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Old February 11th, 2006, 04:42 AM   #1
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Letus35 Flip - Ghosting Issue

Here's the ghosting issue i've been trying to figure out for some time now. The picture will explain it all. And if you still cant see it, it's smack in the center. Basically the entire frame flipped upside down (not 180), shrunk, then superimposed onto the image.

Just a Nikon f/1.4 50mm on the Letus35 Flip on my HC1. Image is from downressed hdv, though in hdv, the ghost is much more detailed of course. (sorry, i didnt have time to compress to jpg)

http://www.mindchattermedia.com/rp's.../ghosting.tiff
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Old February 11th, 2006, 07:32 AM   #2
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Ghosting

I have got some ghosting too. I discovered it yesterday evening when shooting during the "magic hour" when the sun was low: the assembly between the two plastic parts of the flip housing of the Letus35 Fi was not perfectly sealed, and allowed some vicious sun ray to penetrate through the interstices. I will have to seal the flip housing.

Last edited by Daniel Apollon; February 11th, 2006 at 11:35 AM.
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Old February 11th, 2006, 12:44 PM   #3
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probably the GG wasn't shaking enough.

I know you need lots of lights to get sweet letus flip clips and if you have a matte box, it will help also.
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Old February 12th, 2006, 03:10 AM   #4
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It isn't because of the crack between the two halves (which i have already taped over with gaffer tape), and a mattebox wont help. I took some cardboard and folded it into mattebox shape, and tested it out. still the same scenario.

this has got to be some sort of internal optics issue, not just light leaking through the cracks. this is a very discrete and clear image that is being ghosted. i know im not the only with a flip, where are you guys?
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Old February 12th, 2006, 04:30 AM   #5
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ghosting where and under which lighting conditions...

I do not have that kind of ghosting (using Canon FD lenses from 28mm to 135mm). It must appear under some specific circumstances (e.g., intensity of light, contrast area in picture) or is due to some defect in an isolated adapter. Must be due to some kind of angular reflection appearing under some particular lighting conditions....
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Old February 12th, 2006, 12:51 PM   #6
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Sorry that I have been moving and I don't have internet access all the time to follow the posts. I received some reports about ghosting due to the gap between the 2 halves of the flip's housing. I have already taken care of this on recent orders. For flip owners, black electric tape works good. I have never seen the ghosting that R.P. Cuenco reported. Can you make sure that you clean your SLR lens and your camera lens? I try to get that ghosting affect to figure out but can't, thanks for helping me to build better adapter everyday. If everything is going OK, the new flip will be available next weekend, thanks.

Quyen
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Old February 13th, 2006, 12:26 AM   #7
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Thanks guys, i knew i wasnt crazy :-). yes, it is only under certain circumstances that this happens. also, ill try to get my hands on some more lenses to check if it isnt just this lens combination thats causing it.
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Old February 14th, 2006, 12:30 PM   #8
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I'm not seeing any ghosting with mine so far but I've been trying to get around seeing the GG - in any setting I've tested in (sunlight to lowlight) I've been able to see the glass grain pretty bad. I've got a 100a - the best I've been able to reduce the grain is by settings zoom:85 , focus:90. Its really noticable when panning or unmounted.

Quyen's going to get it back in a couple days to take a look at it and give it a cleaning. But does anyone have any advice that they've found to help? If I could solve that issue, I'd be getting some very nice shots...
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Old February 14th, 2006, 01:39 PM   #9
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Letus35A Flip - Grain issues

I tested my Letus35A Flip extensively under different lighting conditions and with a whole range of Canon optics.
Under certain specific but yet difficult to define lighting condition lighting condition my Letus show terrible grain under vibration (I should perhaps insert some foam between the letus body and the Cavision rod system support base... but I hate to SEE and FEEL my whole DVX100A shak and vibrate... not to think of the long-term eventuality of possible failures of the zoom and focus mechanism of the DVX objective).
So I have had (a difficult to solve) dust and dirt issue, and have now an intermittent grain issue, after having had a ghosting issue due to bad bonding between the two part of the flip housing. Should I fork out 92$ and get a Beattie Intenscreen or should I just resignate and apply for memebership in the "early adopters' club"? I still like the design of the Letus35 Flip.
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Old February 14th, 2006, 09:10 PM   #10
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"but I hate to SEE and FEEL my whole DVX100A shak and vibrate... not to think of the long-term eventuality of possible failures of the zoom and focus mechanism of the DVX objective"

I can barely tell that the Letus35A is vibrating on my camera. Can you really see your camera shaking when the Letus is turned on? This doesn't sound right.
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Old February 15th, 2006, 01:17 AM   #11
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FEEL or SEE...

SEE was an overstatement. No I can't "see" it, but definitely FEEL and HEAR it.

However: the sheer length of the camera optics and of the total adapter setup appears to influence the diffusion, amplification and frequency of the vibration . Long setups may under spcific condition amplify the vibration backwards.
Imagine a line starting from x being the vibration source, and going through a centre O and a line ending in y somewhere along the axis of the objective of, say, my DVX100. The vibration applied at point x with energy Ex at ground glass position acts upon a lever at centre 0. If the distance x0 is shorter than the distance Oy and the energy Ex is sufficient and the dampening mass at y is not sufficient, the setup will indeed "amplify" and propagate the vibration at a lower frequency. The transmitted vibration will be some combination of direct physical transmission of a mechanical force through the adapter tube and mount and some gyrational momentum (inertia) not counterbalanced any countermechanism.
Conclusion: the problem may affect long camera more than small and short camera.
Is there anybody out there with a MA in physics to correct and/or supplement this line of thinking?

http://www.vectorpark.com/levers.html

Last edited by Daniel Apollon; February 15th, 2006 at 08:13 AM.
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Old February 15th, 2006, 03:34 AM   #12
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i dont think so. in any case, a smaller camera would be more effected by the shaking than a larger camera due to the fact that a larger camera just has alot more mass, thus more resistance for the motor to start shaking i've found that having the setup entire setup (adapter, cam, rods) well secured, that the shaking is spread throughout the setup and eventually minimized. i wont lie, you can hear and feel it, but its alot worse when the adapter is just by itself.

also, ive been playing around with this problem and it seems that shooting f/4 or slower on the 50mm f/1.4 will cut enough light input to make the ghost disappear. is it possible that the adapter is transmitting too much light? but, wait, that the whole point isnt it? to transmit as much light as possible without seeing through to the other side?

i now think that the problem lies in the achromat facing toward the ground glass (in this fashion gg, pcx, mirrors, achromat: | ) mirrors )<that being the achromat). I'm thinking that just enough light is refracting on the curvature of the lens that its being projected back on to the gg. funny how it isnt just a 180 flipped image right back onto the gg. its really an upside down image.

btw, i hated physics in high school;-)
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