Hi Guys,

A couple of month ago I bought a Letus35 and here are my conclusions:

I tried the Letus35 with both a Gl2 and a FX1 (both Pal models). I made tests with 3 canon fd lenses (28mm f2.8, 55mm f1.2, and 85mm f1.8).

Lets start with the Gl2 - as soon as I hooked up the Letus35 to the GL2 I was amazed with the incredible DOF, but pretty soon, I started realizing how much I had to sacrifice for the DOF (and wondered if it would be worth it). The GL2 is 6lux (barely a great low light camera) and its' image is naturally soft. With the letus35 hooked to it, it lost like 2 stops. Even in extremely well lit conditions, the resulting image was way too soft (a strange, almost blurry kind of soft). Maybe that is the look some people are going for, but not me. I tried all kinds of different camera settings, light conditions, CC and the image was always too soft and still too video like. I consulted Lee a couple of times and received replies almost immediately. He is a very very nice guy and the support is truly awesome. Unfortunately, the Gl2+Letus35 didn't work for me.

In the meanwhile I sold my Gl2 and bought a FX1E (very very sharp and very nice in low light). I bought a 72-58 step down ring and hooked the letus35 to the FX1 straight away. I thought that I would not have the same issues with the FX1 but sadly all the same happened again. Again, I used the same lenses and tried all possible conditions, but no go for me. The image still looked very soft and video like.

Another thing that I was not very please with was the place where the 58mm ring connects to the Letus35...it really feels like it'll come off if you move the camera too fast (I shoot a lot of run and gun, so this would naturally be important for me).

I visited the Letus35 website recently and read that there is a new version available (letus35A), which apparently uses a better achromat and already has a 72mm thread (for about 400 bucks)...but so far I didn't see any FX1+Letus35 footage that would make me want to buy it. I feel bad about it, because I feel that the letus35 could be a nice option to those who cannot afford more expensive solutions. More and more I'm convinced that what you pay for is what you get. I will save some more money and invest on the Guerilla35 (very very sharp, loses way less light, increases the cameras latitude...which really helps overcoming the FX1 "videonish"). Anyway, I hope that Mr.Lee can make some improvements on his product, because I feel it could have potential as a run and gun adapter and I know a lot of filmmakers could benefit from it.

Cheers,

Rafa

Couldn't you jack up the sharpness on both cameras before shooting the videos? To compensate for the softness of the lens?

I did that. Belive me. I tried it all.

Post some screengrabs.

I'm not home right now, so I don't have access to video samples, but when I get home I'll try to rember to post a 5 minute video test I did some time ago. Anyone knows where can I upload it for free?

There are a few weak points in the Letus adapter, but I think the biggest one is the GG--it's image is way soft. I'm replacing it with an Intenscreen as soon as it comes in the mail--I think that'll improve things a lot. Of course, its how it performs as "stock", not modified, that matters, so (I think I've mentioned this before) I wouldn't recommend the Letus for anyone who doesn't like to tinker around a bit with things.

I thought Intenscreen is not usable in Letus kind of adapters.
Isn`t that too big orbital movement of frensel focusing screen?
Dan knows better...

Dan knows better...
Dan has been sharing some results and comparisons on his site long before any other commercial contraption took off (wax, shaking or spinning). Dan tried for a year to contribute some FREE education (for the uninitiated that is) in an attempt to save you hundreds of wasted hours and $ on cutting corners and also to save you from jumping to the first buzzing fly like fish out of the water on a sunny afternoon (excuse my plastic vision)

The "brightness comparison" album on my site is not there for me nor is any other test I have done.

I knew the result of them before I even got to this project. That is WHY I used a focusing screen instead of a GG. in the first contraption (Sept 2004 - with a flipped image)

Check the messages prior to Dec 2004: (how long should I grind the filter?, what grit and what-not). Hobby? Yeah is a lot of fun, but if you want competitive results.... One nice comment I red on this board (deleted or I just can't find it) was: "hey mister, what's wrong with you? we just want a great adapter for a decent price!

But...your wallet vote says I was wrong all along, so what else can I say?

But you're not bitter, right? :)

I used my Nikon D screen in the Letus for a while without any problems. I don't see why a beattie would be any different.

No Bill, I am not.
Ben, do you have frame from footage of a resolution chart?

A chart or screen grab with the D screen on would be nice.

The D screen got scratched up after trying it out on different adapters, so I threw it out. I'll tape a res chart once the intenscreen comes and it's on.

I can't help but think that Rafael has a back-focus problem like I did on my Letus35A. In addition to moving the 35mm lens forward and back to test backfocus, I recommend taking the Letus off the camera and hold it about 1/4" away from your video lens to see if it is easier for it to focus on the ground glass.

What camera do you use Marcus?

I use the VX2000 for which the Letus35 was developed. I had to send mine back initially due to inability to focus on the ground glass. It seems that the tube was to short for my camera. Actually, I have the Letus35A and there may have been a problem introduced when Quyen changed achromats. That is my guess. I'm sure he has that issue solved by now. Regardless, you can experiment with the Letus by unscrewing it and holding it different distances from the camera. To check backfocus, move the camera lens away from the Letus35 slightly. My backfocus was off by about 1.5mm so I heated the hot glue on the sticks that hold the ground glass and repositioned the element.

I made some more intensive tests and I found out that the 58mm thread simply won't work with the FX1. I used a step down ring and it fits but you have to zoom in so much into it that you simply cannot get the right image. Before I start shooting I tried findind the sharp spot without zooming in and with the motor off and it is simply impossible. I set the 55mm lens to infinite and use the FX1s' enhanced focus to manualy look for it but it is never fully on focus. When I turn the focus ring a little bit away from infinite, I achive a fully focussed image, but as soon as I zoom in to fill the entire frame, it reaches a point where the image doesn't seem to be able to fully achive full focus, no mater the setting. So, I decided to test the image I shot without zooming in (where I can see most of the interior of the adapter) just to see if it could be used if I croped it from HD to SD using only the center of the image (which would be useless because I want to be able to have the final results in HD too). The image contains a lot of grain even with a lot of light. I think that maybe the 72mm thread letus35A MIGHT work for the FX1 IF it alows you to frame the image properly without having to zoom in so excessively...but then again...I tried the letus35 with a 58mm thread cam (GL2) where I didn't have to zoom in as much and the image was still way too videosish and soft. I would love to hear from some Letus35A owner who has a FX1...even more I would love to see some footage.

My backfocus was off by about 1.5mm so I heated the hot glue on the sticks that hold the ground glass and repositioned the element.

Marcus, this will throw off your depth of focus drastically. Now all the readings on your lens will be inaccurate and the infinity focus will, well, no longer focus to infinity. Be sure to keep the distance from the SLR lens and the focusing element the same as Quyen built it.

Ben, the way I discovered that I had a backfocus issue was that my ranges were all wrong and infinity would not focus. In my case, it was not built with the correct range. All of my lenses were off and now they all work and have proper focus in relation to their markings.

Ben, the way I discovered that I had a backfocus issue was that my ranges were all wrong and infinity would not focus. In my case, it was not built with the correct range. All of my lenses were off and now they all work and have proper focus in relation to their markings.

I think this might be the case with me. I simply cannot focus when the lens is at infinity (ANY lens).

If the backfocus is out, the image will be inferior with the wide lenses, ie., 28mm, 24mm. I have a 12mm - 24mm digital Nikon which was hopeless, but came in to an acceptable level when I took meticulous trouble to get the back focus right.

Even if can can focus past inifinity with numbers mismatching, the result to infinity still will not as sharp as when the lens os correctly positioned for backfocus.

That's what I have found with my setup anyway. It could be an illusion or delusion on my part, but that is a I saw it.

There is another issue - that of the groundglass being at true right angle to the lens axis, both laterally and vertically and then the camcorder lens axis also being central and parallel to (non-erecting) or parallel to (prism erecting) the SLR lens axis, ie., also at a true right angle to the groundglass.

This is a very real issue for builders of the CD-R spinner versions. For any, it is desirable for the backfocus and angular adjustments to be built in. If we want the results that are obtained with film cameras, then the same meticulous trouble has to be taken to set up the optics.