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Old September 1st, 2006, 06:14 PM   #1
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Brevis vs. Letus35A

Since my recent acquisition of two new adapters, I think I am in a unique position to do a direct tat-for-tat shootout between the Brevis and the Letus. Both of these that are in my possession are the latest and greatest from Quyen and Dennis, and although one costs twice as much as the other I'm sure some people would like to know how they perform from a person's POV first-hand.

I'm busy at college but I can give initial impressions before I set up my tripod next week and do resolution charts, test shots and the like.

The Grain on both units is minimal, but there is definately more in Quyen's Letus. The Letus GG diffuses more however which can be a good thing as the bokeh is better. Neither adapter can be used static.

There is no vignetting with the Brevis. There is more with the Letus but you need to adjust the Plano-convex lens to an acceptable distance depending on the lens size of your camcorder. Even after adjustment I was experiencing vignetting.

I discovered something interesting. The Letus uses an achromat of much lesser power than the Brevis, probably to keep cost down, meaning your camcorder cannot zoom in as much. To compensate for this, the Letus uses a much bigger focusing plane, meaning the GG extends outside of where the image begins to falloff from the edge of the lens. This works fine for longer lenses 50mm+ but for wide angles vignetting becomes a serious issue.

The Brevis on the other hand, uses a standard-size focusing plate about the same size as a true 35mm SLR film plane in conjunction with a very powerful, very expensive achromat. This allows you to zoom into this smaller plane. Albeit you might be getting less "field of view" and therefore less DOF in this situation, but this is how the image is supposed to look like anyway.

I won't go into details about it because it doesn't deserve more than a couple sentences, but the Letus experiences chromatic aberration and the Brevis just doesn't. At least none that is easily visible anyway. Maybe towards the edges of the image I see a little, but you'll see that a lot in real movies anyway. I think it's a characteristic inherent in all lenses.

Noise.The Letus35 has become silent. Nill sound. Nothing. My previous version made a slight buzz, but you literally have to look at the switch position or peer inside to tell if it's running. Not even joking.

The Brevis, on the other hand, has a very powerful vibration unit. You can feel the vibration through the camcorder handle when it's screwed on. It's that powerful. You don't even need the indicator light to know it's on. I wouldn't be surprised if the TSA confiscated the watertight Pelican case the Brevis ships in if it turned on accidentally during transportation and somebody heard/felt it vibrating. It's definately audible, a small hum/buzz in the background. If you've got this screwed onto a camera that has a microphone right above the lens (like most cameras do) you can forget about using the onboard mic. The small hum goes away when you pull away more than about a foot but for a distance of 2 inches like an onboard camera mic, you're pretty much hosed.

The Letus has replacable batteries. The Brevis does not. Convenient when you don't want a silly box attached to the outside, and it definately makes the unit look sleeker, but not so convenient when you run out of battery power and need juice fast. Although you shouldn't run out because I hear the Brevis runs 22+ hours on one charge.

The Letus came with shoddy depth of focus placement. I know! I was surprised too. Quyen isn't usually that sloppy. But sure enough, I peered into the viewfinder the first time to find that half of my image was in focus while the rest wasn't. The GG was installed on a slant! I had to open up my unit and readjust it myself on-set. A real pain.

The Brevis is a tank. If you're a demanding professional I wouldn't trust your image to anything else. The Letus wouldn't stand up to half of what the Brevis does. I know you may not think that's a selling point, you're probably thinking "oh well I take care of my equipment, I don't need to pay for durability, I'll just be careful with it." Well ladies and gentlemen, @#*( happens. The only question is when.

The Brevis imaging adapter
Pros
* Bulletproof
* Great image
* No chromatic aberration or barrel/pincushion distortion
* Rechargable internal battery
* no vignetting, true 35mm image
* Big oscillation movement reduces grain
* All black/carbon fiber construction is sleek!
* Modular design, totally dust-proofed and sealed (unscrew the achromat, you get a metal plate with a glass window between you and the GG)
* Comes with a serious, rugged Pelican case
Cons
* Heavy/bulky (what adapter isn't? you're adding another lens for @*(#'s sake)...well, heavier than the Letus anyway.
* Overly powerful vibration, vibrates camcorder
* Battery can't be replaced/replenished immediately
* Bokeh is meh. Sort of greasy but amazing light-loss performance and Dennis ships a different, swappable focusing screen soon that allows options!

The Letus35
Pros
* Lightweight-ish
* Use Nikon and Canon FD lenses!
* Amazing bokeh, totally film-like. Great diffusion
* External battery pack allows immediate replacement on-set if drained
* Quieter than molasses in January. I guess that comparison doesn't really make sense but I'm guessing molasses doesn't make too much noise so it sort of works.
cons
* Diffusion and bokeh is at the expense of light-loss performance.
* Not as precisely made
* External battery pack is bulky and unsightly
* No indicator light
* Grain is easily apparent at even slightly higher shutter speeds or slightly higher apertures (probably because of the grain's diffusion)
* Distortion, vignetting, aberration, oh my! Even at optimal positioning, the PCXL still induces unavoidable distortion. Chromatic aberration is also very visible. This is with the upgraded 72mm achromat.

All tests were done with my FX1. I'll be back within a week with test frame grabs and movies.
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Old September 1st, 2006, 07:50 PM   #2
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Hi Ben very interesting write up. Good to read stuff like these in the forum.
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Old September 1st, 2006, 09:21 PM   #3
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Letus35A is pretty outdated I believe, the LetusXL v2 has almost none of the issue you mention but it only works on the Canons.


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Old September 1st, 2006, 09:26 PM   #4
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It also wouldnt be a fair comparison as the XL version is a relay setup that mount directly to the Canon body. I am just comparing screw-on vibrating adapters. The Letus35A may be "outdated" as in it hasn't been updated in a while but it's still the only adapter available from Quyen that non-Canon XL owners can get and the only vibrating adapter out there other than the Brevis.
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Old September 2nd, 2006, 03:04 AM   #5
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we order two letus35 and while the device is really smart the way it is built, i was a bit deceived by that final work.
there is a lot of dust left inside, mainly aluminium powder.
the glue work is awful. I think he is not using a glue gun, but a bazooka gun.
the distances are ok, but not perfect, so the focus at infinity is sometime impossible, and position of condenser must be sometime reworked.
I do not like the strange idea to include a rectangular GG and condenser.
You need then to adjust the position of the adapter versus camera, while using a circular GG and condenser would have been not only more practical, but also easy to build.
The original GG definitely needs a replacement.
So if you are looking for an adapter ready out of the box, i would not advise this product (while for some it could work as is). If you can take some time to clean and enhance it, it is definitely a good deal.
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Old September 2nd, 2006, 03:14 AM   #6
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we order two letus35 and while the device is really smart the way it is built, i was a bit deceived by that final work.
there is a lot of dust left inside, mainly aluminium powder.
the glue work is awful. I think he is not using a glue gun, but a bazooka gun.
the distances are ok, but not perfect, so the focus at infinity is sometime impossible, and position of condenser must be sometime reworked.
I do not like the strange idea to include a rectangular GG and condenser.
You need then to adjust the position of the adapter versus camera, while using a circular GG and condenser would have been not only more practical, but also easy to build.
The original GG definitely needs a replacement.
So if you are looking for an adapter ready out of the box, i would not advise this product (while for some it could work as is). If you can take some time to clean and enhance it, it is definitely a good deal.
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Old September 2nd, 2006, 04:04 AM   #7
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Quote:
Originally Posted by Ben Winter
The Letus35A may be "outdated" as in it hasn't been updated in a while but it's still the only adapter available from Quyen that non-Canon XL owners can get and the only vibrating adapter out there other than the Brevis.
The LetusFlip Enhanced I believe is the latest 'screw on' version. This will work with most cams and I beleive solves most of the problems you mentioned in the older A model.

Great read though Ben, very detailed.
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Old September 2nd, 2006, 09:59 AM   #8
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Yes, great writeup. I have the Letus35A. definately not ready to go out of the box. I've since cut out the achromat since my camera, DVC30, can focus on the screen without it (big improvement without it). I can also zoom in enough on the screen so I get no vignetting. I don't care how much you clean it, dust gets in somehow. Still, I got it for a great price, image looks great.
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Old September 2nd, 2006, 11:13 AM   #9
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My mind was already made up....but this was a great review. I wonder with the Brevis' rechargeable battery having such a long endurance, if the powerful vibrator mentioned is only as mentioned when the battery is at or near full charge. Maybe at "half charge" the review about the vibration would be different. Ben, What was the battery's charge status during your review? (or did you use the AC charger/adapter?) Could this be a possible factor?
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Old September 2nd, 2006, 11:24 AM   #10
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Does the vibration from the Brevis affect the image quality? If it vibrates the camcorder, are you seeing it also in the final image?
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Old September 2nd, 2006, 11:31 AM   #11
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Quote:
Originally Posted by Steve Witt
My mind was already made up....but this was a great review. I wonder with the Brevis' rechargeable battery having such a long endurance, if the powerful vibrator mentioned is only as mentioned when the battery is at or near full charge. Maybe at "half charge" the review about the vibration would be different. Ben, What was the battery's charge status during your review? (or did you use the AC charger/adapter?) Could this be a possible factor?
The battery was at full charge so yes this is a possibility...also the falloff of a Lilon battery (which I am assuming this is) is usually linear so this supports your theory.

Quote:
Originally Posted by David Delaney
Does the vibration from the Brevis affect the image quality? If it vibrates the camcorder, are you seeing it also in the final image?
No it definately doesn't vibrate that much. You can just feel the rumble if you hold the handle of my FX1. I don't mind it.
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Old September 2nd, 2006, 01:40 PM   #12
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Awesome write-up Ben, thank you. I was always planning on going with the Brevis and this just sealed my decision.
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Old September 2nd, 2006, 02:22 PM   #13
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Yes good write up, though you commented more on the design of the two units than a comparison of the image quality... NOW, I'd love to see someone compare these adapters to the mighty P+S Technik. It's my impression that many of the much cheaper adapters can match the Technik in image quality (thought I haven't seen much footage from it).

So the question is, exactly how overpriced is the Technik?
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Old September 2nd, 2006, 11:18 PM   #14
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The problem is that PS will never come down in price. It will always be overpriced and the first out there. We just need to concentrate on making lower prices unit that match that quality.
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Old September 2nd, 2006, 11:44 PM   #15
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I would echo what a few have said in this string, the version of the Letus used in the test is an older model. I've owned two different Letus models, including the newest Flip Enhanced and let me tell you, if you own a Canon XL2, it is a great adaptor. Quyen addressed many of the problems on the earlier model and the fact that it connects directly to the XL2 body is a huge bonus.

I've used the LetusXL Flip Enhanced for a music video and have now used it in 4 broadcast political commercials and it is great. Clients love it.
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