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Letus Extreme - First Impressions


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#1 Tim Tyler

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Posted 25 October 2007 - 11:40 PM

I spent a few hours today playing with a new, fresh from the factory, Letus Extreme 35mm lens adapter on an HVX200. Here are some notes.

The powder-coated black finish and milled-aluminum construction appears very good. The device feels solid.

I received the Extreme in three parts:
An 82mm threaded lens adapter for mounting on the HVX200
A Canon FD lens mount
And the adapter itself which houses a prism, oscillating ground glass, achromatic lens, battery compartment and probably some other stuff.

A decent but simple support bracket and two useless rubber port caps (flabby rubber) were also included. The support bracket screws into the front of the adapter?s base directly below the ground glass (focal plane measuring tape connector?) and allows it to be attached to 15mm rods.

I?m not sure if I?d say the adapter was ?sealed? however there is an optic/glass shield that separates the ground glass from the lens port and should protect the ground glass from dust, and the achromatic lens on the back of the unit keeps dust out of that end. A well-designed magnetic door, easily opened with your fingernail, hides two AA batteries on the right side of the Extreme, and a red, plastic, well-positioned push-button power switch is located on the rear and is bright red when switched ON.

To mount the Extreme I carefully screwed the 82mm ring tightly into the HVX?s filter threads. Then I slid the adapter onto the ring, loosely finger-tightened the three socket-head screws, and then gently rotated the adapter until the visible frame/ground glass was level on the camera?s LCD/viewfinder. I then tightened the adapter with the included Allen wrench. The connection felt solid, and I did not feel the HVX?s lens threads were being stressed too much.

I inserted the Canon FD mount into the front of the adapter and tightened the three socket head screws tightly. I mounted my widest lens, a 24mm f/2.0 and checked focus at infinity. Sharp distant focus on the LCD was reading at about 10 feet on the lens dial. In order to get them to match it became necessary to loosen the lens mount from the adapter and position it just a few hairs away from snug. I?ll probably get some gasket material tomorrow, cut it to fit, and use it to shim the mount to eliminate guesswork in the future. Once tightened the lens mount is solidly connected to the adapter.

Focusing the camera lens onto the ground glass was easy with the camera lens zoomed in past 25mm. At f/2.0, the ground glass was sharp at 5.36 feet on the HVX distance display. Judging by the slightly visible moving ground glass grain patterns, powering the adapter seems to oscillate the ground glass in more of a vertical motion than a horizontal motion. Once a lens is mounted the grain disappears as long as the taking lens stop is near open (< f/5.6?).

Here?s the result of a simple light-loss test I did.

HVX lens @ f/3.4 = HVX @ f/2 + Letus + 85mm SLR lens @ f/1.8
HVX lens @ f/2.4 = HVX @ f/2 + Letus + 50mm SLR lens @ f/1.2

That would seem to illustrate that an f/1.0 SLR lens on the Extreme would not require more light than the naked HVX lens. :) I?ll do more precise tests soon.

Upon a casual inspection I did not see any vignetting. I was also surprised to not see any chromatic aberration in the few test shots I took.

The design of the Extreme repositions the taking lens 44mm lower than the camcorder lens. That required me to get creative when mounting a mattebox and follow focus on a non-vertically-adjustable base plate. To temporarily remedy this I mounted a second set of rods to the primary rods using two attached lens support brackets. (Zacuto is making the Z-Riser for just this sort of thing, and two Redrock lens supports would work also.) Some adjustable base plates (like Cavision?s) may not require anything more than a height adjustment. (FWIW: I?ve seen the Cavision rod system though and it doesn?t feel safe to me, especially with a bunch of attached lens accessories.)

Anyway ? That?s about all the time I have left today. At http://timtyler.net/...tremeStills.zip you?ll find a zip file with a few un-retouched PNG?s from some quick shots out the window at dusk. The HVX and taking lenses were wide open. I used a 24mm f/2, 50 f1.2, and an 85mm f1.8. I'm sure better lenses on this device would make prettier pictures than these old Canon's, and Quyen from Letus tells me a PL mount is just a few weeks away from being available.

Attached Images

  • letus_1.jpg
  • letus_2.jpg
  • letus_3.jpg
  • letus_4.jpg

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#2 Tim Terner

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Posted 26 October 2007 - 12:10 AM

Those out of focus highlights in Image 4 look strange Tim
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#3 Saul Rodgar

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Posted 26 October 2007 - 01:13 AM

Hi.

Pretty nice "lens wide open" shallow focus on the images. Image 4 does have some curious looking out of focus distortion, for lack of a better word, on the street lamps in the background. It kind of has its own, distinctive look, like anamorphic out of focus and flares. On image 3 the clipping on the sky where it turns red in the top left is very "video" clipped, but IT IS video. Other than that I like it.

"DUDE, It looks just like 35!"

How much was it?
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#4 Aaron Pinto

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Posted 26 October 2007 - 09:00 AM

Tim,
Thanks for getting that up so quickly. Your setup looks great!

I just wanted to post a note over here to let anyone know that if they had questions, you can ask me directly and I would be happy to help.

The PL mount is in the works. Currently we offer Nikon AI, Canon FD, and Canon EF (EOS) mounts with theses adapters. We also have a 77mm thread ring in development for all of those who will be picking up the new Sony XDCAM.

Thanks again Tim.
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#5 Aaron Pinto

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Posted 26 October 2007 - 09:07 AM

Oh yeah... we have a Pentax K mount as well that was recently released.

and here is a link to low res sample video from the pre-release version of the Extreme
http://downloads.letusdirect.com/video/

and hi-res footage of the same
http://downloads.letusdirect.com/extreme/

Edited by Aaron Pinto, 26 October 2007 - 09:09 AM.

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#6 Shane Kelly

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Posted 26 October 2007 - 10:46 AM

Aaron,
I've tried a brevis on my Hvx and had some issues with the ccd in the camera not being centered. Is this an issue with the extreme? Is there any x/y adjustment on the mount or is it needed at all?
Thanks,
Shane.
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#7 Aaron Pinto

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Posted 26 October 2007 - 11:26 AM

Shane,
I have had other users with the same issue in their HVX. Quyen (the inventor) said that there is a little bit of offset that can be adjusted on the Extreme to compensate. As more of the Extremes go out over the next few days, we should be seeing more HVX users which will allow us to get a better idea of just how much adjustment is needed for the cameras with the shifted sensor.
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#8 Shane Kelly

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Posted 26 October 2007 - 11:56 AM

Thanks Aaron,
I'll be able to test it out myself next week when my extreme comes in and will post the results.
Shane.

Edited by Shane Kelly, 26 October 2007 - 11:56 AM.

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#9 Tim Tyler

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Posted 26 October 2007 - 12:49 PM

I've used a P+S Technics Mini on the HVX and their ground glass was off-center also.

This photo illustrates the offset with the Extreme on an HVX.

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#10 David Chia

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Posted 26 October 2007 - 02:01 PM

Thank you very much for the efford, It is a very good inside to the adapter.

Can you do some more still shoots with light in the background with different lenses. The glow or flare is not very promising for this adapter.

I hope it is just your lens that you are using that is causing these glows and flares . Do you have another kind of 35mm adapter that you can use your canon lens that you were using for the Letus Extreme with. Just to make sure that it is not the adapter but the lens that is causing the glow and flare.

Edited by David Chia, 26 October 2007 - 02:03 PM.

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#11 Shane Kelly

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Posted 26 October 2007 - 02:05 PM

Tim,
It's actually the HVX ccd that is off centre, not so much the ground glass. Different HVX's display different amounts. On the Brevis I had to raise the unit as much as possible with the set screws to get it centred, we'll see what the extreme will do.
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#12 David Chia

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Posted 26 October 2007 - 02:25 PM

Tim,
It's actually the HVX ccd that is off centre, not so much the ground glass. Different HVX's display different amounts. On the Brevis I had to raise the unit as much as possible with the set screws to get it centred, we'll see what the extreme will do.



It is a well know fact that the HVX is off center. A lot of Brevis user with the HVX have that problem too.

Edited by David Chia, 26 October 2007 - 02:27 PM.

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#13 Tim Tyler

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Posted 26 October 2007 - 04:13 PM

Here are a few intentionally over-exposed stills.

http://timtyler.net/extreme-test-2.zip

These were shot with the HVX stop at either 2.8 or 4. The taking lens focal length and stop are in the filename. I put a Tru-Pol polarizer in the matte box too, mainly to cut down the light since I didn't have any ND's handy. I also reset all the HVX scene parameters to "0" with the gamma to "norm" and matrix to "norm". (The shots from yesterday were Cinelike V / Cinelike.)

After some trial and error, I found the corrective shim size for the FD mount to be four sheets of basic laserjet paper.
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#14 David Chia

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Posted 26 October 2007 - 05:25 PM

There seem to be abit, but can't really see the glow, it just seem over exposed, maybe if you can some night shots are evening shoots with some street lights or car lights will be great. especially if they are in the background. I really love to see how it handles bokeh handles the light.

Are you using the same lens or a different lens.

Edited by David Chia, 26 October 2007 - 05:29 PM.

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#15 Chris Keth

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Posted 26 October 2007 - 09:12 PM

Up to shooting some proper test charts for us? This seems much better thought-out and built than the Redrock I shot with last year and hated.
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#16 David Chia

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Posted 27 October 2007 - 02:09 AM

Up to shooting some proper test charts for us? This seems much better thought-out and built than the Redrock I shot with last year and hated.



someone did a test on a proper chart here. But I ilke to see how the Bokeh handles the light. doesn it have the glow or flare. when the light is in the background.

http://www.dvxuser.c...t...067&page=11

Edited by David Chia, 27 October 2007 - 02:11 AM.

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