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Old January 11th, 2006, 12:52 AM   #1
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Guskers35 and inverted rail system...thanks guys!

Well, after many hours in the shop, my "Guskers35" is pretty much done. It's a spinner with a DCX in front of the GG and achromat on the cam side. I cooked up a rail system to run the camera either inverted, or right side up to support everything nicely. I'll post up a clip or two once my wife starts talking to me again!

Props to Wayne Kinney and Dan Diaconu for some tips and ideas along the way. I spent way too much time reading through several years of posts here...but man, there's a treasure trove of ideas and experiments posted here.

Pic1
Pic2

Rail system mock up

I have some aluminum and stainless stock left over so if anyone's interested in a rail system, let me know.
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Old January 11th, 2006, 05:16 AM   #2
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Well done Dennis,

Is it a spinning blank CD or some other material for the GG?
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Old January 11th, 2006, 07:18 AM   #3
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I'm trying a variety of materials for GG. The only glass I can find is 2mm and the cutting is a bit off, so I didn't use it. In my explorations of optical properties of different materials I found that acrylic has as good transmittance as glass, sometimes better. We also found a manufacturer of "optical grade" acrylic willing to cut and drill them to a fairly tight tolerance. Right now I have 2mm in there, and a bunch of 1.5 and 1mm rigid blanks on their way. The company also does optical coatings, but I haven't tried these yet.

Surface prep is either wet sanded (with an air powered "jitterbug") and/or I'm also experimenting with fine grade media blasting. I need to fine tune my procedure here as distance, media type (I'm using very fine glass beads) rotational speed and air pressure play a fairly large role in the coarseness of the finish. The current version is excellent in higher light as it's fairly coarse. I'm seeing about 2 F/stops total loss with the F1.4 lens and adapter in place. I've focussed so far on getting the adapter built and the vignetting in 16:9 mode (the GS400 does the "real" thing) under control. This was achieved basically by moving the achromat back a bit further and extending the cam portion of the tube about an inch. I can zoom in well beyond the vignette now. The F1.4 50mm is a lot easier to deal with than my F3.9 28-130 zoom.

Image tuning is next.
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Old January 11th, 2006, 07:45 AM   #4
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Good show Dennis. Clean and FAST flip! Way to go.
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Old January 11th, 2006, 07:57 AM   #5
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Thanks Dan. The image flip was bit of a surprise. The image is recorded correctly, but the cam senses it's upside down, and rotates the 3.5" LCD image upright in normal operation. That means that with a 35mm adapter attached, the LCD image is always inverted..regardless of the cam's orientation. bummer. My external monitor works fine though in that the image is upright with the cam inverted.

I know, I know, you're shaking your head and mumbling to yourself "Grasshopper, you should have used an oscillating fresnel. Tisk, tisk"

That's for the next version....although I'm not holding my breath on getting the motion right. The spinner is actually pretty small, and very quiet, so if can live with 2 f/stops, I may just stop here.
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Old January 11th, 2006, 08:07 AM   #6
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Looks really good Dennis..

Q: how do you power it? can see an LED etc there but no power socket.

Any chance of some demo footage with the inverted cam.
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Old January 11th, 2006, 08:17 AM   #7
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Thanks Quinn.

There's two lithium AA's in the case. The CD motor is run at 3 volts, the 2V LED is wired in with a 12K resisitor. That's it.

I'll be doing the image testing this week so I'll post up some footage shortly. So far, the image looks very good, but I need to do some carefull checking for distortion and/or chromatic aberration. I need to spend some time with a grid and EIA1956.
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Old January 11th, 2006, 11:47 AM   #8
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Looks great Dennis, nice and slick. Could be commerical!
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Old January 11th, 2006, 11:42 PM   #9
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Here's the first footage...a quick clip playing with focus: http://z10.zupload.com/download.php?...&filepath=5095
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Old January 12th, 2006, 12:30 AM   #10
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Do you have the rods 60 apart and the lens 85 to center?
The image is good! What's the frame size and what lens did you use?
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Old January 12th, 2006, 01:06 AM   #11
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Rods are 60 to center, but I didn't sweat the 85 to center with the cam inverted...should I be? Lens was a 50mm F1.4 at 1.4, the GS400 in wide mode interlaced at F4. This was a new GG that I "blasted" tonight. What frame size are you referring to?
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Old January 12th, 2006, 01:17 AM   #12
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Quote:
Originally Posted by Dennis Wood
but I didn't sweat the 85 to center with the cam inverted...should I be?
Only if you plan to use a MB (camera inverted or no).
Frame size on the GG? (18/24, 24/36mm? The GG looks OK. Post a frame (full rez) from the footage and get an even lit BG. A rez chart if you have.
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Old January 12th, 2006, 01:45 AM   #13
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Quote:
Originally Posted by Dennis Wood
the cam senses it's upside down, and rotates the 3.5" LCD image upright in normal operation.
I tried turning my GS400 upside down as well a while ago with my adapter on it... The cam doesn't sense that it's upside down and flip the image back, it doesn't know which way is up! The problem is when you turn the cam upside down you also turn your monitor (i.e. the LCD) upside down as well, so the image is still upside down when you look at it.
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Old January 12th, 2006, 02:48 AM   #14
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frame grab here: http://z16.zupload.com/download.php?...&filepath=5473

Dan, I'm assuming the frame size is 24x36 as this is a standard 35mm lense. To be honest, I'm not sure what exactly it is as I just zoom in past the vignetting. I don't have a proper EIA1956, just a vectored laser print...but I'll post a grab anyway.

What's "an even lit BG"??
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Old January 12th, 2006, 05:51 AM   #15
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Dennis,
The links dont work for me, would love to see your footage....
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