A few questions about the Letus35

Unfortunatly Barry it seems this problem that you speak of is inherant to all vibrating GG adapters (including the brevis). The problem which I think you are describing is that using higher shutter speeds, or a 180degree shutter at 60fps tends to freeze the grain of the adapter. I have seen this happen with both the letus and the brevis, if there is a way around this that would be great, but I'm not seing how there could be.
I'm still in the market for a new 35mm adapter, currently looking at the brevis, M2 and the SGpro (Although Wayne has yet to get back to any of the emails I have sent him thus far).
I have seen the Brevis go up to 1/200th sec shutter speed without problems, I've seen the spinning adapters go much much further.
While this may not be the problem that Barry is describing, I can't really think of any other problem that could occure at variable frame rates.

Good luck Barry, I hope for the sake of us all you get this problem resolved.
 
That is the problem, and I think it's probably inherent in all GG adapters, but using a finer-grained/more-translucent ground glass did solve the problem perfectly. But it introduced some vignetting.

The original L35FE has gorgeous edge-to-edge sharpness and light distribution (well, for a 35mm adapter, that is) but the grain pattern was very noticeable in skies and bright whites, and even moreso when doing HVX overcranking. The new ground glass solves that, but he needs to put in some manner of condensor or some way to distribute the light more evenly. He's working on it, and I've been impressed with how he responded the first time, so I look forward to seeing the revision.
 
Not to sound pretentious or anything but... When I emailed Quyen about the high shutter speed issues all he said was that the Letus has limitations. He did not offer to replace or try to fix anything for me. That's my experience at least. It may have something to do with your Mod status. Anyways, I hope he can come up with a solution. It would be really helpful to shoot high shutter speed with the shallow DOF.
Jgastelb
 
Barry_Green said:
Until the problem is resolved, I would hesitate to recommend that someone buy it. But yes, knowing what it is would allow you to decide whether you can live with it or not, and that's what the posted clips are all about.
Click to expand...

Thanks Barry.
I'm afraid I didn't look elsewhere: I assumed (rarely a good thing to do), as did others, that your steady involvement in this thread would cause you to return to it after your cliffhanger posts.

I have heard of a similar problem with the Brevis but they seem to know a way around it on the Cinevate.com forum. The person who experienced the issue posted stills and shared the issue with the community, on the product's very own forum...

I don't think it is irresponsible at all to let people know where the product stands at any given point in time. The manufacturer knows that when he releases a product, any flaw he releases it with will get around, and he should be comfortable with that knowledge before releasing the product. If there is a fault, we should all tell each other about it. I thought that was one of the basic premises of this community: helping each other stay on top of the benefits and caveats of the pricey gear we all need to do our thing.
Killing the market? Not at all. Once the problem is fixed, the word about that gets out, and all is good again.

Cheers,
M.
 
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Is this the most current thread regarding the topic of the Letus FE, or should I be watching others as well? I am anxiously awaiting news of the Letus FE getting its issues hammered out...
 
the vibrating GG because it at one point, stops, then goes back in another direction, repeat, rinse...... some times the static grain of the diffuser becomes visible. Perhaps Quyen, can talk to Jhouser, or BklynDV about their almost grainless static diffusers. perhaps vibrating one of them will solve the issue. i knwo for a fact, Jim, (BKLYNDV) has a diffuser that has no Vingetting, but is nearly grainless when static down to F2.8. I have it sitting here next to me, and it perfoms BEAUTIFULLY.
 
Thought this would be the best place to show some frame grabs.
DVC30, Letus35 (original), Canon 50mm f/1.4

1.jpg


2-1.jpg


3-1.jpg


Surprisingly sharp in my opinion. Alot better than i expected from the original Letus. The colours are meant to be really golden-tint-ish, and the duck one is meant to be a bit underexposed. No CC, only flipping, and fake 16:9.

If the original is that good, the Letus35A, and FE but me amazing.
 
Now back to that question, which 35mm adaptor to buy.
Its Down to Letus35FE, Brevis35,M Box
Am i right in assuming the only 35mm adaptor thats flipped already is the Letus35FE.
 
i don think its resolvabale. Its inherent in the Vibrating adapter design, and the makeup up the GG material. Unless Quyen changes the GG material.
 
Exactly. Changing out the ground glass can remove that issue entirely, but introduces another one (hot spot/vignetting). Maybe using a higher-speed motor or something would affect it, I don't know, but right now yeah, it's the way it is. And all adapters should have similar issues, unless they're using really transparent ground glass, and if that's the case they should run into similar hot-spot problems. Not sure what the ultimate solution is here.
 
Part of the design parameter, particularly for CF1, was grain-free operation under all circumstances while giving the shooter an acceptable f stop range. We have never had a complaint of grain with CF1 or CF2, although CF3 is definitely biased to fast lenses run wide open. Performance with long focal length lenses (or lack of) is solely an optics issue...and something that we've invested heavily in. Edge falloff becomes a huge issue that must be addressed when S35 format lenses are used in order to maintain an accurate frame gate. A flip module is coming, but will be removeable, and usable likely with other adapters. Our original, fs mirror prototype has already been scrapped as guaranteeing perfect alignment was extremely difficult, and keeping the surfaces 100% free from dust/debris was considered a liability for shooters. Any static surface, whether an imaging plane, or mirror will eventually end up with dust/debris on it during a shoot...creating a lot of extra work in post. This is less of an issue away from the image plane, but with with an HD cam, it doesn't take much.

T, there are no dead spots with a properly designed oscillator..it does not stop or reverse at any point. Issues with grain at high shutter speeds are a function of shutter speed correlated with oscillation amplitude/frequency and grain morphology...nothing else. High shutter with an oscillator is completely doable, but the tradeoff in NVH would be unacceptable to shooters who spend the majority of time at 1/48s. We are currently prototyping a completely new drive system that allows independent exernal control of both frequency and amplitude.

Here's a quick and dirty clip of a test. The test uses an S35 format 85mm and then an inexpensive f3.5-5.3 28-200mm zoom. Lens is set at f8, (very bright outside) and I'm obviously zoomed out from the GG to demonstrate the edge fall-off performance.
 
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i think i'm gonna get the letus flip. i really couldn't care less about the grain at high shutter speeds, all adapters with vibrating GG has those issues. and plus, i prefer a darker look to my movies (a la david fincher) and i really don't feel like spending over a grand on an adapter.
 
Is this thread still active?

Are you guys still waiting for Barry's final word on Letus32 Flipped or has it been addressed somewhere else? If so could you point to the right link?

Is it confirmed that with the new letus flipped the light loss is about 1.5?

Thank you.
 
The Letus35 Flip works great, the "issue" is one that affects all vibrating glass adapters; once I saw that it happens on the $11,000 mini35 too I decided it's a non-issue.

And yes, a L35FE loses about 1.5 stops of light with an f/1.8 lens attached.
 
the Letus FE is way less sensitive than the M2. But way more convenient especially outside where light is not as big a factor.
 
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