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Old November 1st, 2006, 03:26 PM   #31
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Yeah, both Brevis and Redrock do an HD imaging bundle...be interesting to see a "shootout" between these two.
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Old November 3rd, 2006, 05:34 AM   #32
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M2...

got my M2 today. It's an astonishing piece of kit. Very well made, and in the flight case more professional than Professor Professional, head of professional studies at the University of Professionalism in the town of Professionalberg located in the state of West Professional.

Initial observations compared to my Letus Flip (I must point out there is still a possibility my flip is faulty but as I have had no success in proving or disproving this and after talking to other people with similar problems it may just be the design of the adaptor, in particular the GG and the motor...) IT IS TERRIFIC. Beautiful, crisp, sharp images. NO GRAIN...if I stop right down, and I mean right down you can see the circular lines of the GG in the sky, that's it. Yes it is upside down but with the magnet trick it's fine (although I now cannot use my viewfinder, just lots of using my expanded focus). But the image quality is about 100 times better as far as I can see. I can easily mix these images in with non adaptor stuff no problem.

I am hoping to get my hands on a Brevis in the next week. When I do I will do a direct comparison of all three.

By the way I ordered my Redrock on Monday, received it in London on Friday. Now that is fast!

Phil
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Old November 4th, 2006, 09:05 AM   #33
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Have done some mods on a LetusXL Flip to hopefully deal with the "film of grain issue".

Mods are :-

CD player tracker motor, smaller one, not the mabuchi style motor.

Eccentric weight, 18mm diameter, 2mm thick, 0.7mm countersink on centre hole to allow clearance for set back onto shaft over where the bearing in the motor case sticks out.

The weight is styled after a 180degree shutter, ie., a half-circle. A short section of the black plastic worm drive (screwjack) for the tracker is retained on the motor shaft to mount the eccentric weight on. It is too hard to get a right-size fit on the shaft otherwise

The largest (centre) of the three holes on the side of the groundglass carrier where the original motor is mounted is widened equally to allow a snug fit of the tracker motor which has to be glued in.

There is not enough space front to back for the motor to fit in between the front and the rear and about 2mm has to be trimmed from the end of the shaft with a small cutoff wheel on a Dremel. The motor is glued into the carrier.

The soldering contacts on back of the motor actually have to straddle the lip on the front section which the pillars are mounted into.

The eccentric weight operates behind the groundglass carrier, not in front of it like the standard setup with the smaller motor.

If there is too much clearance, then the weight on the motor shaft will touch the rim of the condenser lens at the rear of the groundglass enclosure tube.

The shaft itself whilst not touching anything will touch the condenser rim once the orbiting motion commences which is why it has to be trimmed.

The dropping resister on the original smaller motor is not used.

The groundglass excursion at approx 3000rpm is about 1.5mm and circular. When starting and stopping, the outer rim of the carrier will make contact with the tube enclosure however this is momentary.

The rubber ends on the front ends of the pillars need to be secured with contact cement. (Quick Grip) to prevent them from working their way out of their holes.

The noise level in operation is louder and an on-camera mike is not an option.

The test clip at the address below has been shot on a Canon XL1 in a manner to provoke the worst performance. 1/400 sec shutter to start with. An artifact will be seen in the sky. Captions on the clip tell the rest. At the end of the clip is a Lemac test chart.

The clip is a m2v file which should play on Power DVD. It is a large file.

http://www.filefactory.com/file/4b0bf1/


The mods are not for the faint hearted and fine engineeering skills are required.

FOOTNOTE: Filefactory has rejected the file for some reason.

I will load up a Divx file but the res on this is not so good.

Divx file is here :-

http://www.filefactory.com/file/fe57fd

FURTHUR FOOTNOTE: This one doesn't work either so there it goes.

I'll give it time for things to change. Maybe it takes a while for the files to be checked or something.

Last edited by Bob Hart; November 4th, 2006 at 10:05 AM.
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Old November 4th, 2006, 12:34 PM   #34
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Quote:
Originally Posted by Bob Hart
The mods are not for the faint hearted
Hmm. Maybe I shouldn't attempt this then. I turn pale and blackout at the sight of trimmed plastic :)
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Old November 4th, 2006, 01:39 PM   #35
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The biggest hurdle is extracting the original small motor without damaging it as the adhesive has to be carefully trimmed away, then the connections unsoldered. I wanted to be able to reinstall it.

As for the rest of the task, a small keyhole file is about all that is needed to reshape the larger hole of the three on the carrier. The larger motor has two flats pressed on the case.

The eccentric has to be turned up as a complete 18mm diameter disk on a lathe, then the waste half less the centre hub cut away in four hacksaw trims then filed to a tidy finish.

Beyond that, provided no damage is done, the original arrangment can be restored. However, ability to work to fine detail and not damage things is required.

I'm not entirely satisfied the fixed pattern has completely gone. I am also beginning to suspect that the mpeg2 codec may have some sort of memory effect on low contrast soft objects it finds in an open clear area of image. On a pan across sky, these might endure across several GOP groups.

I have seen something similar with my own device and that is a full CD-R disk size GG. Distant trees across a valley in a slightly darker triangle of side gulley momentarily did not move when I panned across them, then they jumped into place.

On the .avi file I have only seen artifacts in the sky areas in the 1/400th sec shutter footage. In the m2v file, on playback, there is a fine fixed pattern on the test chart at slower shutter speed.

Because this test was shot on MiniDV SD, there should not be any mpeg2 artifacts but they are there in the mpeg2 exported for web posting.

The truth will out as to the original camera footage when I get to see it on a HD monitor next week.

With the increased movement, things like specks of dust on the GG are no longer a problem.

The files uploaded to File Factory are in the index but when I try to access them by the links here, they are not available for download. If anyone has any ideas on how to set them free, it would be appreciated.

This is the message in red letters I get :-

"Sorry, this file is no longer available. It may have been deleted by the uploader, or has expired." - Yet the files are still there in the index.

FOOTNOTE:

File factory must have a problem or my computer does because now, the upload screen simply does not come on when selected.
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Old November 5th, 2006, 02:03 AM   #36
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The clips referred to in the post above have now been fixedso can be accessed.

The one titled "sequence01" is about a 40mb file and best represented the image quality. The divx file goes soft where the artifacts are present and is sharperwhere the image is best.

An addendum to a post I made some time back about the assembly within the Letus35 XL flip front tube enclosure.

In my wisdom or lack of it, I incorrectly referred to the groundglass screen being groundglass surface to front and motor to top left.

I had forgotten that in initially working on this specimen,I had mounted it in a soft vice for re-assembly, upside down and front to back as I was adding screws to the joints and drilling and tapping the screwholes.

The device had been at one stage in three pieces before I brought it home to fix it and I had to refer to Quyen's website to find an illustration of its correct re-assembly.

----One of many reasons why little heed should be paid to my ramblings.
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Old November 5th, 2006, 01:34 PM   #37
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Bob...you are a genius. Unfortuantely I am not!

Can I send you my Letus, will pay you 100 plus parts and shipping!!!

Love to know how you got on with the HD monitor!
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Old November 5th, 2006, 08:27 PM   #38
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Phil.

It is early days yet.The jury will be still out until I can get my hands on the XLH1 to look for bads in HDV format. That won't happen before tomorow.

I don't know about genius. It is one thing to find an orphan oddsized motor in the ice cream carton and fit it. It is another to source new motors of the same type.

This could well be why Quyen uses the small vibrator motor - availability. You can get anything you like it seems from OEM manufacturers, then comes the tricky question - how many sea-container loads? - You reply "Errr, no container, only just fourteen off plus a spare", then wait for the horse laugh.

So you have to find a middleman or a production run on an obselete mass-produced product coming to a close, then see where their surplus stock has gone.

Quyen also seems to have kept his options open in the design with three different sized holes in the motor mount area of the groundglass carrier, a large one in centre, a smaller one to one side of centre and a smaller one to the other which is the current location of the small motor.

I'll keep you informed as to the XLH1 tests.
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Old November 7th, 2006, 06:46 AM   #39
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I didn't get to shoot a test on the XLH1 as it is otherwise gainfully employed however I did shoot some more SD on the XL2 and looked at it on a high resolution production monitor.

Whilst the soft freckles from the GG are well gone, a background fainter "film-of-grain" fixed pattern artifact remains. Some more testing yet to be done to eliminate the GG as the cause.
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Old November 7th, 2006, 09:26 AM   #40
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I just wanna say u guys r truly doing folks like me a great service for sharing the problems. I'm looking at the M2 for my FX1 too. The Brevis is something new which I can consider for the same price point. Hope to see the comparison in the light loss department especially... THANKS!
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Old November 7th, 2006, 10:19 AM   #41
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A few of the dvx'ers did some work with a Brevis beta and the M2...clips are not active any longer, however I should have these somewhere.
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Old November 14th, 2006, 09:30 PM   #42
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Some furthur testing with the larger motor and weight.

There remains to a lesser degree a fixed pattern artifact. When I stepped the shutter speed up to strobe the groundglass, the orbital pattern has remained elliptoid and remains canted to the left slightly as was the original smaller excursion.

In an earlier post, I had referred to the excursion having become more circular with the extra horsepower and weight. Of course it was, because I had viewed the television set as a strobe and invalidated my research by holding the appliance upright so the light from the CRT would fall on it.

Given the motion remains elliptiod I am convinced the fixed pattern is related to the much slower surface motion which occurs at the end points of the elliptoid excursion.

I am furthur encouraged in this direction by subsequent tests I did with the groundglass removed to see if the optical path alone was generating the fixed pattern. I could not observe any fixed artifacts on the high resolution monitor. This is not to say there aren't any but I could not find them.

Two possible solutions come to mind.

One is to over-drive the excursion with a heavier weight, then limit it to a circular motion by adding fixed pillars to the front of the case which supports the existing moving pillars. On the fixed pillars would rest sleeves which have a very wide clearance both in the groundglass carrier and the pillars.

This method is used for locating and driving caterpillar tracks in a hostile no lube environment. Because of the excessive clearance, the motion is converted to a rolling motion across frictional surfaces rather than a rubbing motion.

The downside is that the motion would become noisier. Think bulldozer or army tank in high speed miniature and you may get the picture. With insulation around the front tube, I think it could be resolved.

At high speeds there likely will be all manner of harmonics and random motions as well as the truly circular ones. There is some randomness in the existing Letus movment which may be why I have been able with some lenses to push to f22 with none other than the fixed pattern artifact turning up.

Another solution might be to add some tension springs to counter the gravity loading and restore the circular motion. These will also serve to maintain added positive retention of the pillars in the front cover.

This has not emerged to become a problem I thought it would with the more violent excursion I have been experimenting with.
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Old November 15th, 2006, 10:54 AM   #43
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i would love it to all work beautifully. the letus fe has the potential to be a cracking adaptor. Just that film of grain and a proper solid nikon mount would be great. hated the flimsy one. the one of the m2 is so solid
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Old November 20th, 2006, 07:05 AM   #44
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I'll be taking a four week break from any experimentation with improving the Letus35 for HD as I have a demo scene to organise and shoot this coming month plus earn the daily bread.

My imaginings of promoting a more circular orbit of the GG is to start with two fine coil springs of about 1/8" diameter such as you find in old copiers, printers or Lexmark Optra S1250 toner cartridges.

The attach points on the groundglass carrier would be midway on each side. The anchor points would be to pins in radius holes bridging the upper cutout space on each side of the upper pillar in the front (base) which holds the base of the pillars.

This method may provoke a "figure of eight" motion of the groundglass which would require more countermass below the motor on the groundglass carrier to counteract.

"Figure of eight" would create an almost stationary spot somewhere on the groundglass which would appear as a very evident patch of fixed pattern.
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