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Old December 5th, 2008, 09:02 AM   #31
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Furthur to the above posts I have fitted up the Sigma for Nikon f1.8 20mm. This has an 82mm filter thread and the 82mm ring for the JVC Fujinon lens will fit right in.

Just be careful as like the Fujinon and many camcorders, the lens filter thread and the body is plastic so you should avoid sideloading it. You will also find that the Les Bosher mount has to be taken from the camera and fitted up to the lens.

The bits and pieces inside the back of the 20mm come up firm against the inside of Les Bosher's mount and it is a snug and fiddly fit, more easily done with the mount off the camera.

On a HDTV, the very corners of the groundglass texture can be seen to be very slightly softer. The image area is very close to still-camera frame.

As previously mentioned, a non-modified Extreme may show an edge, probably the right and you may pick up the left as well.

When relaying with the 20mm, you get a wicked wide view with a 14mm f2.8 prime of the Nikon, Sigma or Tamron flavours. As the 14mm is a rectilinear lens, there is distinct corner stretch at this frame size.

Sharpness is adequate wide-open but it works better at f3.5. You will get brightness fall-off in the corners.

The Sigma f1.8 20mm lens flares wide-open and has to be at f2.8 before it goes away. This leaves little headroom to the f5.6 limit.

The 35mm and 28mm f1.4 lenses flare wide-open and should be regarded as adequate at f1.8 and better at f2.8.

The 20mm lens body is the longest of the lenses tested. Versus the standard Fujinon zoom, it saves you about 68mm in length and loses a bit of weight. The other lenses are shorter. The 35mm saves you about 91mm in length plus any distance stepdown rings may add if they do not all assemble to a common flush face.

Last edited by Bob Hart; December 5th, 2008 at 09:23 AM. Reason: added text
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Old December 5th, 2008, 08:10 PM   #32
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Furthur Update

Furthur to the above posts, Ted Ramasola has done some additional testing and finds that the stock Fujinon lens remains the best overall performer versus 35mm stills primes as substitutes.

The slight gain of a shorter combination does not outweigh the realities. Mass produced consumer 35mm stills lenses cannot be expected to yield a superior result to the professional purposed lens of the JVC, albeit also made in relatively high volumes.

So there it is.

The detachable lens style 3xCCC/CMOS cameras present unique challenges to lens makers, a known fact. Home hackers have hit a wall on this task, which requires the skills and R&D resources of optical engineers to solve.

Quyen, Hien, also Dennis, Wayne and Brian may be quietly observing this highly public exercise with wan sympathetic smiles on their faces. Perhaps they are having a quiet laugh into their coffee cups, a privelidge they have earned, reminded that they have been on the same difficult journey.

So my recommendation is to remain patient. Give them time to get their solution sorted.

They have to be able to offer something that outperforms and is more convenient than the standard lenses for these cameras, which means optical engineering of equal or better quality. That comes neither at mass-produced consumer prices nor at off the shelf convenience in the form of a product which can be re-purposed.


The TV program "Mythbusters" must be a fun thing to do.

Last edited by Bob Hart; December 5th, 2008 at 08:20 PM. Reason: error
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Old December 6th, 2008, 01:20 AM   #33
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Furthur update

Original post died on its bum so this is a quick recall of it.

Test of the Sigma for Nikon f1.8 20mm yields similar results as the other two lenses. The view is wider. Flare reduces the utility of this lens to f2.8 and no wider for relay.

Zebras must be used to keep overblown highlights in check.

The wide 14mm f2.8 lenses exhibit corner brightness fall-off and extreme corner stretching. The longer f1.8 and f1.4 lenses are fine.

Relay focus is harder to set via the viewfinder or LCD screen as the groundglass texture is scaled really fine.

Interiors shot to indoors lighting are killed by flare from any hotspot beams on floors or windows burning out.

With only about three f-stops of headroom, the utility of stills lenses for relay is to be questioned compared to the standard Fujinon which comes with the camera and is made for it. So as mentioned above the purposed relay lenses from the vendors should be patiently awaited.


I fitted the standard Fujinon back onto the camera and then offered up the Letus Extreme via the 82mm adaptor ring. It fitted up with no problem.

As previously mentions, this Extreme has the special EX1 achromatic dioptre installed. I found as have some others have reported previosuly, some difficulty in getting a good relay focus. I removed the EX1 dioptre from the Letus body and into the optical path, substituted a Century Optics 4+ 58mm filter mount achromatic dioptre with a 72mm ring on it.

I installed this to the Fujinon lens within the front of the plastic anti-reflection cone, the same hack as with my own AGUS35. The 72mm thread just bites enough into the shouders of the ribs to hold it. The rear flange face of the dioptre is exactly on line with the front edge of the rim of the rotating focus barrel of the Fujinon. Even closer to the front glass of the Fujinon might be even better but I did not experiment furthur.

I found that with the Fujinon focus set just under halfway between 1 and 1.2 metres and 37mm clearance between the flat face of the Letus rear body (not the rear edge of the achromat rim) and the front edge of the fixed shroud around the Fujinon lens (hood removed), workable sharp focus on the groundglass could be achieved.

With the re-centered and widened path in the modified Extreme, the zoom can be backed off to 20mm before the edge of the path comes in. With an unmodified Extreme with a fixed prism, I expect that the zoom may possibly still be able to be backed off to between 28mm and 35mm before an edge comes in depending upon the centering of the prism and the camcorder optics and their interaction.

Now all I need is an SI2K for about three days. I already have the hack together for that.

Last edited by Bob Hart; December 6th, 2008 at 04:35 AM. Reason: added footnote
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Old December 6th, 2008, 07:51 AM   #34
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Frame Grabs From Last Test.

Here are some low quality grabs from JVC footage via SD DVD recorder - firewire port broken on JVC.

Frames are described as laid out :-

1 2
3 4
5 6

1 - 20mm relay of 35mm prime lens.

2 - 20mm relay of 14mm prime lens.

3 - 20mm relay of 85mm prime lens.

4 - 20mm relay of 85mm prime lens.

5 - 20mm relay of 28mm prime lens. Exposed for exterior natural lighting. (Table number stands are head positions for my intended actors.

6 - 20mm relay of 28mm prime lens. Exposed for interior. Note blue flare across window frames and overall smokey look.

7 - 28mm relay of 105mm prime lens. Note blue flare on car roof.

The location of frames 1 to 6 is The Elizabethan Village, 23 Cannes Road, Bedfordale, about 40 minutes drive south from Perth City, Western Australia. It is a precinct which replicates a tavern William Shakespeare apparently visited and Ann Hathaway's Cottage is replicated nearby.

For a pre-production promotional trailer, I hope to use the building as a representation of a tavern or tourist pub in the former Macedonia by adding a few artifacts and signage and restocking the bottle shelf with authentically labelled product.

If you happen to be in Perth and go out there for a good feed in the restaurant, tell the management I sent you but please be on your best behaviour.

Not far up the road was a replica of late prolific Mills and Boon novel writer Barbara Cartland's "Camfield". The landholding has now been cut up and developed as houseblocks. I don't know if the original residence is still available for public access.

The location for frame 7 is the Jull Street retail dragstrip in nearby Armadale, about 40 minutes south of Perth City in Western Australia.

No colour grading has been done in post. The images are ex camera via DVD recorder, converted in AspectHD, framegrabbed and converted in MSPaint to .jpg for upload. Camera was set up with Paolo Ciccone's Truecolor V3 with exception of detail being reset to "normal" for this test otherwise it was too hard for my weary eyes to see if things were in focus or not.

Here is a link to some vision of the 28mm and 20mm as relays :-
Attached Thumbnails
Roiding The Extreme-letus-direct-relay-20mm-f1.8-sigma-nikon-03.jpg   Roiding The Extreme-letus-direct-relay-20mm-f1.8-sigma-nikon-04.jpg  

Roiding The Extreme-letus-direct-relay-20mm-f1.8-sigma-nikon-05.jpg   Roiding The Extreme-letus-direct-relay-20mm-f1.8-sigma-nikon-06.jpg  

Roiding The Extreme-letus-direct-relay-20mm-f1.8-sigma-nikon-07.jpg   Roiding The Extreme-letus-direct-relay-20mm-f1.8-sigma-nikon-08.jpg  

Roiding The Extreme-letus-direct-relay-28mm-f1.4-nikon-03.jpg  

Last edited by Bob Hart; December 6th, 2008 at 09:41 AM. Reason: upload of pics and link to vision
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Old December 9th, 2008, 09:47 AM   #35
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Sont pmw-ex1 - letus extreme - trucolor v2 trial

In a few idle moments, I decided to try a published profile for the EX1 which can be found in the XDCAM EX forum here.

Below is a link to a very short clip of those shots. There are some stills in the sticky post in the XDCAM EX forum.


There was also a piece of two-stop neutral density filter gel in the path between lens on front and the groundglass.

Last edited by Bob Hart; December 9th, 2008 at 09:50 AM. Reason: added text and corrections
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Old December 18th, 2008, 11:32 PM   #36
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Letus extreme on si2k

Here is a very quick and dirty test of the recentred and widened Letus Extreme on SI2K with Nikon f1.4 35mm lens for relay.

The grabs are .bmp converted to .jpg in MSPaint from 1920 x 1080 25P origination. There was a 2 f-stop lighting gel in the path I forgot about. - I wondered why I was not getting enough light. The gel was also cokeyed in the back of the mount so sharpness may have been degraded by this also.

Relay was on f5.6. Taking lens was on f2.

Garden was through a grubby thick glass window.

Test pattern is undersized in the frame which means the test which has actually derated the performance by about 15%. The "B" block at this reduced size still yields 862 lines.

The images have no look applied.

The limitations of stills lenses for relay to 2/3" are readily apparent. There is softening in the corners. A 28mm lens for relay just brings in edges of the Extreme's prism path on a 2/3" sensor.

It will be interesting to see what the Le brothers' direct relay for 2/3" can do in the SI2K when it comes out.

With an Extreme that has not been re-centred and widened, the 35mm lens for relay will just show a trace of one edge and pick up the other.
Attached Thumbnails
Roiding The Extreme-letus-extreme-si2k-test.jpg   Roiding The Extreme-letus-extreme-si2k-test02.jpg  

Last edited by Bob Hart; December 18th, 2008 at 11:41 PM. Reason: added text
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Old December 20th, 2008, 07:46 AM   #37
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Furthur si2k - letus extreme test.

Here is a link to a furthur test of the Letus Extreme on SI2K.

SI2K - LETUS EXTREME TEST. By Bob Hart On ExposureRoom

The lens used for relay was a Nikon f1.4 35mm. The field-of-view of this lens of the groundglass to the SI2K's 2/3" imager is comparable to the Sigma-for-Nikon 20mm f1.8 I used on the 1/3" JVC GY-HD100.

A 40mm focal length lens might be more realistic to use for relay to get inside the obvious hotspot in thse images. There will be a sharpness hit but edge to edge performance should be better.

Second Episode.

Here's another link to a 20 second clip, this time with a 40mm for relay :-

The shots were under-exposed, especially the shot of the toddler in the outdoor garden dining area. This was almost black and had to be pulled up a long way in brightness and contrast to be visible. The pattern artifact in the left .jpg image was not evident in the motion vision.

The location is again the Elizabethan Village, Shakespeare's Tavern.
Attached Thumbnails
Roiding The Extreme-si2k-letus-extreme-daylight-test-01.jpg   Roiding The Extreme-si2k-letus-extreme-daylight-test-02.jpg  

Last edited by Bob Hart; December 21st, 2008 at 02:16 AM. Reason: errors
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Old December 21st, 2008, 08:33 PM   #38
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Earlier Test Clip

For sake of comparison, here is a link to an earlier test with a f1.2 58mm Noct-Nikkor for relay. The resolution return from the restricted groundglass area "seen" by the the camera is evident but there is no edge falloff.

This is not a valid comparison as the camera was set to 1280 x 720 25P. I think this means that a smaller area of the sensor image is recorded, therefore brightness falloff may have occurred in the areas of the sensor not recorded. Somebody with the knowledge might correct my comment here.

The camera operator in this instance knew what he was doing and did not underexpose the image and the lighting was indoors and controlled.


FOOTNOTE: So as not to duplicate a post, there are a couple of frame grabs of test charts in the SI2K thread :-

FURTHUR FOOTNOTE: A very short clip from which the grabs came is here :-

Last edited by Bob Hart; December 22nd, 2008 at 08:29 PM. Reason: added text
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Old December 23rd, 2008, 01:31 PM   #39
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I received the raw footage tape you mailed to me and have managed to capture to my PC the tests you did.

I must say that the SD thumbs you posted don't do justice to the actual images i viewed on my CRT monitor.

Looking closely at the images, especially at the CA areas I looked back to my own tests way back and was thinking that perhaps it was caused by your achromatic diopters and not the relay lenses themselves.

I'm not sure what comparisons you made, but perhaps comparing different achromats on a setup that can intentionally induce CA, like using shiny metallic objects and high contrast colors, in a controlled set.

I'm continuing on my own tests using a different combination of macro and zoom settings on the stock fujinon to get optimum usable GG area. Pushing the macro to full makes me zoom in tighter. I will posts results later.

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Old December 23rd, 2008, 06:12 PM   #40
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Image quality of my clips aside one way or another, the JVCs may be getting a bit old but they still are a wonderful piece of gear to work with.
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Old December 24th, 2008, 06:04 AM   #41
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Instruction Set for fitting up SI2K and Letus EXtreme

A rough instruction set can be found here :-
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Old June 6th, 2009, 06:45 PM   #42
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Roiding the extreme - a few hints

I was recently requested for some information on the mod I did to a Letus Extreme so here is the essence of the reply.

It is by no means the best or only method but simply a revisit of how I went about it. There may be other better and safer methods so owners who choose to modify their Letus Extremes should examine and enquire with qualified optical and machine engineers as to the best way to go.


As previously stated, the Letus Extreme at its pricepoint is quite satisfactory for aquiring 35mm motion picture size groundglass images into most camcorders it is designed to fit and should require no interference unles it has been damaged in shipping in which case it should be either returned for repair or an insurance claim made.

There are a few of us, who crave that last little bit of extra performance beyond a automotive designer's intent, forged rods and roller rockers, nitrous etc., etc.. Groundglass adaptors are no exception.

In the case of groundglass adaptor owners, such obsessions also exist. It is chasing that little bit extra "apparent" shaprness that can be had by scaling the texture (grains) of the groundglass smaller relative to the camera frame size by using a larger image area off the groundglass.

As previously stated, the risks and consequences associated with entering and making changes to the device are and remain the responsibility of the owner. Warranties and guarantees will become void.

Unless persons have good dextoral skills, basic engineering skills and access to machine shop equipment, this modification should not be attempted as the results may be disastrous.

Firstly, to get the prism central, you may simply get away with replacing the rubber wedge with a squashed piece of clear plastic tube like hospital UV drip tube cut long enough that it goes across the entire width of the prism instead of wedging one end.

You may need to add a bit of soft rubber or blue tack against one end of the prism to stop it from rattling as the plastic tube will not wedge it in all directions like the rubber wedge does.

If you are going to go ahead and do the full adjusmtent mod there are a few things to be aware of.

There are two distinct modifications I did.

Making the compound prism adjustable.

Widening the aperture of the condensor port.

Making the compound prism adjustable is relatively easy, requires good dextoral skills, a basic workshop, an accurate drill press, correct sized drillbits, small grubscrews and matching thread tap (cutter) of good quality silversteel. The discount ones are just not good enough.

Widening the aperture of the condenser port requires a good milling machine and skills to use it. The widened port does not add much more utility because the widest lens you can use will be a 20mm f1.8. Anything wider and anything tigher than f1.8 will vignette.

I did not keep my measurements so you will have to wing it.

You'll also need :-

Shim metal. Brass is okay, steel is better.

Very thin clear hard plastic sheet to wrap over centre spine. Shirt packet plastic should be fine. This is to avoid friction damage to prism surfaces as this becomes a moving bearing surface once you start using the adjustment.

A piece of nylon, or thick plastic to make the clamping piece which replaces the rubber wedge.

Contact adhesive (yellow toluene based glue)

Stick-on black felt material of about 1/16" or less thickness. Craft and hobby stores may have it.

Black parcel marker. You will have the prism out so you may as well blacken the ground areas on the sides and the centre support facet while you are at it. (There is a special carbon paint or dressing lens makers use which is best but probably impossible to aquire outside of the industry.)

Clean padded or cloth work surface lint free and changeable. Essential to avoid damaging gassware if you drop it.

Plenty of toilet tissue or facial tissues.

Several proper (usually purple coloured) microfibre lens cleaning cloths.

Solvent for dissolving grease.

Vernier caliper with depth gauge.

Machine vice for drilliing - desirable for accuracy in drilling the hole on the centre ( facet) corner of the case.

Cotton tips, cotton balls for cleaning.

Jeweller screwdriver set.

Allen key wrench set.

A sheet of thin cardboard or plastic to make the spacer gasket to go between the front of the case and the rear face of the front cover. This has to be twice the thickness of the felt layers you install inside the case.


The inside of the prism enclosure case has been covered with grease to entrap any dust or loose machining particles which might have eluded the cleaning process in manufacture.

This stuff will get all over your fingers and transfer onto the prism faces unless you are exceptionally careful.

Cleaning it off the faces is a real bitch. Practice cleaning with a piece of window glass before you take this on. Until you can clean glass absolutely spotless, it is pointless opening your Letus because you are only going to ruin it and send yourself quite insane trying to get the glass immaculately clean. Anything less than perfectly clean is useless.

My routine for cleaning off grease is > solvent in tissue or cottonwool > Household detergent wash > Wash with simple bathroom soap > Clean water rinse. > Tissue dryoff and polish off with lens cloth. Fogging with breath for dampening to remove missed spots is fine but breathe gently. Microspots of spit are a mongrel to remove.

After cleaning and during re-assembly, soft cotton gloves are a good move to avoid fingerprints. Give them a wash before use to remove loose fibres.

After re-assembly you are going to find bits of dust and fibre everywhere. Use the cotton tips to pick off, don't rub as stuff in the cotton tips may come off.

The achromat is particularly vulnerable to being dropped as the Le brothers have used a UV cure or two-part clear cement to bond the glass elements into the metal rim.

The glass cracks away at the bond points. If it gets edge chips, this is not a showstopper. Use some black to limit the light the chips throw back into the image and maybe make a cardboard ring to mask off the chipped edge.

When fixing a loose achromat back into its rim, first remove completely all the bits of broken glass which will be sticking to the rim. Blacken the frosted side of the lens glass while you ared at it. Blacken any chips.

Use a few spots of water cleanup white bathroom sealer to secure the glass back into the rim. This stuff does not go totally hard and wile help protect the glass against future knocks.

The thin plastic you use to cover the centre spine should not result in a tight fit of the prism over it. The prsim should slip fairly freely. Any tighness needing forece to insert the prism will cause loading of the UV bonded joints in the prism and they may separate destructively.


Remove front tube.

Remove groundglass panel with motor attached.

Unsolder wiring from joint near edge of case. Do not unsolder from the motor end.

You will have to pick off the clear glue used to seal the soldered joint.

Remove battery compartment.

Remove rubber wedge.

With tissues or gloves worn, remove the compound prism by pressing through the achromat hole with finger as close to centre spine as you can get you finger to go.

Support the compound prism from the front with finger over the gap where the centre spine pases through the prism. Keep the prism as closely against the centre spine as you can while sliding it out to avoid contact with crease on the inside of the case.

Clean out all grease from within the case with solvent and tissues. Wipe out all bits of loose fibre and lint left behind. Don't bother to paint the inside black. It is okay as is.

Drill and tap the grubscrew holes.

Side hole on the facet corner is 27mm from rear exterior face of the case (camera side ).

The two end holes are 14mm in from the rounded facet corner more or less at the centre point of the circle of the rounded corner. Measure in 14mm with the tail of the vernier from the flat sides and the centre edge of the round to find the 14mm centre where the radii cross over.

Use a larger bit by hand to scarf out the swarf from the edges of the drill holes.

To tap the threads accurately you may find it easier to control the thread operation by mounting the thread tap in a Dremel tool chuck, mount the case in a vice and to hold the Dremel tool with one hand and rotate the chuck by fingers.

Important. - The grubscrews must have smooth almost flat, slightly rounded ends, not cupped or pointy ends. Cupped or pointy ends will cut through your metal shims and destroy the prism by chipping or cracking it.

Clean the swarf with a the larger drillbit as before.

Cut and glue on two layers of thin felt along the pivot lines front and back.

Cut and glue on single layers of thin felt along the edges of where the small prisms make corner contact on the front and rear faces of the case.

Cut and glue a single layer of felt about 16mm long in centre of the narrow edge of the centre spine directly opposite the screwhole which presses against the nylon strip. This piece of felt is equally important as a pivot point. The adjustment will not work without it. This piece is not evident in the video.

Cut and fit the thin plastic sleeve which fits over the centre spine. Fold it over the spine from the front. Make to holes for the screws to fit through. This stops the plastic from moving about too much. This plastic can be clear hard shirt packet plastic or plastic shim if you can find some.

The fit should be free not binding. Paper instead of plastic is sort of okay in a pinch but may swell in dampness and fret, leaving bits of loose fibre drifting around inside.

Cut your pieces of thin metal shim. These should be thinner than the two layers of felt otherwise the rpsim adjustment cannot work. Glue them down with contact cement along the inner edge of one side only. Leave the screw end corners free.

It is probably okay to glue them all the way across but the thickness of the glue at the corners may be hard to control and will take up space when it sets and make the adjusmtent process impossible.

Cut out your cardboard spacer gasket and fit it. I used two layers of cereal packet cardboard which is almost spot on 1mm thick.

Cut out your nylon pressure strip. Mark it into thirds lengthwise. File down the thickness of the end thirds about 1mm. This will leave the centre third as a raised area.

In centre of this raised area make a shallow hole for the end of the centre grub screw to bottom down in.

Cut it long enough that the centre hole will match the end of the grubscrew when the nylon strip is slipped in but not so long as it will jam tight when the front cover is fitted.

The nylon strip should be a tidy clearance fit between the prism and the case but not bind. You may have to file the side corners to match the slant of the curve in the case so that it is a tidy fit without being able to fall out of place inside.

It is absolutely important there is no direct contact by the end of the grubcrew against the centre facet of the prism otherwise it will surely be chipped or crack.

Re-install your prism. Check to see if it can rock on the felt pivots and no corners are clicking hard onto bare metal anywhere. Clicking is bad. It means a broken prism will happen in any hard knock.

Check your grubscrews can screw right through their holes. Make sure the ends are smooth and polish them so they do not cut through the shim metal.

Assemble the prism, spacer gasket and front cover.

Use your gloves to avoid staining the prism. Check again that the prism can rock on its felt pivots. If it can, put the grubscrews in and play with them.

Snug all up, then loosen the centre screw, loosen one end screw a counted number of quarter turns, tighten the other end screw up the same number of quarter turns to point of resistance only. Do not overtighten. If it works then dismantle everything, clean the prism, then re-aseemble and test.

To refit the pillars in their holes, pull the cups off, shove them into their holes with a blunt ended satay or chopstick filed down to a blunt end so that it can fit in centre of the cup not pushing on the sides. Push each pillar into the cups. You will feel a soft thud as they fit home.

If you want to adjust them forwards for initial backfocus, use tweezers to grab the pillars. Use a satay or roast stick as a lever with one end against the front cover of the prism case and the side of the stick against your tweezers and gently lever forward.

Use the vernier calipers to measure equal distance all around between the groundglass panel and front of prism case.

You should not need to bring the panel any furthur forward than 1mm at most.

So that you do not run out of adjustment, make sure all your faces between camera adaptor ring and rear of Letus are in contact with no gaps. Make sure the support rods and baseplate are adjusted so there is no bending load applied to the front of the camera.

There is enough compliance in the camera casework to allow the lens itself to move off-axis.

Enjoy, but please do not take this on unless you have the skills.
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Old July 23rd, 2009, 10:22 AM   #43
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GM -v- FORD sort of

Prompted by Evangelos and his Thompson Viper - SGPro combination with a custom relay, I thought I would see just how much the Letus Extreme can be pushed. Bear in mind this specimen has been modified.

For a test on the SI2K, the relay lens was Nikon f1.4 50mm, with the Sony PMW-EX1, zoom just under 40mm was used. This is not a fair comparison between camera types. Exposures were not matched either. The EX1 achromat was used in both tests. I did try a forward offset of the Nikon lens with the achromat removed. I did not observe a resolution improvement which suggests to me that the groundglass resolution is the wall now, not the optics.

Here are two grabs. Letus 04 is with the SI2K. Letus 05 is with the EX1.

Resolution block "A" is 1920 horizontal lines of resolution, Block "F" is 1080 vertical lines of resoultion. A note on the back of the Lemac Chart states that the "A" and "F" blocks will not resolve on HD video. The moire patterns on both cameras suggest that sensors are seeing the lines on the groundglass which suggests that the Letus Extreme, when tweaked and given a dose of nitrous (not), can be made to resolve true HD, just.


When resetting the groundglass panel, my personal preference is to adjust to 19mm from front face of groundglass carrier to front face of prism enclosure, not the front face that the pillars are set into, but where the rear face of the tube butts against the prism enclosure. This is easier to measure with the depth tail of vernier calipers at all pillar attach points on the groundglass carrier.
Attached Thumbnails
Roiding The Extreme-letus-04.jpg   Roiding The Extreme-letus-05.jpg  

Last edited by Bob Hart; July 23rd, 2009 at 11:04 AM. Reason: added images
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Old July 24th, 2009, 07:52 AM   #44
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Short Clip of Letus on SI2K

Here is a link to a very short clip of a test with the Letus Extreme on SI2K camera.

LETUS EXTREME ON SI2K TEST By Bob Hart On ExposureRoom

Because I got the whitebalance wrong, (forgot it altogether) I attempted a colour grade so it may not look all that flash as I am a little colour-blind. On the third shot, I forgot to turn the motor on.
Attached Thumbnails
Roiding The Extreme-shot-two-grab.jpg  

Last edited by Bob Hart; July 24th, 2009 at 07:59 AM. Reason: ADDED FRAME GRAB
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Old July 26th, 2009, 08:30 AM   #45
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Furthur try-out of Letus Extreme on SI2K

Here is a link to a bit more testing. I have attempted to colour grade the images as the blue was a bit down and overall colour saturation was also down. There is static grain as I forgot to run the groundglass motor on most shots.

LETUS ON SI2K TEST By Bob Hart On ExposureRoom

The lenses used were Nikon 58mm f1.2 and Nikon 200mm f2, both at f2 - f2.8 with expsoure being controlled mainly at the relay lens which was a Nikon 50mm f1.4.

The lighting conditions were overcast, late winter afternoon so both relay and prime lens were nearly wide-open.

The Letus achromat being used is the one for the Sony PMW-EX1. It may not be correct for the simple prime lens I am using for relay.

(Yeah I know. - Backyard fruit trees are the bane of true orchardists as they tend to be neglected and thus harbour pests. These copped a strong wind a few days ago which dropped the oranges. I do put out bait traps for fruit fly.).

The EX1 achromat was designed because there was necessary some optical trickery to offset a problem specific to the EX1 zoom lens.

Excesssive video noise wil be observed in the citrus images. This is because I forgot to set blacks after shutting the camera down to save the battery.
Attached Thumbnails
Roiding The Extreme-letus2kgrab04.jpg   Roiding The Extreme-letus2kgrab05.jpg  

Roiding The Extreme-letus2kgrab06.jpg   Roiding The Extreme-letus2kgrab07.jpg  

Last edited by Bob Hart; July 26th, 2009 at 08:53 AM. Reason: error
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