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Old August 27th, 2008, 04:55 AM   #1
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Lens adapter like LETUS35 ULTIMATE

Hi everybody,
I'm upgrading my video gears and after 4 wonderfull years with canon XL2 I decided to change brand and to buy Sony EX3.
I'm a filmaker and my productions are shortmovies, music videos, documentaries... I'd like to achieve the best filmic images so I'm thinking about a 35mm lens adapter to mount Nikon lenses. Can someone suggests me the best one? I read very well about Letus35 adapters, I see ULTIMATE costs more or less the half of the P+S Technik. How can be compared this two model?

Thank you very much

Michele Lombardo
Milan - Italy
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Old August 27th, 2008, 11:04 PM   #2
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No one else has replied so I will comment for now on the Letus Extreme and P+S Technik Mini35. The Ultimate shares most structures with the Extreme but is a different adaptor to the Extreme and Mini35 in the way it works.

For the EX3, no one is yet selling a direct relay lens kit for any adaptor to fit to it. The standard camera lens must be used with a custom close-up lens fitted. The direct relays will come soon enough.

The P+S Technik Mini35 is a very precise instrument, designed and built by ex-ARRI film camera engineers. It comes with a lot of custom add-on accessories. Backfocus is set at the factory by a precision projection method and needs no furthur attention unless there is damage or maintenance is done on the groundglass.

There is the P+S Technik Universal mount system which has been adopted for the SI2K camera. Rods for mattebox and follow focus are built in to the adaptor.

The mount systems for the camera baseplate are for individual camera types and sold as separate mount kits. The camera baseplate support is a very small area and can move after being locked in position. The adaptor/camera combination should not be carried by the camera handle.

The camcorder lens to adaptor couplings are very precise, threaded for camera lens filter mounts on one end, containing a custom close-up lens suited to the camera type and fitting to the rear of the adaptor by a very strong and precise PL style bayonet collar and lock.

The P+S Technik Nikon lens mount is by far the very best and uses a screw-on ring to positively retain the Nikon lens. This mount does not wear the flange faces and there is absolutely no movement of the lens in its mount.

The Mini35 and Pro35 adaptors are designed to let the video-camera "see" the 35mm motion picture image frame which is 24mm x 18mm or about 22mm safe area width. All optical and mechanical parts in the groundglass module are made of round parts which means all centres are very accurate and the Mini35/Pro35 are as small as they can be to do the job.

The groundglass movement oscillates in perfect circles on three small cranks at speeds approximately 300rpm - 400rpm. There is a speed control wheel on the left side of the Mini35 to select motor speed. It is effectively silent.

I am only guessing here as this estimate is only by observation and not measurement. The movement of the groundglass seems to be about 3mm.

P+S Technik adaptors are made with the precision of film cameras and require special tools and workshops to service and repair. You get an operator's manual but not much information for self-service and repair.

Recommended lens iris setting is f5.6 or wider.

The Letus Extreme is based on what was originally a much simpler design. The groundglass is much larger than it needs to be for a 24mm x 18mm movie frame. Like the Brevis, SGPro, RedRock M2 and maybe Adriano Apefos' adaptor from Brasil, the image size on the groundglass which the video camera can "see" is larger.

This larger image is useful because more of the still-camera image can be used which helps sharpness. You can use a little of your camcorder zoom for composition and creative effects.

The groundglass movement of the Extreme is also an oscillating movement. A small vibrator motor is mounted on the panel which carries the groundglass. This panel is supported on pillars which are mounted in flexible joints.

The groundglass motion of this system is an elliptoid form (rugby footbal shape) of about 1mm x 0.7mm and is fixed at about 2950rpm. Again, I am guessing here from observation and not precise measurement. The Letus system is very quiet but a vibration can be felt.

If lenses are not firm in their mounts or are cheap and have loose internal mechanisms, this might cause very rarely some artifacts in the image. The Letus Nikon mount does not have a collar spring and movement can occur with worn lenses.

With the image size set at 24mm x 18mm, the Mini35 produces the sharpest image. When the larger image size of the larger groundglass is used, the Extreme's image becomes sharper and of field-of-view, more like the Nikon film still-camera image.

Fitting of parts like adaptors to camera lens filter thread mounts is more basic. Coupling collars are used. These are threaded on one end for lens filter mounts and use a shoulder and grubscrew system of mounting to the back of the Extreme. This is a less precise system than the Mini35 but allows for a little correcting adjustment if the image does not centre in the camera viewfinder.

The original Letus35 was built for the amateur enthusiast and owner repairs were then not discouraged. Backfocus of the flange to groundglass is not as precise as the Mini35 therefore user-adjustment is provide in back of the Nikon mount. Furthur adjustment can be made of the groundglass position itself but I do not encourage this unless infinity focus cannot be achieved. User-adjustment is handy because the Letus might be made workable again in the field if there has been accidental damage.

The Ultimate has an improved operator backfocus feature which is available on some Extreme kits sold by Zacuto.

Rods support is not part of the Letus basic design. A strong rods system comes as part of a production kit Letus sell which includes the Extreme adaptor. The rods system camera baseplate support is very firm and covers a wide area of the baseplate.

Because it is a universal system for very many more camera types than the P+S, initial setting up is a longer task.

This combination should not be carried by the camera handle.

Recommended lens iris setting is f5.6 or wider.

Now to the Ultimate.

The Ultimate uses a spinning disk groundglass. It has speed control. Spinning disks are better for higher shutter speeds and produce less artifacts with iris settings at f5.6 or even tighter in good lighting conditions.

As I mentioned above, there is an improved operator backfocus function.

I do not know the groundglass area. It may be smaller and closer to the motion picture frame size of 24mm x 18mm.

I shall leave it to Philip Bloom and Steven Dempsey to comment on the Ultimate as they have used pre-release versions of it. There are clips shot by them to be found on www.exposureroom.com and I think also on Vimeo, Video Sharing For You.

I hope this helps and this is not too much wordstuff for you to cope with.

Last edited by Bob Hart; August 27th, 2008 at 11:32 PM. Reason: added text
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Old August 28th, 2008, 03:55 AM   #3
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Join Date: Nov 2004
Location: Italy
Posts: 32

thank you very much, your answer is so clear and usefull!! I noticed Letus35 Ultimate costs more or less half of the P+S technik... so i'm wondering if the quality has the same proportion...

Anyway i think both brand must develope a "direct to camera body" system for the EX3 before decide to buy it.

Thank you very very much!

Michele Lombardo
Milan - Italy
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