Homemade 35mm Adapter

[Wayne Morellini]

Bob

I'm interested in the static aldu35 type design too. So the bosscreen is not good enough, what about the holographic screens and the Reflexite screens, are there any sources of really fine ones? Has anybody got one and tried spining it?

[Brett Erskine]

Now heres another idea for dealing with the grain.

As most of us already know the first models of the P +S Technik used a CD-like rotation GG. Because of picture quality and physical size problems the idea was dropped for a better design where the glass is almost vibrated in place.

But I had a third idea...but its much more complicated movement to build. You can get even closer to a "film look" and deal with the grain issue by having the GG rotate and stop 24 times a second (for DVX100. 60 times a second for other camera). The GG would stop just in time for each frame to be captured. The result would be the same beautiful effect subtle film grain has on footage.

Its kind of imbraces the idea of just a little amount of grain in the picture which might help take that harsh edge off of the image that you find only in video.

Now I know what is involved to make this happen in sync as Im sure some of the techs out there do as well and your right - it would be difficult. I only offer it as a third option for anyone that is interested/cazy enough to try it because its sure to give great results.

-Brett

[Filip Kovcin]

just in case you didn't check - take a look at upside down monitor solution thread. the inverting/flipping image problem is finally solved! take a look.

filip

[Bob Hart]

Brett.

You don't need to do that. Just set the disk motor speed slow and camcorder shutter high and it's done.

With my DVD-Video version of my Agus35 footage, which is higher res than .avi files, interestingly there is a faint fine scintillation or random grain effect in the image. I dont know whether this is small bright pinpoints being created by the pits in the groundglass. It is like low-light video noise but is finer. These pinpoints might flash fast enough to register sharply in individual frames. It is visible on a hi-res monitor but goes away when projected or viewed on a standard TV screen.

I made mine with an initial pressing of the 600 grade paper against the CD-R disk. Whilst the surface has been subsequently rubbed with aluminium oxide and back-polished, I suspect the bottoms of the pits originally pressed in, remain and have clean sides, with steeper edges perhaps than pits caused by rolling grit in the conventional polishing method.

If you can play back PAL DVD-Video on DVD+R discs, I'll send you a copy by the mail. It might be something worth going after as an effect.

As for rotating the gg in 25 to 30 ps increments, stepper motors and computer controllers might achieve it. There are kits from electronic hobby shops for this. The motion control people in the video/film industry know how this stuff works.

Wayne.

Holographic screens and reflexite are high science things I don't know anything about, so I can't comment on those.

[Alex Raskin]

OK, so if the GG vibrates rather than rotates, then the grain visibly disappears because:

- the grain is moving with the frequency much higher than shutter speed, thus creating motion blur in camera;

- the image projected on GG is NOT moving, thus staying sharp for the camera.

My understanding is that the amplitude of the vibration should be small enough to keep GG within the DOF of the camcorder's macro lens, but large enough to create grain motion that would translate into motion blur in camera.

Correct?

Questions:

1. If I shoot with 1/60 shutter always, what should be the frequency of the GG vibration? (I assume over 2 times higher than shutter, eg maybe about 150 HZ?)

2. What small vibrating motors are available? (Ladies' devices are out - size matters in the inverted sense here...)

Anyone who's already experimented with vibrating GG - please pitch in!

[Bob Hart]

A linear movement will not work, unless electronically synced to the camera frame rate so that movement is always occurring when the image is being scanned off the CCD. Otherwise there will be intermittant frames of a staionary gg. The motion has to be circular or orbital if it is to run at a free speed.

The movement, rotation vibration or orbital motion of the gg is across the camcorder's field of view, not back and forth towards and away from the camcorder. Ie., it does not deviate from the focal plane of the objective lens on front or the adjusted relay focus of the camcorder.

[Joe Holt]

I was messing with my Agus 35 today. I just wanted to share with you all that I was very pleased with the images I shot today. No visible grain, no hotspotting and no vignetting. Everything was rock solid. I used all of my 35mm SLR lenses and was able to stop down without increasing vignetting. If I get some time, I'll post some images on my web site. Here's what I used to get my results.

thick acryllic CD spacer ground carefully with 9 micron WAO. (I tried CEO and 5 micron WAO but couldn't get an even enough finish)

Coated double convex rectangular lens, 40mm by 27mm wide by 9.5mm thick at the center. Rounded ends. 63mm focal length
found here http://www.surplusshed.com/pages/item/l1584.html for $3 ea.
The condenser was mounted between the spinning GG and the Video camera, as close to the spinning GG as possible.

I shot with all of the following SLR lenses and had great results with all.
35mm F2.8
45mm F2.0
58mm F1.4
28mm-80mm F3.5 Zoom
80mm-200mm F3.5-F4.0 Zoom

I'm now convinced that the spinning plastic CD is still the way to go for the best image. I'm sure a glass disk will give you better light transmission but how much better? I'm curious to hear how the CD motors hold up spinning the extra weight of glass not to mention the cost. Did I read right? $420 for 10 disks???? I'll post some images asap. Joe

[Jim Gauthier]

Maybe grinding the acrylic CD very thin would improve light transmission. It's soft and should grind easily. Another CD may be trimmed down to hub size and glued to the ground CD for strength if needed.

[Bob Hart]

Joe.

Yes you read right. It is a ballpark calc. Yes, it is a bit of overcapitalisation for an Agus. I err a bit on the side of technical obsession versus simplicity. Here follows a copy of Hiro's quote :-

""""""""""""""""""""""""""""""""""""""""
I am finally ready to submit my quotation for 10pcs of S-BSL7 D120.0 - 15.0 X 1.2T disks as follows:

1. Glass Type = Ohara S-BSL7 General Optical Properties as per Ohara Catalog Standard

2. Outer Diameter = 120.0 +/-0.2 (mm)

3. Inner Diameter = 15.0 +/-0.2 (mm)

4. Concentricity between OD and ID = 8 micron meter or less

5. Thickness = 1.2mm +0/-0.3 (mm)

6. Surface condition = Ground

Our price for quantity 10pcs is F.O.B. Japan JPY3,400.- / pc F.O.B. stands for "Free on Board".
This means the price includes the cost of the product itself and the cost for clearing customs in Japan.

Therefore the consignee ( customer ) needs to pay international transportation fee. The reason why we offer F.O.B. price is it we have no idea how the consignee wants to transfer the goods ( by ocean-ship, or air-freight, or postal parcel ).
If you have a specific requirement for transportation method, we can quote our price which includes all such costs and you have only to receive the goods at your door.

Please let me know how you want us to ship the goods. Does my explanation help you understand?

Lead-time = 4 weeks after receiving Payment by remittance

End of quote.

"""""""""""""""""""""""""""""""""""""""""

I don't think the true groundglass is going to yield a quantum leap in image sharpness, more like 3% or thereabouts as our images with the plastic disk are already looking good.

Glass will deal with the inconsistent finish when working with the finer grades of polishing compound you mentioned.

That in turn will deal with issues of variable density and flickering.

The CD spindle motors should not have too much bother once they spool up. We are not expecting them to precisely track a fixed rpm with applied power and braking voltages but putting a constant voltage to them and accepting whatever rpm they operate at.

We are also not operating them for continuous long periods as might be expected spinning a CD disk in a player. Provided we are reasonable about the power we put into them they should last the distance.

They may not be as tolerant of violent movements whilst in use, but I suspect the disks, spindles or the motor mounts may fail first.

[Wayne Morellini]

<<<-- Originally posted by Bob Hart :
Wayne.

Holographic screens and reflexite are high science things I don't know anything about, so I can't comment on those. -->>>

Sorry Bob, I was up all night and must have got a bit confused. Some people are experimenting with ready made holo screens.

[Ray Zschau]

I've spent the past week or so reading all of the posts on the Agus & Aldu35, as well as much supplementary info on basic optics theory. The amount of info available in just these two threads is amazing. I've already 'repurposed' an old portable CD player, and started sketching out my design. I have access to a machine shop, so hopefully my first basic design will still be made out of something a little more sturdy than an empty CD-R package. My optical parts should be here soon.

I've decided to go down this path:

Nikon lenses attached to standard mount --> Maxell frosted CD spinning on a portable CD player subassembly --> glass condenser lens (with convex side pointed away from gg) --> an achromatic diopter (if needed, my Sony seems to be able to focus correctly to closer than a half an inch with no help) --> Sony TRV-9 cam with 37mm lens mount

I have the design from the 35mm lens through the gg pretty much finalized, but have a couple of questions after that point. First, the lens mount on the Sony is 37mm. I was planning on just using a step-up ring before attaching to the Agus35. Then keeping the condenser lens at a larger size, so that I can use the same unit with various cams. Does this sound like a good idea? Or would I be better off in keeping the lenses after the gg on a 37mm mount? Will keeping the condenser lens at a 37mm diameter not work because there will still be vignetting? Is there any practical difference as to the amount of light that is lost due to a different lens diameter? I really want to stay away from glue and the like, and would rather have the unit be easy to take apart and modify over time. I also want the system to be as basic and optically efficient as possible. Does anyone have a good source for step up/down rings of various sizes?

I'll be sure to take pictures along the way, as you all have done, and will also throw together a small description of what was decided on, and why.

For the Agus35 I'm working on, a flipped LCD - with image corrected in post - will probably be used, seeing how flipping the image optically is currently too cost and size prohibitive. The Aldu35 will hopefully be corrected optically using a 45 degree first surface mirror and a roofed pentaprism, such as in a SLR (I love the design of that ARRI Digital Viewfinder). Of course this depends on whether or not a suitable pentaprism can be tracked down. Any new leads available?

Joe, could you please post a few photos of your Agus35 as well as the test frames you mentioned? I'm interested in seeing how you mounted that rectangular DCX from Surplus Shed. It's good to hear you're getting such nice results.

I can't wait till I can finally use DoF in my shots. I've never been satisfied with the permanent 'infinite focus' effect built into video.

Ray

[Alex Raskin]

Just tested the vibrating GG - successfully!

I simply used the Nikon's focus screen as GG, and attached a micro vibrating motor from old cell phone to the side of the GG's frame.

While GG stands up vertically, the motor is attached horizontally to its side.

As a result, the motor's vibration does not change the GG's distance from the cam's lens, but rather moves GG across the cam's view.

Result: it definitely eliminated all small imperfections which were otherwise highly visible with static GG.

Larger areas where GG's structure is uneven were less affected - due to the fact that the amplitide of the vibration is rather small.

So if GG is quality ground with say 3-5 micron grit, no scratches/blemishes/eneven areas, then my test shows that the vibration will completely eliminate any visible grain.

I'm now cautiously optimistic that a HD QUALITY, wonderfully small home-made adapter is possible.

Because no-one (unless i missed it) produced such adapter, do you guys think we should open a NEW thread for it and call the adapter maybe buzz35 or vibro35?

(It seems custom to call adapter variants by the name of their developers, but alra35 does not sound right to my ear :)

[Filip Kovcin]

alex,

can you pass us some footage or jpgs?

it sounds very intersting. what kind of motor did you use - from which phone (model/manufaturer etc)?

some times ago i bought for the same reason (someone already mentioned that in thread - the vibrating motor for cellphones) the stand alone vibrating gadget for cell phones, but i do not know how to change pulsating character of it (buzzz-silence-buzzz-silence-buzzz... etc), so maybe your knowledge will help us.
how dificult is this to build?

filip

[Filip Kovcin]

<<<-- Originally posted by Alex Raskin :
While GG stands up vertically, the motor is attached horizontally to its side.
-->>>

i forgot to ask you about above - can you describe/ draw/picture this in more detail?

thank you

filip

[Ari Shomair]

I might have a lead on cell phone and pager vibrator motors if anyone is interested... I believe they are sold in lots of 10