Homemade 35mm Adapter

[Bob Hart]

Clay.

My tests have been a mixture of fixed groundglass and rotary CD. The .jpg images "agusday" 1 and 2, and "fixed groundglass" 1 to 5, at the address www.dvinfo.net/media/hart used the fixed real groundglass (microscope slide) and had by far the best resolution in spite of not spinning and being in a very improvised enclosure (Pringles Crisps tube).

I have not yet been able to get hold of a glass disk. The Ohara disk I was chasing is apparently a special glass doped to hold an electric charge and it's green but there are other glass disk products available. The Ohara guy in Japan has been really good at answering e-mails. I have yet to go back to the internal website he directed me to for a look.

John.

The CD glass masters may end up being a bit thick and a bit large, but they may use smaller ones for doing the CD business cards or smaller CD mini disks. Please let us know the outcome.

To all.

Taking things to a ridiculous extreme, I tried a Proskar 2x Anamorphic 16 Cinemascope projection lens on front of the Nikon 55mm. It works quite well.

[Taylor Moore]

It apparently looks like an old fashioned Elliot Ness tommy gun sawn off. -->>>

Has a whole new meaning to shooting:)

[Chris Hurd]

Howdy from Texas,

Bob's latest images are up...

http://www.dvinfo.net/media/hart

"Attached are the .jpg images of the Agus35 Australian Plumber's Version I refer to. These have not been cropped or manipulated and were created on a document scanner so should be faithful as to dimensions except the pic of the Agus attached to the PD150 which is grossly distorted. Aside for the PD150 the doc scanner is the only other electronic cam I have. There is also a demo of the Tamron 135mm with a shot taken in bright day f16@ASA 200 level
lighting at about 2pm."

Check the date listing for these most recent pics... or Bob might post the specific file names. Hope this helps,

[Jim Lafferty]

Sorry Jim, I actually meant the parts connecting the 50mm lens to the adapter and the GL1 to the adapter?

That's in the tutorial, man :)

The grey metal coupling is a 2" conduit hub from Home Depot, the mount is a Nikon F mount taken from an F-to-C adapter I got at B&H.

Check the tutorial again -- I added a lot of links today.

- jim

[Taylor Moore]

Thanks for doing this Jim, makes alot easier for us hacks.
Looking forward to part 2.

[Agus Casse]

<<<-- Originally posted by Don Mahr : Agus where did you get the pentaprism from?

And is there any way you could put up a simple little diagram of how yours is put together with the pentaprism?

Thanks -->>>

from here...

http://www.surplusshed.com/pages/item/l2080.html

i got 4 to make some copies :) . That one you put it in the viewfinder of your dv camera so you still shot flipped, but with less loss of light but you can see it flipped in the viewfinder.

and here...

http://www.surplusshed.com/pages/item/l2097d.html

i made some test with that one, but i will make a new adapter from scratch to then compare both versions.

also i will be receivin this in a couple of days to test it up.

http://www.surplusshed.com/pages/item/l3020p.html

They can zoom and have a wide aperture size. F/1.4 !

also i will give this one a try.

http://www.surplusshed.com/pages/item/l1465.html

thanks for all to keep up with this thread, and i am really coming close to a fully comercial version working :)

[Thomas Bruegger]

just returned from a tour through my city here in switzerland in order to get a fresnel.....no chance i give up! if anyone in europe has one and could send me a link of an online-store or any the guys in the states want to make me happy and send me one, perhaps we could make a deal and i could send you some premium swiss chocolate(;-).

Filip. about the 37mm Macro-Lens. I tested my agus with a sony p-100 with 37mm and i took my cheap sony wide angle 0.6 the one that's completly out of plastic(can post a picture if anyone is interested) and took of the front lens. It mus be between seven and ten diopters and only a bit of zooming is needed to capture the picture on GG.

thomas
mailto:maes@maes.ch

[Bob Hart]

Re: www.dvinfo.net/media/hart

Furthur to Chris' post above, the filenames are :-

"agustele.jpg" which is an image of the close-couple optical adaptor for the PD150 and the telescope eyepiece the lens set came from. This is a very big file as I did not downsample the image so as to keep it faithful to 1:1.

"agusassy2.jpg" which is a downsampled version of a an original scan image. This shows the Agus35 "Australian Plumber's Version" attached to the PD150 via its own lens hood mount over the telescope eyepiece lens set in a home-made adaptor which separately attaches into the PD150 58mm filter thread.

"agusaust.jpg" This is a huge 1.1Mb file of several components which were placed face down on a document scanner. The file has not been downsampled in order to keep it faithful to 1:1.

"agusarm3.jpg" is an image which is about the sharpest I have been able to achieve with the rotating CD used as a groundglass. True glass dressed with aluminium oxide 600 grade powder yields a better image but so far I have been only able to make fixed panels out of microscope slides.

It is also critical for that CD to spin true. Even the most slightest run-out will move the image and therefore soften it. Run-out can be checked for by looking at your still frames in an image software at high magnification. If the disk is not running true, the image will be alternately sharp and soft on the CD which will also be moving in and out of camcorder focus. This will be too small to see in the viewfinder. In the highly magnified image you will see minute interlace artifacts which suggests very small movements of the groundglass image between frames.

You solve one of the flickering defects caused by run-out by turning the spindle motor faster but this has the side-effect of the camcorder and 35mm lens seeing a "thicker" groundglass with loss of resolution.

FOOTNOTE ADDED LATER:

I did a websearch tonight on dove prisms. It seems that dove prisms may not be an option for our purposes as those which yield a wide enough image will not fit within the focal lengths of our 35mm lenses or the space between our groundglass image plane and camcorder close-up lenses.

[Agus Casse]

i tried with dove prisms... they only flip the imave vertically, not horizontaly... so no solution.. what you need is a pentaprism and copy the same configuration from a slr camera.

anyone have a site where you can buy fresnel lens online ?

[Chris Hurd]

More from Bob:

"Attached are three .jpg files of cinemascope lens tests with the Agus35. The same lens resolves better into 35mm lenses than into video direct or into 16mm motion picture lenses. Close-up, there is little to tell between the 4:3 and 2x anamorphic image yield via the same prime lens. From about 20ft to infinity it all starts to fall apart. So the scenic vistas are not an option. Finely textured low contrast scenic vistas never were with MiniDV, or CineAlta for that matter, so all is not necessarily lost. For simple use as an effect stitched into another format the results from the Agus35 2x anamorphic combination would be fine in medium to close up shots of actors and action with the background kept soft."

www.dvinfo.net/media/hart/aguscne1.JPG
www.dvinfo.net/media/hart/aguscne3.JPG
www.dvinfo.net/media/hart/aguscne2.JPG

[Agus Casse]

hey bob where i can buy those lens ??!?! can you show up a picture of them ?

[Bob Hart]

Agus.

The cinemascope lens is a "Proskar 2X Anamorphic 16". This and other brands were fairly common in the 70s - 80s for projection of 16mm copies of 35mm movies.

16mm was big before 80s video took the place of film prints for movie distribution to ships at sea, oil rigs, remote workplaces and construction sites.

The Proskars came with an adaptor to directly fit into Bell and Howell 50mm focal length projector lenses. Some others were of the traditional cinema design with a rod and swingdown arrangement.

I'll hunt down a .jpg of the same lens fitted up to a Bolex. I think its still on the computer here somewhere.

They should be findable secondhand as I have seen one or two over the years among professional gear in photographic equipment stores.

You might still find them covered in dust on a shelf in small village cinemas where video projectors have taken over.

Some of the Christian organisations may still have them around in basements and attics, though most if not all the Anderson style movie production was distributed in standard frame (4:3).

[Bob Hart]

Furthur to above, I have sent to Chris some .jpg files titled "Anamorphic On Bolex" and Anamorphic on Bolex2" which illustrate the Proskar lens. It is mounted onto a 1970s Cosmicar 25mm C Mount prime lens in that illustration.

(Note for 16mm motion film experimenters. - The filter thread in the Cosmicar DOES-NOT match the thread on back of the Proskar anamorphic but is close enough that it fastens on for fixed test purposes. The Cosmicar had been dropped and the end was ruined already so it did not matter. The results onto the smaller format standard 16mm camera frame were not impressive. I did not waste film stock on it.)

For the Agus35 test images, the Proskar lens was jigged against the front of the 55mm Nikon lens.

It would be interesting to try the AGUS35 into a 16mm motion film camera once all the exposures are worked out. If it was a viable production tool, P+S Technik would have probably already pushed it as an alternative to 35mm motion film. Might extend the life of 16mm film if it was viable?? but I think the generational losses in image quality would kill it off. - Just a thought!!

[Bob Hart]

Footnote to the above - If you are lucky enough to have the Century Optics or Optex 16:9 anamorphic lenses with the 58mm thread, some 55mm SLR lenses I have run into have a front filter thread which is not rotated when the lens focus is adjusted. The barrel moves back and forth only.

This should enable focus pulls with 16:9 adaptors attached via step-down adaptor rings. The Micro-Nikkor has a 52mm filter thread, the X Fujinon a 49mm filter thread.

The SLR lenses may not like the extra weight of the anamorphic lenses on front so these might need to be supported in a sliding sleeve or separately mounted on rods to avoid loading the SLR lens altogether. Various AGUS35 prototypes might be a bit light for anything but rod mounting the anamorphic anyway.

Other longer lenses and wide-angles tend to have a front element and filter mount which rotates as the focus is adjusted. Rod-mounting the anamorphic lens is the most practical option. If the anamorphic must be coupled direct to the SLR lens, then mounting a sliding keyway on a rod to secure the handle of the adjustment ring of the anamorphic lens then leaving this ring unlocked to allow the lens body to move freely with the rotating barrel of the main lens would be an alternative.

If you have a bayonet-ring style mount as with the Century Optics PD150 model, then life is more difficult. You might at a pinch be able dismantle the lens and have a filter thread machined onto the back of the lens housing and use step rings to fit the SLR lens. This choice would also defeat the adjustment system on the lens and adjustment would be limited to positioning on the threaded mount itself. I don't think I would would want to go there. It is a bit expensive to take those sort of chances with.

To make a bayonet style adaptor, for a machinist it's a relatively simple task requiring a piece of metal stock about 74mm in diameter or an alloy pipe flange of some sort providing a sizeable clearance hole to be made in the centre and a shoulder for the filter thread on the SLR lens.

[Bob Hart]

Agus.

There's two .jpg files of the Proskar Anamorphic 2x in www.dvinfo.net/media/hart They are identifiable by the part filenames "Anamorphic Lens on B"

There's also an illustration of a car window mount for a CP16, made from West Coast truck mirror frames and some added steel. When opening this live on-line, you may encounter a white screen and be led to think theres a fault. The image has a lot of white in it. Just pan it around and you'll soon pick up some details. The logo on the mag does not refer to the movie "Kill Bill" but to a union sticker for a labour rally in WA a few years back which reads "Kill the Bill". I shot some S16 film there for historical archive purposes.