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Old June 2nd, 2006, 12:30 PM   #1396
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For the wider prisms, I found that in being able to go a little wider with the zoom, that the camcorder is now too low by about 1.5mm and picks up the edge of the groundglass disk in the corners.

Moving the camcorder lens axis 1.5mm to 2mm vertically brings the bayonet mount into the edge of the pipe cap which has to have a clearance cut away. The inner face of the cap also has to be kept about 2.5mm out from the image tube end otherwise the bayonet fitting fouls against it.

The SLR lens mount may have to be moved the same amount downwards to compensate for the shift if the SLR lens centre is already too high.

If the SLR lens mount centre was originally correct, the 1.5mm does not seem to make much difference unless you want to go really wide and live with the corner falloff or bury it with dark image areas.

The disk in the new device is a rework of an old glass disk which got scratched on the end of a self-tapping screw in the prsim block which I forgot to trim off.

The aluminium oxide 5 micron was overworked but this time no partial backpolish was done. This seems to cost apparent resolution but the return from the Lemac chart is the same for the backpolished version.

I think this is due to the wider frame now available off the groundglass for the same framing into the camera of the chart.
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Old June 3rd, 2006, 08:21 AM   #1397
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Bob,

I am trying to improved the image quality of my adapter by using an achromatic diopter as advised. Century Optics is too expensive for my budget but I found some Canon achromatic diopters which is affordable. Can you give an advise which one of these is best suited for my adapter set-up. Here's the bhphotovideo link:

Canon 250D achromatic diopter:

http://www.bhphotovideo.com/bnh/cont...ughType=search

Canon 500d achromatic diopter:

http://www.bhphotovideo.com/bnh/cont...ughType=search

Thanks in advance.



Julius
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Old June 4th, 2006, 03:04 AM   #1398
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Julius.

I can't speak for the Canon lens with authority as I have not used it. Comments on the web favour this lens in terms of quality for the task it is intended, a high quality close-up lens for still-cameras.

I did find comment on one website that the lens was in effect 4+ lens or thereabouts.

If it is a 4+, for the 24mm x 18mm 35mm movie frame, I don't think it will be powerful enough. The camera on full zoom may not frame tight enough and you will likely get an image with a hot spot because the frame may be in the ballpark of 40mm x 30mm but I am really only guessing here.

In my original testing for the PD150 which is optically similar to the VX2000, I used an inexpensive three lens in one pack set. This was a 1+,2+ 4+ and stacked you got 7+.

The stack was the only magnification power that worked for my setup.This stack of lenses however causes a real problem with chromatic aberration because they are only single element optics.

The front element of the VX2000/PD150 lens is 52mm diameter. I used the optics out of a 50mm 2" telescope eyepiece which had a diameter of 44mm which just worked with the camera at about 80% zoomed in but these don't come cheap either.

If you can't find a cheaper 7+ acromatic dioptre which will mount to the 58mm filter tread, you may find one with a smaller diameter. As long as it is no smaller than the 44mm I used, it may be okay with a step-up ring to the 58mm.

There is a chance however that there may be a ring shaped defect out towards the corners of the image as the telescope lens set does this with the FX1 which uses more of the groundglass image width than the PD150.

I am not a lens technician so my thoughts on the matter have no validity beyond what lenses I have offered up to my camera and find worked or not.

A 5+ may get you coverage of the 36mm x 24mm??? still-image film camera frame. This size is favoured by the builders of static grounglass devices as the grain or texture of the groundglass is smaller in proportion to the size of the image so resolution is better and the grain artifact is less evident.

At this groundglass image size, builders start talking of hot spots or edge falloff and condenser lenses which even out the lighting across the frame.

I'm sorry I cannot help you with this beyond what I have found is workable for me.

Iv'e done a bit of hunting around and it seems the Century Optics +7 may be the only game in town though the beta 72mm +10 achromatic mentioned on this site looks interesting.
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Old June 4th, 2006, 05:35 PM   #1399
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Quote:
Originally Posted by Bob Hart
I observe you have the disk motor above the lens centreline. This is a working solution for the non-flip version but might add to a sound problem as any motor noise is more in-line with the mike pickup pattern and also may tend to mask off the mike from your sound source.

If you use a separate mike, then this is a non-issue.

Sorry to ask this, but is there anyone in this "HDV room" that is picking their main audio from the on-camera mic position? Please don't tell me there are...

But the motor noise may be an issue even if the mike is closer to the source and the room is really silent.
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Old June 4th, 2006, 11:11 PM   #1400
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Mea culpa.

Presently, I am shooting footage alone for the "special features" section for "The Cage" in between doing other tasks as crew. This means I have to put the camera down and pick it up as opportunity permits and use the on-board mike.

At 1/50th second shutter and with the disk motor on 1.5v the speed is about 1200 - 1500 rpm, more than fast enough to dissolve the grain on a 5" 120mm disk but slow enough to keep things quiet. A glass disk may be more noisy as they are hard to balance. A plastic disk should be okay.

If the motor rattles a bit, perhaps put a drop of auto-transmission oil on the bearing. If it rattles a lot, perhaps try to fit the thrust bearing from the CD player the motor came from.

That is the part which drops down onto the CD after it goes into the CD player. The thrust bearing is only a nylon tit which bears against a smooth metal pressure plate under spring pressure.

I didn't bother as it is a hassle to extract and fit exactly. It also interferes with my backfocus ajustment which on my device moves the entire motor/mount/disk assembly.

An alternative is to remove the spindle hub from the motor without breaking the spindle. You have to do this by getting something underneath the centre of the hub right against the shaft and not pulling on the rim because this will bend or break. A piece may come off the inner neck of the hub but it will still be usable.

I trim off this section anyway because I don't use the original spindle motor but instead use the tray actuator motor or the tracking motor. These motors have a shorter shaft. On the older CD players and DVD players, the motors are identical except for the shaft length.

The tray actuator motors are best. Because they have not been in constant duty in the player, they are less worn and are quieter. The shorter shaft and trimming some of the neck of the hub off means the disk mass can be set closer to the front of the motor.

Any out-of-balance state in the disk has less leverage on the motor therefore less vibration to the case.


In a serious production environment, I would not use the on-camera mike except to create a reference audio track for syncing up later to a separate double-system audio recording.
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Old June 5th, 2006, 04:00 AM   #1401
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Quote:
Originally Posted by Bob Hart
In a serious production environment, I would not use the on-camera mike except to create a reference audio track for syncing up later to a separate double-system audio recording.

Of course your wouldn't. And of course no one should.

You just mentioned the only thing an on-camera mike should be used for, which is for reference audio.

Double-system is indeed the best way to go.
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Old June 17th, 2006, 01:44 PM   #1402
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"The Cage" wrapped today with a good fight scene where Justin is mobbed by three thugs on his way from the train station. Of course he puts them onto the ground in a state of disintegrity.

My shadow footage was not so good today. I was using the 12mm-24mm Nikon lens to enable wide-angle coverage from the boom swinger's position when opportunity permitted. That was my primary occupation for the day. The lighting became a thin high light overcast.

This is the condition which aggravates any flickering tendency with this lens. I had also changed the design and perhaps should have left best alone until this project was complete as the behaviour of the appliance has changed, for the better in some respects, worse in others.

I adapted the old appliance to fit the JVC HD100 on front of the standard lens. The 82mm filter mount on the lens appears to be metal but I think it is plastic. It is not ideal as the 0.7mm thread is easy to crossthread and damage. Some sort of quick release arnangement would be better.

I tried a clamping style of mount onto the lens hood mount around the outside but this causes interruption to the movement of the focus adjustment as the mount distorts enough under compression to bind on the lens body.

The Century Optics +7 dioptre workson front of the standard Fujinon lens but the zone of available sharp focus range onto the groundglass is very much narrower than for the PD150 and FX1.

I think it may be because the focus adjusment physically moves the front of the standard lens forward or backwards and the dioptre moves with it. An image of sharpness comparable to the FX1 ca be had.

Certain combinations of primary focus, camera lens backfocus and zoom can cause the outer zones of the image to become soft in the relay stage. It also performs better if the groundglass image is framed somewhere near midway between the 24mm wide image and the 30mm wide image.

The camera owner also has Les Bosher's Nikon SLR lens adaptor. So we tried the 14mm Sigma f2.8 and the Sigma 20mm f1.8. These work well on it as alternatives to a wide adaptor on front of the standard Fujinon.

The Nikon lens locking pin release button on Les Bosher's adaptor is initially baulky but with practice becomes easy to operate.

The long and arduous road of post-production now begins.

The JVC HD100 camera has been trouble free for the entire shoot. It now goes apparently offshore on another documentary adventure.

"The Cage" hopefully reaches completion in about 6 months time.
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Old June 18th, 2006, 05:19 AM   #1403
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My Mini35 is completed.

Hi all,

Wow! its been a long time since I last posted here and to be honest not sure how much I have missed. Great to be back though. Anyway, if it isn't old story yet, I managed to finish my mini35 using rotating ground glass instead of ground CD. Will be testing the device and see how the video turns out. I left this project in my drawer as I couldn't get a good ground cd. Just a week ago, my bro got excited about videocam and how to get the film DOF look. I told him I had the mini35 built a year ago and its left in my drawer. I took it out and just out of the blue, the idea of getting a round piece of clear glass sprung to mind. I bought the disc today (its off a cheap table clock) and grounded it and it tested well without my DVcam. My DVcam is in the shop due to defective CCDs. I will be posting some pic here in the next couple of days and see if anyone has any comments.

Lately I have looked at two alternatives to the P+S mini35. Its the M@ or Micro35 from REDROCK.COM and the one from GUERILLA35.COM. I think the M2 is much better at USD995. Anyone has any comments on these two mini35? I wouldn't mind getting a set as it is properly built.
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Old June 18th, 2006, 05:35 AM   #1404
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Quote:
Originally Posted by Bob Hart
For the wider prisms, I found that in being able to go a little wider with the zoom, that the camcorder is now too low by about 1.5mm and picks up the edge of the groundglass disk in the corners.

Moving the camcorder lens axis 1.5mm to 2mm vertically brings the bayonet mount into the edge of the pipe cap which has to have a clearance cut away. The inner face of the cap also has to be kept about 2.5mm out from the image tube end otherwise the bayonet fitting fouls against it.

The SLR lens mount may have to be moved the same amount downwards to compensate for the shift if the SLR lens centre is already too high.

If the SLR lens mount centre was originally correct, the 1.5mm does not seem to make much difference unless you want to go really wide and live with the corner falloff or bury it with dark image areas.

The disk in the new device is a rework of an old glass disk which got scratched on the end of a self-tapping screw in the prsim block which I forgot to trim off.

The aluminium oxide 5 micron was overworked but this time no partial backpolish was done. This seems to cost apparent resolution but the return from the Lemac chart is the same for the backpolished version.

I think this is due to the wider frame now available off the groundglass for the same framing into the camera of the chart.
Hi Bob,

Looks like you have managed to make the image upright. Any shots of your mini35? Would like to see how you manage to do it. I have done one as well using the mirror and prism of an SLR camera. I built a casing out of plumbing pipe end caps. The only problem is that the image is so small and my DV cam has to zoom in so much that the angle of view is reduced. I think I may need to use a wide angle lens to compensate for this but have not tried as i don't have a wide angle lens.
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Old June 19th, 2006, 09:27 AM   #1405
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Alex.

The field of view available from the SLR camera viewfinder is really too small. As you mention by the time you get zoomed in past the confining edges of your prism/optical path all you have left is a very small centre image.

My current version uses the following :-

Nikon f1.8 lens >> groundglass >> two x 45mm x 45mm x 62.8mm prisms of 32mm common thickness across all faces. These are set up like porrorprisms in binoculars. >> 7+ Century Optics achromatic dioptre >> camcorder.

The prisms sit in 90 degree opposition which flips the image. One half of the hypotenuse of one prism covers one half of the hypotenuse face of the other. The uncovered half of one prism lets the image in. The uncovered half of the other prism lets the inverted image out.

The prisms are clamped onto a cylindrical shaped block about 10mm thick and rest in channels milled out of the block which is phenolic board.

The cylindrical block prism combination will just fit inside a 100mm PVC pipe and still allow the fit of a Nikon lens mount on one pipe cap at the front end and the camcorder lens hood mount on another pipe cap at the rear end, to fit and still allow true parallel centrelines from SLR lens to camcorder lens.

The FX1 lens hood mount has to be hard against the edge of the cap and about a 0.7mm clearance has to be milled or engraved out of the inside cylindrical surface of the cap to allow the bayonet lug to turn as the camcorder is mounted to the device.

I have not yet redrafted the design to show the new parts. I had the old 40mm x 40mm x 56mm x 40mm common thickness prism design up at savefile.com as a .pdf file but it might have timed out by now. If you want the old design as a general principle guide, send me an email with an email address I can send an attached file to and I'll send it.

The design uses a full CD sized disk. The outer edge comes within 0.5mm of the side of one of the prisms.
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Old June 20th, 2006, 08:09 AM   #1406
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Hi Bob,

Thanks for the explanation. I have just emailed you with my email address. Thanks for the info.

Alex
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Old June 24th, 2006, 02:37 PM   #1407
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They had the wrap party for "The Cage" in Nedlands tonight (last night actually). I think there may be a few sore heads and some late risers well after the sun comes up.

They have assembled a quick trailer for the party and althoug it was at much lower res than HDV and it was framed small on the projection screen, the action was a treat to watch.

I also got to see some of the "special features" footage I have been shooting on the modified AGUS35 projected on a large wall for the first time.

At its best it looks good and seems as sharp as direct-to-camera origination but has much less contrast and faded colours. However, when the SLR camera lens focus is even slightly off, at projection magnification, it then looks dreadful.

The flicker which comes from using the 12mm-24mm f4 Nikon in a bright high-contrast outdoors environment was much less apparent and the image from this was surprisingly sharp, given that it is a zoom lens.

What also became very apparent as that some footage shot with the same lens, groundglass and camcorder combination but of a smaller 24mm image off the groundglass was much softer as projection than later footage shot from a wider 30mm image after I had replaced the prism block.
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Old July 5th, 2006, 01:55 PM   #1408
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quality of the image

I don't see the sharpness in the image. The idea of the adapter is to have a sharp image as you do when not using the adapter, but yet have the ability to control the D.O.F. I don't see the sharpness in your image, perhaps it has to do with the the fact that we are seeing it on the computer screen.



Quote:
Originally Posted by Agus Casse
Brett,

We are all interest, show up the design.

Btw, i have been editing the footage of my short feature, and damnit looks awesome...

Here are some pics.

http://altoque.tv/35mmAdapter/DE35MM19.jpg
http://altoque.tv/35mmAdapter/DE35MM18.jpg
http://altoque.tv/35mmAdapter/DE35MM17.jpg
http://altoque.tv/35mmAdapter/DE35MM16.jpg
http://altoque.tv/35mmAdapter/DE35MM15.jpg
http://altoque.tv/35mmAdapter/DE35MM14.jpg
http://altoque.tv/35mmAdapter/DE35MM13.jpg
http://altoque.tv/35mmAdapter/DE35MM12.jpg
http://altoque.tv/35mmAdapter/DE35MM11.jpg
http://altoque.tv/35mmAdapter/DE35MM10.jpg
http://altoque.tv/35mmAdapter/DE35MM9.jpg
http://altoque.tv/35mmAdapter/DE35MM8.jpg
http://altoque.tv/35mmAdapter/DE35MM7.jpg
http://altoque.tv/35mmAdapter/DE35MM6.jpg
http://altoque.tv/35mmAdapter/DE35MM5.jpg
http://altoque.tv/35mmAdapter/DE35MM4.jpg
http://altoque.tv/35mmAdapter/DE35MM3.jpg
http://altoque.tv/35mmAdapter/DE35MM2.jpg
http://altoque.tv/35mmAdapter/DE35MM1.jpg
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Old July 5th, 2006, 02:12 PM   #1409
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It looks to me as if either the GG-to-35mm lens distance is off, or the 35mm lens being used is extremely soft at the aperture settings being used.
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Old July 5th, 2006, 02:12 PM   #1410
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double post
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