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Old March 21st, 2009, 02:31 PM   #1
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Letus extreme with HVX 200 on HD100?

Rental shop near me has a Letus Extreme kit for the HVX200. They don't know if this will work on a JVC HD100 (with 82mm filter threads).

Will the HD100 require a different apocromat or can the Letus be mounted with only the mounting ring (no glass) for the HVX200? Can the HVX200 apo be removed from it's mounting ring?
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Old March 21st, 2009, 06:27 PM   #2
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The JVC standard Fujinon lens seems to behave a little differently to others.

It will be a case of experimenting. I think you may find that you cannot get the adaptor mounted close enough to the Fujinon lens.

There have been issues reported by some JVC owners of requiring the macro or the backfocus on the Fujinon to be reset to pull in a tiny last bit of focus range for the relay focus.

With home made adaptors, it was found that repositioning the achromat inside the fluted anti-reflection ridges on the Fujinon lens works best. The filter thread on the Fujinon is contained in a fixed extention on front of the lens that the focus barrel moves separately inside of.

You may find that this hack works okay but your rental house may not be all that keen on having to mod the Letus in this way as it leaves the rear open to bits of dust dropping onto the prism.

If you can get it to work, you should be well pleased with the results, especially if you can test on a large unscanning monitor to see just how far back you can set the camcorder zoom before you pick an edge in the prism path.
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Old March 21st, 2009, 08:16 PM   #3
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Quote:
Originally Posted by Bob Hart View Post
George.


The JVC standard Fujinon lens seems to behave a little differently to others.

It will be a case of experimenting. I think you may find that you cannot get the adaptor mounted close enough to the Fujinon lens.

There have been issues reported by some JVC owners of requiring the macro or the backfocus on the Fujinon to be reset to pull in a tiny last bit of focus range for the relay focus.
Should a Letus Extreme, set up for the JVC HD100U/16xFuji combo, typically require a different apo than the HVX, or is it usually set up without an apo and using macro/backfocus?

Restated - Is the position experimenting usual for the JVC, or would the Letus usually just come with a different apo than the HVX?
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Old March 22nd, 2009, 08:12 AM   #4
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There have been mixed accounts regarding the JVC GY-HD100 camera family, some happy campers and some strident critics.

The Letus Extreme comes with a built-in achromatic dioptre. As far as I know, the same dioptre is used across a range of 72mm filter thread mount cameras with built-in lenses. It may be the same for the JVC which is like most others a 1/3" sensor. The actual entry diamater of the front element is little different to the lens-in-camera style camcorders. You cannot operate using the standard Fujinon lens without the built-in achromatic dioptre on the Letus Extreme.

There was a special dioptre designed for the Sony PMW-EX1 which gave all the adaptor makers a bit of a headache due to corner softness issues.

I think you may find that the HVX-200 mount ring might be thicker front-to-back than the 82mm mount ring for the JVC but I may also be wrong. The mount rings for the Sony cams are thicker front-to-back.

The filter thread is positioned quite close to the front element on lens-in-camera style camcorders.

The JVC offers a challenge in that the filter thread is 82mm diameter and is positioned some distance ahead of the lens focus barrel which rotates and moves forward and backward with focus movements.

This arrangement I guess is to both permit direct compatabilty with other ENG lens attachment options and to permit filters like ND grads and polarisers which require a non-moving mount system.

A quality solution for the JVC GY-HD*** camera family is just around the corner in the form of the direct relay lens due to be marketted soon.

This however will lock you into a standard 35mm motion picture frame area off the groundglass rather than the wider area you can aquire with the camcorder's own zoom lens for relay.

The reason for this is to maintain faithful rendition of the actual characteristic of the motion picture lenses.

Your choice between the direct relay lens system and using the Fujinon, is to trade a fixed frame area with high relay resolution for variable framing options with a lesser relay resolution.

Last edited by Bob Hart; March 22nd, 2009 at 08:17 AM. Reason: error
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Old March 22nd, 2009, 05:20 PM   #5
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Bob

So the standard Letus, not for EX1 or HVX200, does come with a diopter element in the basic mount ring. That would imply the HVX200 unit from the rental company probably won't set up correctly on a JVC, with or without the HVX200 diopter element in the ring.

Thanks, and sorry for the second post. I wanted to ask the JVC community, but it was moved here.
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Old March 22nd, 2009, 05:59 PM   #6
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Only Hien, Quyen at adapterplace or Aaron at Letus Direct can answer this question definitively.

I know that the Sony EX1 achromat does work with the Sony Z1 which is a 1/3" camera with 72mm filter mount and it did work to a JVC I hooked it up to using the genuine Letus 82mm ring. So there is a little wriggle room with these things. To get relay focus on the JVC, I had to use the macro function.

The achromat for the HVX-200 is likely but not for surely, to be the same as for the Z1. It should work with possibly adjustment of the backfocus/macro on the Fujinon.

If you have to touch the backfocus/macro, then your zoom functionality is hindered because zooming for fine framing trims on the groundglass will shift focus.
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Old March 22nd, 2009, 06:22 PM   #7
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I can tell you I shot with the Letus FE on the HVX200. Only mod was the step up ring. It worked without adding additional lensing, and had plenty of zoom room. The FE was the early flip adapter which Extreme was based on, and as I recall, primary difference was that FE used mirrors, and Extreme went to prism. Otherwise, extreme was workable for same cameras. That FE also worked fine on my Sony FX1. I also have a Flip adapter I obtained later from Letus which works without additional lensing on my FX1. Based on that, my best bet is the standard Extreme should be fine and that your the HVX version would probably work with other cameras. Real issue would be focus capability at zoom and that would determine whether additional achromat would be needed.
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Old March 23rd, 2009, 07:52 AM   #8
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We've been very firmly in the 'not so happy campers' group when using Letus kits with JVC gyhd cameras.

Our advice would be not to bother at all. Far too much grief and no support from Letus.

The so called relay lens to solve the problem has been 'due for imminent launch' for far too long.

We got bored and went elsewhere.

All depends on whether you need the rig to earn you money. If you do, forget it.
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