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lyd
Joined: 15 Sep 2007
Posts: 390
Location: Lake Mills, Wi
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| Posted: Sat Dec 01, 2007 8:52 pm Post subject: "Establish exact center of the tube face..." Yow! |
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I've been at this forever now. Kee-ripes! How do you measure accurate centers of something with all rounded corners and bowed sides? How do you measure something at all, when it is behind big mounting plates, preventing laying a rule across it, and when the surface you are measuring is behind thick glass, making it a perspective nightmare even if you could lay a rule across it?
You guys all make this sound so simple in your various tutorials and anecdotes, but man, it is giving me fits.
I finally resorted to getting a dry-erase marker and drawing corner-to-corner lines using a peice of paper slipped back there as a straight-edge, which has at least gotten me close to +/- 1/16" consistency on my center point across all three tubes, whether or not it is the actual center. Those rounded corners.
I am going to have to go with this for now, but I'd sure love to hear some better ways to go at it.
lyd
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Heywood Jablome
Joined: 12 Mar 2006
Posts: 1548
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| Posted: Sat Dec 01, 2007 9:12 pm Post subject: |
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I used a circle cutter and cut a cardboard circle with a hole in the center. Simple!
_________________
"Those countries which lag behind in industry, in the application of mechanics and technical chemistry, in the careful selection and utilization of natural products, where the respect for such activities does not permeate all classes of society, will unfailingly decline in prosperity. They will sink faster when neighbor states, with an energetic exchange between science and industry, go forward with renewed vitality."
-- Baron Alexander von Humboldt: 1769-1859
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lyd
Joined: 15 Sep 2007
Posts: 390
Location: Lake Mills, Wi
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| Posted: Sat Dec 01, 2007 9:33 pm Post subject: |
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Do you mean that you made the circle the same diameter as the cutout for the lens in the mounting plate, and then made your mark through the center hole in your circle?
lyd
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Zebu Fellenz
Joined: 21 Dec 2006
Posts: 2567
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| Posted: Sat Dec 01, 2007 9:35 pm Post subject: |
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Not the best way to do it but I maximize the image so it just fit's within all four sides and then I just move it so it is equal distance from all sides.
I seem to recall that someone used an overhead transparency with an X printed on it to center the image.
Erik
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Heywood Jablome
Joined: 12 Mar 2006
Posts: 1548
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| Posted: Sat Dec 01, 2007 9:40 pm Post subject: |
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| lyd wrote: | Do you mean that you made the circle the same diameter as the cutout for the lens in the mounting plate, and then made your mark through the center hole in your circle?
lyd |
I've got a circle cutter with a scale. I measured out the ID of the tube housing just at the tube face and then cut a cardboard circle to match. The circle cutter is like a compass in that it has a point int he center and swings a radius, so a perfect center mark was left.
Poke the center mark open to about 1/4" diameter, slip the cardboard in front of each tube (after having set all electronic adjustments to mid position) and center a cross-hair with the centering magnets.
_________________
"Those countries which lag behind in industry, in the application of mechanics and technical chemistry, in the careful selection and utilization of natural products, where the respect for such activities does not permeate all classes of society, will unfailingly decline in prosperity. They will sink faster when neighbor states, with an energetic exchange between science and industry, go forward with renewed vitality."
-- Baron Alexander von Humboldt: 1769-1859
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lyd
Joined: 15 Sep 2007
Posts: 390
Location: Lake Mills, Wi
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| Posted: Sat Dec 01, 2007 11:46 pm Post subject: Erk, more advice needed with raster centering. |
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| Zebu Fellenz wrote: | | Not the best way to do it but I maximize the image so it just fit's within all four sides and then I just move it so it is equal distance from all sides. |
This is what I wound up doing just now. When I centered the grids (this is an 8500) to my marks, the patterns all looked off to the left. I flipped with # to the pattern that is a solid screen and used that, looking at the edges. It was still difficult because the horizontal is a bit off (which I will be fixing shortly) and because of the deep pincushioning of each pattern. I don't know if that last goes away at some point, or if it was what compensates for the curve of the lenses...
But it gets worse still. Just now, in the middle of typing this, I thought, ok, I'll turn brightness way up and see the raster.... there is a whole grid-column worth of raster to the left of the pattern! What's up with that? So, if my goal here is to be centering the raster, the grid pattern is no good? This is contrary to the Bill Blue setup guide I've been following (of course, so is the solid screen/match the edges thing) and I think I must be missing or misunderstanding something. Can anyone advise?
lyd
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