Letus35HD100 Test Footage

[Dustin Cross]

Aloha,

I just recieved my Letus35HD100 and have some footage to show. This is a beta unit. I am trying to shoot as much usefull footage for Quyen as I can.

The construction of the unit is great. This unit is clean and professional looking. The attachment to the HD100 is solid and atleast as good as the stock lens. No need for rails. There is a small black lens that can be screwed out of the back of the Letus. I think this is the achromat? The actual glass is tiny, about .5" in diameter and .5" thick.

The iris on the Letus works fine, but it only has limited movement from open to close. From f11 to f32 on the markings. The markings go all the way down to f4.7, but you can't adjust the dial that far. The iris works great. It allows for very fine adjustments.

My only issues with construction is all the glass is glued in. I can't think of any reason this is bad, but it makes the contruction seem cheap. Also there is one spec of dust or something on the inside of my adapter. This has been a problem with all the Letus adapters.

For testing the first thing I am trying to figure out is exactly how much light is lost. So I set up a little test using my color slate. I put the Letus on the camera with a lens at f2 and lit the slate so the white bar was showing 95% using zebras on the HD100 viewfinder. I then changed back to the stock lens zoomed in to get the same frame and stopped down until I had the white bar showing 95%. I shot once with my Nikon 55mm and then moved the camera and did the test with my nikon 85mm lens.

Here is the footage. All I did was capture with LumiereHD Beta and demux with MpegStreamClip. So the footage is as native as I can make it. The file is large (175MB).
http://www.scottleemason.com/letus/L...100_Test_2.m2v

Here are stills from MpegStreamClip for those who don't want to wait for the long download.

http://www.scottleemason.com/letus/L...0_55mm_f2.tiff
http://www.scottleemason.com/letus/L...0_85mm_f2.tiff
http://www.scottleemason.com/letus/L...pare_55mm.tiff
http://www.scottleemason.com/letus/L...pare_85mm.tiff

With this setup I am getting 3 stops of light loss with a prime lens at f2. If I open the lens to f1.4 I will be getting 2 stops of light loss. I chose f2 for the test, because most of my Nikon lenses can do f2, but only a couple can do f1.4.

The footage with the letus looks washed out. I need to recheck all the settings on my camera. I have been playing with them. I think I will set them to Paulo's True Colour v3 and reshoot this test later.

I am wondering if the image on the GG is over exposed and the light loss from the GG to the CCD is not causing the washed out look.

With proper lighting I think I can deal with the light loss issue.

My concern right now it the loss in resolution. The Letus footage looks very soft compared to the stock lens. I don't know how much Quyen can do to make the image sharper, but that is the biggest problem so far in my opinion.

I will post more footage as I do more testing.

[Andrew Todd]

color correction can do wonders

[Bob Hart]

Dustin.

I don't think Quyen would turn something loose that didn't work close to his satisfaction even as a beta because he now has several generations of product running around which will be benchmarked against any new innovation he puts out there.

So the issue may be related to experimentation and practice with the system.

Are you using the manual gain/shutter speed settings on your camera?

Over-exposure is certainly going to badly affect the resolution. Your camera may not have an internal aperture system like the Sony's as it normally has the Fujinon manual capable lens on the front.

So you will have to go carefully into the camera menus to find the alternatives, work through them systematically and note the results down in writing. I know the JVC menus are not as intuitive as some others but it is the only way.

Odb video gain would be a good start along with 1/50th sec ( or 1/60th second ) shutter speed, f2.8 on your SLR camera lens, a middle setting on the Letus internal relay lens. The limit on available range on the relay lens may have been purposeful to avoid even more over-exposure.

If the over-exposure is still apparent, maybe try some neutral density filter gels in the path if there are no more ND options already available in the camera.

Don't take too much notice of my suggestions as I am not a Letus owner-operator just an interested home-builder/bystander.

[Tony Tibbetts]

Soft image? Yes, generally speaking all adapters tend to soften the image. This is just a thought, but could it be that the back focus is off? I had to adjust my LetusXL after I got it.

Originally Posted by Bob Hart

If the over-exposure is still apparent, maybe try some neutral density filter gels in the path if there are no more ND options already available in the camera.

This may be a good idea, I've been thinking about doing this myself. I personally find that the best footage I get is usually with the relay lens between f4 and f8 with the SLR lens between f1.8 and f2.8. Does the HD100 have negative gain capabilities like the XL2? That might be another option.

[Dustin Cross]

Tony,

The HD100 doesn't have negative gain. I used that alot on my DV5000. It was always at -3 gain.

Putting an ND in front of the SLR lens won't help. I need that much light to expose the slate so white is at 95%. Color correction helps alot though.

On the Letus35HD100 the relay lens operates from f11 - f32. I don't think the f stop numbers have any meaning on these adapters. I shot this footage with the adapter iris wide open at f11.

There is no backfocus on the Letus35HD100. Quyen told me he removed that feature. I think backfocus is my problem with softness. Looking at the GG with no SLR lens on the camera I don't see any detail in the GG. It is all blured together. With my Letus35, Letus35A, and Letus35flip I could see lots of detail in the GG when the camera was properly focus on the GG.

This was mostly a test to see how much light was lost in the adapter. If I put NDs on or stop down the adapter iris I would be loosing more light and then my assessment of the amount of light lost by the adapter would be inaccurate.

[Tony Tibbetts]

I can see why Quyen removed this feature, it is rather tricky to adjust it. If the GG is not moving can you visibly see the grain? If that isn't in focus then it is more than likely a back focus issue. However the image does get kind of soft if the relay lens is at full open mine goes up to f2.8, but it doesn't get sharp until around f4. Also I can push my XL2 to +3 gain and the image is still very good, not even a noticable difference to the naked eye. I'm not sure how good the gain feature is on the HD100, so I can't tell you whether this is a good option for you.

An ND filter may help...or it may not. I'm definitely going to do some experiments with this in the next few weeks. I am curious to know myself. Have you contacted Quyen?

[Dustin Cross]

Tony,

It seems like my backfocus is wrong. Here is a frame grab of the Letus35HD100 GG not moving. You can see it is not in focus. The middle of the frame is the most out of focus.

http://www.sandust.net/letus/Letus35HD100_GG.tiff

Here is a frame grab of the Letus35flip GG not moving on the stock Fujinon lens. On this one the sides of the frame are out of focus, but the center of the frame is good.

http://www.sandust.net/letus/Letus35...onLens_GG.tiff

Here are frame grabs of a rez chart shot with the stock lens, Letus35HD100 & Nikon 85mm, and Letus35flip on the stock Fujinon lens with Nikon 85mm. The Letus35flip is pretty darn sharp on the stock fujinon lens.

http://www.sandust.net/letus/Letus35HD100_85mm_f2.tiff
http://www.sandust.net/letus/Stock_lens_f5.6.tiff
http://www.sandust.net/letus/Letus35...85mm_f2.8.tiff

These shots are not ment to be used to judge the actual resolution of the LetusHD100, Letus35flip, or the Fujinon lens, just as a comparison of the three in these conditions using this rez chart.

I have all this as .m2v video that I will post later.

I haven't contacted Quyen about this yet. I wanted to do some testing before I told him I think my backfocus is off.

[Tony Tibbetts]

Are these shots with an SLR lens attached to the Letus or without?

I can't say for sure, Quyen would definitely have a better answer for you than me, but my guess would be that it is a back focus issue.

[Dustin Cross]

Tony,

The shots of the GG are with no SLR lens.

I talked to Quyen and he told me to stop down the relay lens iris. So I stopped it down from f11 to f22 and the footage gets sharper, but there is still something wrong. Quyen is looking into it.

Here is a new frame grab of GG with the relay lens iris at f22. There is no SLR lens on the adapter for this image:
http://www.sandust.net/letus/Letus35..._iris_f22.tiff

Here is the resolution chart with the relay lens iris at f22 and the 85mm Nikon lens at f1.4:
http://www.sandust.net/letus/Letus35..._iris_f22.tiff

There is a strip down the middle of the image that is very out of focus. The upper corners of this image seem pretty sharp though. I played with the focus a lot and this is the best it gets.

Stopping down the relay lens means I loose another stop of light. 4 stops of light loss is a bit much. The Letus35flip on the stock fujinon lens only looses about 1.5 stops of light and is pretty sharp.

[Tony Tibbetts]

That is odd. Haven't seen anything like that. I'm sure Quyen will be able to correct it.

[Michael Fossenkemper]

then why not just get the Letus without the flip? That's what I did. I saw the flip and I thought about how I shoot and went with the 35A. Found that I could focus on the GG without the Achromat and took it out. I get a very clean crisp bright image. I do find that Quyen is a little slow in replies if something isn't going right, but eventually gets to it. Over all, I love my Letus35A. I do loose light even with my modest setup but can shoot very nice video with just 100w light indoors at night at f4 on a canon 50mm f/1.4 lens and no gain in my DVC30. with a 3 light setup of 500w lights, I can pretty much shoot from f11 to f1.4. what more can you ask for? After all, the whole idea of attaching one of these adapters is a hack and you have to work around issues. Once I tweeked my camera and tweeked the adapter and found a couple of lens's that worked well, everything kind of clicked into place. it's like anything that you hotrod or modify, You can't just throw a V8 in a Gremlin and think you have a race car, you're going to have to change other things too.

[Henry Clayton]

Originally Posted by Michael Fossenkemper

After all, the whole idea of attaching one of these adapters is a hack and you have to work around issues.

I think that's the key insight here.

The most helpful thing anybody could do whose intention is to help potential buyers of a Letus make a sound decision would be to rein in the subjective opinions & present a good deal of objective data. Ideally this is something Quyen would do, but realizing, in the spirit of Michael's comment, that this is very much a fledgling project not too far out of its infancy in the DIY movement here on the DVinfo.net boards, I'm willing to be more relaxed about that sort of thing if similar information is forthcoming from the community. (I'm no stranger to struggling with a one-man-band business.)

I have been impressed with some of the footage posted in various threads of this forum, but it's rather scattershot. A part of the problem is that the Letus has rapidly gone through several versions, & there has been some question about various performance differences between them, so footage shot with one version is not necesarily indicative of another version's performance. Another part of the problem is inherent in the nature of bulletin boards, with bits & pieces of things buried in sundry threads, so that what information there is requires some work to ferret out. (A collaborative wiki would be perfect for collecting & presenting this sort of information.)

But the principal issue is that there simply isn't enough objective footage done with the various models & under varied shooting circumstances.

I'm very interested in the Letus35XL based on some of the footage I've seen shot with previous models, but enough issues have been raised specific to the 35XL (with its relay lens & a different technology for the flip feature--now there's a prism apparently) that I am somewhat hesitant to purchase it considering the current paucity of thorough product information available. I'd be more inclined to sink my money into the product if there were more information.

By the same token, if I could get hold of a representative 35XL at a beta price, I'd be more than happy to run it though a comprehensive battery of tests & write the whole thing up on a wiki on one of my servers for everyone's edification, including copious photos & video footage. I'm sure it would help Quyen's business as well in terms of giving potential customers the concrete information they need to make the decision to buy.

Does this stike anyone as an attractive proposition? If anyone has any information here I might obtain a 35XL at beta price (anyone selling?), let me know.

[Tony Tibbetts]

Is Quyen not selling them any longer? If thats so, its news to me. I think Tucker might be more than willing to sell his. If you live anywhere near Seattle I'd be happy to bring it by and do some tests.

[Henry Clayton]

Originally Posted by Tony Tibbetts

Is Quyen not selling them any longer? If thats so, its news to me. I think Tucker might be more than willing to sell his. If you live anywhere near Seattle I'd be happy to bring it by and do some tests.

I was under the impression that he'd stopped selling them at beta prices.

Until last I August I lived in New Orleans, but now I'm a little closer in Montana for an indeterminate period. Still quite a drive from Seattle though!

H.

[Michael Fossenkemper]

ohhhh Montana... I'm taking my dad fishing at the base of the Tetons in 3 weeks. Can't wait. What's the weather like there? Should I bring shorts or Jeans?