Grab yourself a PCX lens, and it will even out the vignetting.

Glass Disks.

Some info for anyone who is making glass disks from 1.3mm thick centre-holed blanks from Ohara in Japan using a free platen in a tumbler style machine.

The blanks are thin slices off a large diameter glass rod. It is the nature of the cut-off process that they will have a very slight simple bend in the cut.

It is essential that the first grind to figure the disks true is allowed to proceed right to the centre on the groundglass finish side which is the hub mount face, even if the outer rim starts to get a bit thin.

It is okay for the fine dressing and the polish stages to be limited to the outer image area provided the fine dressing removes the coarser texture in this area.

The free platen tumble process has a defect in that the outer edge dresses down faster because the rubbing action is not a true circular orbit.

This can be offset by another smaller diameter free heavy metal disk being added to bear weight against the platen carrying the glass disk so that pressure transfers from the high surface velocity area.

Failure to allow the dressing to continue to the disk centre will result in a disk which will not run true.

The platen and the added metal disk should be brass or bronze. There is wear between the two metal disks which roll at differing rpm and also from the rolling contact with the barrel. The metal particles which come off brass or bronze are not injurious to the glass.

Castiron or steel rusts and these particles or hard particle inclusions in the steel itself which come free as it wears down will damage the glass. This damage usually shows as narrow elliptoid coil patterns in a band around the groundglass. This will also occurr if contaminants are allowed to get into the mix.

Rotation speed for a 160mm diameter tumbler barrel should not exceed 65 RPM, otherwise there is a tendency for the slurry to throw to the outside and leave a dry spot about 10mm inside the outer edge of the glass disk which may cause non-lubricated glass to glass contact.

This may result in pickup of glass from the disk onto the dressing surface which will then cause gouges in the disk.

It also helps slurry circulation to have a centre-hole drilled through the platen so that slurry can feed up through this hole and the disk centre hole and let worn mix out instead of it remaining in a zone in centre of the disk.

my latest agus35 clip + rundown
 

Hi there here is a link to a short clip i made today that shows my agus35 in action

http://www.filefactory.com/?62cac1

I have experiemented today with the following set ups:

1. pcx lens between gg & slr lens (my usual set up)

2. pcx lens between gg & camcorder lens

3. pcx lenses either side of the gg

I also use a 10x macro lens on the camcorder PLUS i am using the nivea creme on the disc which has been sanded with 320 grit sandpaper (then washed) - thank you Ettorre!.

When i had the pcx lens between the gg and the camcorder the image to my eyes was far too grainy.

When I had a pcx lens either side of the gg I could not get a sharp enough image.

The set up i have come back to is with the pcx lens between the gg & the slr lens. Keeping in mind that green is one of the 'noisiest' colours, to my eyes I find this image the most acceptable. I think for what i want to do with the adapter, this will be A ok! I plan to do a short movie in the next week or so that combines dof adapter footage with std camcorder footage so will get a better idea of how it all blends then.

I am still planning on trying a 'achromat lens' which may or may not improve things.

incidentally I have used a free plug in in 'virtualdub' called MSU denoiser on this footage which i quite like the look of. I also applied an 's' curve, some contrast and some saturation to the footage as well

cheers

Jamie

Day 1 to report on the set of "The Cage", an independent martial arts based movie being created principally in the old Fremantle Prison in Western Australia.

I have participated in order to get some AGUS tests in on a real world shoot when moments permit and to get some hands-on with an action based project. (I get to assist the cameraman and clap the slate and hopefully not my finger instead).

It is looking much better than I had expected. The people are very professional, there's industry experienced people among them and all are putting their heart and soul into it.

So far I have not been able to take any matching AGUS footage of actual takes as my tasking on the project does not allow this. I have managed to do some tests during run throughs and rehearsals but the lighting setup was not completed and the images are a bit dark.

It's 12-hour night shifts until they move on to the dialogue driven scenes where I may have more opportunity to try it out. I won't have time to get any stills up for the next few days.

It's a good gig as they say.

Day 2 of the shoot "The Cage".

They have got more of the fight scenes in the can. From the outside tey are looking quite good and I got some AGUS shots which I hope to get some copied JVC matching footage for.

The old Prison according to an urban myth is haunted. There was a legend at the prison during its occupancy that if a white dove was seen to be flying nearby someone was about to top themself. (suicide in custody).

3-30am yesterday and in a fully enclosed area of the building as sudden chill drift came through. This morning about 3-0am and two different HDV cams, the Sony and the JVC, both on manual settings, spontanously lost sharp focus. - As you say in the US-"Go figure". I am a cycnic when it comes to the creepy stuff but I ope to get some interviews on it for the "Special Features" for the DVD.

As soon as I have some useful stuff, I put it where it can be seen.

spooky!

soundss like alot of fun. i will look forward to seeing some 'in focus' footage!

jamie

Day 3 on location "The Cage".

All is well. "The Bull" fight scene. Lot's of fun watching it done. Cameras being nice to their operators. The lights are not. One is burning out its globes frequently and the other is tripping the overload frequently. We assume the lamps' excuse shall be "The Ghost made me do it."

I understand that a few of the key crew on this one were also involved with "Ozzie Park Boys" which is apparently doing well in direct to DVD-Video distribution.

Day 4.

More interesting times. Some very good performances today. Watching actors reach what you think is their limit, then their coach works them up another level, you think that's it, then it goes up one more notch. Very educative.

We innovated some focus stops for the JVC for focus pulls when handheld. The camera is light and the operator can be pulled off the shot if somebody like good old heavyhanded me gets fingers onto the focus ring.

So, three bits of aluminium for limit stops, a rubber band on the focus ring, another rubber band hanging off that - crude, rude but reasonably effective.

A doorbell went off spontanously in the place today.

At one point, a loud call went out to turn the house lights off so the set was lit by stage lights only. The lights went out. As I understand the story, no one admits to actually turning the lights out and one crewman came up to the cage after lights went back on, quite animated and apparently shaken.

Tried to get some demo footage done, but it was mostly a case of one-handing the camera/Agus combination , operating the slate with the other and picking off what I could get in the meantime which is not a lot. Still, I have a few and will post them once I have clearances and the time to code them to something the internet can handle.

The Agus system is not ideal in a run and gun situation like this as any focus errors are very apparent. I suppose the same goes for the genuine 35mm filem camera.

DAY 5 or is it DAY 6.

Overnight shoots have left me a little confused.

Whatever, they shot some fight sequences today which really worked, the main one being Justin Versus "Bull". They have coverage shots on one particular fight scene and despair of not being able to use them all.

Kenny Low - (Justin) is martial arts trained and is well in tune with where his body is in space and time in split seconds.

Lee Jankowski - (Bull) is a professionally trained actor who went to W.A.A.P.A here in the west which is regarded as being up there with the best. Lee is a big guy but has impeccable timing and ability to move around.

The both of them worked off each other and had trust and confidence in each other's ability. One shot in particular was a launch and bounce off the cage wall straight to a head kick which had a close clearance.

They shot it four times and each time was a winner and was convincing to the point of one feeling compelled to call for the ambulance until the big guy sat up with a big grin on his face after cut was called.

Yet to see how the dialogue driven scenes shape up but the action scenes have wrapped safely.

This little project looks like it may punch well over its weight in terms of the budget and resources available.

They screened some of the JVC HD 25P footage tonight and the images from that camera are remarkable, clear, colourful with deep blacks and no gain noise in the low areas whatever.

Last day of this part of the shoot tomorrow and hopefully some time after that to put a few clips together.

DAY 7 and the first schedule of production has completed and there is now a three day break.

One of my 500watt lights failed. The globe (actually a bar) still looks good so probably a quality issue with the switch or internals.

The production Senneiser 816 broke down today so they have switched to a Sony C74 which I by chance took down today for interviewing a retired prison officer about the Fremantle Prison ghost stories.

It is made of brass and is a heavy brute on the end of a long pole.The Senneiser has been increasingly picking up stray AC fields into the sound.

If anyone has any hints on what might be wrong with the Sennheiser, any advice will be appreciated. Apparently it has been dropped twice in its lifetime.

They shot three good short actions today and I got good Agus35 equivalent shots lighting wise, over the shoulder of the camera op.

As soon as I have clearance to use them, I'll process and post the clips in H264. I'm still not sure whether Premiere Pro is acually capturing high def or not.

Much of what I am shooting indoors looks grainy like pushed Super16mm film.

I tried the Sony flavour of 25P (cineframe??) using the default preset 4. It actually doesn't look too bad.

The production footage is JVC HD 25P.

The AGUS35 stuff I am shooting is intended for a behind the scenes "Special Features" or "Bonus" section on the DVD as well as perhaps a short promotional clip.

Off topic. I have posted details in the sound forum of dvinfo but here goes a short version.

Sennheiser 816 after four days of varying degrees of AC interfence penetrating the audio, finally died completely. Another mike on the same lead does not admit the AC interference so this hints at an internal earthing/shield failure in the Senneiser as I think the cable shield may provide part of the phantom power supply conductive path or be connected to it.

Any advice on tracing the fault and repairing in-field would be appreciated, especially any previous similar experiences on other Sennheiser 816s.

DAY 9

First new location other than the Old Fremantle Prison, the top floor of the Playhouse Theatre in Pier Street, Perth. This is serving duty as the "boardroom".

They shot a scene today which demanded greatly of the two actors playing "Terrence" co-owner of the illegal fight club and trotting track and "Leelu", widow of "Jonathan" and who now has a renewed bond with a principal character, "Justin".

I shot some AGUS35 shadow footage of the reverses and will post these shortly to the new project at savefile I have generated relating to "THE CAGE" the movie.

The lighting was plenty for the JVC HD but only just enough for the FX1 via the AGUS35 setup. A full 18db of gain was needed. I shot it with the factory default PP4 selected which gives "cinelook" and an ersatz 25P.

The images are grainy in this lighting environment with the 18db selected.

Lighting as I remember it consisted of a 1000w "blondie", 2 x 500w halogen bar lights on stands ("Lowell" I think?), with masks and a coloured flouro tube for a blue cast from one side.

I have the blessing of the director to post samples from my footage of the shoot.

This is limited to Windows .bmp frame grabs for the present. These can be found at :-

http://www.savefile.com/projects/618011

DAY 11

I got to try the system out in an exterior lighting situation. It works quite well in an organised lighting environment. Despite +18db gain selected, there was no video noise? It seems a high contrast environment keeps the video noise down.

Lighting was 1000w "blondie" key, 2 x 500w industrial halogens fill, 500w Lowell backlight.

I will be trying to get a half-size H264 Quicktime file of an assembled scene uploaded tonight and will edit this post or add another if successful to advise the savefile address.


FOOTNOTE:

Furthur to above, the clip was successfully uploaded and can be found directly at the following address :-

http://www.savefile.com/files/4071292

This clip as shot as shadow footage via an AGUS35 motion picture film emulator on a Sony HVR Z1P. I do not have current HDV edit-assmebly software so the clip is derived from DV standard transcode and capture as MiniDV.

Viewers are warned that whilst the video clip does not itself comprise of events of injurious physical assault or contain obscene language, it does credibly depict a situation of duress and threat.

The clip should not be regarded as representative of the actual production camera footage or the intended style, edit and final production values of the movie project. "The Cage".

Appreciation is expressed to the director, Morton Willoch and actors, Dein McAskil and Tracy Baker for permitting me to harvest and present shadow footage of their performances.

For anyone building PVC pipe versions, I received the widescreen prisms today. I have yet to make up the new mount plate and to bond the prism pairs. Once this is tested, the altered design will be posted at savefile.com

Slightly Off-topic PS

Go to TOTEM POLE at the bottom of the main dvinfo page and look for :-

"The quest for a Century Optics CE-AD5870"

An interesting phenonomen observed last time I was shadow shooting at the Cage location with the Sony HDV.

The lighting environment was indoors, fairly confined space so everything was lit fairly evenly. Lighting was 1000w key, 1000w masked fill, two x 100w relector downlights in photoflood housings.

The lens was Sigma for Nikon f1.8 20mm prime. To get acceptable exposure from available lighting, the camera gain had to be +18db for a shutter of 1/50sec.

I discovered that compared to operating outside in bright daylight, the camcorder zoom can be retreated furthur and pick up a larger area off the groundglass without the hotspot becoming apparent.

This gives some flexibility for framing and also allows by zoom-back from the GG, a better resolution for wide shots where sharpness matters.

Unfortunately, it is not a consistent feature one can rely on.

I am totally confounded with this one. All I can assume is that the camcorder's internal aperture as something to do with it.