), and when he uploads it on his site - you can compare it. i can bet thay you cannot see the difference. it is frosted in the similar way as MAXELL, same opacity, same look. i also took a picture for comparition with MAXELL CD and FOIL frosted CD side by side.
hope this can help someone. when you find proper gradient of this foil it tooks 2 minutes to prepare your own evenly frosted fake CD.
i tested it with my agus35 and for me it looks absolutelly ok

good luck.

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