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Old February 17th, 2007, 07:51 AM   #1
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35 mm adapter for XL H1

So, dug up almost all of the 35 mm threads here in this section, nice to read all this! What I like to have is a low cost (not the P+S and likes) 35mm adapter for my Canon XL-H1, directly attached to the cam, so not with the lens in between. As far as I can tell and see here is that the Letus is the only one around? Or Am I missing some?
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Old February 17th, 2007, 11:10 PM   #2
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The Letus uses a relay lens. There's always going to be a relay lens (or cam lens/achromat) between the imaging plane and the camera.
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Old February 18th, 2007, 07:24 AM   #3
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ofcourse, you're right about that. But still, in the Letus XL it's all integrated, while the 'others' needs the stock lens at least.
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Old February 19th, 2007, 08:00 PM   #4
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Speaking of the LetusXL, I'm trying to figure this out myself. Theres so many threads on adapters its hard to sort things out. I was wondering about the quality of the LetusXL, it's Bokeh, and if i could see some sample footage.
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Old February 19th, 2007, 08:40 PM   #5
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Correct me if I'm wrong, but something to keep in mind about the Letus XL is the magnification factor caused by the relay lens. I believe it's somewhere around a 1.9 times magification on the lens. For example a 24mm wide angle would become a 45mm lens, a 50mm lens would become a 95mm, etc.

I could be wrong about that, but I thought I read in one of the threads.
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Old February 19th, 2007, 09:18 PM   #6
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For direct relay into the XL camera family, your choices are P+S Technik's Mini35 or Quyen Le's Letus35. The others require flip of the image in post and a method of flipping image in realtime on the shoot.

For practical reasons I won't go into, all of the flip systems aquire an image off a smaller area of the groundglass, typically 22mm to 24mm or thereabouts than some of the non-flip options can do.

Ability to use a larger groundglass image and scale the groundglass textures proportionately smaller is one reason why they can achieve resolutions equal to and apparently sometimes even surpassing the benchmark Mini35.

Read Phil Bloom's posts on the shootouts between alternative devices.

Quyen's device has good bokeh performance and adequate resolution. For consistent vision with minimal groundglass artifacts, the taking lens needs to be kept in the aperture range wide-open to no smaller than f3.5.

Good bokeh and good light transmission/resolution are mutually exclusive commodities with groundlgass based image relay. There is a balance to be struck and different designers have made choices.

The Brevis actually places this choice in your hands with three available diffuser grades and ability to swap them out.

P+S Technik recommend aperture no tighter than f5.6 but are likely being conservative as I have shot f11 and got away with it. The non-flip M2, Brevis and SGPro can apparently go smaller (higher aperture numbers) and there are the forementioned density choices available for the Brevis.

Quyen's device has its genesis in being a low cost service for enthusiasts without the necessary skills or equipment to make their own. His system appears to be a clever implementation of the principle using accessable third party components.

The P+S Technik Mini35 is pretty much a turnkey system from go, that's what you pay for. You still need to learn to install and set it up correctly.

With the Letus35 flip for XL, you should expect to make some adjustments and innovations of your own as the Letus35 is for the low-budget enthusiast.

What may require your attention may be structural integrity. The individual sub-assemblies are all robust but the chosen method of fixing has been adhesive bond of cylindrical metal sleeves over ABS plastic shoulders.

There have been reported bond failures and added security by drilling and tapping for screw fixture has been required in some instances.

Retention of the front lens mount relies on a single friction screw and in combination with the reversable Canon/Nikon dual pupose mount, comprises the main achilles heel of the Letus35 system.

The second has been the unique excursion path of the moving groundglass which is elliptoid and not truly circular. This yields two endpoints of slower groundglass motion.

An artifact described variously as "freckles" or "film of grain" has been reported with consternation by some users. Other users have been entirely satisfied with the performance of their Letus35.

The average enthusiast should be well satisfied with the Letus35 but if you intend to drive it to fully professonal qualities of production, then you may find you have to make additional innovations upon it and may find them unachievable.

Any groundglass based image relay device is no substitute for established best practices such as careful composition, framing and especially good attention to lighting.
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Old February 20th, 2007, 04:18 AM   #7
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Thanks for the response Bob! Think I'm gonna try out the Letus then, since the huge price difference with the Mini35.
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Old February 20th, 2007, 09:16 AM   #8
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If you are buying in the Letus35 flip for XL, consider the still-camera lenses you intend to use with it. If they are Nikons, then request the dedicated mount for Nikons. Don't just go with the reversable Canon/Nikon mount.

The weight of the appliance plus the lenses you choose is a heavy burden both on the mount of your Canon and on the structure of the relay lens Quyen uses.

Whilst you can operate the combination like this, better practice is to add Cavision rods and a little strap-hammock thing they make to sling under the Letus housing to support it.

A fixed rigid mounting is not possible because the relay lens extends and shortens the entire appliance when relay focus is carried out. So the appliance must be left free to move back and forth a millimetre or so.

As to resolution, you will have read above my reference to "adequate". The Letus35 groundglass will yield resolution to the capability of MiniDV at 530 TV lines. I have not tested a Letus35 on HDV.

My own tests of my own unrelated device come up to but do not exceed 850TV lines with my sharpest SLR lens, the Nikon f1.8 85mm.

How the Letus35 flip for XL will fare then with the XLH1, I cannot vouch for.

If you want to see how the Letus35 works on an XL2 in hostile lighting conditions with everything wide-open compared to an XL1 and a Z1P shooting direct-to-camera, have a look at YouTube for the moniker "agus35monk".

In the list of uploaded clips there is a music video "the b-movie heroes". The youtube res is not outstanding. The Xl2 footage with both the SLR lens on front and relay apertures wide-open was a bit soft.

The image is sharper when bright daylight outdoors conditions are encountered and apertures can be closed up a little.

In lighting conditions which require a tighter aperture than f3.5 on the SLR lens and about f5.6 on the relay lens, you may need to use a ND filter in the path to avoid over-exposure otherwise you will likely find the groundglass artifacts I mentioned if you close the apertures up to limit light.

There is a half-baked tutorial on the Letus a fair way back in the Letus threads which gives info on setting up. Groundglass based image relay to video is a craft in its own right which has to be learned and practiced.

It should be about three groups down the page on this address here :-


This tutorial is now dated as a lower aperture number f3.5 rather than f5.6 has since been suggested as the practical tightest aperture before groundglass artifacts may be provoked.

You will find the standard camera viewfinder inadequate for achieving accurate sharp focus on the chosen subject, especially in dynamic situations which will not be helped by the shallow depth of field associated with f3.5 or wider apertures.

In this circumstance you may need to use a wider lens and go closer to subject to preserve a deeper depth of field.

You might also need to purchase a portable monitor to be able to get more accurate focus.

You will find with the Letus and some other adaptors that you need plenty of light to compensate for losses through the image path.

Last edited by Bob Hart; February 20th, 2007 at 10:01 AM.
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Old February 21st, 2007, 04:46 PM   #9
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Would mounting a 35mm lens and a tube extender do a somewhat similar thing, at least in the way of obtaining decreased depth of field? True, from the looks of it a lens extender would not be nearly as long what these products are, but it would be slightly cheaper.
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Old February 22nd, 2007, 08:47 PM   #10
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A dioptre on front of the camcorder lens and a 35mm SLR camera lens without groundglass is my interpretation of what you suggest.

Properly set up, you will get an image and a good one limited by the quality of the camcorder optics and whatever is stuck on in front.

I actually do this with my own device with the groundglass removed for using very long lenses into videocameras with inbuilt lenses.

However there wll be no appreciable reduction in the depth of field or increased field of view because the optical combination remains seen through directly or "coherently" by the limited dimension of the 1/3" CCD.

There are optical methods of doing what the groundglass based image relay systems achieve and optical is said to be the best for resolution, however it is also very expensive and difficult to implement.
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