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Old May 23rd, 2006, 09:34 PM   #1
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Letus35HD100 Beta here

Well, I big thanks to Quyen (Clap, clap, clap)

The unit arrived this morning and I used it this afternoon for a national commercial to air on The Outdoor Channel this summer.

Initial responses:

1. Lighter than expected.
2. I was unable to use my matte box with it. I didn't think it would drop the lens as much. I will have to get some adapters for my matte box, but not a problem. Also, I will need longer rod support.
3. Extreme light loss, I think... When shooting outside in bright sunshine, I was not able to use any ND and the Letus aperature was wide open and my Tamron 35-200 was around F4 for proper exposure. This seems to be a great deal since my standard Fujinon requires ND2 and a drop-in ND filter to achieve the same thing. Inside I had both aperatures wide open using a Nikon lens and I had to set the gain to 18db to see anything under standard office lighting.

Having said this, I don't want to seem negative. I want to know if this is acceptable light loss for this kind of adapter? The images that I shot today seem fabulous in camera. I will post some shots tomorrow.

In the meantime, does anyone have any suggestions about the apparent light loss?

Quyen?

Are there things that I should try to put the adapter though some trials?

BTW, If I would have paid double for the adapter, I would still feel like I have my money's worth. But if I have to shoot with a sun gun inside that might be an issue. :-)

Chris Lognion
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Old May 23rd, 2006, 10:17 PM   #2
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Quote:
Originally Posted by Chris Lognion
Having said this, I don't want to seem negative. I want to know if this is acceptable light loss for this kind of adapter? The images that I shot today seem fabulous in camera. I will post some shots tomorrow.
Well, since the only other adapter thats remotely similar is the $12,000 P+S mini35 I wouldn't be able to tell you, but since the path of light has to go through a lens, then a focusing screen, then a couple of mirrors, and then another lens I'd have to say yes the light loss would be normal.

These type of adapters need light...theres no getting around that.

I know Quyen has improved the design on his relay lens from the original version to be sharper, and that it loses a little more light. At least as far as the XL version is concerned. I would assume the same with the HD100 version, which he took longer to design.

The spinning GG box type adapters (M2, SGpro) tend to lose the least amount of light, about .5 stops. The tube type (Cinemek,Brevis, Original Letus) tend to lose between .8 to 1 stops of light. The Letus35XL loses about 1.5 stops which is reasonable. I assume it's probably the same with the HD100 version.

I'm sure Quyen could answer this better than me. The trick is finding the right balance of exposure between the f stops on the SLR lens and the f stops on the relay lens. Keep at it. The footage will be awesome once you've got the hang of it.

I for one can't wait to see how footage from the HD100 looks using the Letus. Post some when you have some time.
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Old May 23rd, 2006, 11:11 PM   #3
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Quote:
Originally Posted by Tony Tibbetts
The spinning GG box type adapters (M2, SGpro) tend to lose the least amount of light, about .5 stops. The tube type (Cinemek,Brevis, Original Letus) tend to lose between .8 to 1 stops of light. The Letus35XL loses about 1.5 stops which is reasonable. I assume it's probably the same with the HD100 version.
Tony, I think it would have to be established how light loss is measured by each manufacturer, and what the numbers they advertise mean. For example, I think Wayne just recently said the light loss from his adapter was .5 stops, but that was for the adapter alone, without a 35mm lens. The number I’ve heard for the Brevis was .5 to .7 with a 50mm F1.4 lens on. And I’ve heard different numbers for the M2. These numbers are probably all correct; it’s just that, unless someone compares all the adapter side by side with the same lens, in the same conditions, and with the same method, it’s really hard to say which ones have less light loss.
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Old May 23rd, 2006, 11:23 PM   #4
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Pics posted

I just captured a few frame grabs from my home PC. I will post some more when I get to the studio tomorrow. I'm new at putting pics in this forum so I hope it works.

http://www.dvinfo.net/gallery/showimage.php?i=437&c=24
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Old May 24th, 2006, 12:09 AM   #5
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I was just going off the top of my head...wasn't trying to be exacting merely in the ballpark, from what I've personally seen and what I've heard on various boards. I was only saying thats what you start with not necessarily what you end up with.
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Old May 24th, 2006, 09:24 AM   #6
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Letus35HD clips

After reviewing it on a monitor, I can see the GG more than expected. I've posted some clips for those interested and hope I can get some suggestions to minimize this.

http://www.dvinfo.net/gallery/browseimages.php?c=24
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Old May 24th, 2006, 12:10 PM   #7
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Do you know what your lens apertures were on both the SLR lens and the relay lens?
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Old May 25th, 2006, 09:41 AM   #8
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The footage also looks WAAAAYYY soft...and the halation? Did you use a ProMist or is that clean? Yikes!

Henry
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Old May 25th, 2006, 10:01 AM   #9
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I know people will say I'm just being negative, but it looks soft. Way too soft for HD material. I would say for me it looks too soft for SD maetrial, but may be just me.
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Old May 25th, 2006, 10:38 AM   #10
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The longer the optical light path, the more light is lost. This is why flip versions, even from a low loss adapter, will always have more light lost. If optics are not correct, there will be even more light loss as the image cone disperses. As usual, there's no free lunch in the world of optics. Flipping in post, or using the camera inverted will always be the lower loss way to do the flip. Quen is however addressing the demand for an optical flip solution, and with that, there are costs.

Quoted light loss numbers from adapters fluctuate wildly, but if you pay attention to anecdotal reports, you see the trend. The only way IMO to measure this is to frame an identical scene with the same camera, at the same time, with and without the adapter. This must be repeated with different scenes...not just using an ISO chart. ISO chart results are not typical and if I was quoting these, I'd say the Brevis had 0 loss...not a typical field experience. Using the "field average" method, I see .5 to .7 f/stop loss with the Brevis with a 50mm F/1.4 lens with open aperture. Many people are using primes at f/2.8, so light loss there is even greater.

The mini35 (inverts image) sees in the order of 4 f/stops loss as I recall from the DVX review.
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Old May 25th, 2006, 10:52 AM   #11
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The image was captured using F4 lens and adapter IRIS is open all the way. I am not surprise if it's soft since this adapter is designed around the F1.4 lens and adapter IRIS set to 5.6 and up. F4 lens' image is usually soft by itself. Below is an image captured with IRIS setting at f8 by XLH1 camera, Letus35XL of course. Thanks.
http://letus35.com/35XLH1.JPG

Quyen
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Old May 25th, 2006, 11:28 AM   #12
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After Quyen's suggestion, I tried a 50mm 1.4 lens and the image is much better with no significant light loss, I'm sure there is some but very little. The image is sharp, however, there is ghosting of the highlights. I will put this through some more tests when I get a chance and post my findings.
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Old May 25th, 2006, 11:32 AM   #13
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Quote:
Originally Posted by Henry Gretzinger
The footage also looks WAAAAYYY soft...and the halation? Did you use a ProMist or is that clean? Yikes!

Henry

I'm afriad not. Using the Tamron lens with the Letus is just that soft. Way to soft unless one was trying to acheive this look. I did not do anything to the images other than they were shot in DV mode not HDV.
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