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Old January 8th, 2007, 08:19 AM   #1
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HVX200 + Letus35a setup tips or hints?

I have a Letus35a mounted to the HVX, but I'm finding it hard to get a critical focus. I'm finding that I have to focus at MF00 and zoom somewhere between Z65 and Z75 to get close.

Close as in I can almost get a good sharp focus on the ground glass, but not quite. Can someone else share their MF and Z settings with me?

Thanks,

Jim

PS - I'm using a stepdown ring from RedRock
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Old January 8th, 2007, 09:41 AM   #2
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do you focus on the grain with the motor off?
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Old January 8th, 2007, 11:08 AM   #3
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Jim.

My wild guess is that there is not enough distance between your HVX and the groundglass.

Silly question but is there a close-up lens or dioptre in the path between your HVX and the groundglass. My understanding of the Letus35a is that it is not a flip (image erecting) model but I could be wrong.

I think there will be a close-up lens in there because you are manual focussing on infinity? if MF00 = infinity focus and getting near to a sharp image. But maybe not. A condenser element may also be in there also acting in part as a close-up lens.

Quyen uses a single element biconvex lens in reverse orientation about 8mm behind the groundglass on the flip models for a condenser I think. If it is there, don't confuse it with a close-up lens or dioptre.

I think there should be another lens just inside the housing closest to where it fits up to the camcorder. With some small camcorders a close-up lens may not be needed because of their zoom and close-up focus ability.

Did you order your Letus35a from Quyen specifically for the HVX or is it from another source or originally ordered for another camera type?

If there is no close-up lens or dioptre, then for your camera, one will have to be added into the path between the groundglass and video camera and as close as possible to the video camera lens.

The power of the close-up lens or dioptre, if it is there, may not be strong enough for the interactive combination of distance from the groundglass to close-up lens and the built-in lens of your camera.

A rough and ready check would be to dismount the Letus35a from its direct mount to your camera and position it furthur away from your camera to see if you can get sharp camera focus on the groundglass by adding distance between the camera and the groundglass.

Leave the groundglass motor switched off for this test, have the Letus looking at a soft broad light source strong enough you can tighten the SLR lens aperture to f11 or f16 and still see the groundglass in your camera viewfinder or monitor - monitor being better.

If the groundglass texture (sandpaper appearance) becomes sharper with it furthur from the camera, then the task might be as simple as adding some spacers between the camera and the Letus35a to maintain the groundglass within the available camera lens focal range though the close-up lens.

If you cannot get the groundglass close enough to the camera before the Letus body butt up against the camcorder, then you might need to look for a less powerful close-up lens.

Ballpark distance for a 1/3" CCD video camera lens set on zoom about 35mm, focus set on about 1.4M through a +7 close-up lens from front of camera to groundglass for a 24mm wide frame is about 5" or about 120mm.

For a +4 it is closer to about 8" or about 200mm and the zoom has to be 54mm or higher number.

For added close-up lenses between the Letus and videocamera, the contenders are Century Optics or more recent offerings from Redrock (for the M2) or Cinevate ( for the Brevis adaptor ).

Another silly question. Have you contacted Quyen Le for advice?

Don't pay too much heed to my comments. I have only dabbled with the Letus35 flip for XL and JVC HD100 models.
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Old January 8th, 2007, 03:07 PM   #4
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Quote:
Originally Posted by Andrew Todd
do you focus on the grain with the motor off?
Yup, I do focus with the motor off. When I do an AUTOFOCUS it also stops at MF00.
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Old January 8th, 2007, 09:51 PM   #5
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MF00?

If this is camcorder infinity focus and not the close end of the camcorder's own internal focus range, then it seems to me that somehow you need to be able to get the camcorder closer to the groundglass or substitute the Letus35 close-up lens if there is one, for a less powerful one.

If MF00 is the closest available focus position for the camcorder, then there would need to be distance added between the camcorder and the groundglass, using a spacer between the camcorder and the Letus35a body.

Measuring from the front face of the SLR lens mount in front of the Letus housing to the front of the HVX-200, where it fits up to the Letus35a, what is the distance in inches or millmetres?
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Old January 21st, 2007, 04:49 PM   #6
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I know some folks have used the Letus35a with the HVX. Can you post your MF and Z settings?

Thanks!
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