DIY adapters for RB645 and 35mm lenses

[Bob Hart]

Agatha.

Ted's adaptor is the only one which will make close to the best of both Nikon and Mamiya lens image areas on the groundglass. All other adaptors are either 35mm movie frame size, some 35mm still-image frame size or Mamiya size image only.

Do not buy any adaptors off ebay without checking back with us here first.

[Ted Ramasola]

I just acquired a nikon 80-200 ED and did some tests with the adapter.

This lens is heavy BUT its really bright and I think I'll be using this often than primes. I also think this will make me leave behind 3 lenses. my 85mm f 2, 105mm f2.8 and 200mm f3.5. the zoom will be very useful in quickly adjusting framing and composition especially in outdoor set ups.

Heres a pic of the lens on the adapter i posted at the JVC forums. its a monster at 31 inches long.
http://www.dvinfo.net/conf/attachmen...1&d=1201610242

Here are some grabs from some test shots today.

[Bob Hart]

Sweet images.

A trace of arc artifact on the chook shot and another. I guess available light was not your friend there. It this observable in the motion footage or does the action or moving images pretty much bury it? The keyboard shot. Is that an old "Beale" or "Cable" brand piano?

You may find running your disk slower, down to 620 rpm or 310 rpm even, and possibly running a 1/100 sec shutter with an extra wider stop of aperture may help bury the arcs. I am assuming you are shooting 24P.

[Ted Ramasola]

The arc is buried in the motion now unlike the tokina 200mm. Im so curious why the arc shows up in long lenses and not in normal and wide.

I'll try slowing it down.

The piano is a wurlitzer.

[Bob Hart]

My imaging is that the angle of incidence of light from the lens is more closer to ideal for a wider area across the image. Less random scatter so patterns in GG texture might become more apparent.

You may find that a normal to wideangle digital stills lens does it too in adverse lighting conditions. These I understand are optimised for the imagers which share the same problems as groundglasses related to angle of incidence.

The Nikon 12mm -24mm f4 zoom is the worst offender on my setup. I had always attributed this to the f4 aperture but now on having some more thought about it, I am not so sure.

I had the piano tagged as American as it has a sllght backwards tilt to the keys relative to the cabinet work. If ever you are bored and have absolutely nothing to do, lift the top lid and have a look at the writing cast into the frame in centre or possibly right side near the lid.

Mass production piano making apparently shared a a few of the characteristics of our automotive and appliance making of today in that the scale of operation was big enough for specialisation in sub-components like keyboard mechanisms and frames.

So some brands share some parts with others. Like OEMs of today, if enough frames were ordered, apparently you could have your own brand name cast into them.

There you have it, some totally useless information which I gained entirely secondhand and word of mouth.

[Agatha Graselia]

Hi Bob and Ted,

I have a gift from my relative come from USA, and he will bring me Letus FLIP, and I suppose to use 50mm/f1.4 nikon lens.

Upon your posting here, I'm glad that possible to use my 80-200/f2.8 ED as well.
Will post some footage when available. Maybe I have chances to use his HVX200 and brevis too, when he come to Jakarta this time.

Mean time, we use whatever available in the camera to make DOF-look.
If you don't mind I want to share a footage we took recently :

http://www.youtube.com/watch?v=ZbJz8Qd_vxk

we use in this a handicam panasonic gs320, V1P, several raynox, nikonos u/w cam, d300, d200, 18-200 VR, 50mm/1.4, 80-200/f2.8 , fisheye 10.5 , infrared modified camera, and most of all my DIY stabilizer :P

http://www.youtube.com/user/agathagraselia

Regards,
Agatha

[Bob Hart]

Agatha.


You should enjoy the Letus flip. If you get a Nikon to Mamiya adaptor to fit in the Nikon mount, you should be able to achieve a good look on the Letus which has a large groundglass screen.

The Nikon f1.4 lens you propose to use is a sweet lens for groundglass work.

Have a look at the instructions posted at the Letus website or at the "sticky" on the Letus threads posted here titled Clayton's sticky.

(The word Clayton's in English language is meaning fake or substitute. The word comes from "Clayton's", a brand of party drink which is not alcoholic but tastes the same as the alcholic drink it pretends to be.).

There are some things you need to do to the Letus lens mount to get it working best.

[Frank Brodkorb]

Having a free afternoon I played arround with a Zeiss 6x6 lens and some plumbing equipment.

The GG is an focusing screen of an 1950s Exacta.

Plumbing tube and rubber grommets of the plumbing supply shelf keep everything in place.

In the back sits an Achromat (10 dioptr.)

No glue or other modifications, everything bolts right in.

Took me about 10 minutes including quick and dirty backfocusing.

I just clamped it betwen the HVX and the mattebox.

I can not post attachments here, so check out the pictures and screengrabs here:

http://www.dvxuser.com/V6/showthread.php?t=121773

[Bob Hart]

AGUS35 DPVNE ?? (AGUS35 Deuscher Plumber's Version Non-Erecting.).

Can't see the pics as dvxuser won't let me in.

Your project would have to be good for a Guiness Book of Records entry. The closest I have come to that is a Pringles can, two rolled up socks which had the heels out of them, a handground microscope slide, an X-Fujinon f1.8 50mm prime and a PD150, elastic bands, rolled up pizza box for packing under the Pringles can and a piece of flat pinewood the PD150 was bolted down onto and the Pringles can was banded down onto.

It took me the best part of two hours to cobble together.

I called it the Pringlecam. All that is left are the memories, the piece of wood, the X-Fujinon, four pics up on dvinfo and the PD150.

[Ted Ramasola]

Bob,

I tested the adapter for green screen work after you said its possible and i was able to pull a good key. Heres some grabs of a raw and a composite. I shot it with a Nikon 50mm at f1.4 and on the fujinon at f8.

I also recalibrated my zoom settings after i realized i can remove the anti flare ring of the fujinon lens allowing me to further plunge the achromat deeper by 8mm.

After these tests i think i can use the rig now without removing the adapter. my only problem now is adding more counterweight on my DIY jib to offset the added load of the adapter.

Ted

[Bob Hart]

Ted.

Thanks for publishing your experiment. It is encouraging for my own project, just have to do the learning. "Primatte"? Is this a special composing software plug-in or will I get by with Premiere Pro?

As for locating the achromat closer, I seem to recall a memorable repeated line by George Peppard in the "A-Team" a seventies TV program. - "Don't you just love it when a plan comes together."

[Ted Ramasola]

Bob,

Primatte is from red giant, same guys making magic bullet.
http://www.redgiantsoftware.com/primattekeyer.html

I also was able to pull a respectably good key using Edius Pro Chromakeyer.

But for a really clean key that can clean up spills and leave hair detail, i strongly recommend primatte. Especially when using shots from a cam+lens adapter that introduces grain, CA, soft edges and what have you.

Its a plug in for After effects and is better than keylight.


Just added these new grabs because i noticed my first test was underexposed and created so much noise.


Ted

[Bob Hart]

Ted.


One small furthur enquiry.

If you by any remote chance have a some spare time, could you place an operating desk fan in front of your green screen and see if you can pull a workable key. Speed 2 should be about the right RPM.

One composite I would like to attempt will be a head-on of an operating aircraft parked in front of a green painted hangar wall or a greenscreen curtain if I can borrow it. The curtain would be second choice because airflow from the aircraft will ripple it.

With the motor run up to warm-up rpm, there should be enough natural movement of the aircraft on its undercarriage to replicate in-flight movements.

The obvious alternative is to remove the propellor or paint the propeller blades green and fake a spinning prop in afterward but the services of a licenced aircraft maintenance engineer would need to be obtained for prop removel and refitting and that does not come cheaply.

This experiment is by no means something which needs to happen anytime soon.

[Ben Winter]

That primatte key is pretty impressive. Bob, maybe he should try a couple fan tests at different shutter speeds.

[Ted Ramasola]

Bob,

I see that with 3 possible solutions.
1.The actual green screen shot.
2. A composite in After effects of a static propeller shot made to rotate.
3. A CGI prop

The last two shots would require motion blur and careful keyframing for a realistic gradual acceleration using curves.

HHmmmm...

At what camera frame rate do you want this shot in? 24P? 30P? 60P? The frame rate will affect the kind of strobing effect on the spin.

Ben,

The primatte also has a lightwrap feature that when activated, allows you to sample the background image and gradually "smears" for lack of a better term, dominant colors of the backplate and apply it to the edging of the keyed image.

Its like simulated radiosity. A term i use in CGI and photography often. When colors of the surroundings affect the color of the subject.