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Old March 30th, 2006, 12:01 PM   #1
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Letus35A review

Being a huge enthusiast of HDV and trying to achieve better looking images (without the signature video look), I settled on Letus35A made by Quyen Le.

It's available now, and it did receive some high accolades from other reviewers, plus the cost seems to be the lowest for any 35mm adapter.

Here's the link to some image grabs from the video made on Sony Z1U with Letus35A just yesterday in midtown Manhattan:

http://pg.photos.yahoo.com/ph/mo7ies/my_photos

They illustrate quality of DOF, sharpness, bokeh, and chromatic aberration.

I think the adapter does produce a great shallow DOF, and I liked it's bokeh (out-of-focus areas) look.

However the images are very soft, chromatic aberration is huge, and the moving GG can still be seen in darker areas of the video.

In fairness, I don't know how much of aberration is introduced by the cam's own lens - and my guess is probably 50% at least. Also on the positive side: Letus35A seems to produce zero blooming, and negligible geometric distortion of the image.

But does it compensate for the absence of the sharpness? Yeah, when you want that diffused look, here you have it. But I don't want it all the time, and seems that I'm out of luck.

My adapter also had issues with some bright crystals on GG making visible circles when it vibrates. Sent back to Quyen for servicing.

Another issue: adapter's camera mount. It appears to damage the filter groove on camera, even when screwed in with utmost care. Plus, by design, you have to force it to the correct angle after it's screwed into place, so the GG's frame is horizontal. In process, metal particles seem to be scratched off the inner tube surface by the rotating mount, and then I can see them littering the inner side of the macro lens. Maybe a bayonet mount, based on the cam's lens hood ($80 part), would be a better idea for fast, safe, and painless attach/release of the adapter.

I used Canon 50mm 1.4 SLR lens on the front, and had no issues with its mount whatsoever. Maybe Quyen redesigned hsi Canon mount to address other users' complaints, or maybe I just got lucky with my lenses (Canon 28mm 2.8 also seems to fit perfectly, but I did not have a chance to shoot with it yet.)

It'd be interesting to see whether my impressions correlate with such of other Letus35A owners. How do you guys use it for anything larger than web video size, when it's so soft?

Last edited by Alex Raskin; March 30th, 2006 at 06:18 PM.
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Old March 30th, 2006, 02:29 PM   #2
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Alex,

I mostly agree with your review. I don't think the image gets so soft and you describe, but it does get soft.

I haven't had any problem attaching the adapter to my FX1. It screws on just fine.

Adjusting the adapter so the image is square with the frame is a problem. It does get dust shavings inside the adapter, so you have to be very careful. Once I had it aligned I put a hose clap on the adapter and torqued it as tight as I could so I didn't have to realign the adapter again. That works great.

I shot a 15 minute short with my Letus35A and was very impressed. I used all Nikon lenses and the lens I used really made a difference. I have an awesome 50mm f1.2 and a not so great 24mm f2.8. With the 24mm lens the image is really soft and ugly, but with the 50mm it looks sharp and beautiful, so the lens in front of the adapter really makes a difference.

I now have a new Letus35flip and I am happy with it. I just ordered an 82mm to 72mm stepdown ring so I can put it on my JVC HD100 and shoot some test footage with that. I will be one of the first to buy a Letus35HD100 when Quyen makes it.

I have let two people use my Letus35A and they weren't able to get any usable footage. With a little bit of work I was able to get footage I am very happy with. I shot a short at night with the Letus35flip and only two 1K lights. That was hard to get useable footage with all the light loss, but I am happy with what we ended up with.

Here is a link to some of the footage of the short we shot at night with the Letus35flip and only 2 1K lights.
http://www.sandust.net/ghost/HH_theCOMB_WEB.mov
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Old March 30th, 2006, 02:47 PM   #3
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I'm curious. Did you turn up the level of sharpness on your Z1 to compensate for the loss of sharpness with the Letus? Or did you leave the Z1's sharpness level at the default?
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Old March 30th, 2006, 03:30 PM   #4
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Z1's sharpness is at 12 (just a notch above the normal 11 setting).

1/60 shutter; ND1+f/9 (sunny day; I was afraid the adapter would bloom like crazy but it did not, in my view); black stretch on; gain 0; other settings at default I think.

Dustin - great movie! Unusually good acting and editing, too. Is that a prequel to Ringu? ;)
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Old March 30th, 2006, 06:20 PM   #5
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Dustin, what follow focus did you use, if any?
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Old March 30th, 2006, 07:11 PM   #6
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Dustin,

I see the footage playing at 29.97, very impressive and cinematic, did you shoot this with the Sony?

If so what are your settings? using cineframe/cinetone?
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Old March 30th, 2006, 07:11 PM   #7
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*****bump*****
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Old March 30th, 2006, 09:02 PM   #8
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We didn't use any follow focus. That is all fingers on the lens. I need to get a new follow focus. I'll be looking at those at NAB. I had a CAVision follow focus and didn't like it.

We shot this short with the Sony FX1 and the 1st generation Letus35flip. It was 60i, cinematone on, sharpness of 10 (I think). The director/editor was the focus puller. We used two 1k lowel lights and nikon lenses (20mm, 35mm, 55mm, 85mm, and 105mm). I can't rember if the director/editor used film look in post or not.

Thanks for the comments.
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Old April 1st, 2006, 01:40 PM   #9
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hey
good review
check out my post regarding kinks and problems with the Letus
would like to hear from satisfied users about solutions and workarounds
i still want to get the best out of my Letus

http://www.dvinfo.net/conf/showthread.php?t=63331
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Old April 1st, 2006, 03:46 PM   #10
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Thanks, and yes - I'm following your thread too :)

Thankfully, I have no problem with my 2 Canon FD lenses since the locking mechanism is located on the lens itself. No problems with mounting/dismounting them on Letus 35A either, so far...

I'm thinking of making a cage to hold the camera upside down, a small video monitor (shows correct image live), and to support Letus adapter. Quyen says support isn't necessary, but with some large glass (like Canon f1.2) I bet it'll require support.

Anyone made such supportsystem already? Plus, follow-focus maybe?
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Old April 2nd, 2006, 12:22 PM   #11
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I want to say that I have been watching some of these homeade adapter clips and yes some of theses images are a bit soft.

One thing you have to remember is that a lens is usually not that sharp wide open. Some are better than others at this.If you have an m42 adapter the zeiss jena ddr lenses are some of the sharpest lenses that can be had for a cheap price.

Also when you're at say 1.4....and shooting outside...The Depth Of Focus(which is really what we're talking about here) can sometimes be just inches deep.Try stopping down one stop or two and it should be easier to get things sharper.Or use some measuring tape along with the distance markings on the lens(if there are any) to get a more accurate focusing.

Yeah, a bit anal...but it bugs me ... the "Depth of feild" saying they keep throwing around here is incorrect.A shallow depth of feild comes from a longer lens...makes the background appear closer.A deep depth of feild is from a wide angle which can make small rooms look huge. A shallow depth of FOCUS comes from using larger aperatures.

The combination of a somewhat longer lens with a wide aperature makes for a good rack focus shot.Because it is more apparent that the background is out of focus when it is compressed to look closer.
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Old April 4th, 2006, 11:26 AM   #12
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Jeremy;

The "Depth of Field" saying they keep throwing around here is correct. Depth of field is mesured at the object plane. You will not find any "Depth of Focus" tables in American Cinematographer Manul since the cinematographers do not worry about "Depth of Focus".

Depth of Focus is mesured at the film plane (CCD plane in a video camera) and is a concern of camera manufacturers or Depth of Field adaptor designers since they need to know about it when adjusting the back focus of the lens.
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Old April 4th, 2006, 11:56 AM   #13
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True , but when the term is used here it is generally used to convey shallow focus.Which is obtained by a combination of small aperature and longer focal length. However ,you could use a wide angle lens that was extremely fast and get a reasonably shallow depth of acceptable focus and still your dof would be very deep.

Having a shallow depth of feild with a longer lens does help with those shots though,becasue by bringing the background to appear closer...it is more obvious that it is out of focus.
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Old April 10th, 2006, 09:54 PM   #14
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Anyone noticing the drop in contrast on these images?
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Old April 10th, 2006, 11:11 PM   #15
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Ben.

I have observed with my device which uses glass, that there is a apparent drop in contrast. I think what happens is a bit of a diffuse flare is added to the image.

I tried aggravating this fault with a bit of direct light added to the disk from wthin the device itself. This confers a sort of effect like prefogging film or using low contrast stock.

There was a flicker problem, possibly related to me using sunlight fed into the device through a small hole through one of those little fibre optical leads wich go into the back of dvd players.

I did not get it to work like I wanted, got lazy and did not perservere beyond the masking tape and taping the free end of the fire optic lead to a garden stake facing the sun. An internal clear LED would probably be the way to go. It would be a nice effect if it could be perfected.

If you are careful to manually set the apertures and limit the automatic gain on the camera so the dark areas remain dark, I don't see a contrast reduction as a severe setback.

Careful selection and composition of your shot to control the extremities of lighting between the two most significant large areas in your image to about 5 f-stops seems also to help.

When outdoors and no control over lighting is possible, shooting with the light from behind from behind the camera seems to give the most pleasing result.
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